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RAD7 User`s Manual

1. Line 1 is the run number Line 2 shows the date and time of the first reading Line 3 1s the serial number of the instrument Line 4 is the number of completed cycles in the run Line 5 is the arithmetic mean or average of the radon concentrations recorded Line 6 is the standard deviation of the readings taken during the run Lines 7 and 8 are the highest and lowest radon concentrations Following Line 8 is a bar graph of radon concentration through time Time of day is printed along the left hand edge of the graph If there is only one cycle of data the bar graph will not print This printout procedure has been programmed into several protocols When you choose one of the pre programmed protocols this report is 23 printed out automatically at the end of the run together with a cumulative spectrum 2 3 5 Data Free To determine the amount of free memory available for storing new radon readings select gt Data Free and push ENTER For about two seconds the display will look something like this 910 cycles free The RAD can store up to 999 cycles of data As the memory fills with data the Data Free indicator decreases If the Data Free indicator reaches 000 any subsequent attempt to store data to memory will result in a memory full error Keep your eye on this indicator to avoid embarrassment When the amount of free memory gets uncomfortably low 1 e 200 or less consider deleting un needed
2. You will sometimes encounter thoron in indoor air particularly near radon entry points and more often in soil gas Radon 222 or familiar radon is part of the uranium 238 decay chain You will almost always be able to detect radon 222 in indoor air outdoor air and soil gas The radon isotope is the first element in each of the decay chains that is not a metal It is in fact an inert or noble gas So it can escape any chemical compound its parent radium was in and diffuse into the air To focus on these inert gases the thoron and radon decay chains shown below are those parts of the thorium 232 and uranium 238 decay chains that include just these radioactive gases and their short lived progeny It may be noted that only alpha decays change the atomic weight and then only in steps of four Thus the atomic weights of all the members of the radon 220 thoron decay chain are divisible by four while none of the radon 222 are Chapter 3 Basics of RAD7 Technology RADON DECAY SEQUENCE pem 04 5 49 MeV Polonium 210 Polonium 214 138 days 164 usecs Polonium 218 3 05 min Bismuth 210 Bismuth 214 5 01 days a 19 8 min 04 6 00 MeV 5 31 MeV B 7 69 MeV B Lead 206 Lead 210 Lead 214 stable 22 3 yr 26 8 min THORON DECAY SEQUENCE Radon 220 55 6 sec 04 5 29 MeV Polonium 212 0 3 usec Polonium 216 0 15 sec Bismuth 212 60 6 min 04 6 78 MeV 4 36 8 78 MeV
3. 0 45 C Humidity 0 100 non condensing Cycle Range User controllable number of cycles from 1 to 99 to unlimited per run User controllable cycle time from 2 minutes to 24 hours CAPTURE Software Compatible with Microsoft Windows XP and 7 and Mac OS X Automatic RAD7 location connection and data download Graphs radon thoron temperature and humidity over time Automatic humidity correction Statistical analysis tools track concentration averages and uncertainties Chart Recorder mode provides real time RAD7 status monitoring Control RAD7 operations from computer via direct or remote connection Automatic calculation and display of radon in water for RAD AQUA Automatic combination of multiple RAD7 data Table A2 3 Physical Specifications Dimensions 11 5 x 8 5 x 11 29 5 cm x 21 5 cm x 27 9 cm Weight 9 6 pounds 4 35 kg LCD Display Output Case Material 2 line x 16 character alpha numeric display High density polyethylene Infrared Printer Omniprint OM1000 Wireless Infrared Printer included Power Supply 11 15V DC 12V nominal 1 254 center pin positive or included internal EnerSys sealed lead acid rechargeable battery pack 6V nominal 30Wh 5Ah Battery Longevity 24 hours in SNIFF mode 72 hours in Monitor mode 89
4. ACCOSSOPY rea e eaae etse ce et a 62 The RAD H20 Accessory 62 The RAD AQUA Accessory 62 The RAD AQUA Accessory eese eene treten tete eren eret 63 The WATER PROBE ACCESSO Vaiia eerte ene trennen netten nne 63 USING RAD7 ACCESSORIES eere eese eene eene eeneesssesssee ss 2 5 3 Soi Gas Sampling uic dta cU a T Edu d 63 5 3 1 Application i c e e em ede ae 63 5 3 2 The Soil Gas Probe Accessory coocononcnncnnonioncnnnannnnnnnnann cn anna arrancan aran 63 5 3 3 Soil Gas Probe Preparation esee eere nennen 63 5 3 4 RunningtheTesti ii Rae e A e ogee teca AA 64 5 3 5 Interpreting the Data oe teneas 64 5 4 Emission Measure MS tp Y e ORARE EU essen cus RR ae edel 64 5 4 1 Zpplication AS dad e ee RE As Bese dia eal 64 5 4 2 Open Loop Configuration esee eene nr 64 5 4 3 Closed Loop Configuration ie e eee a err eet 64 5 4 4 Very Low Emission Rates esses eese eret etn eene rn naar SEED 65 5 4 5 Bull Emissions ci 65 5 4 6 Yee PO MR 65 The Bulk Emission Chamber 65 The Surface Emission Chamber 66 5 5 Supportino ACCESSONIES coorta it epe o et ater ostii ate desde 66 5 5 1 rau ER 66 5 5 2 Ihe Range Extenders se t tate eb e ete Reto hu 66 The Range Extender 66 5 5 3 Ihe DRYSTIKS e one tene ence nter dettes tee he PEERS 67 The DRYSTIK Model ADS 3R 67 6 PC Connectivity er on 6 1 PE Coniectvity Basics ii 68 6 1 1 Connecting the RAD7 to the Computer esses eene eene 68 Con
5. Also for portability you may remove the external power from the RAD7 and run the RAD7 on its batteries If you have not already done so set the clock as described above RAD7 SNIFF Configuration Sample In Small Drying Tube Exhaust Inlet Filter DURRIDGE RAD7 Radon Monitor a Attach the filter to the tubing push it into the end with the Y ID segment b Carefully remove both plastic caps from the small drying tube you will need them later to reseal the unit Attach the 5 16 ID end of the tubing to one end of the tube c Attach the filter to the Inlet port of the RAD7 Make sure it is firmly fit onto the inlet The air sampling system is now set up for the measurement While testing you can use the small drying tube as a wand to collect your air sample from the location of interest d Plug in the RAD7 and switch on e Push MENU ENTER then push gt four times You should see on the LCD display Test Purge f Push ENTER The pump should start g Set up the printer h Place printer between green lines on the face plate See photo Chapter 1 3 i After purging for a few minutes push MENU and gt two times you will see gt Setup on the display j Push ENTER twice then push either arrow key repeatedly until you see Protocol Thoron on the display Push ENTER See Chapter 2 4 5 for difference between Thoron and Sniff protocols k With Setup on
6. If the printer format has been set to Short the following printout will be made for each cycle of the run 0501 2 69 2 83 p Sniff FRI 21 MAY 99 19 41 26 8 EC RH 7 B 7 06V Line 1 is the run cycle number the radon concentration the two sigma uncertainty the units indicator p picoCuries per liter B Becquerels per cubic meter and the mode indicator Line 2 is the date and time that the cycle was completed and stored to memory Line 3 is the temperature in either C Celsius or F Fahrenheit relative humidity internal and battery voltage at the time the cycle ended 22 If the printer format has been set to Medium or Long then you will see a printout like this for each cycle 0501 2 69 2 83 p Sniff FRI 21 MAY 99 19 41 26 8 EC RH 7 B 7 06V Total Counts 42 Livetime 27 8min A 0 53 0 08 cpm 47 3 B 0 02 0 02 cpm 1 7 C 0 52 0 08 cpm 46 4 D 0 01 0 02 cpm 0 9 0 0 04 0 03 cpm 3 6 Lines 1 2 and 3 are the same as in Short format as outlined above Line 4 is the total number of counts detected during the cycle Line 5 is the livetime the time that the detector was actively collecting data Lines 6 through 10 are the windows data for windows A B C D and O O is the consolidated window for others or counts that are not included in windows A through D Each line of windows data contains the window letter A B C etc followed by the window s counts per minute cpm two sigma stat
7. Save completes the current run so any subsequent test data will be stored as a new run The display momentarily shows the run and cycle number in the form of 0101 Saved This command may be accessed whether the status is Live or Idle It always leaves the status Idle You will find this command especially useful when you wish to move the instrument to another location without waiting for the countdown to reach zero but without losing that last incomplete cycle The calculated radon concentration from the incomplete cycle is still good 2 2 4 Test Clear The gt Test Clear command causes counting to be suspended and the current run to be completed without saving the last suspended incomplete cycle Subsequent test data will be stored as a new run You must answer Yes to the question Are you sure in order to activate this command This command may be accessed whether the status is Live or Idle It always leaves the status Idle 2 2 5 Test Purge The gt Test Purge command suspends counting and begins purging the detector The pump begins running and the high voltage circuit turns off in order to clear the sample chamber of radon gas and daughters as quickly as possible You must provide clean desiccated radon free air to the inlet in order to push out any radon that was previously sampled Outdoor air is usually adequate for this purpose As always use the inlet filter and drying tube Ten minutes is usually sufficient for bri
8. increases the uncertainty in the thoron reading CAPTURE calculates a meaningful thoron threshold taking into account the statistical uncertainty in the spill and will display this threshold on the graph if so instructed e Forced Sniff mode For long term measurements the RAD7 is normally put in Auto mode in which the measurement starts in Sniff mode so as to achieve a fast initial response before automatically switching to Normal mode after three hours when the 214 Po decays have nearly reached equilibrium with the radon concentration This assumes that the radon concentration is steady If it appears that rapid changes in radon concentration were taking place the user can in CAPTURE force the graph to display the data as if the RAD7 stayed in Sniff mode throughout the measurement and thus see the rapid changes with a measurement time constant of just 12 minutes 3 7 RAD7 Spectrum The RAD7 spectrum is a scale of alpha energies from 0 to 10 MeV Of particular interest are the radon and thoron daughters that produce alpha particles in the range of 6 to 9 MeV When the radon and thoron daughters deposited on the surface of the detector decay they emit alpha particles of characteristic energy directly into the solid state detector The detector produces an electrical signal Electronic circuits amplify and condition the signal then convert it to digital form The RAD7 s microprocessor picks up the signal and sto
9. spot reading of radon concentration as a simpler substitute for grab Chapter 4 Using the RAD7 sampling and the other is to locate radon entry points For each application the method will be slightly different 4 3 2 Locating Radon Entry Points There is a very good chance that thoron will be present in the soil gas entering the building It will however be detectable only close to the entry points Thoron therefore if it is in the soil gas can be considered as a tracer for fresh radon gas Sniffing to locate radon entry points may therefore be focused on detecting thoron if it is there to speed and simplify the process The same procedure will also give radon concentrations provided that the sampling point is kept at one spot for at least 15 minutes 4 3 3 Preparation Detailed instructions are given in Chapter 1 5 Choose Thoron in the Setup Protocol menu and set the Tone to Geiger Employ a small drying tube and preferably just a yard of tubing to the inlet filter 4 3 4 Purging While it is always good practice to purge the instrument before using it there is less necessity before sniffing In SNIFF protocol the pump runs continuously so the air sample will be flushed through every minute or two and the measurement chamber will quickly dry out even if the relative humidity starts above 1096 To bring the humidity in the instrument down without wasting desiccant the RAD7 outlet may be connected to the
10. 2 4 1 Preset protocols Cycle Recycle Mode Thoron Pump Sniff 00 05 0 Sniff Off Auto 1 day 00 30 48 Auto Off Auto 2 day 01 00 48 Auto Off Auto Weeks 02 00 0 Auto Off Auto User Xxx XXX XXX XXX XXX Grab 00 05 4 Sniff Off Grab Wat 40 00 05 4 Wat 40 Off Grab Wat250 00 05 4 Wat250 Off Grab Thoron 00 05 0 Sniff On Auto A Recycle number of 00 indicates indefinite test length The test ends only if the operator intervenes or if the RAD7 memory fills 2 4 Setup Cycle How long a test do you want and how often do you want the RAD7 to take a reading a cycle A typical radon test is made up of many cycles Select Setup Cycle to adjust the Cycle time or integration time for a single radon reading The Cycle time can be adjusted anywhere from two minutes to 24 hours For continuous monitoring the Cycle time is usually 30 minutes orlonger For radon sniffing the Cycle time is usually 5 or 10 minutes For thoron sniffing the cycle time may be as little as 3 minutes Upon selection of Setup Cycle push ENTER and you will see something like this Chapter 2 Basics of RAD7 Operation Cycle 00 30 First select the number of hours 00 to 23 and press ENTER Then select the number of minutes 00 to 59 and press ENTER Remember that a run includes many cycles in sequence and the total duration of the radon test is determined by the Cyc
11. 33 Contin d s MON OLS e eet esr nea 33 34 35 3 6 3 6 1 3 7 3 8 3 9 3 10 3 11 3 11 1 3 11 2 3 11 4 3 11 5 3 11 6 3 11 7 3 12 1 3 12 2 3 12 3 3 13 3 13 1 3 13 2 3 13 3 3 13 4 4 4 1 4 2 4 2 1 4 2 2 4 2 3 4 2 4 4 2 5 4 2 6 4 2 7 4 2 8 4 2 9 4 2 10 MS Ae Rc E A AE M A Mut 34 Working evel sace dece td or A ED ett ba e QR 34 RAD Solid State Detecta 35 RAD7 Calibration and Data Correction esses eee 35 RADES eere ace ecce pond hanes aciem au a etes NS 36 WII Gunter naten usc cn Coda ended tetera gee ein 37 Isotope EquilibETUT oso eo ente e ae Monte e herus n ene Ox is 38 Modes Snitf and Att iiio eo p IURE UHR cel tes tbt ep e cosi tei uud 39 Jl A A eR EDU EA LUE 39 Short lived Radon and Thoron Daughters eene 39 Adsorbed Radon Gas z i oa one ee tuu te Ue tete 40 Long lived Radon Daughters eese ener eene rere rentrer nenne 40 Contamination by Radon or Thoron Producing Solids see 40 Other Alphd Emilteks ee A e 40 Beta and Gamma Emile uta it 41 AAN tase ica es che RE RR S Ie TO RUP SO RE Ep DEPO IRE 41 DIY OP CF ALI ON sess Lee EE NU aot ede e E RR e eto eee enano dtp oue Reip EAR TERR 41 Table 3 12 Typical RAD7 precision based on counting statistics only 41 Humidity COFFeCllon ete reete ia 42 Concentration Uncertainties eese eee nana nino 42 Specir m Examplesoc esee ei o etre f ERU Ea ER eie Ei
12. 6 2 1 CAPTURE Installation The latest version of the CAPTURE software may be downloaded from the DURRIDGE website www durridge com capture Download the appropriate version of the software for Windows or Mac OS X In Windows an installer program will install the necessary components and place shortcuts in the Start Menu and on the desktop if desired To install CAPTURE for the Macintosh open the downloaded dmg disk image file and drag the CAPTURE application into the Applications folder or to the location of your choice Next connect the RAD7 to the computer using the provided adaptor cable as described in Section 6 1 CAPTURE a es File Edit View Window Help o j i i Open Data File RAD 0014 RAD 3076 RAD Group 1 Add RAD Options Stop RAD7 Test Test Data Setup Refresh Status Chart Configuration i Next reading Run 17 Cycle 68 17 51 Oh 3m 44s Previous Reading Run 17 Cycle 67 Air Temperature 24 3 C Pump Current 40 mA RAD7 Date 1 30 13 Accumulated counts 1 A 1 B 0 GO D 0 O 0 Radon Conc 15 7264 pCi L Relative Humidity 295 Battery Voltage 6 9 V RAD Time 17 46 35 Logging Settings Boo Download RAD Data Open As Graph e Conc Unit Automatic V e 7 Temp Unit Automatic m j Point Style Normal Sa A pas Chart Recorder Eine Weight Z Show Grid Lines Show Cha
13. 8 78 MeV peak of Po 212 which predicts the amount of thoron progeny activity in the A window due to the 6 05 and 6 09 MeV peaks of Bi 212 Note that the uncertainty figures given with each reading include the effect of these corrections 4 5 4 Avoiding Longer Lived Decay Products Although the RAD7 now corrects for the buildup of the long lived thoron progeny 10 6 hour we recommend that you avoid unnecessary exposure of the instrument to high levels of thoron for long periods of time The presence of these long lived progeny can make low level radon measurements somewhat less accurate than would otherwise be possible But if you err the 10 6 hour half life of Chapter 4 Using the RAD7 the thoron progeny makes for a temporary inconvenience ofa few days at worst 4 5 5 Decay Correction Flow Rate and Thoron Calibration As discussed above thoron s rapid decay causes the intake path and the air flow rate to become important factors in calibration The RAD7 factory calibration for thoron is based on a standard RAD7 inlet filter a standard 3 foot long 3 16 inch inner diameter vinyl hose and a standard small 6 inch drying tube Deviation from this arrangement can change your thoron results For example if you were to use a very long hose for thoron sampling then the sample might decay significantly before it ever reached the instrument inlet The same thing might happen if you substituted the small drying tube with the larg
14. A1 4 Infrared Printer Specifications 87 Appendix 2 RAD7 Specifications Appendix 2 RAD7 Specifications Specifications for the RAD7 exceed those of all radon gas monitors made in North America as well as those in its price range world wide This is a partial list of specifications that make the RAD7 so highly regarded in the field Table A2 1 Functional Specifications Modes of Operation SNIFF Rapid response and rapid recovery radon measurement THORON Radon and thoron measured simultaneously and independently NORMAL High sensitivity AUTO Automatic switch from SNIFF to NORMAL after three hours run GRAB Analysis of grab samples WAT Automatic analysis of water samples with RAD H2O accessory Measurements Radon in air with Sniff protocol for quick spot reading Thoron protocol for searching for radon entry points Radon in air 1 day 2 day or weeks protocol for long term measurement Radon in water batch samples with RAD H20 and Big Bottle RAD H20 Continuous radon in water with RAD AQUA and Radon in Water Probe Radon in soil gas with Soil Gas Probe and Active DRYSTIK Radon emission from soil and hard surfaces with surface emission chamber Bulk radon emission from bulk materials and objects Data Storage 1 000 records each with 23 fields of data Log of printer output also stored Sample Pumping Built in pump draws sample from chosen sampling point Flow rate typically 800mL min Print Output Short
15. Lead 208 stable Lead 212 10 6 hrs Thallium 208 3 min Radon and Thoron decay chains 32 Chapter 3 Basics of RAD7 Technology 3 2 1 Radon 222 Radon Every nucleus of radon 222 eventually decays through the sequence polonium 218 lead 214 bismuth 214 polonium 214 and lead 210 With each transformation along this path the nucleus emits characteristic radiations alpha particles beta particles or gamma rays or combinations of these The RAD7 was designed to detect alpha particles only so we will emphasize alpha radiation Radon 222 is an inert gaseous alpha emitter that does not stick to or react with any materials It has a half life of 3 82 days A particular radon nucleus may decay at any time but it is most likely to decay between now and 8 days two half lives from now When the radon nucleus decays it releases an alpha particle with 5 49 MeV of energy and the nucleus transforms to polonium 218 The polonium nucleus can never go back to radon again Polonium atoms are metals and tend to stick to surfaces they come in contact with e g a dust particle in the air or a wall or the inside of your lung Polonium 218 nuclei have a short half life only 3 05 minutes which means that most of them will decay within 6 minutes of their formation The average polonium 218 nucleus lives for only 4 40 minutes before it decays 1 443 times the half life gives the mean life Like radon polonium 218 emits an alpha part
16. MSDS sheet issued by the battery manufacturer is enclosed with the manual in the RAD documentation A copy of that should be carried and presented when requested when traveling with a RAD7 by air RS 232 Serial Port Air Outlet DC Power Input 2 1 mm x 5 5 mm Air Inlet Switch Key pad The RAD7 Professional Electronic Radon Detector Chapter 1 Getting Started 1 4 Starting a Two day Test You will need the RAD7 and power cord the Laboratory Drying Unit the large tube of desiccant with a screw cap at one end an inlet filter one of the six small filters supplied the piece of tubing with a 5 16 ID segment at one end and a amp ID segment at the other and the printer On first starting up you may need to set the clock for your time zone See Setup Clock Chapter 2 4 11 Switch on the RAD7 push MENU then push gt twice You will see Setup on the display Push ENTER then push gt ten times You will see Setup Clock Push ENTER Use the arrow keys to adjust hours minutes seconds day month and year pushing ENTER to confirm each setting Now we are ready to continue RAD7 Normal Configuration lt Sample In Laboratory Drying Unit Exhaust DURRIDGE RAD7 Radon Monitor 14 a Attach the filter to the tubing push it into the end with the insert b Carefully remove both plastic caps from the Drying Unit you will need them later to reseal the unit Attach the
17. Mode should then be set to Sniff not Auto Note however that counting only Window A and for such short periods the number of counts per cycle will be less than for longer cycles in NORMAL mode and so the individual readings will have more scatter Note also that short cycle times will fill up the memory more quickly the capacity is 1 000 cycles use up the desiccant more quickly and if the printer is being used produce more printout 4 2 5 To Print Or Not To Print It is not necessary to run the printer during a measurement as all data except for the detailed spectra are stored at the end of every cycle and Chapter 4 Using the RAD7 are available for printing or downloading to a PC at any time Furthermore with no printer and the key pad locked it is impossible for any unauthorized snooper to read the radon concentration during the run On the other hand use of the printer gives a convenient and informative hard copy of the results For routine continuous monitoring it is usual to set the printer format to short Setup Format Short ENTER Place the printer on the face plate and switch on Switch the RAD7 off then on again Information about the RAD7 and the setup will print out Data will be printed at the end of every cycle and a summary bar chart and cumulative spectrum will print at the end of the run 4 2 6 Running the Test When everything is ready start the test Test Start ENTER The pump w
18. RAD7 achieves rapid response to changing radon levels by focusing on the 3 minute polonium 218 alpha peak calculating the radon concentration on the basis of this peak alone In NORMAL mode the RAD7 achieves higher statistical precision by counting both polonium 218 and polonium 214 alpha peaks AUTO mode automatically switches from SNIFF mode to NORMAL mode after three hours of continuous measurement This allows time for the equilibrium of the longer lived radon daughter isotopes The earliest part of the run will have the benefit of the SNIFF mode s quick response while the latter parts of the run will benefit from the NORMAL mode s superior statistical precision We recommend that the AUTO mode be used for all screening tests and any tests to measure the average concentration over a period of time With the AUTO mode there is no need to throw away the first three hours of data or to calculate adjustments to correct for disequilibrium The mean concentration reported in the run summary should accurately reflect the actual mean SNIFF mode should be used where the goal is to follow and measure rapid changes in the radon concentration Wat 40 and Wat250 make calculations of the radon concentration in 40 mL and 250 mL water samples respectively They require the RAD H20 water accessory kit to aerate the water under the controlled conditions necessary for these calculations 2 4 5 Setup Thoron Select Setup Thoron Push ENT
19. Test Start and Test Stop To start testing or counting after you have chosen the required setup go to Test Start by pressing MENU ENTER 2 and then ENTER The display will indicate that counting has begun Start counting One second later the Status display will appear with the countdown timer in motion 0501 00 29 37 Sniff 00001 Live When the countdown reaches zero the RAD7 will automatically calculate the radon concentration store or save the counts to memory and clear the counters to begin a new cycle To interrupt the measurement go to gt Test Stop by pressing MENU ENTER gt ENTER The display will respond Stop counting After one second the display will go back to the top of the menu gt Test You may wish to examine the Status display to verify that the status 1s Idle To resume testing from exactly the same point in the cycle where you stopped select Test Start as described above Note that Stop does not terminate the run it is a pause If you do not wish to resume testing from the same point you should select either gt Test Save or gt Test Clear before continuing This will terminate the suspended test store 1t to memory Save or wipe it out Clear and clear the counters to begin a new run 20 2 2 3 Test Save The gt Test Save command suspends counting and saves the suspended test test in progress to memory as if it had reached completion Test
20. The RAD AQUA Accessory The RAD AQUA accessory handles the continuous monitoring of radon in water offering accurate results in as little as half an hour Applications for the RAD AQUA include testing water from running faucets and water being pumped from the bottom of a lake In addition to its rapid response time the RAD AQUA offers a high degree of sensitivity The RAD AQUA functions by bringing air into equilibrium with water passing through an exchanger in a closed loop During this process the RAD7 is set to operate in continuous mode as described in Chapter 4 2 Since the equilibrium ratio of radon in air to radon in water is affected by temperature a temperature probe is used to collect water temperature data and DURRIDGE CAPTURE software for Windows and Mac OS X later accesses the RAD7 data and the water temperature data and calculates the final radon in water readings Users are encouraged to refer to the RAD AQUA manual for further details 5 2 3 The WATER PROBE Accessory The Water Probe is used to collect radon samples from large bodies of water The probe consists of a semi permeable membrane tube mounted on an open wire frame The tube is placed in a closed loop with the RAD7 When the probe is lowered into water radon passes through the membrane until the radon concentration of the air in the loop is in equilibrium with that of the water As with the RAD AQUA the RAD7 data and water temperature data are co
21. and sudden decreases in level Unique to the RAD7 is the ability to sniff for thoron Polonium 216 has a 150 ms half life so the instrument response is virtually instantaneous The only delay is the time required to put the air sample into the measurement chamber which is about 45 seconds Another factor when sniffing is the vulnerability of other instruments to lead 210 buildup Only with the RAD7 can you continue to sample high levels without having to worry about increasing the background 3 5 Working Level Radon concentrations are determined by measuring the radioactivity of the radon or by measuring the radioactivity of the radon decay products Instruments that measure radon decay products in the air are called working level monitors Working level monitors sample air through a fine filter and then analyze the filter for radioactivity The radon progeny are metal and they stick to the filter and are counted by a working level instrument Radon 222 an inert gas passes through the filter so it is not counted Chapter 3 Basics of RAD7 Technology in such an instrument Therefore a working level instrument measures the radon progeny concentration polonium 218 etc in the air but not the radon gas concentration The RAD7 on the other hand measures radon gas concentration Radon daughters do not have any effect on the measurement The RAD7 pulls samples of air through a fine inlet filter which excludes the pro
22. buy this type of filter in almost any auto parts store for around 3 7 1 6 Batteries Your RAD7 has enough battery capacity to go for two to three days without any external power source Electronic circuits control the charging and discharging of the battery avoiding overcharge or destructive discharge If you maintain the batteries according to the following directions you can expect to get two to five years of heavy service from them Keep the batteries fully charged as much as possible Try to recharge promptly after use The RAD batteries charge whenever the unit has DC power With the power cord plugged in and the RAD7 measuring radon the batteries will charge slowly Full recharge takes about 48 hours With the power cord plugged in and the RAD7 in fast charge mode not measuring radon the batteries will charge more quickly Full recharge takes about 24 hours The battery voltage indicator on the display go to Status Window 1 will reach 7 10 to 7 20V when the batteries are Chapter 7 Maintenance fully charged and the power cord is still plugged in If the batteries are deeply discharged to the threshold of battery damage an electronic circuit will completely disconnect them to avoid further discharge The circuit will then not allow battery operation until they are completely recharged If this occurs you may still be able to operate the RAD7 from DC power until the batteries recharge Expect the recharge to ta
23. concern with growth and decay delays The RAD7 responds virtually instantly to the presence of thoron its time constant for response to thoron is less than 1 minute The chief limit on the thoron response speed is the pump s ability to fill the internal cell And the RAD7 clears just as rapidly when you purge the instrument with thoron free air In fact you need not purge the instrument at all as thoron s short half life ensures that it will be gone in a few minutes In thoron measurement the sample pump must run in a continuous fashion at a steady consistent flow rate If the flow rate of the sampling pump changes then the RAD7 thoron result will also change Flow rate affects the amount of thoron in the internal cell since a significant fraction of the thoron decays in the sample intake system as well as within the instrument For the most accurate thoron measurements we recommend that you use a consistent sample intake system always use the same hose and filter arrangement and pay special attention to air flow rate Be sure the filters hoses and RAD7 inlet and outlet ports remain free from obstruction Use a flow meter rotameter or floating ball type to check that the flow remains consistent Note that the flow rate affects the thoron reading but not radon due to its much longer half life The RAD7 measures thoron concentration in the air at the point of sample intake Since thoron varies from place to place depending on th
24. eeeeee eee en ee ense eese 32 Al l A1 1 1 A1 1 2 41 1 3 41 1 4 41 1 5 41 1 6 Al 2 A1 2 1 A1 2 2 A1 2 3 A1 2 4 A1 3 A1 3 1 A1 3 2 41 3 3 41 3 4 Al 4 Infrared Printer Desertptlofbosc Toda dae e eiae General ii s e epe e e IMG 82 DOT OS EE EU 82 Rower Switcher e e E A toa es A ett es 82 INCA LEDS oe ect mette E A E es 82 NIIA Bullohs a titt tat era O E A ERR NRI 82 SENSORS iaunaren ar e a a A di 82 Infrared Printer Component Locations and Functions 83 Infrared Printer Operation coe eet etos e tee aoe Precautions ees eet oerte ev niece eo Hebe Ieri ertet dee rebates ees 4 GUE LOSE EM 84 Sep ModE tet aa ii 84 Table A1 2 3 Sel and Feed Functions 84 Using the Printer itt IA oie Das adel e A cid 85 Using the Infrared Printer 85 Infrared Printer Maintenance i Battery Installation A be t b o t ge Hes ette dtl 85 Paper Installation A a a nee 85 Cleaning the Printer eie A A A ege 86 Cleaning th Print Head s OE He coat e 86 Infrared Printer Special en e ed eran tesis Table A1 4 Infrared Printer Specifications 87 Appendix 2 RAD7 Specifications eeeeeee eee e eee een neenon aseo sse sos el OD Table A2 1 Functional Specifications 88 Table A2 2 Technical Specifications 88 Table A2 3 Physical Specifications 89 INTRODUCTION The RAD is a highly versatile instrument that can form the basis of a comprehensive radon measurement system It may be used in many different modes for different purp
25. have all the items or call us at 978 667 9556 shown in the diagram below or on the packing list RAD7 Packing List RAD7 and Case Accessories RAD7 electronic radon detector 12V adaptor w 4 plugs 12V cord for custom applications RAD7 Carrying Strap Keys for RAD7 case RAD7 Printer Supplies Wireless infrared printer Battery Charger 4 Rechargeable AA batteries 6 Rolls printer paper Drying Tubes and Desiccant Gas drying unit Opener tool for drying unit 5 lbs desiccant 4 drying tubes RAD7 Filters 5 RAD7 inlet filters 1 Dust filter Continued on next page 11 Chapter 1 Getting Started RAD7 Packing List Continued Vinyl Tubing Set 3ft x 3 From sample to drying tube From drying tube to RAD7 inlet From RAD7 outlet to exhaust USB Serial Supplies Null modem cable USB Cable USB to serial adaptor RAD7 Documentation Binder RAD7 User s Manual Infrared Printer Manual Additional documentation DURRIDGE Software USB Stick 1 2 General Safety Instructions For your own safety and the proper operation of RADT7 DO NOT spill liquids onto the machine DO NOT expose operating panel of machine to rain or any other excess moisture DO NOT allow liquid to be sucked into inlet tube If you intend to use the instrument in a harsh environment give it some protection Even just a transparent plastic bag enclosing the RAD7 bu
26. highest serial speed settings the RAD7 may not be able to keep up with incoming character strings unless the characters are paced An echo wait strategy will avoid this problem Also note that the RAD7 recognizes XOFF XON flow control protocol when sending data 2 5 5 Special Status Gives a snapshot of the RAD7 status page including run and cycle numbers countdown timer last reading temperature humidity and so on This is basically the same information that you can get with Test Status but it gives the data in one shot and does not continue to update every second 2 5 6 Special Start Same as Test Start see Chapter 2 2 2 Test Start but does not go into a continuously updating status display 2 5 7 Special Stop Same as Test Stop see Chapter 2 2 2 Test Stop Chapter 2 Basics of RAD7 Operation 2 5 8 Special Comspec Output the current test data including the counts in all 200 alpha energy bins These counts can be imported into a spreadsheet program and displayed as a graph of the energy spectrum 2 5 9 Special ComAIl Version 0244 940221 or later Output complete set of RAD7 test data up to 1000 readings to the serial port in comma delimited format 2 5 10 Special SPrAII Output complete set of RAD7 test data up to 1000 readings to the serial port in standard readable 24 column printer format without affecting the infrared printer 2 5 11 Special S Load Used to load special software into th
27. hold the data for 1 000 cycles in up to 100 runs Many commands in the Data group require you to enter a two digit run number after the command The default run number the one automatically set if you do nothing is the run number of the last complete cycle of data stored The arrow keys allow you to select any other run number 2 3 1 Data Read Select Data Read followed by a two digit run number to examine radon readings from that particular run For example select Data Read 01 to examine readings from run number 01 the first test in memory Chapter 2 Basics of RAD7 Operation You will see something like this 0101 23 3 1 54 p 11 45 19 MAY 99 Line 1 is the run cycle number followed by the radon concentration two sigma uncertainty and unit indicator This example shows Run 01 Cycle 01 23 3 1 54 pCi L Line 2 is the time 24 hour military time and date the reading was completed Press gt to advance to the next reading in memory press the backward arrow to go back to the previous reading To quit examining data press ENTER or MENU Note that large numbers are presented in shorthand notation The symbol K stands for 1 000 and M stands for 1 000 000 For example 33K2 stands for 33 200 2 3 2 Data Print To print out a run of data from memory select gt Data Print followed by the two digit run number For example to print the data from run number 05 select gt Data Print 05
28. in the second and temperature humidity and battery voltage in the third Medium format adds Total Counts 357 Livetime 28 2 min A 5 74 0 98 cpm 45 4 B 0 32 0 29 cpm 2 5 C 6 13 1 01 cpm 48 5 D 0 00 0 14 cpm 0 0 0 0 46 0 34 cpm 3 7 Counts scale auto ranging Peak in window A at 6 00 MeV New radon Where the lifetime is the actual time spent waiting for an event slightly less than the elapsed time The windows A B C D and all the rest O correspond to the different alpha energies in the spectrum Long format adds to the short and medium formats a printed spectrum of the alpha energies as shown below At the end of a run the printer will print a summary see figure in Chapter 1 4 It will include an average of the radon concentrations the high value low value and standard deviation These are followed by a bar chart showing the variation of radon concentration from cycle to cycle throughout the run Finally it prints a cumulative spectrum showing the distribution of energy of all the alpha decays counted during the run This spectrum is very informative It gives a good indication of the condition of the instrument and the quality of the measurement It is a useful habit to look at the cumulative spectrum from time to time just to be sure that it has not changed in character Window indicators A B C and D Dotted lines show B C D PA window boundaries ES Alpha energy sca
29. instrument s environment or contamination of the instrument The RAD7 s design makes it much less susceptible to background than other radon monitors but one should still be aware of background in the RAD7 to avoid mistakes The following list gives possible sources of background in the RAD7 3 11 1 Short lived Radon and Thoron Daughters These are by far the most important components to background in the RAD7 Radon and thoron daughters that normally build up on the RAD7 s solid state alpha detector continue to produce Chapter 3 Basics of RAD7 Technology alpha counts for some time after the radon and thoron gases have been removed from the instrument These lingering daughters can greatly confuse the result when you try to measure a low radon sample immediately after a high radon sample Many radon detectors require that you wait for the daughters to decay away about three hours before counting another sample With the RAD7 however you can go from high to low concentrations in a matter of minutes by counting in SNIFF mode since the RAD7 distinguishes the different alpha emitting daughters by their alpha energy The resulting measurement responds with a 3 05 minute half life Thus 10 minutes after the radon has been removed from the instrument the background will have been reduced by more than 90 and you can count a new sample Thoron daughters are worse behaved than radon daughters One thoron daughter Lead 212 has
30. into its set up mode refer to the Set Up Mode section With the printer in its set up mode use this button to select the desired printer parameter A1 1 6 Sensors Paper Out When the paper roll runs out the printer is disabled to prevent damage to the print head This condition is indicated by the Error LED flashing red Infrared Sensor Located at the front of the printer this sensor receives the infrared output of an external instrument Appendix 1 Wireless Infrared Printer ON lt gt 0FF Infrared Sensor 7 Window y Battery Cover bottom of printer Top View of FEED Button Power LED Green Glows steady when printer is turned ON FEED Button 1 With printer already ON press to advance paper 2 Enter Self Test Mode by holding down this button and turning ON the printer 3 With printer already in its Set Up Mode press to change value of printer parameter as selected by the SEL button SEL Button 1 Enter Set Up Mode by holding down this button and turning ON the printer 2 With printer already in its Set Up Mode press to select printer parameter Change value of selected parameter by pressing the FEED Button Error LED Red Flashes once per second when paper is out set up mode is selected buffer is full or when print head temperature exceeds 140 F 60 C Infrared Printer Component Locations and Functions 83 Appendix 1 Wireless Infrared Printe
31. medium or long format data printed after each cycle Run summary printed at end of run including averages and spectrum PC Connectivity RS232 serial port full remote control implemented in CAPTURE Software Audio Output GEIGER Tone beeps for radon and thoron counts CHIME Chime only at the end of each cycle otherwise silent OFF No sound Tamper Resistance TEST LOCK command locks keypad to secure against tampering Table A2 2 Technical Specifications Principle of Operation Electrostatic collection of alpha emitters with spectral analysis Passivated lon implanted Planar Silicon detector SNIFF mode counts polonium 218 decays NORMAL mode counts both polonium 218 and polonium 214 decays Built In Air Pump Nominal 1 liter minute flow rate Inlet and outlet Luer connectors Connectivity RS 232 port up to 19 200 baud rate USB adaptor is included with every RAD7 Measurement Accuracy 5 absolute accuracy 096 100 RH Nominal Sensitivity SNIFF mode 0 25 cpm pCi L 0 0067 cpm Bq m3 NORMAL mode 0 5 cpm pCi L 0 013 cpm Bq m3 88 Appendix 2 RAD7 Specifications Radon Concentration Range 0 1 20 000 pCi L 4 0 750 000 Bq m3 Intrinsic Background 0 005 pCi L 0 2 Bq m3 or less for the life of the instrument Recovery Time Residual activity in Sniff mode drops by factor of 1 000 in 30 minutes Operating Ranges Temperature 32 113 F
32. no visible water in or on the instrument it can be put in an oven at 50 C for a few hours to dry out completely Additionally desiccated air can be passed through the air path until the air leaving the RAD7 drops below 1096 RH After this treatment further corrosion will be prevented and the RAD7 will boot once more and you can use the internal RH sensor to measure how dry the air path is At this point the instrument should be returned to DURRIDGE for service 8 5 Battery Voltage Low Keep the RAD7 plugged into external power and switched on until the battery voltage Status Window 3 recovers to about 7 1V The RAD7 may safely be left charging all night 8 6 Pathological Values and Error Messages A Bad Offset Voltage error message a 100 duty cycle or leakage L above 15 Status Window 4 all indicate faults in the RAD7 which should be returned to DURRIDGE Company without delay Appendix 1 Wireless Infrared Printer Appendix 1 Wireless Infrared Printer AI 1 Infrared Printer Description A1 1 1 General A portable wireless printer is provided as a standard accessory with the RAD7 It uses infrared technology to communicate with the instrument using the Infrared Data Association IrDA standard or HP protocol The printer is designed around a patented easy loading paper mechanism which consists of a main cavity into which a paper roll is dropped for loading The thermal print head is at the front of the cavity a
33. open end of the drying tube making a closed loop during the purge cycle After detecting high concentrations of radon and or thoron it is good practice to purge the instrument immediately after use 4 3 5 Running the Test With the RAD7 strap over one shoulder holding the small drying tube as a wand start the test The first status window will be displayed in the LCD Push the right arrow five times to reach the B window status screen This will show the cpm for thoron You may also listen to the beeps 54 which have a different pitch for different windows Thoron has a high pitched beep Floor wall wall wall and split level seams are common locations for radon entry points So are sumps wells beam pockets and utility conduits entering the building from below ground level It is useful before starting the sweep to have a sketch map of the area with the likely culprits marked on which to write down the readings While making this sketch map the RAD7 can be taking a benchmark radon measurement in the center of the room Take at least four 5 minute cycle readings Later radon readings at likely entry points can then be compared with this benchmark To start the sweep hold the small drying tube as a wand with the open end either in or as close as possible to the most likely radon entry point Keep it there for at least five minutes Ifthe thoron count in window B during this time exceeds 2 cpm say then you k
34. return to the same set of parameters simply select gt Setup Protocol gt User 27 The User protocol has many possible applications One RAD7 owner uses her instrument for 3 day screening tests To make the setup easy she programs the User protocol with the parameters for a 72 hour screening test To do this she first sets up all the parameters as she wants them She enters 2 hour for the Cycle time 36 for the Recycle number Auto for the Mode setting Off for thoron and Auto for the Pump setting Finally to program the User protocol with these values she selects Setup SavUser and answers Yes to the confirmation question After that she can easily return to the 72 hour protocol by selecting gt Setup Protocol User any time she wishes 2 4 4040 Setup Clock Use gt Setup Clock to change time zones go in or out of daylight savings time or to synchronize the RAD7 clock with another clock The Real Time Clock RTC will maintain time of day and calendar date for as long as 10 years and is accurate to within one minute per month at room temperature Select gt Setup Clock to set the time and date of the RAD7 clock You will see Time 15 05 34 The time is listed with hours first then minutes then seconds The arrow keys can be used to change each value Holding an arrow key down will cause the number to change quickly The cursor blinking square will start on the hour Set the correct number with the arrow key
35. space of the instrument sealed and thus dry while still allowing air flow should the pump start running When moving the RAD7 please treat it with respect It is rugged but it is still an electronic instrument Please avoid hard knocks and very harsh environments 4 2 9 Examining the Data In addition to the printout data may be examined on the LCD during or after a run The records may also be downloaded to a PC where they are then available for creating graphs and tables for printed reports On reviewing a set of data first check that the relative humidity in the instrument stayed below 10 throughout the measurement If it rose above 10 it suggests that the desiccant was either removed or became depleted The RAD7 reads low if the internal RH rises above 1096 The temperature during the measurement should remain fairly steady Sudden changes of temperature in the record suggest that either the windows were opened or the RAD7 was moved from its location 53 Ifthe house was not properly closed up until the measurement was started you may expect to see a rising radon concentration during the first few hours of the run If that is the case any very low early readings should be discarded in the calculation of the mean value for the house That would mean manual calculation of the average from the good readings EPA protocols require at least 48 hours of continuous good data If the house was not closed up beforehan
36. take the grab sample 4 4 3 Protocol Choose the Setup Protocol Grab menu selection and push ENTER This will set up all the measurement parameters correctly For the printout choose Setup Format Short 4 4 Taking the Sample If the RAD7 is at the location simply start the test MENU ENTER gt ENTER Alternatively samples may be taken in tedlar air sampling bags Samples of at least five liters are required Any sampling pump may be used Even the RAD7 could be used as a sampling pump but remember to purge the instrument of old air first These bagged samples may be connected to the RAD and analyzed later Make sure there is active desiccant and the inlet filter in place between the sample bag and the RAD7 4 4 5 Analysis With the grab sample source connected to the RAD7 start the test MENU ENTER gt ENTER The pump will run for five minutes flushing the measurement chamber and then stop The RAD7 will wait for five more minutes and then count for four 5 minute cycles At the end of the run the RAD7 will print out a summary including the average radon concentration a bar chart of the four cycles counted and a cumulative spectrum The measurement process takes 30 minutes If the analysis is made more than an hour after the sample was taken a correction must be applied for the decay of radon in the sample 56 4 5 Thoron Measurement 4 5 1 Thoron and Radon Thoron is an isoto
37. ten Another limitation of the RAD7 is that it loses reporting accuracy under high humidity conditions The use of desiccant ensures that the air entering the RAD7 inlet 1s not too humid but since desiccant is expended quickly when exposed to very moist air DURRIDGE offers the DRYSTIK an instrument which removes moisture from the air entering the RAD7 without removing the radon itself The premium DRYSTIK model is capable of reducing the humidity of a typical air sample to 496 in under 20 minutes greatly prolonging the life of the desiccant or eliminating the need for it altogether The Range Extender and DRYSTIK are described in more detail below For full documentation on each please refer to the Range Extender and DRYSTIK user manuals available in PDF format at the DURRIDGE Website www durridge com 5 5 2 The Range Extender The Range Extender mixes fresh air with the air being sampled reducing the concentration of radon entering the RAD7 by a factor of ten This greatly increases the instrument s effective range The Range Extender consists of two parallel capillary tubes joined at one end to an outlet hose connector Fresh air is fed to the input of one tube while the incident radon sample is fed to the other A differential pressure sensor across the two tube inputs with a needle valve for adjustment is used to ensure that both capillary tubes have the same pressure drop across them With this system the radon conc
38. the FEED button to save the new settings after which the message Data Keeping Setting mode END should be printed Power LED Green Power ON lt gt 0FF A1 2 4 Using the Printer Turn the printer ON and observe that the Power LED should glow green Align the printer s infrared sensor to the infrared output of the RAD The printer should not be more than 18 inches 45 cm away from the instrument at an angle of no more than 30 degrees Issue a RAD7 command such as Data Print to initiate printing If the printer does not print or if random characters are printed check that the baud rate and communication protocol IrDA SIR or HP Ir settings of the printer 1s set to the correct value Align the printer s infrared sensor to the infrared output of the external instrument The printer s sensor should not be more than 18 inches 45 cm away from the instrument at an angle of no more than 30 dearees Using the Infrared Printer Al 3 Infrared Printer Maintenance A1 3 1 Battery Installation The printer requires four AA alkaline batteries To install or replace the batteries first turn the printer OFF Next unlatch and remove the battery cover Remove any old batteries and dispose of them properly Then insert four new AA alkaline batteries observing the polarity marked inside the battery compartment Finally replace the battery cover A1 3 2 Paper Installation When the printer runs out of pap
39. 4 BURRIDGE RADON INSTRUMENTATION RAD7 RADON DETECTOR User Manual Owner Serial SERVICE RECORD Date Service It is recommended that the unit be returned to DURRIDGE Company annually for recalibration DURRIDGE Company Inc 524 Boston Rd Billerica MA 01821 Tel 978 667 9556 Fax 978 667 9557 service durridge com Revision 7 4 0 2015 DURRIDGE Company www durridge com WARNING Opening the cover of this instrument is likely to expose dangerous voltages Disconnect the instrument from all voltage sources while it is being opened Due to battery power the instrument may still be dangerous Using this instrument in a manner not specified by the manufacturer may impair the protection provided by the instrument TABLE OF CONTENTS 2 1 1 1 2 1 2 1 1 3 1 4 1 5 2 1 2 1 1 2 1 2 22 2 2 1 2 2 la 22 3 22 2 2 4 225 2 2 6 2 27 2 2 8 2 2 9 2 9 2 3 1 2 3 2 2 3 3 2 3 4 2 3 5 GETTING STARTED niente dl YOUR FIRST DAY WITH THE RAD7 11 Lac lig cueste Mime Ee A ed ur eed 11 RAD7 Packing List 11 General Safety ASTUCIA d ete e t ores v guae 12 Air Travel s ri E BU ET enm e n I iD SHE 13 Taking a LOOK onse ed o dett 13 The RAD7 Professional Electronic Radon Detector 13 Sta ting a AA M RT ER RE E 14 RAD7 Normal Configuration 14 Starine dS BILE TTO SES ote dece ttem oot ead a ld eei utet 16 RAD7 SNIFF Configuration 16 BASICS OF RAD7 OPERATION cer
40. 56 750 650 534 53 4 Multiplying this result by the sample decay factors calculated above we obtain an overall concentration in the internal cell of 48 1 of the original sample Recognizing the uncertainty of several of the inputs to these formulas particularly the flow rate we will round the overall result to 50 4 5 8 Internal Cell Thoron Sensitivity Calibration Preliminary investigations have shown that the RADT s internal cell thoron sensitivity in cpm pCi L is identical to its radon SNIFF mode sensitivity to within 25 We have no reason to expect any sizable difference between the thoron and radon SNIFF mode sensitivity values so we are presently assuming that the two values are indeed nearly equal and claim an uncalibrated thoron precision of 30 With calibration against a thoron standard assessed by gamma spectrometry we are able to state the thoron sensitivity with much higher certainty This thoron calibration is offered as an option and for this we claim an overall accuracy of 20 Otherwise we estimate the overall thoron sensitivity to be 50 of the radon Sniff sensitivity to account for sample decay in the intake and internal cell The RAD7 has a typical radon Sniff sensitivity of 25 cpm pCi L so we estimate the typical thoron sensitivity to be around 125 cpm pCi L 4 5 9 Setting up a Thoron Measurement Sniffing for thoron is much the same as sniffing for radon except it tends to be
41. 7 3 4 Upgrades Whenever you send your RAD7 in for repair or calibration you have the option of having the latest available software installed Most RAD7 s can be upgraded to the latest hardware Chapter 7 Maintenance configuration as well You will be informed periodically of whatever new features are available for your RAD7 Please advise us if you want to have an upgrade made We intend to keep our RAD7 customers happy by keeping their instruments up to date state of the art 74 RAD Quality Assurance While the annual inspection and calibration carried out by DURRIDGE Company is the most effective quality assurance and the prime requirement of EPA there are other tests and observations that may be made that will give assurance of good performance throughout the year 7 4 1 Spectrum At least once a month the spectrum printed by the IR printer should be observed The cumulative spectrum printed at the end of a run has the most data points and is therefore the most useful for this purpose All that is required is that the printer be placed on the face plate at the end of a 1 day or 2 day run It doesn t matter what format is chosen the summary printed at the end of the run will conclude with a cumulative spectrum after the bar chart Alternatively the RAD7 will print a spectrum at the end of every cycle if the format is set to LONG However this will include only the counts during that cycle For the spectrum to be
42. AD7 which should be returned to DURRIDGE for service without delay H Heavy tails on alpha peaks The peaks are narrow but have unusually thick tails This may be caused by electronic ee noise or by malfunction of the alpha detector f 49 Chapter 4 Using the RAD7 4 USING THE RA4D7 RADON AND THORON MEASUREMENT IN AIR 41 Introduction The different ways of using the RAD7 may be arranged in six categories a continuous monitoring of radon in air b sniffing for radon and or thoron c testing air grab samples d measuring radon in water e testing soil gas f measuring radon and thoron emissions from objects and surfaces While all six are discussed below it is primarily categories a and d that require standard operating procedures The other applications tend to be more interactive and individuals will develop protocols which work best for them This chapter focuses on using the RAD7 to measure radon and thoron in air without the user of special hardware accessories Chapter 5 introduces applications involving the RAD AQUA RAD H20 and other DURRIDGE accessories 4 2 Continuous Monitoring 4 2 1 Preparation The RAD batteries should be fully charged so that even if there is a power cut the test will be completed Similarly there should be more than sufficient active desiccant in the Laboratory Drying Unit For an EPA protocol test the house should be fully closed from 12 ho
43. B Radon in full equilibrium After more than three hours at a constant radon level The count rate in window C is about the same as in window A C New radon The RAD7 spectrum after less than one hour of exposure to radon The peak in window C is just beginning to grow in but its count rate is still much less than in window A D Old radon The RAD spectrum after purging the instrument with radon free air for more than 10 minutes following exposure to radon 44 Chapter 3 Basics of RAD7 Technology 3 13 2 Thoron Spectra A B C D A B Cc D New thoron The RAD7 spectrum while continuously sampling thoron laden air B 6 78 MeV Po216 Thoron in equilibrium The spectrum after continuously sampling thoron laden air for more than 12 hours The count rate in window A should be about half the count rate in window D A 6 05 MeV Bi212 B 6 78 MeV Po216 D 8 78 MeV Po212 Old thoron The spectrum after discontinuing a lengthy sampling of thoron laden air The thoron peak B disappears immediately The remaining two peaks decay together with a 10 6 hour half life The count rate in window A should be about half the count rate in window D Chapter 3 Basics of RAD7 Technology 3 13 3 Combination Spectra Radon and thoron spectra can add together to The RAD7 takes this into account and always form combination spectra Peaks in window B adjusts the window A count rate to correct for the and
44. ER and you will see Thoron Off Chapter 2 Basics of RAD7 Operation Use the arrow keys to toggle between On and Off and press ENTER to complete the selection With Thoron On the calculated thoron concentration will be printed during continuous data logging or in subsequent printing of data Also if the pump is in AUTO mode it will be directed to pump continuously during the thoron measurement Note that the thoron calculation assumes a standard setup for the measurement A small drying tube three feet of vinyl tubing and the inlet filter should be used Typically the small drying tube is held in the hand and used as a wand If the laboratory drying unit is used instead of the small drying tube it creates additional sampling delay which allows more of the thoron to decay before reaching the RAD7 reducing the sensitivity of the measurement to about half that of the standard setup The only difference between Sniff protocol and Thoron protocol is that this setting Setup Thoron is Off in Sniff protocol and On in Thoron protocol See Setup Protocol Chapter 2 4 1 2 4 6 Setup Pump Select Setup Pump to change the Pump setting Four settings are available Auto On Grab and Off Auto means that the RAD7 switches the pump on and off according to a predetermined pattern that allows for sufficient sampling of air while conserving battery charge and pump wear In Auto pump setting the pump always switches
45. a half life of 10 6 hours so that with other radon monitors if you build up huge amounts of this daughter you may have to wait one to two days before using your radon instrument again The RAD7 s ability to distinguish daughters by their alpha energy almost always makes it possible to continue working 3 11 2 Adsorbed Radon Gas Radon atoms can adsorb on or absorb into internal surfaces of the RAD7 on the inside of tubing or on desiccant granules This radon can stay behind after you purge the instrument then desorb or out gas from these surfaces and enter the sample cell volume This effect is ordinarily negligible since only a small fraction of the radon ever becomes adsorbed But at very high radon concentrations over 1000 pCi L even a small fraction can be significant and you can expect to see some lingering radon after purging the instrument The best solution is to purge for 10 minutes every few hours until the count rate goes down Even in the worst possible case the radon must decay with a 3 82 day half life so you will eventually be able to use the instrument again 3 11 3 Intrinsic Background Due to very low concentrations of alpha emitting contaminants in the materials of the RAD7 s construction you can expect to get as much as one count every two hours 0 009 cpm without any radon present This count rate corresponding to about 0 02 pCi L is low enough to neglect when doing routine indoor radon work But
46. a little faster If you are just prospecting you probably will not be very interested in getting the most accurate results possible so technique is not critical But if Chapter 4 Using the RAD7 you are trying to make an accurate measurement technique is of great importance For accurate thoron measurement always use the same sample taking arrangement Keep the sample tubing short no more than 6 feet 2 meters total length Use one of the small drying tubes supplied with the instrument positioned vertically and filled with fresh blue desiccant Always use an inlet filter free from flow restrictions or clogs Avoid obstructing the intake of the sample tube The recommended configuration is pictured below For the most accurate results check the flow rate with a flow gauge to be sure it is consistent from measurement to measurement Use the RAD7 s Setup Protocol command to choose Thoron protocol for a 5 minute repeating cycle Be sure the instrument has been dried out before making a measurement Position the sample tube intake and start the test 4 5 10 Thoron Mode Thoron mode causes the RAD7 to print both thoron and radon concentrations in pCi L or Bq m3 in continuous data logging or in subsequent printing of data Thoron mode also directs the automatic pump setting to continuous pump operation to assure a fresh sample The setup parameter Setup Thoron allows you to select Thoron mode On Off for configuring a p
47. ae uid 44 Operational Radon Spectra cerisier areire Ee iA osea set E ovest ed 44 Thoron Spectra s A rete dee ete re eee acies tee pese utt tern 45 Combination Spectr ER itis ele e ce Ue oe ae ee ee 46 Pathological Spectra e ie lee be ene i tela 48 RADON AND THORON MEASUREMENT IN AIR 50 Introd cHol ue tco Cone Dae dee cdi le tua hatter dad 50 Contin o s Monto Eier echte reti ee eoe Gee satee tent ag ottime ntur di 50 PH CDOS OUON NEC 50 PULSE 50 Test LOCA INEA e tr dd a de es peon ed o do 51 LEER AAA 51 TO Print OF NOE TO Prifit d A ties 51 Runn ing the Test du ec em tete eee Hee onus 52 Security and Quality Control ssepe ae de RH e CH e Ht do 52 Finishing ihe RUM docete aa 52 Examining the Dalai t deal eee ee etes 53 Very Short Term Monitoring 4 3 4 3 1 4 3 2 4 3 3 4 3 4 4 3 5 4 3 6 4 3 7 4 4 4 4 1 4 4 2 4 4 3 4 4 4 4 4 5 4 5 4 5 1 4 5 2 4 5 3 4 5 4 4 5 5 4 5 6 4 5 7 4 5 8 4 5 9 4 5 10 4 6 4 7 4 7 1 4 7 2 4 8 4 6 1 4 8 2 4 8 3 5 5 1 5 2 5 2 1 5 2 2 5 2 3 SAMAD ox ea e E WhySriff 25 eer ote eee eee de qe IRA 53 Locating Radon Entry Points sese 54 DPreparOtlOWz esercita d oe des sse US D P LA S E e 54 Pup d MM aes 54 RUNNER esca 54 Drilled Sampling POU ts sac iei ise cia 55 SPOURCAGINGS A A at ete tel t etu e Mte e rt 55 Grabando purus an Vindel PR 55 Prepa
48. allows for the display of radon thoron temperature and humidity data Navigation controls make it possible to select the data points within a specific date range and zoom in to that region for a closer look Accompanying the graph display is a statistics panel showing information about the point nearest to the cursor and the points within the selected region as well as the points comprising the entire data set A synthesized spectrum display appears in another panel providing an indication of the changes that occur within the RAD7 as a testing session progresses RAD Profiles based on device calibration data may be applied to graphs to improve the accuracy of the data shown Data points may also be corrected for temperature humidity and other variables Any problematic data records will be examined by CAPTURE s comprehensive error catching system and reported to the user CAPTURE supports the exporting of both raw RAD data and more complete error corrected RAD data in a number of formats for use in spreadsheets and other analysis tools Summary reports may also be generated providing general overviews of the collected data 6 2 5 Real Time RAD7 Monitoring CAPTURE is capable of monitoring multiple local and remote RAD7s simultaneously in a Chart Recorder displaying status details and plotting radon concentrations in real time as they are recorded A statistics panel is automatically refreshed as new information arrive
49. alpha peaks decay at different rates The polonium 218 peak in window A decays with a 3 05 minute half life So in 10 minutes it will be down to about one tenth of its original count rate The peak in window C however will take over two hours to get down to one tenth its count rate Rather than wait around for hours you can start the next radon test in SNIFF mode which ignores window C In fact the preset one and two day monitoring protocols in the RAD7 use AUTO mode which starts a measurement in SNIFF mode and automatically changes to NORMAL mode after three hours This takes care of all but extreme exposure to very high radon You can always measure the short term background with 5 minute SNIFF mode tests Run a few to see that the background is low 4 7 Airflow Rate Limits When the RAD7 s pump is set to OFF Setup Pump Off ENTER it is permissible to use an external pump device such as the DRYSTIK which may provide a higher or lower airflow rate than the RAD7 s built in pump However certain flow rate limits should be observed 60 High flow rates are useful for thoron measurement and for fast response RAD AQUA monitoring of radon and thoron in water Low flow rates are useful for continuous soil gas monitoring and for sampling gases such as stack gases that need significant conditioning 4 7 1 Maximum Airflow Rate The maximum recommended airflow rate is 2 5L minute Beyond that rate the RAD7 s sensi
50. ansformations to Lead 208 The main distinction is the very different half lives involved Thoron has a half life of only 55 6 seconds It emits a 6 29 MeV alpha particle and transforms to polonium 216 which in turn has only a 0 15 second half life before emitting a 6 78 MeV alpha particle and transforming to Lead 212 Lead 212 hangs around for a long time with a half life of 10 6 hours It transforms by beta decay to bismuth 212 which in turn has a half life of 60 6 min Bismuth 212 has a 2 1 split with two thirds transforming by beta decay to polonium 212 and one third transforming by 6 05 MeV alpha decay to thallium 208 The polonium 212 decays immediately to lead 208 emitting an 8 78 MeV alpha particle in the process while the thallium 208 with a half life of 3 min undergoes a beta decay to the same destination lead 208 3 3 Continuous Monitors There are several types of continuous radon monitors on the market Nearly all of these are designed to detect alpha radiation but not beta or gamma radiation Why Because it is very difficult to build a portable detector of beta or gamma radiation that has both low background and high sensitivity Chapter 3 Basics of RAD7 Technology Three types of alpha particle detectors are presently used in electronic radon monitors 1 Scintillation cells or Lucas cells 2 lon chambers 3 Solid state alpha detectors Each of these types has advantages and disadvantages relativ
51. appears with its characteristic half life of 3 05 minutes After 3 05 minutes the count rate in window A is half of what it was before After 6 10 minutes the count rate is half of that or one quarter of what it was before You get the picture After 10 minutes there are hardly any counts at all in window A Not so for window C however The spectrum still shows a single strong peak in window C The peak in Window C takes hours to disappear After half an hour the count rate in window C has not even halved Polonium 214 may have a very short half life but its parents lead 214 and bismuth 214 certainly don t One has a half life of 26 8 minutes and the other has a half life of 19 8 minutes And they are sequential which makes matters worse After you completely remove the radon it may be a good 3 or more hours before the counts really die down in window C We call window C the old radon window since it represents counts from radon that was present in the RAD7 an hour or more before Chapter 3 Basics of RAD7 Technology The effects of time in windows B and D is similar but much more pronounced There is no delay in the RAD7 to polonium 216 so the count rate in window B is always in equilibrium with the thoron gas in the measurement chamber In contrast there is a 10 hour half life in the decay chain down to polonium 212 so it will take days for window D to reach equilibrium Window D is therefore not counted when sn
52. articular test to perform thoron readings The protocol Protocol Thoron provides a standard test for sniffing both radon and thoron in 5 minute cycles Recommended RAD7 Thoron Configuration 36 L 3 16 ID Air Flow 5 16 to 3 16 Reducer 2 L 5 16 ID Small Drying Tube Thoron Sampling Point 3 16 to 1 8 Reducer 2 L 1 8 ID Inlet Filter 2 L 1 8 ID External Power Optional Air Output e Air Flow 3 16 to 1 8 Reducer RAD7 Thoron Protocol 59 Chapter 4 Using the RAD7 4 6 Managing Background A major concern in radon testing is background The RAD7 has a number of features that help to keep short and long term background under control These are discussed in Chapter 3 11 Following a few simple rules will help to keep background to a minimum Short term background is activity left in the detector after the air sample has been flushed from the measurement chamber The higher the radon concentration and the longer the sample is held in the cell the more daughter activity it leaves behind So to avoid background when you see high radon readings finish your measurement and purge the sample cell promptly Take the instrument somewhere with little radon such as outdoors Make sure the drying tube is connected and select gt Test Purge Let the RAD purge for 5 to 10 minutes or longer if the sample was exceptionally hot The two
53. at the sampling point upstream of everything A suitable dust filter is supplied with every RAD7 The filter should be replaced when it becomes soiled Replacements may be purchased from a car parts supplier as 1960 s VW Beetle in line gasoline filters part number 803 201 511C or FRAM G4164 or from DURRIDGE Company Please note that any restriction to air flow including a plugged dust filter upstream of a passive DRYSTIK will reduce the effectiveness of the DRYSTIK In a dusty environment with a dust filter in place an Active DRYSTIK will continue to work well even if the dust filter becomes partially blocked 4 8 3 Radiation Hazard Ifthe RAD7 is to be placed in a location that is hazardous to the health of individuals remote communication may be established through either a wireless Bluetooth connection or a local wireless network For details please see Chapter 6 and the Long Distance Connectivity section of the CAPTURE user s manual The CAPTURE manual is available from within the program s Help Menu as well as from the DURRIDGE website Chapter 5 Using RAD7 Accessories S USING RAD7 ACCESSORIES TESTING FOR RADON IN THE GROUND AND WATER 5 1 Introduction With the addition of various accessories offered by DURRIDGE the RAD7 can acquire the ability to detect radon in water samples flowing water soil gas hard and soft surfaces and collected objects These applications and the accessories required for each are
54. be tested or when the RAD7 is pre occupied with continuous monitoring and will not be available until later The Grab functionality is also useful when many samples must be gathered from different rooms of a building within a short timeframe However if the RAD7 is available and can be taken to the test location then data quality is much improved by a monitoring the radon level over an extended period of time such as 1 day or if that 1s not a possibility b making a short term measurement such as described in Chapter 4 2 10 or else just sniffing for a spot reading as described above Grab samples have the same shortcomings as spot readings The radon concentration grabbed is unlikely to be representative of the EPA average level at the location of the sample The precision of the reading is also limited by the short time for counting 4 4 2 Preparation It is important that the RAD7 be well dried out prior to accepting the grab sample First purge the unit with fresh dry air for five minutes Then connect the laboratory drying unit in a closed loop Chapter 4 Using the RAD7 with the RAD7 so that air from the outlet passes through the desiccant and back into the inlet Note that air should always flow the same way through the desiccant Purge for ten minutes then check the relative humidity push MENU ENTER ENTER then gt 1 If the RH is not below 8 repeat the process Keep the pump running until ready to
55. c D 48 DURRIDGE immediately Email to service durridge com would be a good way to initiate the contact A No counts Try a longer counting time If there is not a single count in an hour that is clear indication of instrument malfunction B Few counts Normal for low radon levels and short counting times Abnormally low counts could be caused by disruption of the air flow or by malfunction in the high voltage circuit C Lead 210 polonium 210 A persistent peak at 5 3 MeV will develop from many years of regular use or from sustained exposure to very high radon levels It results from the buildup of lead 210 on the detector surface Lead 210 has a 22 year half life It is not a problem for the RAD7 because the peak is outside window A and thus does not contribute to the background D Wide alpha peaks Typically caused by electronic noise in the system May be associated with vibration with high operating temperature or with degradation of the surface barrier detectors used in older model RAD7 s built prior to 1996 Chapter 3 Basics of RAD7 Technology E Smeared spectrum A B C D Alpha peaks cannot be discerned by the eye Severe electronic noise F Low energy noise Independent of radon or thoron such electronic noise may be intermittent or be associated with vibration G Shifted peaks Peaks appear normal but are shifted in alg Sl position Shows a malfunction of the R
56. calibration factor is applied to achieve the necessary conversion After RAD7 data has been downloaded onto a computer the DURRIDGE CAPTURE software can perform additional calculations and corrections a B window to A window spill correction This is important when measuring low radon levels in the presence of high thoron b Humidity correction This is essential if the desiccant becomes completely hydrated during a measurement c Radon in water calculation With the RAD AQUA and Radon in Water Probe the equilibrium ratio between the radon concentration in the water and that of the air entering the RAD7 is a function of the temperature at the air water interface CAPTURE can be given the necessary temperature information via a data file produced by a temperature logger or it can use the air temperature as measured by the RAD or it can be given a single temperature value This temperature information is then used along with the radon in air readings to calculate the radon concentration of the water d Meaningful thoron threshold The spill from window C to window B produces counts that must be deducted from the B count rate before the thoron concentration can be determined but those spill counts have 36 statistical uncertainty That means that a count rate in B that is slightly above the calculated spill from C may in fact be merely a statistical variation of the spill rather than actual thoron The spill therefore
57. cannot understand your command for example if you typed words in the wrong order or misspelled something it will respond with ERROR followed by a list of acceptable command words The case of the command does not matter nor does the numeric format of numbers In the last example data com 03 Data Com 3 and dAtA coM 03 00 all work equally well 6 3 3 Parsing RAD7 Data Stored RAD7 data can be obtained through the Data Com command Specify the run number in the command line and finish with a carriage return Alternatively issue the Special ComATll command to download all runs from the RAD7 Each cycle produces a record containing 23 fields Carriage return line feeds separate the records and within each record commas separate the fields Fields may have leading zeros extra space characters trailing decimals etc which may need to be trimmed When the RAD7 responds to a Data Com or Special ComAll command each line returned represents a different cycle Here is an example of a single line 009 99 10 29 04 18 4823 337 8 45 4 2 9 46 6 0 3 2201 14 23 7 5 7 7 09 00 125 28 32743 8500846 255 lt CRLF gt The meaning of each of these values is described in the table on the next page Chapter 6 PC Connectivity Table 6 3 3 RAD7 Data Record Content ID Field Name Notes 1 Record Number Ranges from 001 to 999 2 Year 2 digit value 3 Mo
58. centered at 7 69 MeV The second example spectrum shown in Chapter 3 13 1s the characteristic signature of radon at equilibrium with its alpha emitting daughters We would expect to see a spectrum like this after several hours at a constant radon level The 5 49 MeV alpha particle directly emitted by radon 222 does not appear on the RAD7 spectrum because it was created in the air not on the surface of the detector The radon 222 atom is inert and electrically neutral and cannot be attracted to the solid state detector Only after it decays to polonium 218 does the atom become positively charged and is thus driven to the detector surface The RAD7 spectrum shows radon daughters but not radon itself Do not confuse the RAD7 s spectrum with that of a working level instrument The alpha peaks may appear the same but the RAD7 is really measuring radon gas not working level 37 3 8 Windows The RAD7 groups the spectrum s 200 channels into 8 separate windows or energy ranges Window A for example covers the energy range of 5 40 to 6 40 MeV So window A includes the 6 00 MeV alpha particle from polonium 218 The first step toward converting raw spectral data to radon measurement is to add up all the counts in each window and divide by the detector livetime or duration of active data collection The RAD7 microprocessor does this task and stores the results to memory in this form You can recall and print window data from past m
59. certainty For past data use CAPTURE to graph the data and use Smoothing to smooth out the statistical scatter in the data 8 2 3 Run Cycle Number 0000 A Run Cycle number of 0000 indicates that the RAD7 s memory is full Download the RAD7 s contents to a computer using CAPTURE Then erase the RAD7 data using gt Data Erase The memory will be emptied and the data structure reset 8 3 Relative Humidity high Relative humidity displayed in the third status window normally starts high unless the instrument has been well purged just before Chapter 8 Troubleshooting starting the run Depending on how long it has been since the last measurement it may take an hour or more of measurement to bring the relative humidity down to below 1096 If it takes too long to bring down the relative humidity check the following a The desiccant is used up Replace it b The desiccant insufficiently regenerated Follow the instructions in Chapter 7 1 1 c There is a leak in the drying unit Clean the O ring and seating before replacing the desiccant Be sure to draw the air sample from the end furthest from the screw cap d There is a leak in the connection to RAD7 e There is a blockage in the air path Squeeze the inlet tubing and note any change in the sound of the pump Feel for suction at the sampling point If none of the above succeed in lowering the relative humidity there may be a problem with the humidity sensor Meas
60. chnician A surprising number of minor disasters can be avoided by long distance consultation The next step 1f consultation fails usually is to send your instrument in for evaluation and repair Please send any documentation of the problem that you might have notes printouts etc and a short note describing the problem Be sure that you put your name and telephone number on the note Within 48 hours of our receipt of the instrument we will call you to give a prognosis Bear in mind that a repaired instrument often requires complete re calibration so a one week turn around may be the best we can do If you absolutely need an instrument during the repair time we can sometimes arrange to send you a loaner instrument 7 3 3 Shipping The RAD7 is shipped to you in a plastic bag packed in a box with styrofoam peanuts and finally packed inside another box that also holds all the accessories The inner box by itself is too small for the return trip when you need a calibration or repair job You need to find a bigger box with space for one inch packing all round the RAD7 A 14 cube box is fine Pack and seal the box carefully Please do not ship any accessories unless they are relevant to the problem All return shipments to DURRIDGE must be prepaid and unless you instruct us otherwise we ll return it to you via the same shipping method you used to get it to us from slow boat to next day air freight collect
61. cision of the measurement In indoor environments the radon concentrations rarely fluctuate quickly enough to justify using SNIFF mode for continuous monitoring 39 The best of both worlds 1s provided by AUTO mode Here the RAD starts a test run in SNIFF mode and then after three hours switches automatically to NORMAL mode In this way the first few cycles give readings without any bias from either old radon daughters left on the detector or the slow build up to reach equilibrium in window C while the rest of the readings benefit from the higher precision given by twice the number of counts in each cycle For real time monitoring you are always better off to leave the mode in AUTO The RAD7 is up to speed quickly and is not influenced by old measurements The final average of the run is therefore more accurate and more reliable CAPTURE can read a data file and force SNIFF mode presentation of the data allowing the user to change the setting retrospectively Thus if on looking at data taken in NORMAL mode there is what appears to be a rapid change in radon concentration changing to forced SNIFF mode presentation in CAPTURE will permit another look at the changes with better time resolution 3 11 Background Background in a radon detector refers to spurious counts that occur even in the absence of radon Background can arise from the properties of the instrument or its components other forms of radiation in the
62. ctor The printer runs on its own batteries Parameter Minimum Value Maximum Value Temperature 0 C 32 F 40 C 104 F Relative Humidity external 95 Must be non condensing Relative Humidity internal 10 Battery Voltage 6 00V 7 20V Pump Current pump off 10mA Pump Current pump on 30mA 90mA High Voltage 2100V 2400V HV Duty Cycle 2096 Leakage Current room temp 20 Leakage Current max temp 80 Signal voltage level 0 15V 0 30V Table 7 2 RAD7 Operating Ranges Chapter 7 Maintenance 73 Service and Repair 7 3 4 Calibration DURRIDGE maintains a professional radon calibration facility that includes a controlled standard source of radon gas and a controlled temperature environmental chamber All RAD7 alignment and calibration is done here as well as basic testing and quality assurance We determine calibration factors by direct comparison to master RAD7 s which were themselves compared with EPA and DOE instruments and which have participated in international inter comparisons of radon instrumentation The calibration accuracy 1s independently verified by direct determination of the radon chamber level from the calibrated activity and emission of the standard radon source In addition we periodically intercompare with other radon chambers We generally achieve a reproducibility of better than 296 with our standard RAD7 calibration Overall calibration accuracy is in
63. d a 3 day test could satisfy the EPA requirement If the air sampling point was changed for a while or some windows opened during the run you may expect to see a change in air temperature and change in radon concentration during that period Simultaneous changes of these two parameters is an indicator of tampering 4 2 10 Very Short Term Monitoring Some Home Inspectors choose to use the RAD7 for a short term test just during the home inspection This means that they have full control over the test and they can take the RAD7 with them when they leave on completion of the home inspection They close up the house set up the RAD7 in the basement choose a half hour cycle time and a total run length recycles of typically four or five cycles At the end of the run the RAD7 prints out a bar chart of the increasing radon concentration at half hour intervals The data gives the Home Inspector and his client a good indication of the radon situation Adding 50 to the final half hour reading gives an estimate of what would be the average radon level for closed house conditions If during those two hours of the test the radon concentration climbs towards or over the 4 pCi L mark then they can be confident that with a full EPA protocol test covering 2 days or more the result would surely exceed the 4 pCi L action level 43 Sniffing 4 3 1 Why Sniff There are two main reasons for sniffing One is to obtain a quick
64. d at the DURRIDGE website www durridge com The basic procedure can be summarized as follows Insert the soil probe Make sure that there is a reasonable seal between the probe shaft and the surrounding soil so that ambient air does not descend around the probe and dilute the soil gas sample Between the probe and the RAD7 connect the included water trap which could be just a jar with two air tight hose connectors in the lid Then connect the laboratory drying unit and the inlet filter A water trap is included in the package when the DURRIDGE soil gas probe is purchased Chapter 5 Using RAD7 Accessories Set the protocol to Sniff Soil gas is normally so high in radon that it 1s not necessary to use long cycle times to gain precision Five minute cycle times are sufficient 5 3 4 Running the Test Start the test Test Start ENTER On the LCD screen you will see the first status window Push the right arrow twice and the screen will display the temperature relative humidity battery voltage and pump current Pay particular attention to the relative humidity and pump current The humidity should gradually drop down to below 10 and stay there If the pump current starts to rise much above 100 mA it suggests that the soil is not porous in which case it may be that a good soil gas sample cannot be drawn no matter how powerful the pump is With the RAD7 pump current above 100 mA the air flow rate will be significan
65. d humidity inside the measurement chamber and the battery voltage Medium and Long format settings print more information each cycle Note that the Po 218 has a 3 minute half life After moving to a new location it will take about 15 minutes for the count rate to reach equilibrium with the new radon concentration So not until after the third 5 minute cycle will the reading indicate the new level However the thoron daughter Po 216 has a very short half life 150 ms so the response of the RAD7 to thoron is virtually instantaneous For thoron the first 5 minute cycle is as good as any other Thoron will only be found very close to radon entry points That together with its fast response makes thoron sniffing an excellent sleuth for radon entry points To terminate the run any time you may switch off the RAD7 The data collected of completed cycles is stored in the RAD7 memory and available for later display printing or downloading to a PC Chapter 2 Basics of RAD7 Operation 2 BASICS OF RAD7 OPERATION 2 1 Introduction 2 1 1 The Key Pad The RAD7 is operated through a four key menu driven interface These four keys allow you to look at the commands select one and then do it Menu Key Press MENU and you see the menu prompt gt and the word Test gt Test Arrow Keys Press the forward and backward arrow keys to go through the available options To advance quickly through the options hold down the k
66. ddle shows the detector status Idle or Live and the upper right gives the current test mode Sniff Normal or Grab Note that in AUTO mode the indication will change from Sniff to Normal after three hours of measurement Lower left shows the count down timer 00 30 00 30 minutes which counts down to zero when the detector is Live 1 e a test is in progress The lower right shows the total number of counts since the beginning of the current cycle The arrow keys may now be used to access additional status information Press 3 once and you will see something like this Last reading 0409 1 80 0 74 p The lower left is the run number 2 digits and cycle number 2 digits of the last completed cycle stored to memory The lower right is the radon reading and two sigma statistical uncertainty followed by p Chapter 2 Basics of RAD7 Operation indicating picoCuries liter or b for Becquerels cubic meter When a cycle ends the information on this display is updated If there have been no readings yet the display will show No readings yet Press gt once again and now you will see something like this RH 3 00mA 24 8 C B 6 36V P Top left is the internal temperature To change from Celsius to Fahrenheit see Chapter 2 4 9 Setup Units Top right shows the internal Relative Humidity reading When testing maintain this value at 10 or less by using the desiccant Bottom left is t
67. described below The accessories discussed here are not included with the RAD7 For full details on the usage ofa given accessory please see its user manual All product manuals are available in print form and on the DURRIDGE website www durridge com in PDF format 5 2 Radon in Water 5 2 1 The RAD H20 Accessory The RAD H20 is an accessory for the RAD7 that enables you to measure collected water samples to detect radon with high accuracy over a wide range of concentrations obtaining your reading within an hour of taking the sample It is particularly suited for well water testing where immediate results are often required The RAD H20 uses a standard pre calibrated degassing system and pre set protocols built into the RAD7 which give a direct reading of the radon concentration in the water sample itself The method is in fact a special variation of the grab sampling method described in the previous chapter The most widely supported sample sizes are 40mL and 250mL as these correspond to the RADT s built in Wat 40 and Wat250 protocols d Large water samples of up to 2 5L may be os sampled using a separate product the Big Bottle op System in which radon concentrations are calculated using the provided CAPTURE software for Windows and Mac OS X p mano The RAD H20 and Big Bottle System manuals contain further information on these products The RAD AQUA Accessory 62 Chapter 5 Using RAD7 Accessories 5 2 2
68. door air usually 0 10 to 1 00 pCi L Now introduce some radon into the RAD7 What do you see At first maybe nothing But within a few minutes you begin to get counts in the A window The RAD7 chirps merrily with each count That s polonium 218 a result of the decay of radon 222 within the RAD7 sample chamber For the first 5 minutes or so the count rate increases then begins to approach a steady level 38 After about 10 minutes we say that the polonium 218 daughter has reached close to equilibrium with the radon 222 parent Equilibrium is when the activity of the daughter stabilizes neither increasing or decreasing At this point nearly all of the counts land in window A and you see a single peak in the spectrum printout But the total count rate is still increasing more slowly now You begin to see counts appear in window C Just a few but more and more of them over the course of the next hour or two After 3 hours or so we reach full equilibrium when the activities of all the daughters stabilize Now the spectrum shows the characteristic twin peaks polonium 218 in window A and polonium 214 in window C The peaks are of almost identical size Now flush the RAD7 with fresh radon free air The count rate in window A immediately begins to drop just as fast as it rose when you first put the radon in Without radon inside the RAD7 there is no source to replace the polonium 218 that decays So the polonium 218 dis
69. e motion of the air the instrument operator may 57 find it necessary to make measurements in several locations to properly assess a thoron situation Fortunately rapid fire thoron measurements are very easy to do with the RAD7 4 5 3 Calculation and Interference Correction The RAD7 calculates thoron concentration on the basis of the count rate in spectrum window B which is centered on the 6 78 MeV alpha line of Po 216 the first decay product of thoron gas To further avoid interference from radon the RAD7 applies a correction to the thoron count rate to compensate for a small percentage of spillover from window C If the spill from window C to window B is too great relative to the base amount in window B it becomes impossible to calculate thoron concentrations with sufficient certainty This situation can be avoided by purging the RAD7 with fresh air and waiting with the unit turned off for two hours prior to testing for thoron This provides enough time for the peak in window C to decay to one tenth of its original value As of firmware version 2 5 the RAD7 calculates radon concentration from the count rate in window A SNIFF mode or windows A plus C NORMAL mode The RAD7 compensates for interference from the long lived progeny of thoron 10 6 hours by applying a correction to the radon count rate in both SNIFF and NORMAL modes The correction 1s based on a fixed fraction of the count rate in the D window around the
70. e RAD7 through the serial port 2 5 12 Special Version Output the special extension version number 2 5 13 Special Model Output the RAD7 hardware version number 2 5 14 Special Serial Output the RAD7 unit serial number 2 5 15 Special Beep The RAD7 gives an audible beep tone Does not make any sound if the tone setting is Off 2 5 16 Special Relays Access the RELAYS set of commands At the end of every cycle if the function is enabled the RAD will set or reset two external relays according to the individually set thresholds and the measured radon level The commands consist of relay1 relay2 enable and disable Use the arrow keys to scroll between these commands Relayl permits the user to set a level above which the RAD7 will turn on relayl and below which it will turn the relay off Relay2 does the 29 same for the second relay Enable causes the function to go into effect Note that the command to the relays is sent after the RAD7 has finished printing data at the end of the cycle Disable stops the RAD7 from sending any commands to the relays 2 6 Infrared Printer The RAD7 uses an infrared link to print to the supplied printer Note that all references to the RAD printer in this manual apply to the Omniprint OM1000 printer and to the Chamjin I amp C New Handy printer model 700 BT The most significant difference between these printers and the previously supplied now obso
71. e drying column If you were to use a non recommended inlet filter the flow might be restricted enough to greatly lower the result 4 5 6 Calculating Sample Decay The thoron concentration at the inlet of the RAD C1 can be expressed mathematically as Cl CO exp L V1 q where CO is the original sample concentration V1 is the volume of the sample tube drying tube filter around 50 mL q is the flow rate around 650 mL min and L is the decay constant for thoron 756 min A typical value for C1 CO is then C1 CO exp 756 50 650 943 94 3 This is the number DURRIDGE assumes in the factory calibration Adding a few extra feet of hose will not matter much about 0 5 per foot but if we were to use a 100 foot hose instead V1 is around 580 mL then the same calculation would give 509 or 50 9 a significant reduction from 94 3 4 5 7 Calculating Internal Cell Concentration The sample decays slightly in going from the RAD inlet to the internal cell due to internal hose and filter volumes This decay can be calculated in a similar fashion to the above giving the internal cell inlet concentration C2 about 95 5 of Cl Within the RAD7 internal cell the equilibrium thoron concentration C3 will be determined by the following formula C3 C2 1 L V2 q where L and q are as above and V2 is the volume of the internal cell around 750 mL Typical values then give C3 C2 as C3 C2 1 1 7
72. e half life sample decay during acquisition is significant c The required response speed of the RAD7 a low flow rate may cause an unacceptably long Chapter 4 Using the RAD7 time to change the sample in the measurement chamber d The radioactive decay during residence in the RAD7 s measurement chamber Regarding point c the amount of time it takes to change the measurement sample should be short compared to the required response time Regarding point d the radon sample in the measurement chamber should have nearly the same concentration as the radon at the sampling point to within a small fraction of the acceptable uncertainty Ideally less than 1 of the original sample concentration will be lost to radioactive decay before the measurement occurs This requires that the transit time from the sampling point plus the time that radon remains in the RAD7 s chamber is less than one hour The RAD has a volume of less than 1L so a flow rate of 1 L hour or 0 016L min is sufficient to satisfy the residence criterion but the response time to a step change in radon concentration at the sampling point would then be about 1 hour Fora 15min response time the flow rate would have to be at least five times greater or 0 08L min The 3min half life of 218 Po limits the radon response time to a little less than 15 minutes so there is little benefit in a flow rate greater than 0 1L min unless the source is far away or thoron
73. e to the others All of these types can be used for low background alpha particle counting The DURRIDGE RAD uses a solid state alpha detector A solid state detector is a semiconductor material usually silicon that converts alpha radiation directly to an electrical signal One important advantage of solid state devices is ruggedness Another advantage is the ability to electronically determine the energy of each alpha particle This makes it possible to tell exactly which isotope polonium 218 polonium 214 etc produced the radiation so that you can immediately distinguish old radon from new radon radon from thoron and signal from noise This technique known as alpha spectrometry is a tremendous advantage in sniffing or grab sampling applications Very few instruments other than the RAD7 are able to do this A distinction should be made between true real time continuous monitors and other instruments and devices With a continuous monitor you are able to observe the variation of radon level during the period of the measurement This can sometimes show big swings in radon concentration and may allow you to infer the presence of processes influencing the level For good data it 1s important that there be sufficient counts to provide statistically precise readings Devices which give just a single average reading or whose precision is inadequate except after a long measurement time are not in this sense continuous moni
74. e to work a little harder But the resistance added by a drying tube is much less than the resistance of the inlet filter so you should be able to cascade several without severely restricting the air flow Second each additional tube adds a time lag between sample intake and instrument response For continuous monitoring a 10 to 20 minute lag may be perfectly acceptable but for sniffing it may not be You can conservatively estimate the time lag by taking four times the volume of the drying system and dividing by the average flow rate Consider a continuous monitor application using a laboratory drying column of volume 0 8 liter with the pump in timed operation giving an average flow rate of 0 2 liters per minute Four times the volume divided by the flow rate gives 16 minutes for the estimated lag time This would be perfectly acceptable for continuous monitoring For radon sniffing you will usually use the small drying tubes volume 032 liter which create negligible delays of less than a minute even at low flow rates You can cascade several small drying tubes without trouble Do not cascade drying tubes when sniffing for thoron since thoron s 56 second half life necessitates that you keep delays to an absolute minimum For thoron sniffing use a single small drying tube and set the pump for continuous on operation Keep hose length to 6 feet 1 8 meter or less 7 1 5 Filters Inlet filters are supplied that fit the metal
75. easurements The RAD7 adds windows E F G and H together to form window O for other before storing the data to memory Spectrum printouts clearly mark windows A B C and D with dotted lines Each window s function A Radon Sniffer Mode counts The total counts of alpha particles from the 3 minute 6 00 MeV Po218 decay Thoron 1 Window The total counts in the region of the 0 15 second 6 78 MeV decay of Po216 This window lies between windows A and C of the radon groups and may have some counts from spill over from adjacent windows Radon Po214 counts The total counts of the 7 69 MeV alpha particles from the decay of the great great granddaughter of radon which has an effective half life of nearly an hour Thoron 2 Window The total counts in the region of the effective 8 78 MeV decay of Po212 which has a half life of about 10 hours High Energy Window A diagnostics window that normally has close to zero counts If the counts in this window are a large fraction of the counts in A or B or C or D the RAD7 is probably not working properly F Low Noise counts A diagnostics window that gives the total counts in the first 10 channels The count rate in Window F is a measure of the noise in the system The counts may be high if the RAD7 is operated at very high temperatures Chapter 3 Basics of RAD7 Technology G Medium Noise counts A diagnostics window that gives the total count in the region around chan
76. entration delivered to the RAD7 is reduced by an order of magnitude regardless of the strength and flow velocity of the RAD7 s internal pump The RAD7 pump can cycle on and off without affecting the reduction factor The Range Extender can be used for the measurement of very high radon concentrations in air in soil gas and in water It can also be used with any other instrument that has its own pump for any gas If used to extend the range of thoron measurement care must be taken to assess and correct for the additional decay of the thoron due to sample acquisition delay The Range Extender Chapter 5 Using RAD7 Accessories 5 5 3 The DRYSTIK The DRYSTIK reduces the humidity of the air entering the RAD7 by transferring moisture from the sample about to enter the RAD7 to the air being pumped out of the instrument As the air enters the desiccant in the drying unit which is not included with the DRYSTIK on its way to the RAD7 it will have already lost most of its moisture greatly extending the life of the desiccant in the drying unit In certain cases the need for desiccant is eliminated altogether The DRYSTIK has at its heart a Nafion humidity exchanger with diaphragm pump fixed and variable flow limiters and a built in Duty Cycle Controller These are all contained in a compact portable enclosure The DRYSTIK s pump compresses the sample air inside the membrane tubing initiating the transfer of water molecules to t
77. eper will emit a chirp whenever a particle is detected much like the familiar Geiger counter But unlike a Geiger counter the pitch of the chirp depends on the energy of the alpha particle A trained ear can distinguish old radon from new radon by the sound of the chirps The thoron beep is the highest pitch In the Geiger setting anyone will recognize a radon gusher by the rapid fire chirping the RAD7 produces 2 4 8 Setup Format Select gt Setup Format to change the way data are printed out Four settings are available Short Medium Long and Off Short causes the RAD to print results in an abbreviated form Three lines of printed text contain a cycle s most important data the run cycle number radon concentration and two sigma uncertainty units and mode time and date temperature relative humidity internal and battery voltage Medium and Long printouts include seven additional lines of data total counts livetime and counts per minute for five alpha energy windows These seven lines are the raw data from which the Chapter 2 Basics of RAD7 Operation radon concentrations shown in the first line of the printout are calculated The Long format when printing from a test in progress Live includes a graph of the alpha energy spectrum Since spectra cannot be saved to long term memory the spectrum will not be printed when retrieving past data Off means that no data will print out at the end of each cycle bu
78. er as indicated by the front panel red LED flashing install a new paper roll as follows 1 Lift up paper cover latch and then open paper cover as illustrated on the following page 2 Remove spent paper core and dispose it it 3 Drop in a new paper roll so that it will rotate in the direction shown in the illustration 4 Close the paper cover so that the paper is pinched between the roller and the print head Remove any slack by pulling out about 1 2 inch of paper from printer Note If there was unprinted data in memory when the paper ran out and the printer was not shut OFF then the printer will automatically print the remaining data 5 seconds after closing the paper cover Appendix 1 Wireless Infrared Printer Close Paper Cover so that paper is pinched between the Roller and Print Head Paper Roller Paper Cover Lach Paper Cover Paper Roll Print Head Red LED flashes when paper runs out M N Battey Cover bottom of printer Infrared Printer Maintenance A1 3 3 Cleaning the Printer External surfaces of the printer may be kept clean by simply wiping with a damp cloth Do not use any solvents that may attack the plastic case Be sure that the inside surfaces are kept dry at all times A1 3 4 Cleaning the Print Head To maintain a good print quality it is recommended that the print head be cleaned at least once a year or up to once a month if the printer is used heavily The
79. er directly or by modem connection The following command set are those available with RADLINK version 0252 Earlier versions will have a subset of these 2 5 1 Special Ident Output the RAD7 identification sequence including firmware version hardware model number unit serial number and last calibration date 2 5 2 Special SPrOn Re direct subsequent output from the infrared printer to the serial port In other words everything that would ordinarily be printed will 28 shoot out the serial port but nothing will be printed even when you say Print One reason to use this might be to move the data very quickly into a computer without waiting for the slow infrared printer link You can cancel the re direction order and restore the use to the infrared printer with the Special SPrOff command When you turn off the RAD7 and turn it on again it always restores output to the infrared printer Note that the spectra that would be printed on the infrared printer are not sent to the serial port by Special SprOn 2 5 3 Special SPrOff Cancel the printer to serial port re direction so that output can go to the printer again 2 5 4 Special SetBaud Set the serial port bit rate The following standard speeds are available 300 600 1200 2400 4800 9600 and 19 200 bps The other communication settings are always 8 bit no parity and 1 stop bit The RAD7 remembers the serial port speed when you power down Note that at the
80. es eene enne eene esseneeessees LO is suos Late eia Gu O eai adt 18 The Ka Pad see heteg e e ea eerie bent eene te bd egeta 18 CommandoListi i osos to er e S T 18 Cc mc TP PME EN S 18 ASES TA A AN A A AA A A A A 18 Quick Save and Restart eee eee 19 Test Start Gnd Test SIop uui bete eee det b e fe bei iaa tipicas 20 TeSt NAVE AAA etude eed ed e EU Cte E te tort 20 Test Clero 1 o e Ain eeu e ec e et rte edes Jes de MUR e robo oe Idee Lot SUE 20 LOSE Purge i ec A n ole eU e o m tete 20 JestLooku un eot cepe tias aposto C atn DES EA EET tu e SEL Lu dah oud 21 Test Sleep usu ode e oa d Ee bt a 21 Test PERIERE tete t ete ov et eo ET Ba ON P P RAE GENUS 21 Test COM Ende Ie rae MA A nr AR 21 Bri c A IA 21 Data Redde Ree daa 21 Data ta RR MU A APRN A d t 22 Data Comi A AT A EE ete ete eaeque E E 22 IIA eere netnretretheetree tet tret tee tree nre nen nete enters eret trennen 23 IBI 2 EL 23 2 3 6 2 3 7 2 3 8 2 4 2 4 2 2 4 3 2 4 4 2 4 5 2 4 6 2 4 7 2 4 8 2 4 9 2 4 10 2 4 11 2 4 12 25 29 1 2 5 2 2 5 3 2 5 4 2 29 3 2 5 6 219 4 2 5 8 2 5 9 2 5 10 2 5 11 2 5 12 2 5 13 2 5 14 2 5 15 2 5 16 2 6 3 3 1 3 2 3 2 1 3 2 2 3 3 Pata Delete tol A A Mad Re anc e e dd iE DA 23 Data Renumber cm rcx Nu EON SN Me MUN aM SA DIE IC Ea cl 24 DATA POS Oui ote AUREOS e E DRE REN UNE PEE REP ER ORE ERAN BERI aa 24 so Me ETE 24 SetuptProtoGcol d e dee tede ette er ates et t iR Eu 24 Table 2 4 1 Pre
81. es of different energy Different isotopes have different alpha energies and produce different strength signals in the detector The RAD7 amplifies filters and sorts the signals according to their strength In SNIFF mode the 35 RAD uses only the polonium 218 signal to determine radon concentration and the polonium 216 signal to determine thoron concentration ignoring the subsequent and longer lived radon daughters In this way the RAD achieves fast response to changes in radon concentration and fast recovery from high concentrations 3 6 RAD Calibration and Data Correction The RAD7 depends on calibration to determine the radon and thoron concentrations it measures Built into the RAD7 firmware are three sensitivities 1 Sniffsensitivity counting only 218 Po for fast response 2 Normal sensitivity counting both 218 Po and 214 Po decays for higher precision 3 Thoron sensitivity counting 216 Po decays for thoron In calibration the RAD7 is exposed to a known concentration of radon or thoron and the count rates are measured Your radon calibration certificate gives the two radon sensitivities For thoron calibration a separate calibration letter gives the calibrated thoron sensitivity If thoron calibration is not conducted the thoron sensitivity is estimated to be half the radon Sniff sensitivity which is usually a reasonable estimate In either case when making a thoron measurement the RAD has to be s
82. et up and used in Thoron Protocol for the thoron reading to be valid In addition to the bare count rates in the three windows there are various corrections and calculations that may be applied to calculate more precise radon and thoron concentrations Some of these corrections are made automatically by the RAD7 itself Others are optionally applied using DURRIDGE s CAPTURE software after the data has been downloaded onto your computer The RAD7 s internal corrections and calculations are a Spill from window C into window B This is important when measuring thoron in the presence of radon 222 The DURRIDGE calibration system has no thoron in the sample air and it is therefore easy during Chapter 3 Basics of RAD7 Technology calibration to measure the spill and calculate it as a fraction of the count rate in window C b Bi 212 alpha decays occurring in the A window This is important when measuring low radon concentrations in the presence of high thoron The Bi 212 count rate is approximately half the Po 212 count rate whose decays are in the D window So again it is easy to measure the Po 212 count rate and use it to determine the Bi 212 count rate and consequently the correction to be applied to the 218 Po count rate in window A c In WAT 40 and WAT250 protocols used when recording RAD H20 data the RAD7 calculates the radon concentration of a water sample based on the radon concentration in the air loop A known
83. ey so that it auto repeats The arrow keys allow you to move right and left through the various commands looking for the action you want Enter Key When you have decided on a certain menu option you select it by pressing ENTER The enter key tells the RAD7 that you have made your selection You are telling it what you want it to do The enter key makes it happen 2 1 2 Command List The RAD7 command list has four command groups Test Data Setup and Special The Test group of commands controls the collection of new radon data The Data group retrieves data from memory outputs them and gets rid of old unwanted data The Setup group prepares the RAD7 to operate according to your requirements The Special group is a set of commands that are available when RADLINK the remote control software is loaded 2 2 Test The Test group of commands controls the collection of radon data and allows you to manipulate the current test test in progress You can start and stop data collection save or clear the current test or print the current test as it stands The Test commands do not allow access to stored data You have to go to Data for that 2 2 1 Test Status To see the status display enter the Test Status command Press MENU ENTER ENTER On the LCD display you will see 0501 Idle 00 30 00 Sniff 00000 On the upper left you see the current run number cycle number 0501 run 05 cycle 01 The mi
84. for very low leveled outdoor radon levels or special clean room applications this background may be significant With painstaking technique and long term monitoring it can be measured Very low level readings can then be corrected for background bringing the detection threshold of the instrument down below 0 02 pCi L 3 11 4 Long lived Radon Daughters After many years of use at elevated radon levels your RAD7 s detector will accumulate lead 210 an isotope with a 22 year half life Though Lead 210 is itself a beta emitter one of its daughters is polonium 210 which produces a 5 3 MeV alpha particle The RAD7 is able to distinguish this isotope by its energy and exclude it from all calculations We do not expect lead 210 buildup to contribute significantly to background in the RAD7 even after years of ordinary use 3 11 5 Contamination by Radon or Thoron Producing Solids If radon or thoron producing solids such as radium 226 or thorium 228 become trapped in inlet hoses or filters they may emanate radon or thoron gas that will be carried through the filters and into the instrument Certain dusty soils may contain enough of these isotopes to make this scenario possible If you suspect this kind of contamination please call DURRIDGE We would like to discuss your experience with you and help you solve your problem 3 11 6 Other Alpha Emitters As long as you filter the incoming air stream there is little or no possibil
85. geny into a chamber for analysis The radon in the RAD7 chamber decays producing detectable alpha emitting progeny particularly the polonium isotopes Though the RAD detects progeny radiation internally the only measurement it makes is of radon gas concentration In short the RAD7 does not measure radon daughter concentrations working levels only radon gas concentrations 3 6 RAD7 Solid State Detector The RAD s internal sample cell is a 0 7 liter hemisphere coated on the inside with an electrical conductor A solid state Ion implanted Planar Silicon alpha detector is at the center of the hemisphere The high voltage power circuit charges the inside conductor to a potential of 2000 to 2500V relative to the detector creating an electric field throughout the volume of the cell The electric field propels positively charged particles onto the detector A radon 222 nucleus that decays within the cell leaves its transformed nucleus polonium 218 as a positively charged ion The electric field within the cell drives this positively charged ion to the detector to which it sticks When the short lived polonium 218 nucleus decays upon the detector s active surface its alpha particle has a 50 probability of entering the detector and producing an electrical signal proportional in strength to the energy of the alpha particle Subsequent decays of the same nucleus produce beta particles which are not detected or alpha particl
86. he battery voltage This should range from about 6 00V to 7 10V A discharged battery less than 6 00 should be recharged as soon as possible A fully charged battery will rest at 6 40 to 6 50 V During a recharge the voltage will eventually rise above 7 00 V At no time should this read higher than 7 20V In the lower right is the pump current This number should vary from 00mA pump off to 80mA When the pump is running with a light load the current will range from 40 70mA When the pump is running with a heavy load clogged filter or blocked hose the current will go to 90mA or higher Pump currents above 90mA are considered a sign of trouble Try changing the filters and check for blockage Press gt again and you will see something like this HV 2218V 10 Li 02 S 0 21V This is a display of diagnostic values Ordinarily it will be of little interest to you The top line is the high voltage reading and duty cycle The range of normal values is from 2000 to 2500V and from 8 to 18 19 The lower left corner is the leakage current At room temperature this value will normally range from 0 to 10 Higher temperatures ordinarily cause this value to rise Excessive leakage current will result in noise in the lower energy end of the spectrum and will also cause broadening of the alpha peaks The lower right corner is the signal voltage from the analog circuit This number should be stable that is fluctuations
87. he command to change the cycle time to 1 hour is SETUP CYCLE 01 00 The command to turn off the audio beeper is SETUP TONE OFF The command to send over the data from run number 3 in comma delimited form is DATA COM 3 This particular command is described further in Chapter 6 3 3 Parsing RAD7 Data Besides the ordinary RAD7 commands additional commands have been implemented via RADLINK which add functionality and in some cases substitute for other commands These commands all start with the word SPECIAL One such command is SPECIAL STATUS which gives information about the current status of the instrument It is like TEST STATUS but does not continue to update the information every second instead it returns control to the user The third standard ASCII character ETX functions as a remote menu key that can be used to interrupt certain RAD7 activities and prepare it to accept a new command The RAD7 replies with a prompt the greater than character gt that tells you it is ready for a new command When 72 using a terminal emulator program you will always type commands at the prompt All commands must be followed by a carriage return the thirteenth standard ASCII character denoted here as CR No command will be activated until the CR goes through Once you have typed a command always end with a carriage return keystroke This key may be marked Enter or Return on your keyboard If the RAD7
88. he outer purge flow drying the incoming air as it moves through the device The DRYSTIK is available in three variants based on the length of Nafion tubing used The premium 144 ADS model is capable of bringing the relative humidity of air flowing at 0 15 L min down below 109 in less than four hours and maintaining the RH below 696 indefinitely without any desiccant This allows a RAD7 to operate under optimum conditions with the highest sensitivity and lowest operating cost Ata higher flow rate of 1 2 L min the DRYSTIK can bring the RH down below 1295 which is sufficient for enhanced sensitivity thoron measurement 67 For soil gas measurement the DRYSTIK provides a high flow capability supporting the detection of short lived thoron For radon the ability to lower the flow with the built in Duty Cycle Controller means that continuous soil gas readings may be made indefinitely without any risk of fresh air diluting the soil gas sample by diffusing from the surface down to the extraction point Given its versatility the DRYSTIK is effective for a wide range of applications The DRYSTIK Model ADS 3R Chapter 6 PC Connectivity 6 PC Connectivity 6 1 PC Connectivity Basics The RADT s built in serial port allows you to transfer radon data to your computer and to communicate with the device remotely in real time DURRIDGE provides a free software utility for Windows and Macintosh OS X CAPTURE which make
89. icator of the radon level at any location This is not only because a short term reading is less precise but also because it does not average out the fluctuations in radon level through a typical day The EPA protocol calls for a measurement to cover at least two days Quite often the indoor radon concentration tends to be higher in the early morning after a cold night and lower at the end of a warm day Furthermore the radon concentration typically takes hours to recover from open doors and windows so unless the house was closed up tight for many hours beforehand the spot reading radon level will be significantly lower than an 55 average taken over several days in closed house conditions For this spot reading the sampling point should be away from walls and floor Thoron is not an issue in this measurement so the larger laboratory drying unit may be used instead of a small drying tube The cycle time may be left at five minutes At least four better six cycles should be taken of which the first two should be ignored Alternatively increase the cycle time to 10 minutes or more and ignore the first reading To measure a radon level of 4 pCi L with a standard deviation of no more than 10 needs a run of one hour six cycles of ten minutes say 44 Grab Sampling 4 4 1 Applicability The ability of the RAD7 to grab a collected sample is useful when it is not possible to take the RAD7 to the location to
90. icle when it decays but with an energy of 6 00 MeV rather than radon s 5 49 MeV When polonium 218 decays it transforms to lead 214 also a radioactive solid But lead 214 has a half life of 26 8 minutes and it emits beta radiation rather than alpha radiation When lead 214 decays it becomes bismuth 214 also a radioactive solid and a beta emitter Bismuth 214 has a half life of 19 8 minutes and transforms to polonium 214 when it decays Polonium 214 is a bit different It has a half life of only 164 microseconds 0 000164 seconds and it emits a 7 69 MeV alpha particle when it decays When polonium 214 decays it becomes lead 210 which has a half life of 22 3 years This means that an average lead 210 nucleus takes 1 443 times 22 3 years or 32 2 years to decay Because of its long half life we usually ignore lead 210 as a factor in radon measurement though it 33 adversely affects the background of some instruments not the RAD7 Lead 210 eventually undergoes beta decay to Bismuth 210 which quickly 5 days half life undergoes a further beta decay to Polonium 210 Polonium 210 has a half life of 138 days and decays with a 5 30 MeV alpha particle to Lead 206 which is stable The 5 30 MeV alpha particle from Polonium 210 creates unwanted background in most radon monitors but not in the RAD 3 2 2 Radon 220 Thoron Similarly to radon 222 every radon 220 thoron nucleus eventually decays through a sequence of 5 tr
91. iffing for thoron Note however that for every 66 counts in window D there will be 34 counts in window A This is because of the two way split from Bismuth 212 So in calculating radon concentration the RAD7 corrects the counts in window A for any thoron daughters that show in window D 3 10 Modes Sniff and Auto Old radon daughters can be a real pain in the neck if you can t tell them apart from new radon Most radon monitors don t help you at all here but the RAD7 does Waiting around for equilibrium is also a trial if it means sitting around for more than 2 hours It is possible to calculate your way out of that problem but the old radon always comes back to bite you With the RAD the solution is simple and painless Put the RAD7 in SNIFF mode SNIFF mode means that the RAD7 calculates radon concentration from the data in window A only It ignores window C Now the instrument responds to changes almost instantaneously Hit a hot spot No problem In SNIFF mode you can purge the sample chamber and in 10 minutes you re ready to measure low levels again with reasonable accuracy You can move from point to point in minutes looking for radon entry points in foundation cracks or test holes For continuous monitoring in one location over many hours NORMAL mode is the way to go NORMAL mode means that the RAD7 uses both radon peaks A and C to calculate concentration With double the count rate you increase the pre
92. ill start running and the LCD display will go to the first status window The house should remain in closed condition for the duration of the run At any time the status windows can be viewed The relative humidity temperature and battery voltage are all parameters that are worth observing Rising relative humidity may indicate that the desiccant is exhausted or that there is a leak in the sample path The temperature reading gives a base for future reference see below A dropping battery voltage may indicate that the power is not connected 4 2 7 Security and Quality Control For a good measurement it is essential that the RAD or any measurement device for that matter remain in its place and the house remain closed throughout the run Anti tampering tapes are available for the windows and doors A soft plastic adhesive such as Blue Tack HOLDIT or Tac N Stik under the RAD will stick better the first time than in subsequent placings An experienced hand can tell if the RAD7 has been moved But perhaps the best anti tampering defense is the data itself With the time resolution in the data provided by the RAD7 anomalies are clearly revealed A 52 sudden change in radon concentration and in air temperature during the measurement is a strong indication of tampering either by moving the instrument or by opening windows The key pad lock prevents tamperers from looking at the data or interfering with the measure
93. ing point The air outlet should be left in the container so that the RAD7 becomes surrounded by clean and dry air 7 1 Accessories Usage and Care 7 1 1 Desiccant Two sizes of desiccant tubes are supplied In the NORMAL mode use the large 2 diameter tube laboratory drying unit This unit will last for days under continuous operation at high humidity before it needs regeneration When used as a Sniffer the small desiccant tube is recommended It will last for several hours before replacement or refilling of the tube is necessary To regenerate the desiccant the granules should be removed from the tube and spread evenly in a thin layer on a metal or Pyrex glass tray Heat at about 200 C 400 F for at least two hours or until granules turn uniformly blue Allow the desiccant to cool in a closed but not airtight container before refilling the acrylic laboratory drying unit or small drying tube The following sections provide insight into how long the desiccant will last in various scenarios 7 1 2 Laboratory Drying Unit The column holds approximately 500 grams of Drierite desiccant This desiccant can adsorb at least 10 of its weight in water so the water capacity of the column is at least 50 grams The RAD7 pump develops a flow rate of about 1 liter per minute With the RAD7 set for continuous monitoring with timed pump operation the pump operates 20 to 3096 of the time We will assume an average flow rate of 0 3 l
94. inlet fitting male Luer type These filters block ultra fine dust particles and all radon daughters from entering the RAD7 test chamber The filters are manufactured in various pore sizes by several companies including Millipore and SRI We favor pore sizes of 1 0 microns or less pore sizes as small as 0 4 microns can be used with the RAD7 pump 76 The filter should be replaced when it has become noticeably discolored or has clogged enough to impede the flow of air If you cannot suck air easily through the filter yourself it s time to change the filter When you operate the RAD7 in construction areas or basements dust can quickly build up in sampling hoses drying tubes and inlet filters This dust will slowly clog the filter restrict air flow and create strain on the pump You will have to replace the inlet filter To greatly slow the buildup of dust we recommend that you attach a prefilter to the intake of the sampling hose to prevent coarse dust particles from entering Then the inlet filter will remove the ultra fine dust particles that pass through the prefilter and drying system We find that automotive gasoline filters can serve as convenient and inexpensive prefilters A particular filter intended for Volkswagens is a small disposable clear plastic capsule containing a pleated paper filter This filter effectively removes most dust from the air stream greatly extending the life of the inlet filter You can
95. internal memory capacity of 1 000 cycles will last nearly 12 weeks If data is periodically downloaded to a PC and erased from the RAD7 there is no limit to the measurement duration With the laboratory drying unit used to dry the sampled air the desiccant will have to be replaced every 7 to 14 days depending on the humidity The RAD7 needs external power for indefinite operation but can survive without loss of data an interruption of power lasting up to 50 hours or more depending on the condition of the batteries For any other measurement period you will need to set the parameters yourself The cycle time times the number of recycles gives the duration of the total measurement In almost every case for continuous monitoring choose Mode Auto Thoron Off and Pump Auto Once the RAD7 switches after three hours to NORMAL mode the counts are included from Window C which come from Po 214 atoms These were once radon atoms that entered the measurement chamber as much as an hour or more beforehand Therefore in NORMAL mode the RAD7 is averaging the radon concentration from less than 20 minutes ago Po 218 with the radon concentration from less than three hours ago Po 214 So fora long testin NORMAL mode the cycle time should be set to one hour or more Where there is a requirement for a fast response and detailed time resolution the cycle time may be set as short as half an hour or even 20 minutes but the
96. is being measured 4 8 Harsh and Hazardous Environments 4 8 1 Splashing Water Extra care should be taken to prevent water from splashing onto the RAD7 face plate or entering the instrument through the RAD7 inlet Either situation can cause malfunctions and corrosion If the RAD7 is to be operated in a harsh environment such as a cave or mine where water may splash around the RAD7 may be protected in two Ways a A thin plastic film may be stretched over the face plate and down the sides of the case It can be pushed down around the hose connectors and plugs can be pushed into data 61 and power sockets pushing the plastic film down around the pins The result is to make the instrument almost waterproof b The RAD7 can be enclosed in a large transparent plastic bag with the opening gathered and held with an elastic band around the incoming air sample tubing c The dry air from the RAD7 outlet may be exhausted to the interior of the bag ensuring that the operating environment is clean and dry If water ever enters the RAD7 immediate steps should be taken to minimize the impact on the instrument For detailed instruction see Section 8 4 Water Catastrophe 4 8 2 Dusty Environment Dust may contaminate the desiccant and cause elevated radon background due to radon emitted by trace amounts of radium deposited in the desiccant by the contaminating dust To prevent this a dust filter should be attached to the tubing
97. istical uncertainty of the counts per minute and percent of the total counts included within that window NOTE The RAD7 does not store spectra from old cycles so no spectra will print from memory even if the printer format is Long If you need a spectrum be sure you print while the test is still running If no data are available to print the RAD7 will beep and display No tests stored To abort a printout press the menu key then press the printer paper advance button 2 3 3 Data Com The RAD7 has an RS232 port that can transfer data to your computer Status must be Idle To send a run of data to the serial port select gt Data Com followed by the two digit run number When ready push ENTER Chapter 2 Basics of RAD7 Operation The following message will appear on the display as the data 1s sent Data transfer When the data transfer finishes the RAD7 will beep To enable your PC to receive data appropriate software should be running A terminal emulation program or CAPTURE the data link software provided with the RAD7 may be used See Chapter 6 for more details on data communication 2 3 4 Data Summary To print a summary report and time graph ofa run s data select gt Data Summary followed by the two digit run number The following information will be printed Run 31 Begin 01 Jun 99 12 49 Serial 00500 Cycles 048 Mean 0 77 pCi l S D 0 27 pCi l High 1 41 pCi l Low 0 20 pCi l where
98. iters per minute The following table shows the expected lifetime of a charge of desiccant in the Laboratory Drying Unit under various temperature and humidity conditions Table 7 1 2 Laboratory Drying Unit Life RH Deg C Deg F Column Life 3096 20 68 23 1 Days 3096 35 95 9 8 Days 5096 20 68 13 3 Days 5096 25 77 10 0 Days 90 10 50 13 7 Days 90 15 59 10 0 Days 90 20 68 7 4 Days 90 25 77 5 5 Days 90 30 86 4 2 Days 7 1 3 Small Drying Tube The small drying tubes each contain 30 grams of Drierite desiccant The water capacity of each tube is 3 grams We will assume that the RAD7 pump operates continuously for an average flow rate of 1 0 liter per minute The following table shows the expected lifetime of a small drying tube under a variety of temperature and humidity conditions Table 7 1 3 Small Drying Tube Life RH Deg C Deg F Tube Life 3096 20 68 10 Days 3096 35 95 4 2 Days 5096 20 68 5 7 Days 5096 25 77 4 3 Days 90 10 50 5 9 Days 90 15 59 4 3 Days 90 20 68 3 2 Days 90 25 77 2 4 Days 90 30 86 1 8 Days Chapter 7 Maintenance 7 1 4 Cascading Drying Tubes To extend the time before desiccant depletion you may cascade several drying tubes in series Two factors limit the number of drying tubes you can use First each additional drying tube or column adds a small amount of resistance to the air flow so the pump will hav
99. ity for contamination of the instrument with other alpha emitters Virtually all solids will be stopped by the inlet filters The only naturally occurring alpha emitting gas other than radon and thoron is radon 219 or actinon Actinon which has a Chapter 3 Basics of RAD7 Technology very short half life less than four seconds results from the decay of naturally occurring uranium 235 But since uranium 235 is so much less abundant than uranium 238 the ancestor of radon 222 we do not expect to ever see actinon in significant quantities apart from even more significant quantities of radon 3 11 7 Beta and Gamma Emitters The RADT s solid state alpha particle detector is almost completely insensitive to beta or gamma radiation so there will be no interference from beta emitting gases or from gamma radiation fields The most likely effect of high levels of beta or gamma radiation will probably be an increase in detector leakage current and increased alpha peak width Typical environmental levels of beta and gamma emitters have absolutely no effect on the RAD7 3 12 Precision amp Accuracy 3 12 1 Dry operation Precision means exactness of measurement with regard to reliability consistency and repeatability Accuracy means exactness of measurement with regard to conformity to a measurement standard An accurate instrument is necessarily precise but a precise instrument can be inaccurate due to mis calibration for exam
100. ke 48 hours Never store the RAD7 without first recharging the batteries If you intend to store the RAD7 fora long period of time you must recharge the batteries at least every four months as they can be damaged by self discharge on the shelf Otherwise you may have to replace the batteries before you can use your instrument again Battery voltage can be read from the Status display and appears on printed output A fully charged battery will rest at 6 40 to 6 50V As the battery discharges its voltage drops steadily to 6V If the battery voltage ever goes below 6 00V it is fully discharged and should be recharged as 7 2 Operating ranges soon as possible As the battery charges its voltage rises steadily until it goes above 7V Consider the battery fully charged if it charges at or above 7V 7 4 7 Real time Clock and Non volatile Memory The RAD7 s Real Time Clock RTC and Non Volatile Memory unit NVRAM allows the RAD operator to switch power off without losing data or disrupting the clock time and date These functions are powered by a lithium cell with an expected lifetime of ten years 7 1 8 Printer and Adapter Infrared printer documentation is provided in Appendix A at the end of this manual It is important to familiarize yourself with its operation and to be aware that the printer operates through an infrared optical link and should be positioned on the top of the RAD7 to match the data link on the dete
101. l equal the increase in radon concentration times the flow rate The precision will depend on the radon concentration and the duration of the measurement 5 4 3 Closed Loop Configuration In a closed loop configuration the system is first purged then sealed Next the radon concentration within the loop is monitored in SNIFF mode with short e g 15 min cycle times for a few hours It is necessary to know the total volume of the Chapter 5 Using RAD7 Accessories closed loop system For this purpose the volume inside the RAD7 may be taken as 800mL The initial rate of increase in radon concentration neglecting the first 15 min cycle multiplied by the volume gives the rate of radon emission A reduction in the slope as the radon level builds up may be due to leaks in the system or to a reduction in the net emission DURRIDGE s CAPTURE software can be used to position a slope line on the graph and inspect the change in radon concentration over time The line should be set to begin after the initial response delay and before any observable drop from either leakage or decay CAPTURE will express the slope of the line in the units of your choice 5 4 4 Very Low Emission Rates Very low emission rates can be measured by placing the sample in an airtight container with sealable inlet and outlet valves and allowing the ingrowth of radon to occur over at least a week after which the ingrowth must be calculated and preferably a m
102. le in MeV units Peak in window C at 7 69 MeV Old radon Alpha Energy Spectrum 30 Chapter 3 Basics of RAD7 Technology 3 BASICS OF RAD7 TECHNOLOGY HOW IT WORKS 3 1 Introduction This chapter deals with a number of fundamental facts concerning radon and thoron their measurement in general and their measurement specifically with the RAD7 It is not necessary to master the underlying physics to become proficient in the use of the instrument but some understanding of what is happening is helpful It is recommended that the user read the entire manual including this chapter on first acquiring the instrument and then again after gaining some experience in the field 3 2 Radon Decay Chain When the earth was formed billions of years ago there were probably many radioactive elements included in the mix of material that became the earth Three of interest have survived to this day namely uranium 235 uranium 238 and thorium 232 Each has a half life measured in billions of years and each stands at the top ofa natural radioactive decay chain A radioactive element is unstable At some indeterminate moment it will change to another element emitting some form of radiation in the process While it is impossible to predict exactly when the transformation of an individual atom will take place we have a very good measure of the probability of decay within a given time slot If we started with a very large number
103. le time multiplied by the number of cycles or Recycle number To adjust the Recycle number use the gt Setup Recycle command 2 4 3 Setup Recycle How long a test do you want and how often do you want the RAD7 to take a reading a cycle You determine the length of your test by choosing both the length and number of cycles If you make a reading every 30 minutes you will need 48 cycles to get a 24 hour test In this case 48 is the Recycle number Use Setup Recycle to set the total number of cycles in a complete run Multiply Cycle time by Recycle number to determine the total duration of the run Select gt Setup Recycle Push ENTER and you will see something like this Recycle 48 Use the arrow keys to change the Recycle number and press ENTER to complete the selection Recycle number may be set from 00 to 99 If 00 is selected then the number of cycles is assumed to be infinite Select 00 if you want the RAD7 to collect data indefinitely or to go beyond the 99th cycle After the 99th cycle the RAD7 will then simply start a new run and continue collecting data Data collection will stop only when the operator intervenes or when the memory completely fills up 25 2 4 4 Setup Mode Select gt Setup Mode to change the RAD7 mode of operation Five modes are available Sniff Auto Wat 40 Wat 250 and Normal SNIFF mode is used when you want to follow rapid changes of radon concentration In SNIFF mode the
104. lete HP 82240B printer is that the HP printer had to have external 12V power supplied in order to stay awake for more than 10 minutes between printouts The newer printer models do not accept external power The printer should be placed on the RAD7 face plate between the green lines as indicated Because the print mechanism uses thermal technology only thermal paper will work Detailed instructions are provided in Appendix 1 at the end of this manual If the printer is placed in position and switched on before switching on the RADT it will print out identity information and a review of the setup before the RAD7 goes to gt Test It is good practice to do this if the measurement data are to be printed out because it automatically provides a header for the data printout with instrument identity and setup DURRIDGE RAD7 Vers 2 5f 991128 Model 711 Serial 00512 Calib 20 MAY 11 Last used FRI 21 MAY 11 17 30 Current settings FRI 21 MAY 11 19 09 Protocol 2 Day Cycle 00 60 Recycle 48 Chapter 2 Basics of RAD7 Operation Mode Auto Thoron Off Pump Auto Tone Geiger Format Short Units pCi L EC At the end of every cycle the printer will print the data of that cycle according to the format setting In short format it prints 0102 2 69 0 73 p Sniff FRI 21 MAY 99 19 41 26 8 EC RH 7 B 7 06V With the run and cycle number radon level two sigma uncertainty units and mode in the top row date and time
105. llected simultaneously and accessed by CAPTURE to determine the final result As compared to the RAD AQUA the Water Probe takes longer to make a spot measurement However it does not require a pump so power requirements are reduced 5 3 Soil Gas Sampling 5 3 1 Application The radon concentration in the soil gas surrounding a house is one of many parameters that impact radon health risk The construction of the house the porosity of the soil the height of the water table and several other factors are all important Even if there is no radon in the surrounding soil the house may still be at risk if it has a well in the basement or is built on rock over a fissure Regardless it is often of interest to determine the radon concentration in soil gas Thoron is usually associated with radon in the soil When measuring soil gas it is therefore particularly useful to determine the thoron content as well as the radon content Should there be significant thoron it may be used as a tracer to find radon entry points inside the house See Chapter 4 3 2 for details 5 3 2 The Soil Gas Probe Accessory The cost and complexity of a soil gas probe increases with the depth to which it can be inserted A variety of probes are available from DURRIDGE the simplest of which will penetrate to a depth of 3 feet 5 3 3 Soil Gas Probe Preparation For full details on using a soil gas probe please refer to the appropriate user s manual foun
106. llows you to turn off most of the electronic circuits with the power switch on in order to conserve battery charge A fully charged RAD7 should be able to sleep for about one week on batteries alone Press the menu key to wake up the RAD7 The Sleep function was for older models that did not have the Real Time Clock RTC and Non Volatile Memory NVRAM options New and upgraded instruments may be shut down completely power switch off without losing any stored data or clock 21 2 2 8 Test Print The gt Test Print command calculates results for an incomplete or suspended test cycle and prints them according to the print format that is currently set Spectrum output is available by selecting gt Setup Format Long beforehand If you wish to abort printing press the MENU key The run number and cycle number that ordinarily appear on printed data are replaced by 0000 to signify that the cycle is not completed 2 2 9 Test Com The Test Com command outputs the results for an incomplete test cycle to the serial port If you wish to abort output press the menu key The run number and cycle number that ordinarily appear with the data are replaced by 0000 to signify that the cycle is not completed 2 3 Data The Data group of commands retrieves data from memory displays it prints it reports it graphically and outputs it to the serial port The Data group also includes commands for managing memory The memory will
107. ment A detailed and systematic quality control protocol must be established by any user seeking certification This should include a description of the measurement process and the steps taken to ensure that the readings are reproducible The RAD7 is too accurate for any procedure in the field to be able to verify that it is working within specifications However it is good practice on a regular basis to compare the RAD7 readings with some other device such as a passive charcoal collector The two devices should be placed close together with the RAD7 sampling point near to but not touching the charcoal collector The measurements should also cover the same time period The charcoal reading may then be compared with the RAD7 mean for the period Remember however that some charcoal devices and labs may give readings which are in error by as much as 25 If the RAD and the charcoal device differ by more than 1096 repeat the comparison as soon as possible preferably with a different charcoal device from a different lab Look at the RAD7 cumulative spectrum printed out at the end of a run to see if it appears normal If the RAD7 mean is consistently significantly different from the readings of other devices in side by side tests or if the spectrum looks abnormal please call or email DURRIDGE for advice In any case we recommend that the RAD7 be returned to DURRIDGE Company for recalibration annually An excellent q
108. molecules gathers around each of them These cluster molecules move more slowly in the electrostatic field and thus there is more time for the 218 Po atoms to become neutralized en route to the detector surface and therefore lost So with high humidity the sensitivity of the instrument drops In addition the high voltage 2 200V that maintains the electrostatic field is from a high impedance source Excessive humidity inside the chamber makes it more difficult to maintain the high insulation resistance necessary At normal room temperature and with good desiccant in the air sample path the humidity in the measurement chamber at the start of a measurement will quickly be brought down below 10 RH and will eventually settle below 6 In these conditions the collection has maximum efficiency and there is no humidity correction required Should the desiccant expire and or should the operating temperature rise well above normal room temperature the absolute humidity may become significant and a humidity correction may be required to compensate for the drop in sensitivity While high humidity reduces the sensitivity ofa RAD7 CAPTURE offers an automatic correction of the data bringing readings back close to dry values Please note however that the precision will be degraded compared with readings taken in dry conditions See Chapter 6 42 3 12 3 Concentration Uncertainties Obtaining accurate readings of a low radon concentrations
109. n both the closed loop and open loop modes are steady state measurements 5 4 6 Surface Emission DURRIDGE offers two surface emission chambers one for solid hard surfaces and another for soft soil surfaces Each consists of an circular plate which is sealed against the surface under investigation The Solid Surface Emission Chamber accomplishes this using a rubber seal while the Soil Surface Emission Chamber uses a penetrating metal rim The measurement procedure is similar to that of the Bulk Emission Chamber described above Once the total emission rate within the enclosure has been calculated it may be divided by the area of the surface within the sealed boundary to determine the emission per unit area The Bulk Emission Chamber Chapter 5 Using RAD7 Accessories The Surface Emission Chamber 5 5 Supporting Accessories 5 5 1 Overview DURRIDGE offers additional RAD7 accessories which improve the accuracy of radon and thoron reporting by optimizing operating conditions The RAD7 is able to detect radon in concentrations of up to 20 000 pCi L 750 000 Bq m For applications involving higher concentrations of radon DURRIDGE offers the Range Extender a device which removes 90 of the radon from the air sample entering the RAD7 giving the instrument the ability to operate in conditions under which it would otherwise be unable to cope final concentration figure is attamed by multiplying the reported result by
110. n a discharged state they will lose capacity After running the RAD7 on its batteries please recharge them as soon as possible by plugging in the unit With careful use the batteries will last five years or more Finally there is one security feature that is sometimes inadvertently set by an inexperienced though authorized user namely the key pad lockout If the key pad ceases to function and all you see is DURRIDGE RAD7 on the display just do the following Hold down the ENTER and two arrow keys until you hear a beep release the three keys and immediately push MENU You should then be rewarded by gt Test on the display If the tone was set to OFF then you will not hear the beep so hold the three keys down for three to four seconds before releasing them and pushing MENU try hold down times a little longer or shorter if at first you do not succeed DURRIDGE Company Inc European Representative 524 Boston Ra Billerica MA 01821 USA Dr Martyn J Key Tel 978 667 9556 Fax 978 667 9557 c o Radiansa Consulting S L Email Service durridge com Montcalm 20 22 17006 Girona Spain Web www durridge com Tel 34 972 243232 10 Chapter 1 Getting Started 1 GETTING STARTED YOUR FIRST DAY WITH THE RAD7 1 1 Unpacking First make sure you have everything you are enclosed with the shipment If anything is supposed to have Take the materials out of the missing please email DURRIDGE immediately packing boxes and see if you
111. n the following table Table 3 12 Typical RAD7 precision based on counting statistics only NORMAL mode with sensitivity 0 500 cpm pCi L Table values are two sigma uncertainty or 9596 confidence interval in units of pCi L percent 1 pCi L 4 pCi L 20 pCi L 100 pCi L 1 hr 0 37 37 0 73 18 1 64 8 2 3 65 3 7 2 hr 0 26 26 0 52 13 1 15 5 8 2 58 2 6 6 hr 0 15 15 0 30 7 4 0 67 3 4 1 49 1 5 24 hr 0 07 7 4 0 15 3 8 0 33 1 796 0 74 0 796 48 hr 0 05 5 3 0 10 2 696 0 23 1 296 0 53 0 596 72 hr 0 04 4 396 0 09 2 196 0 19 1 0 0 43 0 496 41 Chapter 3 Basics of RAD7 Technology 3 12 2 Humidity Correction Much of the superior functionality of the RAD7 is a result of the high precision real time spectral analysis it performs The high resolution of the energy spectrum is obtained by precipitating the radon daughters formed by the decay of radon right onto the active surface of the alpha detector The high sensitivity of the RAD7 is a result of the large collecting volume of the measurement chamber The combination of a precipitation process and large collecting volume means that humidity inside the measurement chamber will affect the sensitivity of the instrument The affect is a function of the absolute humidity specifically ions in the presence of water vapor will attract water molecules as they are polar until a cluster of 6 10 water
112. nd a rubber roller is attached to the lid of the mechanism When the lid is closed the paper is pinched between the rubber roller and the print head to give a close alignment and a consistent pressure A1 1 2 Features Wireless printing IrDA standard or HP protocol Small size Quiet and fast printing Direct line thermal printing Easy loading paper Easy maintenance and head cleaning User settable parameters using external buttons e Self test function A1 1 3 Power Switch The Power switch located on the left side of the printer is used to turn the unit ON and OFF A1 1 4 Indicator LEDs Power LED Green Glows steadily when the printer is turned ON Error LED Red Flashes once per second when the printer is out of paper the buffer is full or when the print head temperature exceeds 140 F 60 C This LED will also flash one time when the printer is placed into its set up mode refer to Section Set Up Mode A1 1 5 Push Buttons FEED Button Momentarily press the FEED button to advance the paper Press and hold down to feed paper continuously This button in conjunction with the ON OFF switch is used to start the printer s self test function refer to the Self Test section When the printer is in its set up mode this button is used to modify the selected printer parameter refer to the Set Up Mode section SEL Button Used in conjunction with the ON OFF switch to place the printer
113. necting the RAD7 to a computer using the StarTech USB to Serial Adaptor 69 Connecting the RAD7 to a computer using the KeySpan USB to Serial Adaptor 69 6 2 CAPTURE SoftWare e ier tun or ER naw ds 70 6 2 1 CAPTURE Installation eet ette etre e E SN A Mus 70 CAPTURE Software running in Windows 7 70 6 2 2 Feature Summary eneore E 71 6 2 3 Downloadimng RAD 7 Dala ttes quete qd ane e nS 71 6 2 4 Graphing and An lysis use edet E Pee EP ee ree e bets 71 6 2 5 Real Time RAD7 Monitoring esses eene nn 71 6 3 RAD Communication Protocol nia 72 6 3 1 Communication Requirements esee eterne trennen rere tenes nen nes 72 6 3 2 RAD7 Command Format essere terere enne 72 6 3 3 Parsing RADZ Dald ettet ere re ables eee e eo ae Ee ete eee sh ERR een 72 Table 6 3 3 RAD7 Data Record Content 73 6 3 4 Terminal Emulator TIPS diese et e eese bec eb eene efe tbe tegere 74 6 4 Serial Port Speciticdtiolbs de iue tite tea 74 6 4 1 Communication Protocol AAA O 74 Table 6 4 1a Serial Port Pin Assignments 74 Table 6 4 1b Communication Parameters 74 6 4 2 Extending the RS 232 Range iu e eae tet etin 74 T MEN NN 7D 7 1 Accessories Usage and C Are ouo Ser oor od e i su t DR qp i Ed LS 7 1 1 DESTA A ac 75 7 1 2 Laboratory Drying Uit iria 75 Table 7 1 2 Laboratory Drying Unit Life 75 7 1 3 Small Drying Tube ost sto est ee o M cte T 75 Table 7 1 3 Small Drying Tube Life 75 7 1 4 Cascading Drying Tubes i qe a b He e petes de
114. nels 30 to 40 Window G normally has few counts even when Window F shows a high count rate High Noise or Po210 Window The total counts in the region of the 5 31 MeV alpha particle due to Po210 polonium 210 the grand daughter of Pb210 lead 210 Since lead 210 22 year half life results from the decay of the radon progeny we measure this isotope will build up on the detector s sensitive surface through sustained measurement of very high radon concentrations or many years of normal use This window is not used in calculating radon levels so the RAD7 will function well even with this isotope present and the background will not be affected Composite window for Others The RAD7 groups windows E F G and H together to form the composite window O Window O catches all the counts that did not go into the major windows A B C and D If window O consistently receives more than 30 of the total counts you should inspect the spectrum printout for signs of trouble 3 9 Isotope Equilibrium Take a RAD7 that is completely clean with no radon or daughters inside What does the detector see Close to nothing Less than one alpha count per hour due to unavoidable contamination of the materials of the instrument s construction That is the instrument s intrinsic background It is ignored by most people as of no consequence Intrinsic background may add 0 01 pCi L to a typical measurement far below the radon concentration of out
115. nge is cause for further study of the instrument and an examination of the spectrum Chapter 8 Troubleshooting 8 8 1 Display TROUBLESHOOTING 8 1 Blank Display If the unit is switched on the most likely cause of a blank display is discharged batteries Please see Chapter 7 1 6 Make sure the RAD7 is properly plugged in to an external power source and is switched on If the instrument has been run on the batteries and not recharged or if it has been left untouched for a lengthy period the batteries may be completely flat In that case the instrument should be left plugged in and switched on for many hours preferably 24 hours or more If this fails to restore the display the RAD7 should be returned to DURRIDGE Company for service 8 1 2 Frozen Display If the display shows DURRIDGE RAD7 and does not respond to key strokes the key pad has been locked Hold down the ENTER and two arrow keys until you hear a beep release the three keys and immediately push MENU You should then be rewarded by Test on the display If the tone was set to OFF then you will not hear the beep so hold the three keys down for three to four seconds before releasing them and pushing MENU try hold down times a little longer or shorter if at first you do not succeed Please refer to paragraph 2 2 6 8 1 5 Incomplete Or Garbage Characters Incomplete or garbage characters may indicate a faulty LCD display Please return RAD7 t
116. nging the background down after exposure to moderate amounts of radon In order to dry out the RAD7 without using up much desiccant connect the hoses from the RAD to the drying unit as a loop When the pump runs the same air will circulate repeatedly through the desiccant This procedure will Chapter 2 Basics of RAD7 Operation efficiently remove residual moisture from the RAD This does not introduce any fresh air and so does not change the radon level in the instrument but you can make a measurement of the background while it is set up in this configuration To end the purge answer Yes to the question Stop purge which appears on the display Alternatively you may push MENU to end the purge 2 2 6 Test Lock If you push ENTER when this is displayed it will lock the key pad The LCD display will just show DURRIDGE RAD7 Nobody will be able to unlock the key pad unless they know the secret If the key pad was locked during a measurement then the readings will continue as normal with the RAD7 recording all the data until the end of the run Switching the unit off while locked will stop the measurement but the key pad will still be locked when the RAD7 is switched on again To unlock the key pad hold the ENTER and both arrow keys down all together for 3 4 seconds or until the unit beeps then release the three keys and push MENU immediately 2 2 7 Test Sleep The gt Test Sleep command a
117. not possible to start averaging the readings to reduce uncertainty only after the first two cycles It is possible to measure radon and thoron concentrations simultaneously but since their requirements are sufficiently different it may be desirable to optimize the measurement first for one gas and then for the other For radon it is advisable to select SNIFF protocol and then change the cycle time to 10 minutes After starting a run the first reading can be ignored with only the second and subsequent readings being used As more readings are recorded more precise concentrations will be obtainable Chapter 3 Basics of RAD7 Technology Occasionally a concentration uncertainty greater than the base value may be reported e g 0 00 83 1 Bq m3 Such values are typical for cycles containing zero counts This should not be taken to suggest that a negative concentration may have occurred The RAD7 does not report different positive and negative uncertainties and it is expected that the user will recognize that the negative uncertainty can never be greater than the base value of the reading 43 Chapter 3 Basics of RAD7 Technology 3 13 Spectrum Examples 3 13 1 Operational Radon Spectra IA B C D A Idealized radon in equilibrium This is what you would see if both the detector and electronics reached theoretical perfection At full equilibrium both peaks are at the same height A 6 00 MeV Po218 C 7 69 MeV Po214
118. now a that you were right in your suspicion and that you are indeed close to a radon entry point and b that thoron is present in the soil gas so you can concentrate on thoron for the rest of the survey Move the wand a foot or so in any direction to see if the window B cpm changes appreciably in the next cycle If there are few or no counts in window B then either the location is not a radon entry point or there is no appreciable thoron in the soil gas You must then keep the wand in that position for another 10 minutes or until the counts in window A start to rise rapidly If after fifteen minutes there are still only a few counts in window A and the radon concentration displayed at the end of the third 5 minute cycle is still very low then you can be confident that the position is not a radon entry point On the other hand a high radon concentration without thoron does not necessarily indicate a radon entry point if the whole basement is high In either case you need to note the reading on your sketch map and move to another likely point to repeat the process first looking for thoron If no thoron is found at any time then the map of radon concentrations will help to identify entry points Once thoron has been detected the whole search is made much easier Reset the cycle time to two minutes Spend one complete cycle at Chapter 4 Using the RAD7 each suspected radon entry point observing the counts in windo
119. nth 2 digit value 4 Day 2 digit value 5 Hour 2 digit value 6 Minute 2 digit value 7 Total Counts Integer indicating total counts recorded during test 8 Live Time Expressed in minutes 9 Percent of total counts in win A These 4 windows will not always add up to 10096 since 10 Percent of total counts in win B counts can come into channels below or above these 11 Percent of total counts in win C windows 12 Percent of total counts in win D 13 High Voltage Level Ranges from 2200V to 2300V 14 High Voltage Duty Cycle Ranges from 0 100 typically 10 20 15 Temperature Measured in C or F depending on RAD7 setup 16 Relative humidity of sampled air Should be kept below 10 for most accurate test 17 Leakage Current Ranges from O to 255 Above 20 is cause for concern 18 Battery Voltage Below 6 00V is a discharged battery Does not affect accuracy of test but indicates need for recharge 19 Pump Current Ranges from 0 260mA Typically 40 80mA Above 100mA possible clogged filter or obstruction 20 Flags Byte Bit O indicates whether pump is in TIMED mode Bit 1 indicates whether pump ON continuously Bit 2 is not defined Bit 3 indicates whether tone is in GEIGER mode Bit 4 indicates whether beeper is activated Bit 5 indicates if spectrum will print after each test Bit 6 indicates if there are multiple recycle tests Bit 7 indicates whether RAD7 is in SNIFF test mode 21 Radon concentration Expressed in pCi l Bq m3 cpm or counts depending
120. o DURRIDGE Company for service 8 2 Readings 8 2 1 No Counts The total number of counts so far in any cycle is displayed in the bottom righthand corner of Status Window 1 If near the end of a cycle there are no counts or less than 10 say it probably means 80 the cycle length is too short Increase the cycle length to increase the number of counts in a cycle and to improve the precision of the individual readings gt Setup Cycle HH MM ENTER If with a cycle time of one hour or more the total count near the end of a cycle continues to be zero and it is known that there is radon in the sample then either the sample path is blocked or there is a fault with the RAD7 and it should be returned to DURRIDGE Company Check that air is flowing using any of the following measures a Feel the air exiting the outlet when the pump is running b Stop the outlet of the RAD7 and feel the buildup of pressure c Clamp the sample input tubing hear the change in pump sound and see the change in pump current third status window d Feel the suction at the sampling point 8 2 2 Excessive Uncertainty In Reading If the uncertainty in the reading is greater than the base concentration value or if there is a large scatter in the readings the cycle length is too short for the radon concentration being measured Increase the cycle time to reduce the scatter Four times the cycle time will produce half the scatter and half the un
121. o a computer using two different kinds of USB to Serial adaptors the Star Tech adaptor top and the Keyspan adaptor bottom Chapter 6 PC Connectivity External Power StarTech USB to Serial Adaptor Cable Computer with StarTech Adaptor DURRIDGE RAD7 Driver and CAPTURE Software Connecting the RAD7 to a computer using the StarTech USB to Serial Adaptor Null Modem Cable External Power USB Serial Adaptor Computer with USB Serial Driver USB B Cable DURRIDGE RAD7 and CAPTURE Software Connecting the RAD7 to a computer using the KeySpan USB to Serial Adaptor It is recommended that the RAD7 remain plugged into a USB port on the computer it is not into external power to prevent its battery from advisable to plug multiple adaptors into a single dying while it is connected to the computer USB hub Alternatively a multi port USB to serial adaptor may be purchased For connecting more than one RAD7 to a computer it is possible to use several USB to serial adaptors simultaneously with each plugged 69 Chapter 6 PC Connectivity 6 2 CAPTURE Software CAPTURE is intended to simplify the transfer of data from the RAD7 to a computer It also provides a wealth of graphing and data analysis options and offers the ability to export data to other programs for further review The software is available for Windows and Macintosh OS X This section serves as a brief introduction to the CAPTURE software
122. of atoms of a radioactive element we know quite precisely how long it would take before half those atoms had decayed though we could not identify the decaying atoms individually beforehand This time interval is called the half life of that particular element A natural radioactive transformation is accompanied by the emission of one or more of alpha beta or gamma radiation An alpha particle is the nucleus of a helium atom It has two protons and two neutrons Thus an alpha decay will reduce the atomic number by two and reduce the atomic weight by four A beta particle is an electron with its negative charge Thus a beta decay will increase the atomic number by one and leave the atomic weight unchanged A gamma ray is just a packet of energy so a gamma decay by itself would leave both the atomic number and atomic weight unchanged A decay chain is a series of distinct transformations A uranium 235 nucleus goes through a series of 11 transformations to become stable lead 207 A thorium 232 nucleus goes through 10 transformations to become stable lead 208 And a uranium 238 nucleus goes through 14 transformations to become stable lead 206 All three of these natural decay chains include isotopes of radon Radon 219 or actinon is a link in the uranium 235 chain You will probably never encounter actinon in indoor air due to its scarcity and short half life Radon 220 or thoron is part of the thorium 232 decay chain
123. often requires long cycle times because when there are zero or very few counts within a given timeframe the statistical uncertainty is proportionately high Radioactive decays obey Poisson statistics where the standard deviation one sigma is the square root of the count However at very low counts Poisson statistics underestimates the uncertainty To compensate the RAD7 defines sigma as 1 SQR N 1 where N is the number of counts Thus when there are no counts instead of reporting a nonsensical zero uncertainty the RAD7 reports an uncertainty value based on a two sigma 9596 confidence interval equivalent to t 4 counts for a cycle in which zero counts were recorded Typically an average count rate of 0 2 cpm i e one count in five minutes would indicate a radon concentration of about 36 Bq m3 but sigma would be 1 SOR N 1 or 2 4 counts and the reported two sigma value would be 4 8 counts Thus after 5 minutes the uncertainty would be reported as 0 96 cpm or 173 Bq m3 Large uncertainty values are often the product of the fact that it is impossible to measure low radon concentrations quickly Greater certainty can be achieved by increasing the cycle time and or by averaging multiple cycles In Sniff mode 218 Po which has a 3 05 min half life takes more than 10 minutes to reach equilibrium with the radon concentration in the RAD7 chamber Note that in Sniff protocol which uses 5 minute cycles it is important
124. old data to open up space for new data See Data Delete and Data Erase 2 3 6 Data Delete To delete an entire run of data select Data Delete followed by the two digit run number The display will prompt you for confirmation Delete run 31 No Press gt to find Yes then press ENTER to delete the run s data from memory and free the space for new data No other run s data will be affected After deletion of a run s data any attempt to retrieve the data will result in a No tests stored message The main purpose of the Data Delete command is to selectively free up memory space for new tests Do not confuse Data Delete with Data Erase which wipes out all runs of data from memory See also Data Free Data Renumber and Data Erase Chapter 2 Basics of RAD7 Operation 2 3 7 Data Renumber Select gt Data Renumber to renumber remaining runs into consecutive order after deleting one or more runs This allows you to free up run numbers for new runs to be added which is necessary when the run number approaches 99 Say you have used all 99 runs and you wish to clear out some space for new runs Furthermore you have decided that you no longer need the data from runs 01 to 10 Delete these runs using Data Delete Now select Data Renumber to renumber runs Runs 11 to 99 become runs 01 to 89 leaving 90 to 99 free to take new data The Data Renumber command does not free up memory space only run numbers The 999 cycle memo
125. on the units the RAD7 has been set to use 22 Radon concentration uncertainty Two sigma uncertainty of concentration in the SAME units as the base radon concentration not 96 23 Units Byte Bits O and 1 indicate the concentration unit 00 counts per minute 01 number of counts 10 Bq m3 11 pCi L Bit 2 through Bit 6 are not defined Bit 7 indicates the temperature unit 0 F 1 C 73 Chapter 6 PC Connectivity 6 3 4 Terminal Emulator Tips If you are using a terminal emulator to interact with the RAD7 you can gain access to additional functionality by making sure the terminal has been set up to give ANSI standard escape codes for the function keys and cursor control keys Set the terminal for either ANSI VT 52 or VT 100 mode to get these functions The function keys F1 F2 F3 and F4 act as a remote RAD7 keypad corresponding to the RAD7 keys MENU ENTER and gt The Control C character also acts as the remote MENU key ETX The backspace delete key on your keyboard allows you to correct misspelled commands before the carriage return If this key does not work then Control H may handle the same function 6 4 Serial Port Specifications 6 4 1 Communication Protocol The RAD7 serial port follows RS 232C convention for signal levels Positive voltage 3V to 15V indicates logic state 0 SPACE while negative voltage 3V to 15V indicates logic state 1 MARK The connect
126. on for 4 minutes at the beginning of a new test cycle to ensure a good initial sample If the humidity in the sample cell remains above 10 then the pump stays on to allow the cell to dry out Then the pump runs for just one minute in every five until the end of the cycle On means the pump is always on whether the RAD7 is counting Live or not Idle Grab initiates a standard grab sampling sequence at the beginning of a run When you start a new run with the pump set to Grab the pump will run for exactly 5 minutes This is followed by a five 26 minute equilibrium delay after which the counting period begins The pump does not run at all during the counting period As usual you can determine the length of the count period by multiplying the cycle time by the recycle number The total time to complete a test is the pump sample time 5 minutes plus the delay period 5 minutes plus the count period Note that the Grab Wat 40 and Wat250 protocols under gt Setup Protocol above all use this pump setting Off means the pump is always off Use Auto pump setting for routine radon testing The RAD7 has been factory calibrated with the pump in this setting 2 4 7 Setup Tone Select gt Setup Tone to choose the audible tone type Three settings are available Off Chime and Geiger Off means the beeper remains quiet Chime means the beeper will sound only at the end of a cycle and is otherwise silent Geiger means the be
127. onth or more after which the ingrowth may be assumed to have reached equilibrium The container is then connected to the RAD7 in a closed loop The valves are opened and the RAD7 measures the radon concentration The concentration will rise as the radon is distributed around the loop Eventually the concentration will settle to a slowly decreasing value 5 4 5 Bulk Emissions The DURRIDGE Bulk Emission Chamber is an airtight box with two well separated hose connectors The material to be tested is placed in the chamber which is then connected to the laboratory drying unit and thence to the inlet filter on the RAD7 The other box connector has tubing attached which is either connected to the RAD outlet for closed loop operation or to a cylinder of zero gas or ambient air Note that bulk emissions are affected by pressure fluctuations and by temperature and humidity AII these parameters can and should be controlled in both the closed loop and open loop configurations Radon emission is also dependent on the grain size of loose materials and the porosity of any bulk material 65 In addition to radon thoron can also be measured in the Bulk Emission Chamber In the open loop mode a correction is required for the decay of the thoron during the time between its emission and measurement in the RAD7 In closed loop mode another correction must be made for the portion of thoron that gets fed back to the enclosure Note that for thoro
128. or D come from thoron while a peak in Bi212 count before calculating the radon window C comes from radon The peak in concentration The spectra below have window A is usually entirely from radon but if comparable amounts of radon and thoron but you there is a peak in window D then there will a will usually see one of the two much stronger than contribution of about half the D count rate to the the other peak in window A A B C D A New radon with new thoron IR B C D B Equilibrium radon with new thoron C Equilibrium radon with equilibrium thoron The count rate in window A is roughly the rate of window C plus half the rate of window D 6 00 MeV Po218 6 05 MeV Bi212 6 78 MeV Po216 7 69 MeV Po214 8 78 MeV Po212 coU gt 46 Chapter 3 Basics of RAD7 Technology R B C D D Equilibrium radon with old thoron The count rate of A is roughly the rate of window C plus half the rate of window D E Oldradon with old thoron The count rate in window A is no more than about half the count rate of window D New radon with old thoron Looks like an old thoron spectrum but the count rate of window A is significantly more than half the count rate of window D A B C D G New thoron with old radon 47 Chapter 3 Basics of RAD7 Technology 3 13 4 Pathological Spectra If any of the following occur and an external cause is not identified the user should contact IA Bi
129. or pin out follows the IBM PC convention for the 9 pin serial port The handshaking lines DTR DSR RTS and CTS are not fully implemented and should be considered non functional NF but X on X off flow control can be used Table 6 4 1a Serial Port Pin Assignments Pin Function Comment 1 Carrier Detect CD NF 2 Receive Data RD 3 Transmit Data TD 4 Data Terminal Ready DTR NF 5 Signal Ground SG 6 Data Set Ready DSR NF 7 Request To Send RTS NF 8 Clear To Send CTS NF 9 Ring Indicator RI NF 74 The RAD serial port implements two way communication at 300 600 1200 2400 4800 9600 and 19200 bits per second baud these speeds are available through the Special commands of the RADLINK remote control package The default speed is 1200 bps If a terminal emulator or custom software application is used it is recommended that communication be conducted at a data rate not exceeding 9600 baud This will significantly reduce the risk of characters being dropped from sent commands Table 6 4 1b Communication Parameters Default Rate 1200 bps Maximum Rate 19200 bps Recommended Rate 9600 bps Data Bits 8 bits Parity Bit None Stop Bits 1 bit The RADLINK remote control software resides in the RAD7 s non volatile memory NVRAM but its presence does not decrease the amount of memory available for storing radon data 6 4 2 E
130. oses This manual adopts a progressive approach in which there is first a simple step by step description of how to get readings for a real time monitoring and b sniffing Next comes a more detailed description of the many features of the instrument and how to access them The rest of the manual covers a whole range of topics in somewhat arbitrary order We recommend that as soon as possible you read the entire text just so that you will have an idea of what there is While you can start to make good measurements on the first day of ownership of the RAD7 it can take years to master the subtleties of radon and thoron behavior and to appreciate the full capabilities of the instrument We have tried to make the manual easy to use with a useful table of contents Please let us know how well we have succeeded If there are some topics inadequately covered please tell us We will issue updates from time to time Points of special note The RAD is a rugged and long lasting piece of equipment There are many units still in daily use that were sold ten years ago or more However it is a sophisticated precision electronic device and it is not hermetically sealed so please treat it with respect Please do not allow water other liquids or dirt to get into the machine If using it somewhere where it may get splashed damaged or exposed to rain please protect it See Chapter 4 8 1 The batteries are lead acid technology like a car s If left i
131. pe of the element radon having an atomic mass of 220 so it is also known as radon 220 The word radon without a mass number almost always refers to radon 222 Thoron and radon have very similar properties They are both chemically inert radioactive gases that occur naturally from the decay of radioactive elements in soils and minerals Both thoron and radon are members of decay chains or long sequences of radioactive decay While radon results from the decay of natural uranium thoron results from the decay of natural thorium Both uranium and thorium are commonly found in soils and minerals sometimes separately sometimes together The radioactive gases radon and thoron that are produced in these soils and minerals can diffuse out of the material and travel long distances before they themselves decay Both radon and thoron decay into radioactive decay products or progeny of polonium lead and bismuth before finally reaching stable forms as lead Thoron and radon and their respective progeny differ very significantly in their half lives and in the energies of their radiations While radon has a half life of nearly 4 days thoron has a half life of only 55 seconds Since thoron is so short lived it cannot travel as far from its source as radon can before it decays It is commonly observed that compared to that of radon gas a much smaller fraction of the thoron gas in soil ever reaches the interior of a building Even so thoron can
132. ple As long as the operator follows consistent procedures counting statistics will dominate the RAD7 s precision Environmental factors have proven to be much less significant over normal ranges of operation Aside from precision the most important factor in RAD7 accuracy is calibration DURRIDGE calibrates all instruments to a set of four master instrument with a calibration precision of about 1 The master instruments have been calibrated by way of inter comparison with secondary standard radon chambers designed by the U S EPA We estimate the accuracy of the master instrument to be within 496 based on inter comparison results We estimate the overall calibration accuracy of your RAD7 to be better than 5 We look forward to new developments in calibration standardization and traceability which we expect will help improve calibration accuracy The table below summarizes the precision of the RAD according to the contribution of counting statistics Counting statistics depend on sensitivity calibration factor and background count rate The RAD7 s intrinsic or fixed background count rate is so low as to bea negligible contributor to precision for the range of radon concentrations covered by the table Environmental and other factors may affect precision by as much as 2 The uncertainty values reported by the RAD7 are estimates of precision based on counting statistics alone and are two sigma values as are the values i
133. print head should be cleaned immediately however if the print becomes visibly fainter due to contamination of the print head The cleaning procedure requires 86 isopropyl alcohol and cotton swabs and should be completed as follows 1 Switch the printer OFF and allow the print head to cool before cleaning otherwise damage to the print head may occur Open the paper cover and remove paper roll Using a cotton swab dampened with alcohol wipe the heating dots of the print head Be careful not to touch the heating dots with your fingers Allow the alcohol to dry Reload the paper and close the paper cover Appendix 1 Wireless Infrared Printer Al 4 Infrared Printer Specifications The following table contains the physical and technical specifications for the infrared printer Printing Method Direct thermal Number of Columns 32 48 columns 384 dots line Character Size 0 06 x 0 12 in 1 5 x 3 0 mm Line Pitch 0 1 in 4 0 mm Paper Width 2 25 in 57 5 mm Interface IrDA and Serial RS 232C Protocol IrDA SIR HP Ir IIDA Off International Characters U S A France U K Denmark I Sweden Italy Spain Japan Norway Denmark II Korea Buffer 7 kB Baud Rate 300 115 200 bps IrDA 9 600 115 200 bps Power 4 AN Alkaline Batteries Weight with batteries 0 8 Ib 0 4 kg Dimensions 3 2 W x 5 6 Lx 1 6 H 81 x 142 x 41mm Table
134. r Al 2 Infrared Printer Operation A1 2 1 Precautions To ensure the proper operation of the printer and prevent the possibility of voiding the warranty be sure to observe the following precautions e Avoid dirty or dusty locations or those with excessive heat or humidity Choose a stable level surface to place the printer Use only alkaline batteries Use only the appropriate thermal paper A1 2 2 Self Test The self test mode checks the printer s control circuit functions setup parameters software version and printer quality Before running the self test make sure there is sufficient paper to run the test 18 46 cm the paper cover is closed and that the printer is switched OFF With the printer initially switched OFF press and hold down the FEED pushbutton and then switch ON the printer to begin the test Note The test can be aborted by switching OFF the printer The following typical information is printed followed by the printer s complete character set Version X XX Data bit 8 bit Parity None Baud rate 9600bps Handshaking DTR Country U S A Print Mode Text upright Paper Normal paper Density 10055 IrDA IrDA SIR Buffer Size 7000Byte Head volt 6 0V Head temp 25 C 84 A1 2 3 Setup Mode The printer has been set up at the factory with the following default parameters Baud rate 9600bps Handshaking DTR Country U S A Print Mode Text upright Paper Normal pape
135. r Density 100 IrDA IrDA SIR Ifnecessary the default parameters can be changed as follows With the printer initially switched OFF press and hold down the SEL pushbutton and then switch ON the printer 2 The printer now goes into its set up mode as indicated by the red LED flashing At this time all of the printer s current parameter settings are printed followed by the first parameter that can be modified Note that if no button is pressed within 15 seconds the set up mode is automatically terminated without changing the original parameters 3 IrDA is the first parameter printed Pressing the FEED button causes the value of that parameter to change in the sequence shown in the following table Table A1 2 3 Sel and Feed Functions SEL Button FEED Button Baud Rate 300 115 200 Handshaking DTR X on X off Country U S A Korea Cyrillic Denmark2 Norway Japanese Spain Italy Sweden Denmark U K Germany France Print Mode Text upright Data inverted Paper Normal Paper Reprint Paper Density 50 150 in 5 steps IrDA IrDA Off IrDA SIR HP Ir 4 Press the SEL button to print the next parameter and then use the FEED button to change that parameter to the desired value Appendix 1 Wireless Infrared Printer 5 Repeat Step 4 as necessary to change all desired parameters 6 Once all parameters have been set press and hold down the SEL button and then press
136. r en route to the test site Locate an inlet filter a piece of tubing with a sleeve at one end and small tube at the other and the laboratory drying unit Connect the filter to the tubing It should be a tight fit into the small diameter section Remove the plastic caps from the drying unit and push the sleeved end of the tubing onto the tube connector on the drying unit farthest from the metal screw cap Now attach the filter to the inlet of the RAD7 Switch on the RAD7 push MENU ENTER gt four times to see gt Test Purge on the display then push ENTER The pump will start The display will show Stop purge No Leave the unit purging for five minutes or longer When you are ready to start the test the easiest way to stop purging is to push the Menu key or switch off the instrument Chapter 4 Using the RAD7 4 2 3 Test Location In general the test should be conducted in the lowest area in the house that is used or could be adapted for use as a living area This would include a full height basement but not a crawl space Place the RAD7 near the center of the room about 3 4 feet above the floor Avoid walls vents fireplaces windows draft and direct sunlight Where possible connect DC power to the RAD7 to conserve and recharge the batteries The air intake will be the connector of the drying unit without any tubing attached nearest the end with the metal screw cap or the far end of the t
137. res it in a special place in its memory according to the energy of the particle The accumulations of many signals results in a spectrum The RAD7 divides the spectrum s 0 to 10 MeV energy scale into a series of 200 individual counters each representing a 0 05 MeV channel Whenever the RAD7 detects an alpha particle it increments one of these 200 counters by one Chapter 3 Basics of RAD7 Technology Every so often the RAD7 manipulates condenses prints out and stores data to long term memory Then it resets all 200 counters to zero and begins the process anew The idealized spectrum of a 6 00 MeV alpha emitter looks like a single needle thin spike at exactly 6 00 MeV Although the RAD7 approaches this ideal the actual spectrum shows a broadened peak centered at or near 6 00 MeV with a characteristic tail that stretches into lower energy channels Electronic noise in the detector and amplifier causes the peaks to widen while alpha particles that enter the detector at glancing angles cause the tail Higher than normal operating temperatures tend to increase electronic noise and so increase the width of the peaks A combination of different alpha emitters appears on the spectrum as a series of different peaks For example a combination of equal amounts of Po218 and Po214 as would occur in the case of radon daughter equilibrium appears as twin alpha peaks One peak Po218 is centered at 6 00 MeV while the other Po214 is
138. ro cennere A ree leere gene RR EBD P PE EE ES 55 IProloCOLl S sat etsi eto equite T E te E E E 56 Taking the SQMpPle 4 eat I Re DR eerte eee cede CR tee te ies 56 Andlysiss cnet ettet et en MI o NU e a e 56 ii IDE ose eben ree eit opido ba uoo bain inm es PROTON and Radon ro prt erae aee tede a e eter ARS 56 Thoron Measurement Issues oe d esee diete at ete de et Bose 56 Calculation and Interference Correction esses eene 57 Avoiding Longer Lived Decay Products seen 57 Decay Correction Flow Rate and Thoron Calibration sse 58 Calculating Sample Decay esee 58 Calculating Internal Cell Concentration essen 58 Internal Cell Thoron Sensitivity Calibration eee 58 Setting up a Thoron Measurement sse eene nennen eren 58 ThoromMOOes si iiec dde ei NI PIER tatuxs ied E 59 Recommended RAD7 Thoron Configuration 59 Managing DIO ose tte tcc tt occu e ote ett me bar Airflow Rate Lihitsx ue ddr Maximum Airflow Rate essent eene nennen nennen three nennen ener entente 60 Minimum Airflow Rate ti i t ee IL ee ede e ede ete e EAS 60 Harsh and Hazardous Environments see Splashing EE 61 Dusty Environment stanie en eet te e tede ae e ee ee ee bei ce bd eee ae 61 Radiation Hazard isse ER OH Rd 61 TESTING FOR RADON IN THE GROUND AND WATER 62 line M R Radon in Water e pst ip Rae The RAD AIO
139. rom objects and surfaces Furthermore the ability to count only the polonium 218 decays means that dynamic measurements are clean and not complicated by long half life events 5 4 2 Open Loop Configuration Emissions may be sampled from collected objects using DURRIDGE s Bulk Emission Chamber It is also possible to analyze emissions from soft or hard surfaces with the aid of a DURRIDGE Surface Emission Chamber which consists of a plate like enclosure capable of forming a tight seal around the surface in question In both cases the RAD7 draws air from within the enclosed space through the desiccant and inlet filter and into the measurement chamber The air may then be returned to the enclosure from the RAD7 outlet to form a closed loop Alternatively in an open loop configuration the air being drawn from the enclosure may be replaced with zero air from a cylinder or with ambient air which should have a low but known radon concentration With the open loop configuration a steady and known flow rate must be established Ifa cylinder of zero air or nitrogen is used then the RAD7 s internal pump may be set to Off and a pressure reduction valve and needle valve may be used to control the flow rate With ambient air the RAD7 s internal pump may be set to On for a continuos flow In both cases a flow meter is required Once a steady state has been achieved a long term measurement may be made The rate of emission wil
140. rt Legend aL 20 View Range Automatic M Q Issue RAD7 Command DS asia EP Plot Lines v Radon 4 Thoron Radon In Water 48 Thoron In Water Relay RAD7 Commands El AirTemperature Water Temperature LL Relative Humidity 1 30 13 1 30 13 1 30 13 1 30 13 En 14 00 15 00 16 00 17 00 pCi L Y RAD Printer Present 1745 RAD 3076 connected to COM19 at 19200 Baud Calibration Date 11 12 12 Scan for RAD7s CAPTURE Software running in Windows 7 70 Chapter 6 PC Connectivity 6 2 2 Feature Summary CAPTURE s capabilities fall into three main categories downloading RAD7 data graphing and analysis and real time RAD7 monitoring An overview of each is described below 6 2 3 Downloading RAD7 Data CAPTURE s original and primary function is to download RAD7 data Once connected to a RAD the program can download all of the device s data or a particular data run For a more complete record set supplementary output containing thoron concentration records may also be obtained When a download operation is complete the results are saved to disk in the format of the user s choice In addition to being able to download data from RADTSs connected directly to the computer CAPTURE can obtain data from remote RAD7s connected via a remote desktop software a local network or a modem 6 2 4 Graphing and Analysis Once RAD7 data has been downloaded and saved to disk it may be displayed as a graph CAPTURE s Graph Window
141. ry limit remains whether or not all 99 runs have been used 2 3 8 Data Erase Select gt Data Erase only if you wish to completely wipe all data from the entire RAD7 memory Data Erase deletes all runs and resets the current run cycle number to 0101 Select Data Erase The RAD7 will ask for confirmation Erase all Tests No Press gt to find Yes Press ENTER to complete the erasure Use with caution 2 4 Setup The Setup group of commands configures the RAD to perform tests according to your needs The RAD7 remembers all Setup parameters when it is turned off so access the Setup commands only to change parameters Setup includes a 1 step Setup Protocol command to configure the most frequently used parameters Cycle time Recycle number Mode setting and Pump setting according to preset protocols These standard preset protocols include None Sniff 1 day 2 day Weeks that is indefinite User which lets you preset your 24 own Grab Wat 40 and Wat250 for use with the RAD H20 and Thoron The special command Setup SavUser defines the user protocol according to the current parameter settings 2 4 1 Setup Protocol Select gt Setup Protocol to automatically load in a group of predefined Setup parameters under one of the standardized protocols or the User protocol If you do not wish to select a protocol you may abort the command by pressing the menu key and no parameters will be changed Table
142. s Besides tracking the sate of each connected RAD it is also possible to issue menu commands performing such tasks as starting and stopping tests and setting the protocol All of the functionality of the RAD7 s physical controls are accessible from within CAPTURE s graphical interface As stated above it 1s suggested that users examine the complete CAPTURE documentation available from the www durridge com capturehelp and from within the program s Help menu Chapter 6 PC Connectivity 63 RAD7 Communication Protocol 6 3 1 Communication Requirements Although DURRIDGE s CAPTURE software for Windows and Mac OS X provides a complete solution for downloading RAD7 data and issuing RAD7 commands it may be desirable to communicate with the device using a terminal window or with custom communication tools designed to fulfill specific needs The RADLINK firmware installed standard with every RAD7 sold enables the RAD7 to respond to commands issued through its serial port With RADLINK installed all of the commands available through the RAD7 keypad will also be available via the serial port From a computer you may for example change the RAD7 s operating parameters complete a test and then download the accumulated data 6 3 2 RAD7 Command Format The format of commands issued to the RAD7 serial port generally match as closely as possible the format of the commands available to the user at the RAD7 keypad For example t
143. s pCi L C m Push MENU ENTER gt You should see on the LCD display gt Test Start n Push ENTER The pump will start running On the LCD display you will see something like 0101 00 59 37 Sniff 00001 Live You are now monitoring the radon level right where you are Every hour the printer will print out a reading something like this 0102 2 69 0 73 p Sniff FRI 21 MAY 13 19 41 26 8 C RH 7 B 7 06V Where 0102 are the run 01 and cycle 02 numbers 2 69 is the measured radon concentration 0 73 is the two sigma STATISTICAL uncertainty p indicates the units in this case pCi L and Sniff shows that for this reading only the Po 218 decays are being counted after three hours the mode changes automatically to Normal The second line is clearly the date and time while the third shows the temperature and humidity inside the measurement chamber and the battery voltage Medium and Long format settings print more information each cycle If you allow the RAD7 to complete a run it will print out a summary of the entire run including Date and time Machine serial number Average value for the test Bar chart of the individual readings and Cumulative alpha energy spectrum Qno o9 pa 15 In the example shown it may be seen that the average level was 3 71 pCi L or 137 Bq m To terminate the run early you may switch off the RAD7 The data collected to the end of the last completed cycle i
144. s then push ENTER to confirm Do the same for the minutes and seconds Next you should see Date 13 DEC 11 Dates are listed with the day of the month first then the month then the year As with the RAD7 clock the date is set by using the arrow keys to change each value Press ENTER after each figure 1s set to move on to the next Chapter 2 Basics of RAD7 Operation 2 4 12 Setup Review The gt Setup Review command allows you to display and print a listing of the current instrument settings including Date and Time Protocol CycleTime Recycle Mode Thoron Pump Tone Format and Units Thus you can check that the instrument is set up properly and confirm this in hard copy right on the data printout 2 5 Special The Special menu offers access to a selection of additional commands provided by the RAD7 s RADLINK remote control software If for any reason RADLINK is not present you will see the following when entering the Special menu Not installed Install No Use the arrow keys to toggle between Yes and No If you confirm Yes the RAD7 will sit waiting for a data string at the RS232 port If necessary DURRIDGE will complete this RADLINK installation process when the RAD7 is returned for calibration If RADLINK is installed then gt Special opens a menu of special commands available from the keypad of the RAD7 All the commands both standard and special will also be accessible from a remote PC eith
145. s automatically stored in the RAD7 memory and available for later display printing or download to a PC If you wish to store the last incomplete cycle data as well use Test Save before switching off the RAD7 When you do this the end of run printout does not take place The summary is stored in memory and may be printed at any time except that the cumulative spectrum which would have been printed out at the end of the run is lost End of Run Printout Run BZ Begin 03 JAN 98 15 33 Serial 028 i EEE PO Po P eh et t t to oh 2 Sra IEEE f CO P3 e O CD TT B CO PO e RO S OO OP CTI e CO PO e 0 C0 PO e Gs Cn x LO CT UB 9H HP UV HH UV UE UH PU HU EV VU UE UE WM NU ED Wi an 23 3 3 LES 3 ao LES 3 3 3 3 LES B 3 23 3 3 3 19 3 11 3 12 33 13 3 14 3 15 3 16 33 17 3 15 3 12 3 20 3 21 3 22 3 3 3 g1 3 B2 3 93 3 B43 esi 6 3 Br 3 98 3 a2 3 19 3 11 3 12 3 13 3 14 3 Cumulative Run Spectrum lnJeje D Chapter 1 Getting Started 1 5 Starting a Sniff Test Sniffing lets you make quick qualitative surveys of radon and thoron levels It may be used to search for radon entry points There are some advantages in sniffing for both thoron and radon at the same time see Chapter 3 13 3 so that 1s the procedure described here You will need the same equipment as for the 2 day test above except that a small drying tube should be used instead of the laboratory drying unit
146. s it easy to perform these actions as well as to monitor the RAD7 s status graph radon and thoron data apply corrections to account for environmental factors and export the results for analysis in a spreadsheet program or other software Itis also possible to use a terminal emulator program to interface with the RAD7 and to write your own RAD7 communications software using the protocol documented later in this chapter An overview of the CAPTURE software is provided in Section 6 2 and the full program documentation is available at www durridge com capturehelp This documentation is also accessible from within the CAPTURE application using the Help menu 68 Following the section on CAPTURE the remainder of this chapter contains technical information which will be of interest to advanced users who intend to communicate with the RAD7 via a terminal window and those who wish to write their own software for communicating with the RAD7 6 1 1 Connecting the RAD7 to the Computer On most systems the RAD7 should be connected to the computer using the included USB to Serial adaptor and it will be necessary to install the included adaptor driver software If your computer has a physical serial port however it is possible to instead use an RS232 DB9 female to female null modem cable to connect the RAD7 directly to the computer without the need for adaptors or drivers The diagrams on the next page show how to connect the RAD7 t
147. set protocols 24 DTU CV Jg LE 24 Seiup Recycle 5 e A e o e od ete e E 25 Setup Modez 34 AL eese ted ete ic tedetu meme E 25 NZD MT 25 DCP Pulp ttti te eter A onde 26 NY mM Ic 26 Setup Format ta ette d tein nea et edet te dated IES 26 AY METER Ex 27 SetupiSQVlsernic sessione io e i eme EO Et rtt 27 NZTUNS T EE 27 DOLD IREVICW PT EC S 28 A EM 28 Spe idl AMES ii a eene me ps de ee e eet 28 SDOCIGlSPFOn a sce ete satt ete ee dete eoe rette peto de cad s 28 SOCIAL SS PRO d ees ettet eee eter a 28 Special SetBaud OETA Leno e EP te anu Un EE ENSE 28 SDeClal A ci tena ene tee due qua es 28 SDOCIOL SIOED S ees e Me Ma i M EL M ut VILA 28 Moz P ee 28 Special GOmspeG ibi tst ee tee eM ree eet ee dee desee 29 Special ComAll e te p HD REO DR P RE 29 Special SPAIN A a e e ee E ts 29 Special S LO ese d n o Red im eot 29 Special Veksiofiz susci diei estie eere tlie fleret redes edet cdta ads 29 Special Model 2 12 5 osse ie i te D eee aes 29 Special Serialo s i a Re A 29 SPECIAL BECP sne eor es O etta rio PUE 29 Special Relays et Rite e ets 29 A te DIR Se eS Ue MAE 29 Alpha Energy Spectrum 30 BASICS OF RAD7 TECHNOLOGY eeeeeeeeee nee eene eneeeneees 3 T HOW IT WORKS 31 Eo AA oen le ete e dolo ip SE lale ied 31 Radon Decay AA ds eats 31 Radon and Thoron decay chains 32 Rddon 222 Radon aa ssa huetii iseset iii Se aegen bena tantea 33 Radon 220 Thoron it e ent aro nte de nin etie
148. should be no more than 0 05V from the average value Press gt yet again and you will see something like this w cpm A 6 0 This is the display for the A window data You may press gt to advance to B C D etc The RAD records 8 windows A H every time you make a measurement They separate counts due to daughters of radon and thoron and the background Specific alpha particles end up in specific windows W The window letter cpm The counts per minute observed in the window The two sigma statistical uncertainty of the cpm value also in units of cpm tot The number of counts in the window as a percentage of the total counts in the spectrum This tells you quickly where the majority of the counts are In the 3 minute radon peak window A or the long lived radon peak window C etc As always you press the MENU key to exit this display and return to the start of the menu 2 2 1a Quick Save and Restart This function allows the user to end a sniff test store it to memory and start up a new sniff test all using a single key It operates only from the SNIFF mode From the status display showing the countdown timer press the ENTER key once The display will show Save and restart Chapter 2 Basics of RAD7 Operation Yes Press the ENTER key once more to confirm your intention To escape push the MENU key or push an arrow key to select No and push ENTER 2 2 2
149. sleeved end of the tubing to the tube fitting on the Drying Unit farthest from the screw cap c Attach the filter to the Inlet port of the RAD7 The air sampling system is now set up for the measurement See RAD7 Standard Configuration diagram at left d Plug in the RAD7 and switch on e Push MENU ENTER then push gt four times You should see on the LCD display Test Purge f Push ENTER The pump should start g Set up the printer insert paper and batteries see manual h Place printer between green lines on face plate See photo Chapter 1 3 1 After purging for some time normally at least five minutes push MENU and gt two times you will see Setup on the display j Push ENTER twice then push either arrow key repeatedly until you see Protocol 2 Day on the display Push ENTER k With Setup on the display push ENTER then gt seven times to see Setup Format on the display Push ENTER then use arrow keys to select Format Short Push ENTER 1 Switch off the RAD7 Switch on the printer now switch the RAD7 back on The printer will print out something like the following DURRIDGE RAD7 Vers 2 5f 991128 Model 711 Serial 00512 Calib 21 MAY 13 Last used Chapter 1 Getting Started FRI 21 MAY 13 17 30 Current settings FRI 21 MAY 13 19 09 Protocol 2 Day Cycle 01 00 Recycle 48 Mode Auto Thoron Off Pump Auto Tone Geiger Format Short Unit
150. still be a hazard since its progeny include lead 212 which has a half life of 10 6 hours more than long enough to accumulate to significant levels in breathable air 4 5 2 Thoron Measurement Issues Many difficulties impede the accurate measurement of thoron gas The presence of radon gas often found together with thoron can interfere with a measurement The short half life of thoron gas makes some aspects of the measurement easier but makes sampling method a critical issue Thoron concentration can vary greatly through a space depending on the speed Chapter 4 Using the RAD7 and direction of air movement as well as turbulence The position of the sample intake can strongly affect the results For many instruments radon and thoron interfere with each other Generally speaking it is difficult to measure one isotope accurately in the presence of the other But compared to other instruments the RAD7 is much less susceptible to radon thoron interference due to its ability to distinguish the isotopes by their unique alpha particle energies The RAD7 separates radon and thoron signals and counts the two isotopes at the same time with little interference from one to the other Some issues of concern in measuring radon do not apply to thoron The short half lives of thoron 55 seconds and its first decay product Po 216 0 15 seconds mean that thoron measurements can be made quickly and in rapid succession since there is little
151. t not the air sampling tube can protect it from splashing mud and water Allowing the dry air from the RAD7 outlet to exhaust into the interior of the bag will keep the RAD7 in a clean and dry environment 12 If liquid does get into the machine please disconnect the power cord turn off the power switch and follow the instructions in Chapter 4 8 1 Harsh and Hazardous Environments Splashing Water It will be necessary to return the RAD7 to DURRIDGE for repair Do not use your RAD7 if the instrument is damaged or malfunctioning Please call or email the DURRIDGE service department who will advise what to do about the problem Replace a frayed or damaged power cord immediately Electrical equipment may be hazardous if misused Keep away from children Do not open or attempt to repair the machine The detector has an internal high voltage supply that can generate more than 2 500V Chapter 1 Getting Started The batteries are Gates Monobloc type 0819 0012 6V 2 5Ah There are two installed in the instrument They are not user replaceable 1 2 1 Air Travel The RAD 7 is safe to take on an airplane either as carry on or checked baggage Itis probably easiest and least likely to cause problems if it is put inside a suitcase with clothes and checked in 1 3 Taking a Look Printer Infra red LED Some airlines and some airline staff are concerned about lead technology batteries such as those in the RAD7 An
152. t 76 AL JU o M WUO ee 76 7 1 6 Batteries RS eben eek abate abe seda eda 76 7417 Real time Clock and Non volatile Memory eene 77 7 1 8 Printercand Adapter di e e Het eee e eie e e eet 77 7 2 Operating TOC uade ee EA eC M RR NEED eb E AE AREE T Table 7 2 RAD7 Operating Ranges 77 7 3 Serviee and Repa od 78 7 3 1 Calibration eo Moby Hn es o A M 78 4 3 2 Pug d M 78 7 3 3 SHIPPING etai Ee o es DU rU EE rd LE LU UE Ed 78 7 3 4 Upsrades dice Re ee e eei mette 78 7 4 RAD Quality Assurance emot eine e be aei tato 79 7 4 1 DDOCIF ADL ENIRAR NESARA ANAE a a EN 79 7 4 2 Spill Faeto M ER 79 8 TROUBLESHOOTING ERE EEE e e ad S 8 1 A A E UU 80 8 1 1 Blank Displays E AA 80 8 1 2 T YOZen Display A E A Ed teak a UE I an 80 8 1 3 Incomplete Or Garbage Characters esses eene eene 80 8 2 Reddings ehcp O eil SU ee eu 80 8 2 1 Xe D P 0 8 2 2 Excessive Uncertainty In Reading sese enana er 80 8 2 3 Run Cycle Number 0000 te ia te et erts 80 8 3 Relative Humidity OVO eoe eee esce mem ies stas petenti ea hares ege 80 8 4 Meca dietam sauce setate datu E te a 81 8 5 Battery Voltage Lo voter Colts teet opt Gore oe aoa Gers Sate qure oL d 81 8 6 Pathological Values and Error Messages ooooooccccconccnconononcnncnnnconcnnnonncnnccnncnnos 81 Appendix 1 Wireless Infrared Printer eere
153. t the summary and cumulative spectrum will print at the end of the run if the printer is set up and switched on 2 4 9 Setup Units Select gt Setup Units to change the measurement units with which the RAD7 reports radon concentration and temperature First enter the radon concentration unit pCi L picoCuries per liter Bq m3 Becquerels per cubic meter cpm counts per minute Zcnts number of raw counts Next enter the temperature unit _F degrees Fahrenheit C degrees Celsius or Centigrade PicoCurie is the favored unit of radon activity in the U S while Becquerel is the favored unit in Europe and Canada 1 pCi L equals 37 Bq m Counts per minute is the direct output of the RAD7 while number of raw counts is the raw direct output With livetime mode and calibration factor one can convert from any of these units to any other but it is usually easier to let the RAD7 do the work The choice is retroactive Change the unit using the gt Setup Units command then print out the same data Everything will print as before but in the new units 2 4 10 Setup Savuser Select gt Setup SavUser to program the special User protocol according to the present Setup parameters You must answer Yes and push ENTER to confirm that you wish to change the User protocol The purpose of this command is to give you an opportunity to customize a protocol according to a set of favorite parameters Thereafter it s a cinch to
154. the range of 5 The EPA recommends and we agree that all continuous radon monitors be calibrated at least every six months in a radon calibration chamber although most RAD7 users are satisfied with annual recalibration DURRIDGE s standard RAD7 calibration requires four to five working days from the receipt of the instrument Asa preliminary to recalibration we give every RAD7 a brief inspection and test one or two critical parts If additional service is required this may delay the return of the instrument We recommend that you arrange for your RAD7 calibration to be conducted ahead of time to avoid possible delays When sending the RAD7 for calibration please send the instrument only without the accessories and please pack it well with at least an inch of padding on all sides of the instrument At present only DURRIDGE can make adjustments to your instrument s alignment and calibration factors If you determine on the basis of an independent intercomparison e g another calibration chamber that you would like to adjust your RAD7 s calibration by a known amount we can generally perform this service and send back your instrument within one day Requested 78 calibration adjustments of more than 10 are considered highly unusual and require the written permission of the instrument s owner 7 3 2 Repair If you discover that your RAD7 is malfunctioning we recommend that you first call DURRIDGE and talk to a te
155. the display push ENTER then 3 seven times to see Setup Format on the display Push ENTER then use arrow keys to select Format Short Push ENTER 1 Switch off the RAD7 Switch on the printer now switch the RAD7 back on The printer will print out something like the following Chapter 1 Getting Started DURRIDGE RAD7 Vers 2 5f 991128 Model 711 Serial 00512 Calib 21 MAY 08 Last used WED 23 MAY 08 17 30 Current settings FRI 25 MAY 08 19 09 Protocol Thoron Cycle 00 05 Recycle 00 Mode Sniff Thoron On Pump Auto Tone Geiger Format Short Units pCi L C m Push MENU ENTER gt You should see on the LCD display gt Test Start n Push ENTER The pump will start running On the LCD display you will see something like 0201 00 04 37 Sniff 00001 Live You are now sniffing for thoron and radon Every five minutes the printer will print out a reading something like this 0203 2 69 2 83 p Sniff 1 68 2 15 p Thoron FRI 21 MAY 99 19 41 26 8 C RH 7 B 7 06V 17 Where 0203 are the run 02 and cycle 03 numbers 2 69 is the measured radon concentration 2 83 is the two sigma STATISTICAL uncertainty p indicates the units in this case pCi L and Sniff shows that for this reading only the Po 218 decays are being counted The second line is the measured thoron concentration and uncertainty The third line is now the date and time while the fourth shows the temperature an
156. tivity will eventually drop because the very fast movement of air interferes with the electrostatic precipitation process Airflow rates approaching the 2 5L min limit are suitable for measuring thoron which must be brought into the RAD7 swiftly due to its rapid decay Ifthe RAD7 has been specifically calibrated for thoron however the specified thoron sensitivity will remain in effect only when the RAD7 is configured exactly as instructed on the Thoron Calibration Certificate Generally this entails operating the RAD7 in Thoron Protocol causing its internal pump to run continuously producing an airflow rate of about 800mL min 4 7 2 Minimum Airflow Rate Ifthe RAD7 s cycle time exceeds 5 minutes and its internal pump is set to Auto the pump normally runs continuously to dry out the RAD7 until the RH drops below 10 After that the pump runs for 5 minutes at the start of every cycle to put an entirely fresh sample into the measurement chamber and thereafter for one minute in every five to keep the air sample fresh Therefore the typical average flow rate is less than 0 2 L min For certain applications lower airflow rates may be preferred To determine the minimum acceptable airflow rate consider the following parameters a The distance from the sample source to the RAD very slow flow rates may allow significant radioactive decay of the radon before it reaches the RAD7 b Whether thoron is being measured with a one minut
157. tly reduced from the nominal 1 L min This will not affect the radon reading but will reduce the effective sensitivity to thoron as more of the thoron will decay en route to the RAD7 If desired an additional pump may be used but it should be placed upstream of the RAD7 so that the RAD7 is operating at normal pressure In fact with an external sampling pump in use the RAD7 pump can even be switched off altogether 5 3 5 Interpreting the Data As with any Sniff test the first two 5 minute cycles should be ignored The next one or two cycles should be averaged to arrive at the radon concentration of the soil gas For thoron some estimate has to be made of the time taken for the sample after it has left the soil to reach the RAD7 This requires an estimate of the volume of the sample path including the probe water trap tubing and drying unit and an estimate or measurement of the flow rate For example if the total volume of the sample path is 2L and the flow rate is 0 5 L min then the sample delay is about 4 minutes If the thoron decays by half every minute then after four minutes the concentration will be just 1 16th of the concentration in the ground So the thoron concentration measured by the RAD7 would be multiplied by 16 64 5 4 Emission Measurements 5 4 1 Application With its internal pump sealed sample path and inlet and outlet connectors the RAD7 is well suited to the measurement of radon emissions f
158. tors Another important parameter is background This is the reading given by the instrument when there is no radon in the air sample For low level continuous monitoring it is necessary that the background be extremely low and stable Because of the high quality alpha detector and unique real time spectral analysis the RAD7 background is vanishingly small and is immune to the buildup of lead 210 which plagues other instruments 34 3 4 Sniffers Sniffing means taking quick spot readings Thus you can get a rough idea of the radon level without waiting for a full 48 hour EPA protocol test The technique is often used to locate radon entry points in a building Any fast response continuous radon monitor with a pump can be used for sniffing However there are some factors to consider One is the rate of recovery after exposure to high radon levels When the sniffer finds a radon gusher the whole radon decay chain builds up inside the instrument and the various daughters become well populated If the sniffer now moves to a low level region it will take many hours for the lead bismuth polonium 214 daughters to decay away In the RAD this doesn t matter because in SNIFF mode it looks only at the polonium 218 decays and ignores the polonium 214 decays left over from previous sniffs The polonium 218 has a three minute half life so the RAD7 sniffing for radon has a 15 minute response time to both sudden increases
159. uality test for the RAD7 is simply an examination of the cumulative spectrum printed out at the end of every run If the spectrum looks normal and the humidity temperature and battery voltage are within normal range then that is very strong evidence that the RAD7 is working properly and the readings are reliable 4 2 8 Finishing the Run Even if no printout has been made at the end of every cycle it is still useful to have a printout at Chapter 4 Using the RAD7 the end of the run If the RAD7 can be accessed before the run is finished simply place the printer in position on the face plate and switch it on After the last cycle is completed the RAD7 will print the run summary including the mean value the bar chart of all the readings and the cumulative spectrum If the instrument cannot be accessed before the end of the run the summary can be printed out later but without the cumulative spectrum Switch off the printer and the RAD7 Disconnect the tubing from the desiccant and replace the plastic caps over the hose connectors If the caps have been lost a single piece of tubing may be attached between the two connectors thus providing a seal to keep the desiccant dry Remove the inlet filter from the RAD7 It is good practice to leave the inlet filter attached to the plastic tubing Replace the short piece of tubing connecting the inlet to the outlet Putting the jumper between the inlet and outlet keeps the internal
160. ube if one is attached to this connector Make sure the air intake is at least 30 inches 75 cm above the floor and away from the walls Once set up in location let the RAD7 continue to purge until ready to start the test 4 2 4 Test Protocol In any location there is often a diurnal variation of radon level It is preferable therefore that the test period be an exact number of whole days The EPA protocols require an average taken over at least two days The RAD7 gives time resolution as well A choice must be made therefore of the cycle time and the number of cycles recycle For 24 hour and 48 hour tests the RAD7 has preset protocols which will make the choice for you You can always change the choices even in the middle of a test and if you wish save your preferences as the user protocol You may for instance prefer to conduct 3 day tests and perhaps use 24 cycles each 3 hours long The longer the test the greater the precision of the result For a 24 hour or 48 hour test using the preset protocol before starting the test go to gt Setup Protocol gt 1 day or 2 day and push ENTER You need also to decide whether to leave the tone Off Chime or Geiger and whether to have short medium or long format of printouts at the end of each cycle and set the parameters accordingly 51 For very long term monitoring use the Weeks protocol This sets the RAD7 to run indefinitely with 2 hour cycles The
161. ure the relative humidity of the air leaving the RAD7 If no humidity sensor is available another RAD7 if one is available would do The two RAD7s can be connected in series Set the downstream RAD7 pump to OFF Setup Pump Off ENTER If the downstream RAD7 reads a lower relative humidity than the upstream one then the upstream humidity sensor is wrong and should be replaced Return the RAD7 to DURRIDGE Company for service If none of these solutions are applicable measurements made at high humidity can be corrected automatically using CAPTURE See Chapter 3 12 2 8 4 Water Catastrophe If water ever enters the RAD7 or if the RAD7 ever goes swimming in the water it will probably cease to operate and immediate steps should be taken to minimize the impact on the instrument Keep the RAD7 upright This will prevent water from touching the detector which is close to the face plate at the top of the dome Put a piece of tubing on the RAD7 outlet with the other end in a sink Use the RAD7 pump if it still works or otherwise an external pump into the inlet to blow air through the instrument When water ceases to be blown out of the outlet put desiccant upstream of the RAD7 to dry out the air path When the air path is fully dry after dry air has been blown through it for approximately one hour remove the face plate from the case empty the water out of the case and blow dry the case and the RAD7 electronics Once there is
162. urs before the start of the test This means that ALL doors and windows should be shut tight No air exchange system or ventilation fans may be running In winter it is not difficult to satisfy this requirement Continued operation of the furnace is permitted Closed house conditions are usually maintained anyway to save heating costs Doors may be opened momentarily for access but should otherwise remain closed throughout the test In summer it may be impossible to satisfy the requirement without the residents moving out for the duration of the test If doors and windows are left open it can nullify the test except that if there is a radon problem under these conditions then there will be a greater problem under closed house conditions Air conditioning often includes some fresh air ventilation which dilutes the radon Even if there is no ventilation the cold air in the house will want to sink increasing pressure in the basement and thus reducing any flow of soil gas into the house So air conditioning in the summer will tend to lower the radon level in the house For further detailed information see the EPA Indoor Radon and Radon Decay Product Measurement Device Protocols publication EPA 402 R 92 004 or view it at http www epa gov radon pubs devprot1 html 4 2 2 Purging For the RAD7 to be all set to go ready to start a test it should be purged for at least five minutes beforehand This may be done in the ca
163. useful it should have at least 100 counts There should be clearly defined peaks and little or no 79 noise across the spectrum The peaks should be located in the middle of the windows A clean spectrum is indicative of an instrument in perfect working order and hence of reliable and accurate readings 7 4 2 Spill Factor Due to the occasional alpha particle emitted from a polonium atom on the detector surface at grazing incidence to the surface there is always a small low energy tail to the peaks This may be observed in the printed spectra There is thus a spill of 214 Po counts from window C into window B It is normally around 1 to 1 5 ina current production RAD7 The actual value is measured during the calibration process and the spill factor used to compensate for this phenomenon when measuring thoron in the presence of radon If the detector becomes contaminated in use or either electronic or detector failure causes noise in the system thus making the low energy tail thicker or the peaks broader then this spill factor will increase The value can be calculated from any reading provided that it is known for sure that there was no thoron in the chamber The percentage of counts in windows B and C is given in fields 10 and 11 of each record in memory see Chapter 6 3 3 The spill factor is simply the ratio of the values in those two fields It is recommended that the spill factor be noted every month Any sudden cha
164. w B or listening for the characteristic thoron beeps You will quickly determine the location and relative strengths of the radon entry points from the cpm in window B for the different locations Note that in this procedure you must ignore the counts in window A because they refer to radon that entered the measurement chamber as much as 10 minutes previous to the observed counts Even if thoron is present at some points there is still a possibility that there may be a radon entry point showing little or no thoron This could occur if the path taken by the soil gas was very long or the flow was slow Conduit for a utility service or a path up a hidden shaft in a wall could delay the entry of the soil gas by several minutes Each minute s delay halves the concentration of thoron 4 3 6 Drilled Sampling Points Some mitigators drill a number of test holes through the concrete slab to sniff the soil gas beneath and to test the communication between different areas of the slab They then install the suction points of the mitigation system where the sub slab radon readings are highest This approach is complementary to the search for actual radon entry points as described above Both methods are likely to result in a similar final configuration of the mitigation system though locating the entry points can also indicate where additional sealing is required 4 3 7 Spot Readings A spot reading may be accepted only as a rough ind
165. xtending the RS 232 Range The simple direct serial port to serial port connection has a range limited to around 50 feet 15 meters by the RS 232 C standard Options for extending this range include RS 232 line boosters current loop and other types of interface converters short haul modems and leased line modems You may use standard data modems to communicate over the telephone system to one or more remote RAD7 monitors so that when you want to get some data or start a new run just dial up the instrument of your choice The modem should be Hayes compatible and should be set to auto answer The CAPTURE user s manual contains a section titled Long Distance Communication detailing several strategies for communicating with distant RAD 7s that are fully supported by CAPTURE These include the transmission of commends via Bluetooth local area networks and more Chapter 7 Maintenance 7 Maintenance If the RAD7 is treated with respect the only maintenance required is its regular recalibration For this it should be returned to DURRIDGE Company who will check the health of the instrument and who will incorporate the new calibration factors in the instrument firmware If the instrument is to be used in a harsh environment where water and or mud may be splashed on the face plate the RAD7 should be put in a box or large transparent plastic bag The air input may be brought into the container by a plastic tube from the sampl

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