to the AIM user manual
Contents
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4. etd cim cup M Sacer Rene EES M Pe 25 ATIMEEIUCONIMAND SET SUMMARY ces veo vao oc Deae cos dee cuia 26 I 1 8 OR MN 26 CONFIGURATION AND SETUP COMMANDS rue eate oso suas nae ose 26 dU E E nse eee 27 SERVICE AND CALIBRATION eve eese Denon 27 S prr Hr 27 GP BIET TION sg aie occa esses ch aco TE E eee 27 PNEUMATIC NIAINTENANE ER ETT cunt ENDS 27 o 4 DIFEBRENTEAL PRESSURE ordi Moselle Ed LS de e m M Sina E LP LL 27 59 JADIUSTNIENI dci Poste emt cites Longo cut eec bue cato aat iate cite ca a oto dd reote ce 27 A I E EEE c 27 Sa PREVENTIVE MAINTENANCE a 27 Chell PartNo 900005 Issue 3 6 28 September 2011 ECO No 0651 Due to a policy of continuously updating products this manual may cont
5. E Pep EAM IA ele LA LM tahoe 17 SEC TION eee C eC M i 18 PRONTPANEL 5 c ovra dece ao eco oue sepe cese ee cese eux eue ep de Seen eoa so cce oue ce ewe 18 M Evo sel B TION 18 6 2 ALTERNA TIVE DISPEAY INFORMA TION uuu des be 18 6 3 DIFFERENTIAL PRESSURE INPUT ZERO FUNCTION de n tva I ave eases 19 CONDITION AND ERROR GODES i od ota ER a IMS n dtes aed 20 H o 22 UN TER EAC cnn e a 22 Hid 8 8 BE C TION er NEN E PTR EP SST PL E OEE RON RMT HEN SNH Rd NS ETN 22 TUB ASICCOMMUNICATION PROTOCQOED eti b REA 22 y MP VM 22 E nasa ea 23 TO SERIAL INTERFACE CONTROL COMMANDS i eric pass ah e E a a mU e 24 S OCC THERQCCONINPANDS
6. Chell Instruments Ltd Folgate House Folgate Road North Walsham United Kingdom Tel 01692 500555 Fax 01692 500088 http Wwww chell co uk INSTALLATION AND OPERATING MANUAL AIR INGRESS MONITOR AIM 100 AND VARIANTS 900005 3 6 Please read this manual carefully before using this instrument Use not in accordance with the instructions in this manual may result in the protection offered to the user being impaired INDEX SEC TION E VET dev cues vabesauccact Genova 3 GENERAL DESCRIPTION z 4 3 3 LS ITT LOIN rr 3 IX a a 3 eatery bu CL D aN OU UE RE Te SOON 5 SPECIEL ING sss fe cose 5 Cini sio NR act hs Sade ea E ty ete ote ee Gaede 5 222 NIEASUREMENT 6 2 2 P84 TER SEER M M M M MC Cw MU M M 6 DAN SOE DE RE SS TE 6 Fas BIR 54 SH DRIN
7. RS485 network has been configured then it will be necessary to set each unit to a different address To change the unit address see section 7 5 The serial interface can use an 5 232 protocol RS485 protocol The default is RS 232 To check and change the protocol see section 7 5 17 Section 6 Front Panel Operation 6 1 Introduction The front panel contains a 4 digit 1 red LED 7 segment display plus 5 legends to indicate the units of the measurement Also on the front panel is the keypad which consists of 4 momentary action IP65 sealed keys labelled Duct Temperature Absolute Pressure Differential Pressure Air Content With no front panel keys pressed the instrument will display Air Ingress Air Mass Flow in the units indicated by the right hand legend Pressing either of the Duct Temperature Absolute Pressure Differential Pressure or Air Content keys will cause the instrument to display the current temperature as measured by the RTD the absolute pressure in the duct the differential pressure developed across the pitot due to the passing steam air flow or the percentage air content respectively in the units as indicated for the AMFM variant the Air Content Key just displays the Air Mass Flow as default When any switch 15 released the instrument will continue to display the relevant parameter for a further 20 seconds before reverting to Air Ingress allowing ample time for any readings to be recorded 6 2 Alternat
8. better than 1 in 2000 for 0 to 20 mA lt 10 Uncertainty 0 25 of calculated value Compliance Maximum load resistance 6002 6V wrt earth for both I and Equivalence between output current and measured parameter assumes user offset 5 zero user gain 15 unity Parameter Units Current Output Air Ingress 0 to 1000 Ibs hr to 20mA 0 to 500 kg hr 4 to 20mA Air Mass Flow 0 to 1700 slpm 4 to 20mA AMFM variant to 130 kg hr 4 to 20mA Temperature 0 to 70 C 32 to 158 F 4 to 20mA Absolute P ressure 0 to FS 100 Torr 0 to FS 1000 Torr 4 to 20mA 0to 133 322 mbar 0to 1333 22 mbar 0 to 3 937 inHg 0 to 39 37 inHg 0 to 13 3322 kPa 0 to 133 322 kPa Differential Pressure 0 to FS 1 Torr 0 to FS 10 Torr to 20mA 0to 1 33322 mbar 0to 13 3322 mbar 0 to 13 595 mmH 0 0 to 135 95 mmH 0 0 to 0 53524 inH 0 0 to 5 3524 inH 0 0 to 133 322 0 to 1333 22 air 0 to 100 90 to 20mA Out of range signals and error conditions are indicated by 1mA 2 9 Calculated Mass Flow AMFM variant The principal source of error will be dependant onthe flow within the pipework and the repeatability and accuracy of the pitot tube used The instrumentation will contribute approximately 0 596 FS error Actual achievable uncertainty is likely to be in the region of 2 5 FSD 2 10 Serial Outputs User RS232 or RS485 For connection to PC for data logging setup calibration etc Selection of RS 232 485 via co
9. checked by sending the query commands coa and csa to which the AIM will reply with the stored values These can only be changed by sending new values Power cycling or changing the current output selection does not reset the values The default values are coa0 0 and csal 0 7 5 Serial Interface Control Commands To change the baud rate it is necessary to send the unit address followed by the command bra and a value n representing the required baud rate For example to change to 300 baud on the unit with address a the following string needs to be sent to the AIM abra 300 1 The AIM will reply with at the old baud rate and then at the new baud rate All communication should now take place at the new setting The default setting 15 9600 baud rate setting value forn 300 19200 1200 38400 2400 57600 4800 9600 The units baud rate may be discovered by sending the query command bra The unit address may be from to 1 To change address use the command add where x is the new address All subsequent communication must refer to this address The serial interface protocol can be either RS232 or RS485 and is selectable by sending the command pro where n 5 0 5485 or 1 5232 Sending pro returns the current protocol setting 24 7 6 Other Commands Recall Serial No asn The serial number of the unit may be recalled with the command 5 As supplied this will be the
10. connections need to be made to RTS and CTS It may be necessary to loop back one or more of the handshake lines on the cable connector at the computer DSR DTR and CTS RTS so that time out errors are eliminated If the RS485 option has been chosen this must operate with software handshaking enabled Note that the distance between the loop and each instrument should be less than 300 metres Host Computer 4 13 4 20mA Analogue Output connections optional When using these outputs a conduit junction box may be required to allow separate cable glands for RTD and current Insert the different wires into the appropriate terminals of the Current O P block as shown on the pcb and tighten the terminal block screws 4 14 RTD connection at pitot The PRT is terminated in a aeger connector 533801000 The mating half is aeger 530801006 socket with 530332006 cable gland Interconnect cable is 4m of Alpha 5098C 20swg foil shield 5 7mm diameter wired as follows Function J aeger Colour M 1 Red 2 Yellow 3 Green M 4 Black Guard Screen 15 4 15 Serial Port Connections for AIM and A complete list of all the RS 232 connections is given in the table below Connects to 1 _ 3 Input Input 25 way male 9 way male Tx Tx Data Out RX Data In Data Out MEN 5 RTS Output 4 2 2 3 7 DSR Input DTR Output 4 Note that it is necessary to connect an ou
11. extract data from the AIM as required or be used to configure the AIM 1 2 General Information If the instrument is supplied with a pitot tube the following accessories will be included 4 metres 7 O D Nylon Tube 2 off 4 metres AIM to RTD cable with appropriate terminations The following accessories are available for use with the Air Ingress Monitors Pitot tube with RTD fitted available in various lengths ranging from 50mm to 1800mm 7 NPT to 1 O D tube fitting male or female 7 O D Nylon tube 5 valve manifold Shut off valve with quick connect Insertion ball valve AIR INGRESS MONITOR C e Air Ingress Monitor AIM 100 RS232 RS485 eas Absolute 4 20 mA Output and RTD 1 9 7 5 Pressure m Interface kg Hr Differential 3 Pressure Air Power Supply Content Chell e 3 valve optional 5 valve Pu manifold Connection to velocity and absolute pressure sensor Section 2 Specifications 2 1 General Mechanical Model Height Width Depth Weight Construction mm mm mm kg AIM 100 330 230 110 10 Diecast Aluminium sealed enclosure with sealed keypad hinged lid Connections via screw terminals Power Supply Line voltage 100 240 V AC Line frequency 50 60 Hz Consumption less than 20 VA Protection T1 6A anti surge fuse internal Operating conditions Operating temperature range 5 C to 50 C 40 F to 122 F Storage temperature range 40 C to 7
12. from all subsequent measurements Should the reading be greater than 10 of FS then the zero will fail and the display will indicate C71 Close the cross port valve to the differential transducer open the isolation valves allowing the differential pressure developed across the pitot to be measured 19 6 4 Condition and Error Codes Under certain operational conditions the AIM may be unable to calculate the air ingress it will then indicate a code on the display There are two types of codes a CONDITION code preceded with a 5 used to indicate an abnormal operating regime The table below outlines the codes and suggests possible causes with actions that may be taken The other situations that may be reported are ERRORS proceeded with a These indicate that there is an internal processing problem with the measurements taken In this case check internal fittings and sensors and if this fails to solve the problem contact the AIM service centre Note Condition and Error codes marked with an asterisk do not occur in the AMFM variant because they are not applicable for the typical applications of that variant Condition codes that indicate an abnormal operating regime Absolute pressure 15 greater than 500 Torr Air flow rates will not be meaningful at these levels A possible reason is that the turbine generator unit is off load or running up to down from load If however the condenser is known to be under running conditions
13. or scale as a floating point value and defines the output to be adjusted as shown 0 Differential Pressure a Absolute Pressure t Duct Temperature p Percentage Air f Air Mass Flow The current offset and scale for the outputs may be found by entering co amp 5 where 15 defined as above Eg If working with absolute pressure the actual current output lout is given by the equation lout Ugain 16 Pabs PabsFS Uzero 4 23 Worked example of user offset and scaling Using absolute pressure as an example As default 0 mbar 15 represented by 4 mA and 133 2 mbar 15 represented by 20 mA In practice the absolute pressure 15 only expected to vary between 50 and 60 mbar It 15 therefore required that 50 mbar produces 5 mA and that 60 mbar produces 20 mA Therefore P max 60 250 Imax 20 Imin 25 PabsFS 133 2 Pressure in mbar current in mA First itis necessary to calculate the required scaling by substituting the above values into the following equation Ugain Imax Imin Pmax Pmin x 16 PabsFS Ugain 20 5 60 50 x16 133 2 212 4875 It is now possible to calculate the required zero by substituting into the following equation Uzero Ugain x 16 x Pmin PabsFS Imin 4 Ugain Uzero 12 4875 x 16x50 133 2 5 44 12 4875 25 9259 The values for Uzero and Ugain may now be entered using the coa5 9259 and 12 4875 commands The values already in use can be
14. the power supply immediately to prevent damage Always mount the instrument to allow for adequate ventilation to avoid over heating When connecting the pneumatic lines always ensure that the compression fittings are assembled correctly and avoid over or under tightening Nylon tubing should be kept away from heat as it can cause weakening and possible failure If you have any queries as to the safety procedures of the instrument please contact Chell Instruments Ltd for assistance 4 2 Introduction This section contains information and instructions for unpacking and installing the Chell AIM 100 Air Ingress Monitor 4 3 Unpacking E very care is taken in the choice of packing material to ensure that the equipment arrives in perfect condition If the equipment has been subject to excessive mishandling in transit the fact will probably be visible as external damage the shipping container and cushioning material should be kept for the carrier s inspection Unpack the equipment and check for external damage to the case fittings etc If damage is found notify the carrier and sales agent immediately 4 4 Preparation for operation The instrument should be mounted above the pitot so that the connecting pneumatic lines will allow any condensation to drain away from the measuring instrument Mounting holes in the rear panel are available to secure the instrument in a fixed position access being gained by removal of the front panel The instrumen
15. then check the ve or L measurement vacuum line for air leaks Make a visual inspection from the Pitot head to the AIM On fixed AIM models isolate the ve port at the AIM and cross port the line by opening the equalising valve If the absolute pressure changes to a sensible reading then check ve line for leaks downstream of the AIM Isolation valve Absolute pressure over range 110 full scale The accuracy of the absolute pressure sensor is out of limits The validity of this measurement should be considered check for possible water blockage clogging by purging the Pitot and vacuum lines to atmospheric pressure Protect the differential pressure sensor if possible whilst purging check the Pitot ve line for leaks Isolate Pitot and disconnect ve line Apply suction and observe absolute pressure sensor response Temperature over range greater than 70 C 160 F carefully check the extraction pipework for the possibility of a genuinely high temperature check RTD connections for a bad circuit Temperature less than zero carefully check the extraction pipework for the possibility of a genuinely low temperature check RTD connections for a bad circuit Differential pressure over range 11096 full scale This could be a genuine condition due to a high flow in the extraction pipe This flow is a combination of air and steam Either the air in leakage 15 high steam carryover is high due to steam breakthrough or s
16. units serial number allocated by Chell Instruments It may however be redefined to be a plant I D number if required by sending the command asn where xxxx is any four characters Recall Date of Last Calibration dlc When the instrument is calibrated the date is entered into the AIM This may be recalled to see if the unit requires recalibrating The date is recalled with the command dic 4 The AIM will reply with the date in the format YYMMDD where YY is the year MM is the month and DD is the day For example 930120 would indicate that the unit was calibrated on the 20th J anuary 1993 List All Commands cmd To list all the commands to which the AIM can respond send the command cmd Differential Pressure Input Zero idz As the differential pressure produced across the pitot can be very low and the differential transducer is very sensitive to any leaks in the pneumatic lines it is necessary to ensure that it is correctly zeroed This command is similar to the Input Zero described in section 6 3 in that it measures the current differential pressure and then subtracts the value from all subsequent readings The value of the input zero can be found by using the query command 142 1 This will return the value in Torr The value can be set back to zero thus applying no zero offset using the command 1972 0 Pipe Diameter pdi The pipe diameter can be changed by using the command pdi x where i
17. 0 40 F to 158 F Maximum Relative humidity 95 at 50 C non condensing Warm up time to full accuracy lt 2 hours assumes unit already stabilised at ambient Pressure Ports AIM 100 2 X 0 5 Swagelok on 3 valve manifold Pitot tubes Pitot tubes are available trom 50mm up to 1800mm depending on model type Read rate 1 complete set of readings 15 taken and calculations performed once per second 2 2 Measurement Performance The following specifications are valid over an instrument ambient temperature range of 5 to 50 C and within 1 year of calibration at between 20 and 25 C Accuracy figures quoted include traceability to National Standards It is also assumed that the installation and orientation of the Pitot tube is correct It should be lower than the AIM 100 The AIM should be mounted vertically with the vacuum ports downwards as per calibration Pitot should be mounted normal to the horizontal pipe with ports uppermost Pitot should be aligned with the flow Pneumatic lines should be less than 10m in length and positioned such that condensation cannot collect and water traps form Pipe disturbances bends intersections gate valves must be greater than 12 pipe diameters upstream and greater than 4 pipe diameters downstream The pitot length must match the internal pipe diameter The RTD cable should be less than 10m in length 2 3 Temperature Transducer type 100 Q PRT to DIN 43760 BS 1904 1984 Temperature range
18. 0 to 70 Transducer error 0 15 Overall error 0 3 Display units 2 4 Absolute Pressure Transducer type Absolute Capacitance Manometer FS ranges 100 Torr giving 10V output Optional 1000 Torr giving 10V output Manufacturers Accuracy 0 5 reading 0 03 reading C 0 005 FS C Display Units mbar in Hg kPa Torr 2 5 Differential Pressure within 1 month of input zero It is also assumed that the transducer has not been over pressurised Transducer type Differential Capacitance Manometer fitted into a heated enclosure FS range 1 Torr Optional 10 Torr Error 0 3 reading 0 04 reading C 0 1 FS C Heater temperature Nominal 55 C stability 0 2 C Display Units mmH 0 Pa Torr 2 6 Calculated Air Ingress The actual uncertainty is dependent on the specific operating conditions within the pipe and is typically 10 Ibs hr Uncertainty for pipe internal diameters lt 18 less than 34 Ibs hr over the range 10 to 40 C steam temperature 15 to 120 mbar absolute pressure 0 5 to 5 mmH 0 differential pressure provided that air is gt 10 and lt 50 and total mass flow lt 2000 Ibs hr Display units Ibs hr kg hr scfm slom 2 7 Calculated air Uncertainty for pipe internal diameters lt 18 less than 2 over the range 10 to 40 C steam temperature 15 to 120 mbar absolute pressure provided that air is gt 10 and lt 50 2 8 4 20 mA Outputs Resolution
19. 1 Section 7 Serial Interface 7 1 Introduction The serial interface may be configured as either RS232 or RS485 protocol RS485 15 used where many AIM 100s are connected to the same serial port of a host computer The serial port may be used to control the units set up e g pipe diameter 4 20mA scaling or data format etc It is also used to return readings to a host computer either on an ongoing basis or via the optional data logger For interconnection details see Section 4 As supplied the unit is configured for a baud rate of 57600 The baud rate may be displayed on the front panel by simultaneously pressing the Duct Temperature and Absolute P ressure keys 7 2 Basic communication protocol All communication from the computer is in lower case alphanumeric characters any reply from the AIM is in upper case As multiple AIMs may be connected together on an RS485 system each unit has an address which may be from to h The computer must prefix any command sent with the particular units address The default address is When an AIM recognises its address it will respond by echoing back the address plus the ensuing command Depending on the command sent the AIM will respond either with data or in the case of a set up command If the AIM does not recognise the command or it has invalid or an incorrect number of parameters the AIM will repsond with If a command has accompanying parameters then the command mus
20. NECTION EO PE OP cui nn um Rar Le 13 4 9 INTERCONNECTIONS AIME IO edo ox pv e e oe ov OL Ee loea use E vus oss OL Ev P ee oec OL Erde 14 TAD ONIN S JUS cuum 14 All POWER S UPELY CONNECTION nub anand 15 4 12 USER PORT RS232 RS485 CONNECTION OPTIONAL 15 4 13 4 20 ANALOGUE OUTPUT CONNECTIONS OPTIONAL cccccceccssccessccseccsccesecesececsceescseeceecseseseseceeuceeucseseseeceuscsueseueceusess 15 A A PA CONNEC TIONGAT PLEO E 15 AIS SERAL PORT ONNECTIONS FORJAIIVI ANDY EE d calc elias cones an tne canna LL Er E Den 16 SEC TION S ae A e 17 INSTRUMENT CONFIGURATION AND INITIAL SET 17 SB INSTRUMENT SET BE cott enc 17 AWA 17 2 95 DIPPEREN TIAL ERANSDUCER Z PPO 5 D Sad resem on 17 SBRIALINTEREACE SETTINGS
21. NI SIN3AQLISNI SM toa a 8 H 9 115 UU COED E Ta 1ndino T Aas 4E gozn I 8 05 2199 1835 C 0 0 0 D voen aas 001n S N lt gt e NOMIVMVS saz Gs m amp liz iozr o nu o _ NS 601n l dow 2 vor NER 00 001A 1013 0018 O CI _ 10915 7018 oosak 6 001 OLED E 2 ve D ES 4 XN ONL SLNAWNYLSNI S corn zoen 4 Andino 8 O0 N ul 791435 oben DDD goin zorn LOCO SOSO SOLO zozr D lt gt NOYLVYVE 1 voco 019 H zoiu ZOSdUSL Loga zoea eosa BOE c 50 Plain y 3 OFT zogo ko eGo Mora ony 97 f 108419 Cel voeu oosn dg ont 0070 Oval zova Cezy 5 LOVG gory ee o o 9 M Hs ERAS N L60vM Bord BO M amp NS e sozr zovn HAF Xl leon 9 SSS Joor alla ul Cera 5 coni 9 A 0 oorr Logn cac LO
22. SUREMENT ccccscescececcecscscccscccsceccsceccecscescecescececscescscnecscescecsseecssescecescscecscescscesescesescesescecescs 9 3 9 AANALOGUE WIBASURING C IR CULDES 25 ele eode oad EE ot dote credite M hd 9 saa sid 9 SIM iS CRISE MEHR 9 vidi id oss rp 12 INS TALEA TION AND INTERCONNECTIONS 2 ad uev egeret e Pee oc eor oe 12 TIVMIPOR TANT ABEL E E 12 NTR CC HON 12 enda A LM 12 ad PREPARATION FOR OPERATION wots OU Fo eite deat beso fusion oe SE 12 AS PITOT TUBE LOCATION AND MOU NTIN Ge since sees sie sto ur coss fet La sete dead uds anos ee ne 12 WNACUUNMCIINE CONNECTION aeter uale tuu eti nae c E LL Lum 13 2 9 dL CON
23. ain minor differences in specification components and circuit design to the actual instrument supplied Section 1 General Description 1 1 Introduction Chell s AIM 100 microprocessor controlled Air Ingress Monitor is a high precision measuring instrument featuring multi measurement capability with both analogue and digital interfacing The instrument provides measurement and readout of duct temperature absolute pressure and differential pressure relating to the steam air flow The on board microprocessor not only controls the measurement sequence and front panel interface but also calculates for display the air ingress and percentage air of the total mass flow As of firmware version 2 08 an Air Mass Flow Meter variant AMFM exists who s main functionality is purely looking at mass flow rather than air ingress it is used in applications where the gas is just air there will be no steam to check for steam air mix The percentage air display is disabled in this variant The instrument may be powered from a wide range line supply voltage and frequency 100 240 V AC 50 60Hz There are five 4 20mA outputs relating to each of the measured and calculated parameters that are available to drive a chart recorder or remote panel meter With user programmable offset and scaling factors the range of the chart recorder may be optimised A digital serial interface RS232 or RS485 provides interconnection to a host computer The computer may then
24. d against an internal precision reference resistor A 4 wire measurement is taken to eliminate unknown lead and contact resistance s From standard curves for resistance against temperature the equivalent temperature may then be calculated 3 3 Absolute Pressure Measurement The absolute pressure from the static side of the pitot is measured by a capacitance diaphragm transducer It s all metal construction is corrosion resistant with only Inconel and 316 stainless steel being exposed to the steam air mixture The 0 to 10V output proportional to the absolute pressure is then measured by the analogue circuits 3 4 Differential Pressure Measurement The differential pressure developed across the pitot due to the passing flow is measured using a differential capacitance manometer of similar construction to the absolute sensor above To eliminate the possibility of vapour condensing in the transducer it is enclosed in a controlled heated enclosure The 0 to 10V output proportional to the differential pressure is once again measured by the analogue circuits 3 5 Analogue Measuring Circuits Each signal from the above transducers is buffered and scaled before being fed to the 16 bit analogue to digital converter To remove short term fluctuations in the differential pressure signal there is both an analogue and digital filter associated with this channel 3 6 Digital Control The sequence of measuring each transducer calibrating converting to disp
25. ing ro x where x is between 0 and 4 as dictated by the following No Interval use this to disable the repeated recall Repeat every second Repeat every minute Repeat every hour Repeat every day I U RO Fco The timing commences from the point at which the ro command is entered The recall setting is remembered through a power cycle If the repeated recall is active and the AIM is restarted due to a power outage etc then the display will show AO x where x is one of the above numbers to indicate that repeated recall is in operation Format of data output fmt Data is output from the AIM in one of two formats To determine the current setting send the command fmt The AIM will reply with a number where 0 Original format 1 Excel CSV compatible format To change the current setting send the command fmt x where x is 0 or 1 as listed above 7 4 4 20mA Output Control The 4 20mA outputs are normally used to send a signal to a chart recorder proportional to air ingress The exact values that represent particular currents are given in the specification see section 2 8 To enable the chart recorder to be more suitably used the user may apply a zero offset and gain correction to control the range of currents output There are commands to do this for each of the five outputs available To apply an offset use the command co x x and for a scaling correction use where is the offset
26. ive Display Information Key Combination To Display Duct Temperature and Air Content Displays the selected pipe diameter Duct Temperature and Differential Pressure Displays the instrument S oftware Issue Duct Temperature and Absolute Pressure Displays Serial Interface baud rate setting Absolute and Differential Pressure Selects the Differential Pressure Input Zero function 18 6 3 Differential Pressure Input Zero function As the differential pressure produced across the pitot can be very low and the differential transducer is very sensitive to any leaks in the pneumatic lines it is necessary to ensure that it is correctly zeroed To either adjust or check the zero of the transducer perform the following sequence 1 2 Close the isolation valves open the cross port valve to the differential transducer Press Differential Pressure key and wait for reading to settle This may well take 30 seconds If the reading is not sufficiently close to zero continue with steps 3 to 8 otherwise goto step 8 Simultaneously press Absolute and Differential keys The display will indicate 0000 Press Duct Temperature key The display will indicate 000 Press Absolute Pressure key The display will indicate 00 Press Differential Pressure key The display will indicate Press Air Content key The display will now indicate zero The instrument will now measure the output of the differential transducer and subtract this result
27. layed units and calculation of the air ingress as Well as the front panel key operation information display and serial interface are all controlled by an ST10 derived microprocessor During the power up sequence the contents of the setup and calibration memory are verified As the unit is intended for continuous use they are also reverified every minute 3 7 Analogue Outputs The instruments 4 20 mA outputs are essentially a four wire transmitter with the loop power derived internally The current output signals can therefore drive a passive resistive load Five 4 20 mA outputs represent the calculated air ingress percentage air differential pressure absolute pressure and temperature A programmable offset and scaling for each output enables the recorder range to be optimised Air Inaress Monitor AIM100 TH RS232 Interface 4 20mA Output TH Power Supply 10 B m RID Interface Ji Lid DIRECTION RTD probe interface connector t3 t EE Velocity amp Absolute pressure sensor Steam 7 mixture from condenser TYPICAL AIR INGRESS MONITOR INSTALLATION 10 s G 99 ONIX 6isd oy jgnss3sd WROWIXVIN C SUE S SEM
28. lties be encountered in the use of the instrument it is recommended that you contact Chell Instruments Ltd for advice and instructions 8 2 Calibration Calibration is recommended on an annual basis and should only be carried out by Chell Instruments Ltd 8 3 Pneumatic Maintenance Periodic checking of the pipework between the pitot and the AIM should be carried out to ensure that they are free trom any condensation build up This could cause pipe restriction and interfere with the pressure transmission from the pitot to the AIM Leak tests should also be carried out to avoid erroneous pressure readings 8 4 Differential Pressure Zero Periodically the zero of the differential pressure transducer should be checked as described in section 6 3 8 5 Adjustment There are no user adjustments in the instrument 8 6 Cleaning The instruments may be wiped clean with a damp but not wet cloth Ensure the instrument is not left damp 8 7 Preventive Maintenance There are no user servicable parts contained within the AIM 100 If the instrument 5 suspected faulty then it should be returned to Chell Instruments Ltd for fault investigation and repair 27
29. nfiguration command Baud rates available 300 1200 2400 4800 9600 19200 38400 57600 1 Start 1 Stop 8 data bits No parity 2 11 High Accuracy Option This option replaces the compensated absolute pressure sensor with a heated absolute pressure sensor The following specifications change Measurement performance The following specifications are valid over an instrument ambient temperature range of 10 to 30 C and within 1 year of calibration at 20 C Absolute Pressure Transducer type Heated Absolute Capacitance Manometer FS ranges 100 Torr giving 10V output Optional 1000 Torr giving 10V output Accuracy 0 15 reading 0 02 reading C 0 005 FS C Heater Temperature 45 C nominal Calculated Air Ingress The actual uncertainty is dependent on the specific operating conditions within the pipe and is typically 3 Ibs hr Uncertainty for pipe internal diameters lt 18 less than 12 lbs hr over the range 10 to 40 C steam temperature 15 to 120 mbar absolute pressure 0 5 to 5 mmH 0 differential pressure provided that air is gt 10 and lt 50 and total mass flow lt 2000 Ibs hr Section 3 Principle of Operation 3 1 Introduction The following section gives an outline of the basic principles used in the AIM100 3 2 Temperature Measurement The temperature measurement is derived from measuring the resistance of a platinum resistance thermometer PRT located in the pitot tube Its resistance is compare
30. oss the duct diameter 3 Complete the welding of the fitting 4 Slide the compression fitting assembly onto the pitot 5 Insert the pitot through the welded fitting into the duct until ittouches the opposite internal wall 6 After applying the appropriate sealantto the threads of the compression fitting gently tighten into the welded fitting 7 Turn the pitot until the indentation marks on the head are positioned downstream of the flow 8 Fully tighten the compression fitting whilst ensuring that the pitot does not turn 9 Check that the pitot is correctly installed and aligned 4 7 Vacuum Line connection Ensure that the vacuum lines slope downward from the measuring instrument to the pitot and that there are no loops where condensation could collect Connect the upstream side of the pitot marked to the port marked on the instrument Likewise connect the downstream side of the pitot marked L to the port marked For fixed installations the vacuum lines should run where it is free from vibration or damage and should be supported over its entire length 4 8 RTD connection to pitot tube Remove the sealing cap from the RTD plug located on the head of the pitot Connect the RTD cable ensuring a good fit so that the connection is fully sealed 13 4 9 Interconnections AIM 100 The AIM 100 provides M20 threads to allow the fitting of suitable cable glands or flexible conduit The instrument 15 Supplied with blank
31. our 4 Repeat every day Configuration and Setup Commands oee DD ey emee es Default AimSeralNo asn Any four characters Pipe Diameter Bieter 1 lt lt 3000 1 3000 millimetres Pitot Tube Type pit 0 4 0 97 Torbar pitot 7 hole 1 1 lt Model 400 700 Torbar pitot 2 Furness pitot 3 Model 300 600 Torbar pitot 4 Model 500 800 Torbar pitot User Serial Port baud rate 300 57600 300 1200 2400 4800 9600 19200 38400 57600 57600 User Serial Port Address ere tbe add pro pro Effective Immediate 0 RS485 1 5232 Current Output user RealNumber indicates which output d Differential Pressure a Absolute Pressure t Temperature Percentage Air f Air Ingress Mass Flow Parameter Format is x x RealNumber indicates which output d Differential Pressure a Absolute Pressure t Temperature p Percentage Air f Air Ingress Mass Flow Parameter Format is X X Date of Last Calibration foo 4 List all Commands cmd 56 the AIM commands Format of data output fmt fm 01 Ocoriginal 1 Excel Differential Pressure Input idz idz optional 0 Performs a differential input zero Zero Option 0 clears current setting 26 Current Output user scale 1 SV C Section 8 Service and Calibration 8 1 Service There are no user serviceable parts or consumables inside the instrument Should any difficu
32. perheated steam condition The measured temperature is higher than the saturation temperature of the absolute pressure in the extraction pipework The steam partial pressure 15 therefore higher than the absolute pressure and Dalton s Law of Partial Pressures cannot be applied This law is the principle on which the Air Ingress Monitor relies to calculate the mass ratio of steam to air in the pipe This condition is probably caused by steam bypassing Steps should be taken to eliminate reduce this condition Differential pressure input zero out of range The difference between the indicated reading for zero differential pressure input and the calibration set value 15 greater than 10 of full scale The instrument cannot be adjusted to allow for this degree of offset cancel any previous offset using the software commands given section 7 wait for the differential sensor temperature to change and bring the indicated offset within adjustable range Error Codes relating to internal processing Calibration stores are corrupt The instrument must be re calibrated Air specific volume equal to or less than zero Steam specific volume equal to zero Partial pressure of steam equal to zero Steam air ratio equals 1 Density of mixture equal to or less than zero Total mass flow equal to or less than zero Only if Pitot constant or pipe diameter is in error In AMFM variant the error only occurs if Mass Flow is less than zero 2
33. s fitted which should be replaced as required The cable glands chosen should be compatible with the cable diameter After the wires have been passed through the cable gland and terminated the gland should be tightened to provide a moisture proof seal Terminal Connector Enclosure PL7 RS232z um eS L rO Lb x PL6 4 10 RTD connection Insert the free end of the RTD cable through the cable gland one up from the bottom Insert the different coloured wires into the appropriate terminals of the RTD block as shown on the diagram above and tighten the terminal block screws The cable screen should be connected to the guard terminal 14 4 11 Power Supply connection A 3 core supply cable should be passed through the lower cable gland inserted into the appropriate terminals and screws tightened Note that the instrument MUST be connected to earth to ensure safety 4 12 User Port RS232 RS485 connection optional The Serial communications connect via the internal terminal strip Ensure the power is isolated before removing the instrument covers Also see section 4 15 The AIM communicates with a host computer by using software handshaking Therefore no
34. s the diameter between 1 amp 3000mm The default is 300mm For example to set the pipe diameter to 50mm on the AIM with address a enter 50 1 To find out the current pipe diameter enter the query command pdi I Pitot Tube Type pit The pitot tubes commonly used with the AIM 100 are from Torbar but they come in several model types one designed pre 1997 which has 7 holes upstream and several newer versions which have 6 holes upstream different model numbers cover the wide range of pipe diameters available It is also possible to connect a different type of pitot available from Furness Controls The selection of which one is being used is important because it dictates the algorithm and coefficients used to calculate the mass flow To select the pitot tube use the pit x command where x is a number between 0 amp 4 as follows 0 Pre97 Torbar pitot 7 hole 1 Model 400 700 Torbar pitot 2 Furness pitot 3 Model 300 600 Torbar pitot 4 lt Model 500 800 Torbar pitot To find out the current pitot tube type being used enter the query command 25 AIM 100 Command Set Summary Fora full explanation of each command refer to previous sections in this manual Basic Commands Output Instantaneous Reading Output format as defined by last Format command Output Instantaneous Reading rp 0 4 0 No repeat Repeatedly 1 Repeat every second 2 Repeat every minute 3 Repeat every h
35. t be followed by a space before the parameters are entered and parameters must be comma separated Any other response generally means there has been an internal comms error indicated by BUSY or ERROR If this type of response persists then refer to the AIM service centre NOTE The symbol is used to denote a carriage return Fora summary of each command see page 26 7 3 Basic Commands Recall current readings To recall data from address the host computer needs to transmit ar The AIM will echo this back then send the data The data is returned in one of two formats where the elements are either separated or comma separated The exact number of digits and position of the decimal point is dependent on the units and the FS range Details are shown below Format 0 Original A XXX XXX air ingress air mass flow temperature XXX XXX absolute pressure D XXX XXX differential pressure EXxx XXX 1 Format 1 Excel CSV XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX air ingress temperature absolute pressure differential pressure 96 air The format chosen is controlled by the fmt command under instrument set up 22 Repeated recall of current readings rp In addition to recalling readings upon request the AIM can automatically report the readings at a given interval using the command The output is the same as with the command Set the interval by send
36. t should be mounted vertically with the vacuum ports downward The use of shock mounts is recommended if the instrument is to be located on a surface that is subject to vibration 4 5 Pitot tube location and mounting Select a location where there will be sufficient clearance for the installation of the pitot and vacuum connections in a horizontal pipe run The pitot must be installed vertically at right angles to the pipe run and across the pipe diameter with connections uppermost To avoid noisy signal outputs do not locate the pitot in a pulsating flow and position in an area of least vibration It should also be ensured that the pitot is mounted below the measuring instrument to prevent condensation from entering the transducers and water traps forming 12 In order to meet the quoted accuracy figures the distances of the pitot from disturbances in the pipe e g bend pipe intersection gate valve must not be less than 12 pipe diameters upstream and not less than 4 pipe diameters downstream If it is fitted within distances less than those above then the absolute accuracy may be downgraded but repeatability of the measurement will still be excellent due to the inherent stability of the instrument 1 Make a clean 35mm 1 3 8 diameter hole in the duct for the pitot 2 Tack weld the threaded fitting over the hole Using a suitably threaded piece of pipe ensure concentricity of the fitting and alignment for vertical mounting of the pitot acr
37. team bypass conditions or both However due to the sensitivity of this measurement it would be prudent to check the vacuum lines and connections for leaks It is more likely to be a leak on the or H line giving a higher pressure on the ve side of the differential sensor Use the isolation and cross porting technique C51 to identify a leak condition check for water blockage clogging in the vacuum lines and Pitot Purge these lines to atmospheric pressure protecting the differential pressure sensor if possible 20 Differential pressure equal to or less than zero This could be a genuine condition with a very low pulsating flow in the extraction pipe Averaging of the Differential measurement in the processing is used to smooth this effect out Other possible causes should be examined by checking the Pitot tube for the correct alignment in the pipe The high pressure sensing holes should face upstream and be in line with the flow direction check the ve vacuum line for leaks check that the differential sensor zero is correct The sensor may still be warming up to its elevated operating temperature and therefore have an offset at zero or a prior zeroing procedure that accounts for any offset has drifted with the passage of time To check this zero isolate the AIM from the vacuum lines and equalise the pressure across the two AIM measuring ports If the zero is in error follow the procedure in section 6 4 Su
38. tput from the AIM to an input on the PC Similarly an output from the PC connects to an input on the AIM Therefore Tx on the AIM connects to Rx at the PC NENNEN MEE MENO 5 Lom NENNEN o6 Depending on the exact configuration of the PC it may be necessary to join DTR and DSR atthe computer 16 Section 5 Instrument Configuration and Initial Set up 5 1 Instrument Set Up After installation the set up of the instrument needs to be checked and modified if necessary 5 2 Pipe Diameter To check the pipe diameter setting simultaneously press the Duct Temperature and Air Content keys The display will now indicate the pipe diameter in millimetres If this is incorrect then see section 7 6 on how to change the setting 5 3 Differential Transducer Zero After the instrument has been allowed to warm up for at least 2 hours it is necessary to zero the differential transducer See section 6 3 5 4 Serial Interface Settings If the serial interface is to be used check the baud rate by simultaneously pressing the Duct Temperature and Absolute Pressure keys The display now indicates the current setting The host computer should be set to the same setting Changing the baud rate requires that communication 15 established at the current setting before issuing a new command To change the baud rate see section 7 5 The unit is supplied with a serial port address of a If a multiple installation of AIMS on
39. vn Levu FEE 0080 2059 F3 085 Sorel Scvu OG 099 ran e Z LOSH vorn corn por 6LvM E 909 0189 SS 27 OON EE OoosaL ei d MEM Y J Pii ra N E 8080 01 6106 ozm g 092 Lum Doris 77 e 5071 3 5 govn m LOST ae 9osn 2095 5 fg 1095 00v2 o e 60rd O 159 6169 007b LOVO mE e nisues 9NINNVA OS ef PERMANENT AIR INGRESS MONITOR MOUNTING GUIDE 11 Section 4 Installation and Interconnections 4 1 Important Safety Notice The power supply must be earthed to prevent the risk of an electric shock Correctly rated fuses should always be used A suitable mains isolation switch and circuit breaker should always be mounted near to the instrument Ensure that the mains supply is isolated before the cover is removed for any servicing Due to the presence of high voltages inside the instrument NO internal adjustments should be made while the instrument is connected to a mains supply If adjustments are required they should be performed by suitably trained personnel only Never use the instrument near water and if water is spilled into the instrument turn off
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