YSI Model 55 Operations Manual
Contents
1. Chlorinity 0 10 0 ppt 15 0 ppt 20 0 ppt Salinity 0 18 1 ppt 27 1 ppt 36 1 ppt 19 Chlorinity 0 Salinity 0 This table is provided for your information only It is NOT required when calibrating the Model 55 in accordance with the instructions outlined in the chapter entitled Calibration 20 12 Appendix B Conversion Chart Degrees Celsius Degrees Fahrenheit C x 9 5 32 Degrees Fahrenheit Degrees Celsius F 32 x 5 9 Milligrams per liter mg L Parts per million ppm Multiply by 1 21 YSI incorporated 1725 Brannum Lane Yellow Springs Ohio 45387 USA 937 767 7241 e 800 765 4974 e Fax 937 767 9353 environmental ysi com e www YSI com 1997 YSI Incorporated 055207 552070 Web January 072. YSI incorporated ON OFF LIGHT YSI Model 55 Handheld Dissolved and Temperature System Operations Manual Table of Contents 1 General Description mm 1 2 Specification Cost 2 3 Preparing The Meter uu usa nr a Ue ERE RE RS 3 3 l Unpacking ua u asas 3 3 2 Warranty Card a Rn Epi ue e Moses 3 3 3 BatterteS as sau aa nes 3 3 4 Calibration Sterase Chamber sense ne 4 SM Hand Sta Deenen a Ea au ee ee 4 Meter d a 4 4 Preparing The Probe cc nun UU 5 OH son E S 5 4 2 Choosing The Right Membrane u a 5 4 Prob Preparation doe odes lee er 5 4 4 Membrane ooi dotes arto er sedente abs udo Modes SE 6 4 5 Probe Operation and Precautions iio sere theses 7 5 AAU OM ice yu u m Ee dm au muri se a unun Eu c UM T ON eR FU 8 S LoBefore You AN DIRE dep d Balls 8 2 2 The Calibration Process orders e RARI sine insel 8 6 Principles Of OperatlOn 5 2 c entire rut coro hoan aan ann nn anna aor cux Er qn nennen En iS 10 6 1 Discussion Of Measurement Errors u a eer ba ee een 10 7 Troubleshooting 12 8 Warranty And RepaiFr i iivdecavsatesiaseeccsnstesasceusinaanetussdvacnsesnahusedsantexsanedueadeseuncudadsducensascenans 14 Bale ElEamneI
3. 0 15 mg L B Component and circuitry error 0 05 mg L Type 2 Errors A DO errors caused by temperature compensation for measurements at 10 C from calibration temperature 190 0 08 mg L at 25 C DO errors caused by temperature measurement errors A maximum 0 2 C temperature error is equal to 0 5 0 04mg L at 25 C 10 Type 3 Errors A Altitude Operator Error A 1000 foot error in altitude when calibrating is equal to an error of approximately 3 6 at the 10 mg L level Instrument Error The maximum DO error caused by calibrating to altitude in increments of 100 feet 0 18 lt 0 015 mg L at 25 C B Humidity Errors occur if calibration is performed at less than 10096 humidity The worst possible case would be calibration at 0 humidity The error varies with the calibration temperature as follows Approximating The Error It is unlikely that the actual error in any measurement will be the maximum possible error A better error approximation is obtained using a root mean squared r m s calculation r m s error la 1b 2a 2b 3b mg L NOTE This sample calculation is for a near extreme set of conditions 11 7 Troubleshooting NOTE An error displayed briefly during the first few seconds after turning the instrument on does NOT indicate a problem SYMPTOM 1 Instrument will not turn on 2 Instrument will not calibrate 3 Instrument locks up 4 In
4. 15 C and at dissolved oxygen levels below 20 air saturation the low signal current resulting from the use of the standard membranes tends to magnify the probe s inherent constant background signal Using the high sensitivity membranes in this situation will decrease the percentage of error due to the probe s background current For long term monitoring situations ONLY a half sensitivity double thickness 2 mil 002 membrane is available For these applications order the YSI Model 5685 Membrane Kit which includes membranes and electrolyte 4 3 Probe Preparation The YSI Model 55 probe is shipped dry Before using the Model 55 the protective membrane on the probe tip must be removed the probe must be filled with KCI solution and a new membrane must be installed Follow the instructions below to install the KCl solution and membrane To prepare for installation of a new membrane on your YSI Model 55 dissolved oxygen probe Unscrew the probe sensor guard 2 Remove the old O ring and membrane 3 Thoroughly rinse the sensor tip and KCI reservoir with distilled water 4 Prepare the electrolyte according to the directions on the KCI solution bottle 4 4 Membrane Installation A With the thumb and forefinger of your other hand Secure the end of the membrane under your Secure a membrane between your thumb and the probe body Add electrolyte to the probe until a large meniscus completely covers the gold cathode NO
5. 3 Replace batteries Page 3 Return system for service Page 14 A Recalibrate w correct value Page 8 B C Recalibrate w correct value Page 8 Moisten sponge and place in Cal chamber w probe and Recal Page 4 8 Replace membrane Page 6 Clean anode Page 7 Clean cathode Page 7 Return system for service Page 14 Replace batteries Page 3 Replace membrane and KCI Page 6 Clean anode Page 7 Clean cathode Page 7 Return system for service Page 14 Recalibrate using correct altitude and salinity compensation Page 8 Replace membrane and KCI Page 6 Clean cathode Page 7 Clean anode Page 7 Return system for service Page 14 Replace membrane and KCI Page 6 Clean anode Page 7 Clean cathode Page 7 Return system for service Page 14 SYMPTOM POSSIBLE CAUSE ACTION 9 display reads Er 1 Main display reads Err Secondary display reads ra 10 Main display reads Er 2 or Main display reads Err Secondary display reads ro 11 Main display reads Er 3 or Main display reads FAIL secondary display reads 12 Main display reads Er 4 13 Main display reads Er 5 14 Main display reads Er 6 15 Main display reads Er 7 16 Secondary display reads Er 8 or Main Display reads OVEr Secondary display reads ovr 17 Secondary display reads Er 9 or
6. Conductivity Temperature meter to determine it 5 2 The Calibration Process 1 Ensure that the sponge inside the instrument s calibration chamber is wet Insert the probe into the calibration chamber 2 Turn the instrument on by pressing the ON OFF button on the front of the instrument Wait for the dissolved oxygen and temperature readings to stabilize usually 15 minutes is required after turning the instrument on 3 Toenter the calibration menu use two fingers to press and release both the UP ARROW and DOWN ARROW keys at the same time 4 TheLCD will prompt you to enter the local altitude in hundreds of feet Use the arrow keys to increase or decrease the altitude EXAMPLE Entering the number 12 here indicates 1200 feet 5 When the proper altitude appears on the LCD press the ENTER key The Model 55 should now display CAL in lower left of the display the calibration value should be displayed in the lower right of the display and the current DO reading before calibration should be on the main display 6 Make sure that the DO reading large display is stable then press the ENTER button The LCD will prompt you to enter the approximate salinity of the water you are about to analyze You can enter any number from 0 to 40 parts per thousand PPT of salinity Use the arrow keys to increase or decrease the salinity setting When the correct salinity appears on the LCD zero for fresh water press the ENTER key
7. Main Display reads OVEr Secondary display reads udr 18 Main display reads Er A A Short in probe cable assembly B System requires service A Instrument s self test detects a variance in RAM B System requires service A Instrument s self test detects a variance in ROM checksum B System requires service A Instrument s self test detects a system malfunction or component failure B System requires service A Sample O concentration is more than 20 mg L B System requires service A Displayed O concentration is below 0 5 mg L B System requires service A Sample O concentration is over range mode B System requires service A Displayed O concentration is below 3 0 B System requires service A Sample temperature is more than 45 9 System requires service A Sample temperature is less than 5 C B System requires service 13 A Remove battery lid wait 15 seconds for reset replace lid Page 3 B Return system for service Page 14 A Remove battery lid wait 15 seconds for reset replace lid Page 3 B Return system for service Page 14 A Remove battery lid wait 15 seconds for reset replace lid Page 3 B Return system for service Page 14 A Recalibrate using correct altitude and salinity compensation Page 8 B Replace membrane and KCI Page 6 C Clean anode Page 7 D Clean cathode Page 7 E Return system for service P
8. precautions to prevent radioactive contamination and must use appropriate decontamination procedures should exposure occur 3 If exposure has occurred the customer must certify that decontamination has been accomplished and that no radioactivity is detectable by survey equipment 4 Any product being returned to the YSI Repair Center should be packed securely to prevent damage 5 Cleaning must be completed and certified on any product before returning it to YSI 15 8 2 Packing Instructions 1 Clean and decontaminate items to insure the safety of the handler 2 Complete and include the Cleaning Certificate 3 Place the product in a plastic bag to keep out dirt and packing material 4 Use a large carton preferably the original and surround the product completely with packing material 5 Insure for the replacement value of the product Cleaning Certificate Organization Department Address City Zip Country Phone Model No of Device Lot Number Contaminant if known Cleaning Agent s used Radioactive Decontamination Certified Answer only if there has been radioactive exposure Yes No Cleaning Certified By 16 9 Required Notice The Federal Communications Commission defines this product as a computing device and requires the following notice This equipment generates and uses radio frequency energy and if not installed and used properly may cause interference to radio and television rece
9. 37 767 1058 e Email environmental ysi com 14 8 1 Cleaning Instructions NOTE Before they can be serviced equipment exposed to biological radioactive or toxic materials must be cleaned and disinfected Biological contamination is presumed for any instrument probe or other device that has been used with body fluids or tissues or with waste water Radioactive contamination 15 presumed for any instrument probe or other device that has been used near any radioactive source If an instrument probe or other part is returned or presented for service without a Cleaning Certificate and if in our opinion 1t represents a potential biological or radioactive hazard our service personnel reserve the right to withhold service until appropriate cleaning decontamination and certification has been completed We will contact the sender for instructions as to the disposition of the equipment Disposition costs will be the responsibility of the sender When service is required either at the user s facility at YSI the following steps must be taken to insure the safety of our service personnel 1 Ina manner appropriate to each device decontaminate all exposed surfaces including any containers 70 isopropyl alcohol or a solution of 1 4 cup bleach to 1 gallon tap water are suitable for most disinfecting Instruments used with waste water may be disinfected with 596 Lysol if this is more convenient to the user 2 The user shall take normal
10. TE Handle the membrane material with care touching it at the ends only grasp the free end of the membrane With a continuous motion stretch the membrane up over and down the other side of the sensor Stretching forms the membrane to the contour of the sensor tip forefinger while continuing to hold the probe Roll the O ring over the end of the probe being careful not to touch the membrane surface There should be no wrinkles in the membrane or trapped air bubbles under the membrane Some wrinkles may be removed by lightly tugging on the edges of the membrane beyond the O ring Trim off excess membrane with scissors or a sharp knife Check that the stainless steel temperature sensor is not covered by excess membrane Shake off excess KCI Rinse the stainless steel thoroughly with distilled water to prevent corrosion Reinstall the sensor guard The sensor should be kept in a humid environment such as the calibration chamber between measurements and when not in use 4 5 Probe Operation and Precautions 1 Membrane life depends on usage Membranes will last a long time if installed properly and treated with care Erratic readings are a result of loose wrinkled damaged or fouled membranes or from large more than 1 8 diameter bubbles in the electrolyte reservoir If erratic readings or evidence of membrane damage occurs you should replace the membrane and the KCI solution The average replacement interval is
11. The instrument will return to normal operation Once the calibration process is complete the only keys which will remain operational are the MODE key the LIGHT key and the ON OFF key You can move back and forth from reading dissolved oxygen in the mg L mode or the air saturation mode by pressing the MODE key If you are working in a dark area and have difficulty reading the LCD press and hold the LIGHT key to activate the back light of the YSI Model 55 The ON OFF key turns the instrument on or off For best results e Each time the Model 55 is turned off re calibrate before taking measurements e Calibrate at a temperature within 10 C of the sample temperature 6 Principles Of Operation The sensor consists of an acrylic body with a circular gold cathode embedded in the end Inside the gold ring there is a small chamber containing a porous silver anode In operation this chamber is filled with a solution of KCI electrolyte containing a small amount of surfactant to improve wetting action A thin permeable membrane stretched over the sensor isolates the electrodes from the environment while allowing gases to enter When a polarizing voltage is applied to the sensor electrodes oxygen which has passed through the membrane reacts at the cathode causing a current to flow The membrane passes oxygen at a rate proportional to the pressure difference across it Since oxygen is rapidly consumed at the cathode it can be assumed that the o
12. age 14 A Recalibrate using correct altitude and salinity compensation Page 8 B Return system for service Page 14 A Recalibrate using correct altitude and salinity compensation Page 8 B Replace membrane and KCI Page 6 C Clean anode Page 7 D Clean cathode Page 7 E Return system for service Page 14 A Recalibrate using correct altitude and salinity compensation Page 8 B Return system for service Page 14 A Reduce the sample temperature B Return system for service Page 14 A Increase sample temperature B Return system for service Page 14 A Replace probe cable assembly B Return system for service Page 14 8 Warranty And Repair YSI Model 55 Dissolved Oxygen and Temperature Meters are warranted for two years from date of purchase by the end user against defects in materials and workmanship YSI Model 55 probes and cables are warranted for one year from date of purchase by the end user against defects in material and workmanship Within the warranty period YSI will repair or replace at its sole discretion free of charge any product that YSI determines to be covered by this warranty To exercise this warranty write or call your local YSI representative or contact YSI Customer Service in Yellow Springs Ohio Send the product and proof of purchase transportation prepaid to the Authorized Service Center selected by YSI Repair or replacement will be made and the product retu
13. ew KCI solution and install a new membrane and O ring Turn the instrument on and allow the system to stabilize for at least 30 minutes If after several hours you are still unable to calibrate return the YSI Model 55 system to an authorized service center for service If the sensor O ring is worn or loose replace it with the appropriate O ring provided in the YSI Model 5945 O ring Pack To keep the electrolyte from drying out store the probe in the calibration storage chamber with the wet sponge 5 Calibration Dissolved oxygen calibration must be done in an environment with a known oxygen content Since the amount of oxygen in the atmosphere is known it makes an excellent environment for calibration at 100 relative humidity The calibration storage chamber contains a moist sponge to create a 100 water saturated air environment 5 1 Before You Calibrate Before you calibrate the YSI Model 55 complete the procedures discussed in the Preparing the Meter and Preparing the Probe chapters of this manual To accurately calibrate the YSI Model 55 you will need to know the following information The approximate altitude of the region in which you are located e The approximate salinity of the water you will be analyzing Fresh water has a salinity of approximately zero Sea water has a salinity of approximately 35 parts per thousand ppt If you are not certain what the salinity of the sample water is use a YSI Model 30 Salinity
14. he system simultaneously displays temperature in and dissolved oxygen in either mg L milligrams per liter or air saturation The system requires only a single calibration regardless of which dissolved oxygen display you use You can switch back and forth from air saturation to mg L with a single push of the MODE key A calibration chamber is built into the instrument A small sponge in the chamber can be moistened to provide a water saturated air environment which is ideal for air calibration This chamber is also designed for transporting and storing the probe When the probe is stored in the chamber the moist environment will prolong effective membrane performance and probe life The instrument is powered by six AA size alkaline batteries A new set of alkaline batteries will provide approximately 100 hours of continuous operation When batteries need to be replaced the LCD will display a LO message The YSI Model 55 instrument case is splash resistant You can operate your Model 55 in a steady rain without damage to the instrument 2 Specifications Probe Operating Environment Medium fresh sea or polluted water Temperature 5 to 45 C Depth 0 to 12 0 to 25 or 0 to 50 feet depending on cable length Meter Ambient Operatine Storage Temperature 10 to 50 C Material ABS Stainless Steel Acrylic and other materials Dimensions Height 9 5 inches 24 13 cm Thickness 2 2 inches 5 6 cm Width 3 5 inche
15. leather cover and pull the two Velcro strips apart Place your hand between the meter and the strap and adjust the strap length so that your hand is snugly held in place Press the two Velcro strips back together and snap the leather cover back into place 3 6 The Meter Case The meter case is sealed at the factory and is not intended to be opened except by authorized service technicians Do not attempt to separate the two halves of the meter case as this may damage the instrument break the water proof seal and may void the manufacturer s warranty 4 Preparing The Probe 4 1 Description The YSI Model 55 dissolved oxygen probe is a non detachable polarographic sensor designed specifically for the YSI Model 55 Handheld Dissolved Oxygen System Probe cables are available in lengths of 12 25 or 50 feet 4 2 Choosing The Right Membrane The YSI Model 5775 Standard Membrane Kit is supplied with the YSI Model 55 This kit contains thirty 1 mil 001 membranes and a bottle of KCl solution YSI recommends the 5775 membranes for most applications STRAIN RELIEF STAINLESS STEEL PROBE BODY PROBE GUARD For special conditions a 0 5 mil 0005 membrane is available Order YSI Model 5776 High Sensitivity Membrane Kit This half thickness membrane improves measurement time at low temperatures and helps suppress background current at very low dissolved oxygen levels When data is routinely collected at sample temperatures below
16. nstweuons ntu des pieles b SU NIMM MN d Leu UPS aaa 15 8 2 PACKING SEC Hole obe Au ate NOS ee ase s 16 9 Required Notice 17 10 Accessories And Replacement Parts J J J J J anne 18 11 Appendix A Solubility Table 19 12 Appendix B Conversion Chart J 21 1 General Description The YSI Model 55 Handheld Dissolved System is rugged micro processor based digital meter with an attached YSI dissolved oxygen probe The YSI Model 55 is designed for field use and is available with cable lengths of 12 25 or 50 feet The body of the probe has been manufactured with stainless steel to add rugged durability and sinking weight The large Liquid Crystal Display LCD is easy to read and is equipped with a back light for use in dark or poorly lighted areas The Model 55 s micro processor allows the system to be easily calibrated with the press of a few keys Additionally the micro processor performs a self diagnostic routine each time the instrument is turned on The self diagnostic routine provides you with useful information about the function of the instrument circuitry and the quality of the readings you obtain For a list of these diagnostic features see chapter 7 Troubleshooting T
17. omplete the Warranty Card and return it to YSI This will record your purchase of this quality instrument in our computer system Once your purchase is recorded you will receive prompt efficient service in the event any part of your YSI Model 55 should ever need repair 3 3 Batteries There are a few things you must do to prepare your YSI Model 55 for use First locate the six AA size alkaline batteries which were included Use a screwdriver or a small coin to W remove the thumbscrew on the bottom of the O RING v UJ instrument This thumbscrew holds the battery chamber cover in place The battery chamber NY HAND STRAP cover is marked with the words OPEN and e CLOSE d POLARITY LABEL NOTE On some models the battery cover BATTERY CHAMBER LID thumbscrew may be unscrewed by hand a screwdriver may not be required There is a small label inside each of the two battery chamber sleeves These labels illustrate the correct way to install the batteries into each sleeve of the battery chamber NOTE It is very important that the batteries be installed ONLY as illustrated The instrument will not function if the batteries are installed incorrectly Turn the instrument on by pressing and releasing the ON OFF button the front of the instrument The instrument will activate all segments of the display for a few seconds which will be followed by a self test procedure which will last for several more second
18. ption There is no guarantee that interference will not occur in a particular installation If this equipment does cause interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures re orient the receiving antenna relocate the computer with respect to the receiver move the computer away from the receiver plug the computer into a different outlet so that the computer and receiver are on different branch circuits If necessary the user should consult the dealer or an experienced radio television technician for additional suggestions The user may find the following booklet prepared by the Federal Communications Commission helpful How to Identify and Resolve Radio TV Interference Problems This booklet is available from the U S Government Printing Office Washington DC 20402 Stock No 0004 000 00345 4 17 10 Accessories And Replacement Parts The following parts and accessories are available from YSI or any Franchise Dealer authorized by YSI se High Sensitivity Membrane and KCI kit 5 mil 18 11 Appendix A Solubility Table Solubility of Oxygen in mg L in Water Exposed to Water Saturated Air at 760 mm Hg Pressure Salinity Measure of quantity of dissolved salts in water Chlorinity Measure of chloride content by mass of water S 1 80655 x Chlorinity
19. rned transportation prepaid Repaired or replaced products are warranted for the balance of the original warranty period or at least 90 days from date of repair or replacement Limitation of Warranty This Warranty does not apply to any YSI product damage or failure caused by 1 failure to install operate or use the product in accordance with YSI s written instructions ii abuse or misuse of the product iii failure to maintain the product in accordance with YSI s written instructions or standard industry procedure iv any improper repairs to the product v use by you of defective or improper components or parts in servicing or repairing the product or vi modification of the product in any way not expressly authorized by YSI THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE YSI s LIABILITY UNDER THIS WARRANTY IS LIMITED TO REPAIR OR REPLACEMENT OF THE PRODUCT AND THIS SHALL BE YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY DEFECTIVE PRODUCT COVERED BY THIS WARRANTY IN NO EVENT SHALL YSI BELIABLE FOR ANY SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM ANY DEFECTIVE PRODUCT COVERED BY THIS WARRANTY YSI Authorized Service Centers Please visit www ysi com or contact YSI Technical Support for the nearest authorized service center YSI Incorporated e Technical Support e Phone 1 937 767 7241 800 897 4151 Fax 9
20. s During this power on self test sequence the instrument s microprocessor is verifying that the instrument is working If the instrument were to detect a problem a continuous error message would be displayed If the instrument does not operate consult chapter 7 Troubleshooting NOTE The information on the display will be meaningless since the probe has not yet been prepared You may also want to take the instrument into a dark room and with the instrument ON hold down the LIGHT key The instrument back light should illuminate the LCD so that the display can be easily read 3 4 Calibration Storage Chamber The Model 55 has a convenient calibration storage chamber built into the instrument s side This chamber provides an ideal storage area for the probe during transport and extended non use If you look into the chamber you should notice a small round sponge in the bottom Carefully put 3 to 6 drops of clean water into the sponge Turn the instrument over and allow any excess water to drain out of the chamber The wet sponge creates a 10096 water saturated air environment for the probe which is ideal for dissolved oxygen calibration 3 5 Hand Strap The hand strap is designed to allow comfortable operation of the Model 55 with minimum effort If the hand strap is adjusted correctly it is unlikely that the instrument will be easily dropped or bumped from your hand To adjust the hand strap on the back of the meter unsnap the
21. s max 8 89 cm Weight 1 7 pounds 0 77 kg Power 9 VDC 6 AA size Alkaline Batteries included Approximately 100 hours operation from each new set of batteries Water Tightness Meets or exceeds IP65 standards Extensive testing of the YSI Model 55 suggests the following typical performance Temperature Sensor Type Thermistor Range 5 to 45 C Accuracy 0 2 C Resolution 0 1 C Dissolved Oxygen Saturation Sensor Type Membrane covered polarographic 0 to 200 air saturation Accuracy 2 air saturation Resolution 0 1 96 air saturation Dissolved Oxygen mg L Sensor Type Calculated from air saturation temperature and salinity Ranger ne 0 to 20 mg L Accuracy 0 3 mg L Resolution 0 01 mg L 3 Preparing The Meter 3 1 Unpacking When you unpack your new YSI Model 55 Handheld Dissolved Oxygen System for the first time check the packing list to make sure you have received everything you should have If there is anything missing or damaged call the dealer from whom you purchased the Model 55 If you do not know which of our authorized dealers sold the system to you call YSI Customer Service at 800 765 4974 or 937 767 7241 and we ll be happy to help you 3 2 Warranty Card Before you do anything else please c
22. strument readings are inaccurate 5 LCD displays LO BAT or Main display flashes OFF 6 Main display reads undr 7 Main display reads OVEr 8 Main display reads Er 0 POSSIBLE CAUSE A Low battery voltage B Batteries installed incorrectly C Meter requires service A Membrane is fouled or damaged B Probe anode is fouled or dark C Probe cathode is tarnished D System requires service A Instrument has received a shock B Batteries are low or damaged C System requires service A Cal altitude is incorrect B Salinity setting is incorrect C Probe not in 100 water saturated air during Cal procedure D Membrane fouled or damaged E Probe anode is fouled or dark F Probe cathode is tarnished G System requires service A Batteries are low or damaged A Probe current too low to calibrate B System requires service A Sample O concentration is more than 20 mg L B Probe current too high to calibrate C System requires service A Calibration current out of range B Instrument s self test detects improper probe voltage during calibration ACTION A Replace batteries Page 3 B C Check battery polarity Page 3 Return system for service Page 14 A Replace membrane and KCI Page 6 B C Clean anode Page 7 Clean cathode Page 7 D Return system for service Page 14 A Remove battery lid wait 15 seconds B C for reset replace lid Page
23. two to four weeks If the membrane is coated with oxygen consuming e g bacteria or oxygen evolving organisms e g algae erroneous readings may occur Chlorine sulfur dioxide nitric oxide and nitrous oxide can affect readings by behaving like oxygen at the probe If you suspect erroneous readings it may be necessary to determine if these gases are the cause Avoid any environment which contains substances that may attack the probe materials Some of these substances are concentrated acids caustics and strong solvents The probe materials that come in contact with the sample include FEP Teflon acrylic plastic EPR rubber stainless steel epoxy polyetherimide and the polyurethane cable covering For correct probe operation the gold cathode must always be bright If it is tarnished which can result from contact with certain gases or plated with silver which can result from extended use with a loose or wrinkled membrane the gold surface must be restored To restore the cathode you may either return the instrument to the factory or clean it using the YSI Model 5680 Probe Reconditioning Kit Never use chemicals or abrasives not supplied with this Kit It is also possible for the silver anode to become contaminated which will prevent successful calibration To clean the anode remove the O ring and membrane and soak the probe overnight in 3 ammonium hydroxide Next rinse the sensor tip and KCI reservoir with deionized water add n
24. xygen pressure inside the membrane is zero Hence the force causing the oxygen to diffuse through the membrane is proportional to the partial pressure of oxygen outside the membrane As the oxygen partial pressure varies so does the oxygen diffusion through the membrane This causes the probe current to change proportionally It is important to recognize that oxygen dissolved in the sample is consumed during the test It is therefore essential that the sample be continuously stirred at the sensor tip If stagnation occurs your readings will be artificially low Stirring may be accomplished by mechanically moving the sample around the probe tip or by rapidly moving the probe through the sample The rate of stirring should be at least 1 foot per second 6 1 Discussion Of Measurement Errors There are three basic types of dissolved oxygen errors Type 1 errors are related to limitations of instrument design and tolerances of instrument components These are primarily the meter linearity and the resistor tolerances Type 2 errors are due to basic probe accuracy tolerances mainly background signal probe linearity and variations in membrane temperature coefficient Type 3 errors are related to the operator s ability to determine the conditions at the time of calibration If calibration is performed against more accurately known conditions type 3 errors are appropriately reduced Type 1 Errors A Meter linearity error 1 of full scale reading or
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