MiniPID User Manual V1.9
Contents
1. MiniPID User Manual V1 9 Intrinsically Safe Volatile Organic Compound VOC Sensor Register your instrument online to receive your Extended 2 Year Warranty See page 19 for details Mini PID User Manual Part Number 846236 Advanced Gas Sensing Technologies lon Science Ltd The Way Fowlmere Cambs SG8 7UJ UK Registered in England No 2359038 Vat No GB 532 2024 00 Tel 44 0 1763 208 503 Fax 44 0 1763 208 814 Registered office address Lake House Market Hill Royston Herts SG8 SUN U K Email info ionscience com Web www ionscience com Mini PID Std Reg Ion Science Ltd Page 1 of 23 Mini PID Std Reg Ion Science Ltd Declaration of Conformity Manufacturer lon Science Ltd The Way Fowlmere Cambridge SG8 7UJ UK Product MiniPID Std or MiniPID Reg Product Description Intrinsically safe photo ionisation sensor for volatile organic compounds Directive 94 9 EC ATEX Identification E 11 1G Ex ia IIC T4 40 C lt Ta lt 55 C 1 1W limitation 40 C lt Ta lt 65 C 0 9W limitation Notified Body Baseefa Ltd 1180 Buxton UK Intertek Cortland NY 13045 USA EC Type Examination Certificate s Baseefa07ATEX0060U latest supplement Baseefa07ATEX0060U 3 issued 24 September 2008 Ref Baseefa Cert Report 07 A 0688 10 T 0168 IECEx BAS 07 0030U latest revision no 4 issued 28 May 2010 Ref IECEx Text Reports GB BAS EX TRO7 0056 00 TRO7 0146 00 TRO7 0181 00 T1R08 0135 00 TRO3 0195 00 ETL2. AA A Re ea 5 Physical Propertie S ca a aaa 6 SPECIHC ALON aid iia 7 Common EleciicalSpeclilicalonS sui de a 7 Gas Detection Specifications specific coononncnnccoonnncnncnononnnnncnonancnnnononancnnnnnnnnnconnnonnnnrnnnnnnannnnnnnnnanens 8 Average Ine ari OF respons G a A A 9 Natural physical effects Of humidity coria A a a 10 Schematic Block dad sms 10 Instrument Interfacing Application Notes ooccconnncccnonncccnncononennanonennanoncnnnnnonnnanornnnanrrrnnannrrnnannrrenaanrnenass 11 Selecting the correct supply voltage for your MINIPID occcccnonncnnncccccncnnncnnnoncnnnonnnnncnnnnononncnnnnonnnnennnnnnnns 11 FF OWE UP A heh tice ecoarate seta ements aia em neath a a aa dae ananastom nin date au dceeydaclemenrait 11 gto o lo 18 018 018 E PRA AO o e a a a e E age a a Sosiuonaiantaet drebrated 12 Temperature CO meclO Nantes 12 Mechanical Instala Na ii as 13 Sealing th RD ear ia 13 POB layout tor ENG Nos TEA CIA e dd 14 Intrinsic Safety circuit implementation occcccccconccnncccnocnnnncnononcnnncnononnnnnnnnnnncnnnonnnnnrrnnnnnnnnrnnnnnnnnnrnnnononanens 14 Mantenance canica is 16 When does my MiniPID require Maintenance cccccccsseeececcceeseeeeecceeeeceeeceeeseceeecsaaseeeeesseaeeeeeessaseeess 16 Wien do I cleanthe MNIPID ISMO santi di ds 16 When do replace the MiniPID electrode pellet o cccocccoconncnnccccooncnncnononncnnononannnnnononancnnnononanenns 16 Rem vino Mini Pelletand
3. Any other tools for example screwdrivers may damage your MiniPID body and will invalidate your warranty 1 Gently remove the sensor from equipment 2 Place the MiniPID pellet side down onto a clean surface 3 Locate pellet removal tool into the side slots of the MiniPID and squeeze together until pellet and lamp are released 4 Lift carefully the MiniPID body away from the pellet and lamp 5 Occasionally the lamp may be temporarily lodged in the cell and will need to be freed carefully with tweezers 6 Occasionally the small spring behind the lamp will come out when the lamp is removed from the sensor Simply replace it in to the sensor house A Q a gt Light Eye PID Lamp Page 16 of 23 Mini PID Std Reg Ion Science Ltd Maintenance Cleaning the MiniPID Lamp Inspection of the lamp may reveal a layer of contamination on the detection window that presents itself as a blue hue To check for contamination hold the lamp in front of a light source and look across the window surface Only clean the lamp using our recommended lamp cleaning kit and detailed instructions To avoid contaminating the sensor and affecting accuracy do not touch the lamp window with bare fingers You may touch the lamp body with clean fingers PID lamp cleaning kit A 31063 The vial of cleaning compound contains alumina CAS Number 1344 28 1 as a very fine powder Cleaning should be undertaken in a well ventilated area A full material safety da
4. 8 cCETL Test Report No 3176983CRT 003 Issued May 2010 Standards BS EN 60079 0 2006 Electrical Apparatus for Potentially Explosive Atmospheres General Requirement BS EN 60079 11 2007 Explosive Atmospheres Equipment Protection by Intrinsic Safety i BS EN 61010 1 2001 Safety requirements for electrical equipment for measurement control and laboratory use General requirements UL913 2 Edition Intrinsically safe apparatus and associated apparatus for use in Class Il IH Division 1 Hazardous Classified Locations CSA C22 2 No157 92 Intrinsically safe and non incendive equipment for use in Hazardous Locations Update 2 Other Standards BS EN ISO 9001 2008 Quality Management Systems Requirements BS EN 13980 2002 Potentially Explosive Atmospheres Application of Quality Systems On behalf of lon Science Ltd declare that on the date this product accompanied by this declaration is placed on the market the product conforms with all technical and regulatory requirements of the above listed directives Name Mark Stockdale Position Technical Director Signature Y Y bl Date 11 August 2010 Doc Ref 846238 issue Page 2 of 23 Mini PID Std Reg Ion Science Ltd Contents Declaration Of COmfOnmuny cia A AS 2 A o i edecta rua aadaastocn i eieaeeeteiiatecaaenies 4 Responsible A circo ocio A Sone 4 INMOdUC ION iaa A bass eeticlesecadio A E AES A A 5 Applications sinos ean aaa paa ASEE E aoaaa EEEa a Eia 5
5. ionscience com Web www ism d de Page 21 of 23 Mini PID Std Reg Ion Science Ltd Manual Lo Version number Update Page V1 9 Manual reformatted throughout Factory lamp testing minimum voltage updated Page 10 Log added Page 21 Page 22 of 23
6. or to 70 mV for the MiniPID HI The best way to zero this offset voltage is to apply clean gas and reset the zero outside the MiniPID to become this new offset voltage Important note The 2 mV and 20 mV increase from 50 mV is purely dependant upon cell contamination which can be one or more of the factors given below where a b are most dominant dependant upon the type of usage a Temporary contamination within the layers of the cell that requires some minutes of lamp illumination to burn off this debris b Excessive permanent contamination through salts or the suchlike deposited along the walls bridging the fence electrode to reduce it effectiveness The cell needs to be replaced if this is suspected to be the cause c A much lower signal caused by photo ejection from the back electrode that is used to monitor the status of the lamp condition to create our error status messages This combined signal is part of the lamp out detection circuit presently unique to this type of sensor and thus allows for continuous real time in cell monitoring However the end user must be made aware that lamp out detection failing to occur can only be due to a heavily contaminated electrode stack where surface leakage and or salt build up within the cell creates unwanted currents similar to that created by lamp illumination thus always ensure a clean pellet is used Excessive cell contamination can always be checked with the lamp re
7. powered eo of and on This confers less of a temperature effect and is recommended response vs 20degC 3 40 20 30 10 10 30 50 temperature deg C Page 9 of 23 Mini PID Std Reg Ion Science Ltd Specification Natural physical effects of humidity Water is not itself detected by PID but it adsorbs a portion of the light that otherwise promotes a response from a photoionisable gas The response of the MiniPID to humidity can be adjusted according to the figures presented below for Fahrenheit and Celsius temperatures For example humidity RH a response is decreased from that in detectable gas 100 x o 95 30 F gt o DT 90 50 F gt 85 o o 70 F 80 S 80 F o 75 70 30 F 0 S 65 100 F 8 c 60 E 55 5 o 50 T T T T T T T T T 0 10 20 30 40 50 60 70 80 90 100 Relative humidity R H Schematic Block diagram DISPOSABLE CELL COVER DETECTOR 15Kv ESD protection 250 ms debounce Safety Enable LAMP DRIVER 9004 Mostet H Bridge 900 and 200 transforme 900V sine wave Feedback PID signal E BASEEFA CLAMP A is REF VOLTAGE 50mv Offset E BASEEFA CLAMP DC RECTIFIER Pneumatic Seal it can be seen that at 80 F and 90 relative dry air by 20 This effect will be the same for any 100 5 95 90 85 80 15 4 70 4 65 60 55 50 0 10 C 20 C 30 C 40 C percenta
8. ppb 100 ppb Linear Range 3 deviation Ri full range 100 ppm Minimum over range Ro 50 ppm 4 000 ppm Over range typical Rr 80 ppm 10 000 ppm Sensitivity Linear range S gt 25 mV ppm gt 1 mV ppm Full Stabilisation Time HI to 20 ppb LO to 100 ppb Ts 5 min 10s Warm up Time Tw lt OS lt OS Offset Voltage Vos 60 70 mV 50 51 mV Response Time in diffusion mode tgo TR lt 3s lt 3s Offset Voltage Vos 60 70 mV 50 51 mV Gas Detection Specifications general Target Gases VOC s with ionisation potentials lt 10 6 eV Temperature related response variance 10 between 20 and 60 C vs 20 C response please check item 4 on page 14 Relative humidity range 0 to 99 RH non condensing Product Specifications general Lamp replacement User replaceable 10 6 eV Electrode Stack User replaceable Onboard filter within disposable pellet Removes liquids and particulates Package Type Alphasense CH A3 City Technology 4P 20 mm dia x 16 6 mm high Weight lt 99 Positional Sensitivity None Warranty 12 months from date of shipment Please see page 21 for details on extended warranty Caution Note on Silicones PIDs are not permanently damaged by Silicones but they do potentially foul the windows of the lamps and reduce response to some gases This can usually be remedied by polishing the lamp window with alumina powder However instrument manufactures incorporating the miniPID sensors should be careful to avoid any sil
9. sensor is mounted within a Faraday cage which should be electrically connected to the ground plane Very important Notes 1 An electrically grounded Faraday cage is required for MiniPIDs mounted near to or on the outside of an instrument for the sole reason of electro static discharge that may falsely give a Lamp Out error state This is because electrical currents in the order of sub picoamps generated within the sensing cell are being carefully monitored by the internal electronics for a lamp out occurrence Thus any spurious capacitive coupled emc discharge on an ungrounded case covering will be transmitted to these circuits and cause a false lamp out error message to be registered on the signal line of The MiniPID output This will be seen by the signal step changing from about 52 mV to about 32 mV The duration of this change will be dependant upon the severity of the close coupled emc discharge it is self resetting This cannot be designed out within the product because it is part of The Signal and any attempt to stop this other than by the use of a screening case over the whole product particularly at the pellet will also effect VOC generated signal 2 Also RF interference may effect the resonance detection only in the first second of power up Thus the use of a Faraday cage will give more consistent calibrations because the same resonance frequency will be detected each time on power up Similarly circuits that use
10. the lamp needs cleaning When do clean the MiniPID lamp Cleaning of the MiniPID lamp is recommended as a first action when presented with a MiniPID that needs cleaning Use the procedure described below It is recommended that a cell is recalibrated after cleaning a lamp especially if the cell has been used for a few months since the sensor was last used When do replace the MiniPID electrode pellet The MiniPID pellet can last the lifetime of the MiniPID if used in clean environments or may only last a month if used in heavily contaminated sites The electrode stack is a disposable item so always hold a spare electrode stack if you are working in a dirty environment If the cell shows signs of contamination after the lamp window has been cleaned or is Known to have been subjected to severe contamination then it should be replaced Instructions for replacing the electrode stack are below It is recommended that the MiniPID is recalibrated after replacing the electrode stack When do I replace the MiniPID lamp A MiniPID will last a long time typically a few thousand hours Lamps are warranted for 6 months replacement bulbs are available and are not expensive to replace The sensitivity of the MiniPID is approximately in direct proportion to the lamp light intensity so as a bulb fails the response to a particular low gas concentration becomes more noisy Removing Mini Pellet and Lamp Caution Always use the Pellet removal tool
11. LAMP erinra ea d ia 16 Cleaning Me MINIP EAO aeaa e E O o A A a a aos a aai 17 Re fitting MiniPID pellet and lamp vivir titi aeweveduens choudheualvaadeiaiaaes 18 FIOW GOSS IE WOK iana a A aa a aa a KE AE 19 What is a volatile organic compound VOC ccccceecccceccseeeeeeeeceeseeeeeseeeeeceeeeeeeseeeeesseaeeeeeessaaeeeeeessageeeess 19 Wiha Sa response TACION escri did 20 Instrument Warranty and Servite unan i 21 Wan annaa a a ancia 21 SIC Se raat a ne eae apne a a a a ancemmecntelonaenes 21 COMtACL Detalla a da anes 21 Manual O qeeeeas 22 Page 3 of 23 Mini PID Std Reg Ion Science Ltd Statements Responsibility for Use Inadequate performance of the gas detection equipment described in this manual may not necessarily be self evident and consequently equipment must be regularly inspected and maintained lon Science recommends that personnel responsible for equipment use institute a regime of regular checks to ensure it performs within calibration limits and that a record be maintained which logs calibration check data The equipment should be used in accordance with this manual and in compliance with local safety standards Legal Notice Whilst every attempt is made to ensure the accuracy of the information contained in this manual Ion Science accepts no liability for errors or omissions or any consequences deriving from the use of information contained herein It is provided as is and without any representation term condition
12. Mini PID Std Reg Ton Science Ltd How does it work What is a response factor The sensitivity of PID varies according to the type of lamp used krypton argon or xenon and the VOC detected A response factor is a number which relates the PID response to a particular VOC to the PID response to the calibration gas usually isobutylene If the response of a PID to a particular VOC is eight times smaller than it is for the same concentration of isobutylene then the response factor would be 8 Similarly if the response factor for a particular VOC is 0 5 the PID response is twice that for isobutylene at the same concentration Example e Asensor is calibrated using isobutylene and found to have a sensitivity of 2 mV ppm If the sensor is exposed to 100 ppm isobutylene the output will be 200 mV Toluene is known to generate twice the response of isobutylene If the sensor is exposed to 100 ppm toluene the output will be 400 mV In order to correct the response it is multiplied by the response factor for toluene of 0 5 If response factors are programmed into an instrument you are able to specify a volatile compound and the instrument will internally compensate for the response factor corresponding to that volatile and display and record the corrected volatile concentration See MiniPID response factors and the inverse sensitivity Page 20 of 23 Mini PID Std Reg Ion Science Ltd Instrument Warranty and Service Warranty
13. PID pellet Discard the contaminated electrode stack The electrode stack does not have any toxic components but if it has been contaminated by toxic materials then show due care when disposing Page 17 of 23 Mini PID Std Reg Ion Science Ltd Maintenance Re fitting MiniPID pellet and lamp Caution Never refit a damaged lamp 1 Place the lamp inside the O ring seal in the pellet as illustrated Twisting the lamp slightly during insertion will help to ensure the lamp window Is snug against the pellet s front electrode The lamp should be freely supported by the O ring 2 Lay the pellet front face down on a clean flat surface and then screw the lamp down into the O ring until it firmly abuts against the front electrode face this is most important Then bring the MiniPID body carefully down over the lamp so as not to disturb its positioning within the pellet and then push the body firmly onto the face down pellet so that it clicks into place 3 Refit the sensor into the sensing equipment 4 Re calibrate the equipment in accordance with manufacturer s instructions Page 18 of 23 Mini PID Std Reg Ton Science Ltd How does it work The lon Science MiniPID measures volatile organic compounds VOCs in air by photoionisation detection PID which is shown schematically below Test gas 1 is presented to the membrane filter at the top of the photoionisation cell and freely diffuses into and out of the underlying chamber formed by the fi
14. Standard Warranty can be extended to up to 2 years on the Mini PID when registering your instrument via our website www ionscience com instrument registration To receive your Extended Warranty you need to register within one month of purchase Terms and Conditions apply You will then receive a confirmation email that your Extended Warranty Period has been activated and processed Full details along with a copy of our Warranty Statement can be found by visiting www ionscience com instrument registration Service lon Science is pleased to offer a number of service options on our Mini PID product range that allow you to choose the instrument cover that best suits your needs At lon Science we recommend that all of our gas detection instruments be returned for service and factory calibration once every 12 months Contact lon Science or your local distributor for service options in your area Find your local distributor by visiting www ionscience com Contact Details UK Head Office USA Office German Office lon Science Ltd lon Science LLC lon Science Messtechnik GMBH The Way Fowlmere 33 Commercial Drive Laubach 30 Cambridge Waterbury Metmann Neandertal SG8 7UJ VT 05676 40822 UK USA GERMANY Tel 44 0 1763 207206 Tel 1 802 244 5153 Tel 49 2104 14480 Fax 44 0 1763 208814 Fax 1 802 244 8942 Fax 49 2104 144825 Email info ionscience com Email info ionscienceusa com Email info ism d de Web www ionscience com Web www
15. d by the window face at one end an O Ring located around the outside of the window sealing to the volume that contains the electrode stack arrangement through the PTFE filter up onto the front face It is at this front face the OEM designer must seal upon ensuring that the seal lies within the three segmented arcs visible on the front face This gives a very small detector cavity of about 15 mm that opens up many exciting possibilities for analytical work in pump drawn systems Due to the potential for minor leakage through the layers within the cell do not exceed 500 Pa 5 mbar differential pressure between the PID and the gas detector internal cavity to ensure good signal integrity within 1 Typically 5000 Pa 50 mBar gives 10 Suggested Pneumatic Installation May be used in open asperated systems or natural diffusion applications Also open closed pumped systems at pressures other than atmosphere lt 50 mbar gauge Gas Sample Inlet Perpendicular or parallel to face O Ring Seal required If pulling upstream of pump Pellet Front Face l z TD A oO Rear Electrical Pins I lon Science ini Pl Exhaust Note Gauge pressures gt 50 mbar will progressively dilute sample Important note While every care has been taken to ensure that the lamp sits abutted against the underside of the visible electrode always ensure that the lamp is firmly pushed up against the underside of the visible electrode S
16. ey are virtually insensitive to humidity changes providing unparalleled performance in a variety of applications The Mini PID LO has a dynamic range of lt 100 ppb to gt 4 000 ppm isobutylene The Mini PID HI has a linear dynamic range of lt 5 ppb to gt 50 ppm isobutylene Please contact lon Science at www ionscience com for a comprehensive list of response factors for various VOCs The miniPID sensor pack includes a sensor incorporating a 10 6 eV lamp lamp driver amplifier circuitry and removable electrode stack with particulate filter and electrode stack removal tool Features Applications Patented guard electrode for excellent e Industrial hygiene amp safety humidity immunity monitoring Reliable lamp illuminates at low Soil contamination and remediation temperatures Hazmat sites and spills Superior lamp life Low concentration leak detection User replaceable electrode stack keeps EPA Method 21 and emissions your PID working even after bad monitoring contamination Arson investigation Intrinsically safe ATEX IECEx ETL CETL Indoor air quality monitoring Bulb out error detection MiniPID LO onlv Page 5 of 23 Mini PID Std Reg Ion Science Ltd Physical Properties The illustration shows the gas sensing pellet head at the top of the MiniPID The gas enters the small circular hole in the middle A flat face is provided to allow for sealing in manifold pumped systems The pellet slatted side wing mountings are clear
17. ge of response at RH 10 30 40 50 60 70 80 90 100 Relative humidity R H PID SERIES 4 DETECTOR MODULE ASIC LAMP IN OUT Lamp ASIC Selector Chip Select Diagnostic Selector Synchronise In ASIC Status ASIC LAMP DRIVER 7004 ASIC with VCO Pulse generator Blanking and inhibit driver Minimum current detector QP ofc sc fault detector 7 OK fFault ByPass Link ts OK Fault e 8 z z gt Z co Y supply S OV supply Eb 2 a Za Z PID signal a y E Signal Lamp out Detection Comparator Page 10 of 23 Mini PID Std Reg Ion Science Ltd Instrument Interfacing Application Notes This section explains how to connect electrically and mechanically the PID to your gas detector Please also take careful notice in the differences stated when a MiniPID is used in a Safe Zone and where it might be also be used in a flammable atmosphere Intrinsically Safe operation Selecting the correct supply voltage for your miniPID The MiniPID module is protected from power supply reversal on any pins provided the supply is limited to the rated voltage and the source current is limited to 150mA over several minutes The supply is either internally or externally regulated depending upon the infilling with solder a small circular solder well located on the underside of the sensor Note The solder needs to bridge from the bottom to the upper layer but need not fill the hole completely Checking the quality of Pi
18. gnal output signal is scaled from 50 mV because a The input amplifier has the best input bias current characteristics when biased at 50 mV b This allows the OEM external amplifiers to operate with their inputs above OV for more flexibility c This allows the use of error status signal levels below the normal 50 mV base signal level These error status levels are listed below Error states units shipped beginning 2009 Normal operation signal output is between 50mV and V 0 1 V externally regulated on a supply voltage of 3 0V to 3 6V or 3 2 V when internally regulated on a supply of 3 6 V to 18 V Voltages below 50mV indicate an error condition 32 4 mV indicates lamp out but oscillator operating correctly Change Clean lamp 22 6 mV indicates the oscillator is not working There are two fault levels here One fault state is a 5Hz rectangular pulse to 50 mV and the other is a dc level Change the pellet and or MiniPID 2 2 mV indicates power removed Fault in OEM supply voltage Note Voltages outside these limits are not rigorously defined Zero offset correction When determining VOC concentration you must first subtract at least 50 mV from the MiniPID LO signal and at least 60 mV from the MiniPID HI signal The increased output voltage above the stated 50 mV minimum for the MiniPID is due to amplified electrode stack leakage current When the cell is dirty then this current may increase to 52 mV for the MiniPID LO
19. hould the lamp not firmly abut the front electrode relative to the lamp then the user will experience severe degradation in accuracy combined reduced signal levels and poorer linearity at high VOC concentrations Incorrect abutment will also cause a loss in pneumatic sealing Page 13 of 23 Mini PID Std Reg Ion Science Ltd Instrument Interfacing Application Notes PCB layout for EMC noise reduction To optimise the performance out of the PID it is recommended that micro strip layout techniques be used to reduce susceptibility to emc noise To minimise externally created noise superimposing itself onto the signal the lines should be located close to the ground plane balanced and directly coupled to a differential input Analogue to Digital Converter ADC or differential input amplifier A separate signal OV line should be connected direct to the OV pin of the PID and run parallel with the signal line to the differential input ADC or amplifier This single pair of signal lines should ideally be located between two ground planes or at least run for its full length directly over the top of a ground plane Since the PID responds in 50 100 ms you can include an RC network on both signal lines located directly at the input of the differential input ADC or amplifier to remove 100Hz and higher frequency noise While the MiniPID has its own internal screening it is possible to achieve maximal noise reduction if the entire MiniPID
20. icones even as may occur in labels and plastics such as from moulding release agents Over months of storage the silicones may leach into the sensor and lead to window fouling and sensitivity lost Ordering parts Mini PID HI PID 5 ppb to 50 ppm range Includes bulb and electrode stack Mini PID LO PID 0 1 pom to 4000 ppm range Includes bulb and electrode stack LA4SM600 Replacement bulb 10 6 eV only MSF Replacement electrode stack 846216 Extraction tool required for replacing bulb or electrode stack 846217 Replacement spring A 31063 PID Lamp Cleaning Kit Page 8 of 23 Mini PID Std Reg Ion Science Ltd Specification Average linearity of response Typical low gain miniPID linearity 140 130 120 110 100 90 80 70 60 50 40 30 20 10 100 response linearity 100 ppm 0 1 1 10 100 1000 10000 isobutylene conc ppm Average temperature variance 160 aadi This graph here shows temperature effect on 120 response of a miniPID powered initially at o 20 C and continually powered during the lie change of temperature to the indicated 80 temperature Error bars indicate variance o between PIDs S40 20 30 20 10 0 10 20 30 40 50 60 temperature deg C 140 120 The graph here shows the same effect of temperature except that after temperature equilibration a PID us repowered
21. ied by another fuse If two zones are required then very low current signals may be passed between the two zones by isolating resistors to limit any potentially shared high current between the two zones and thus maintaining separate zone integrity Page 14 of 23 Mini PID Std Reg Ion Science Ltd Instrument Interfacing Application Notes Summary for use of the MiniPID in intrinsic safe applications Maximum temperature for intrinsically safe operation MiniPID is designed to have minimum response change over their full temperature range and because performance of potting compounds changes with temperature there is no potting compound in the sensor However this meant serious design considerations were imposed on the Mini PID for its T4 temperature rating due to the lack of internal soace for components capable of operating at the 55 C for 1 1 W T4 class 60 C for 1 0 W and 65 C for 0 9 W The MiniPID may be plugged directly into an LEL sensor PCB position whose power is supplied by an external 125 mA fuse for a 14 rating in an ambient temperature of up to 55 C The MiniPID is not rated above the power ratings given for the temperature limits because the internal zener diodes would exceed their rated temperature rise based upon the 3W zeners die temperature rating at the stated maximum ambient temperature when tested at the fused clamped current Summary for use of the MiniPID in intrinsic safe applications 1 External sup
22. lter housing walls and a UV lamp window The lamp emits photons shown by arrows of high energy UV light transmitted through the window Photoionisation occurs in the chamber when a photon is adsorbed by the molecule generating two electrically charged ions one positively charged X and one negatively charged Y 2a An electric field generated between the cathode and anode electrodes attracts ions 2b The resulting current which is proportional to the concentration of the VOC is measured and used to determine the gas concentration The Mini PID includes a third fence electrode patented to ensure that the amplified current does not include significant contributions due to other current sources such as water condensation on the chamber walls Test gas F Cathode Ara PRE o Sera PRE Fence electrode Anode Lamp X ZY window AN Photon Lamp bod X To cathode Lamp gas eg 2b Y krypton To anode Copyright Ion Science Ltd 2007 What is a volatile organic compound VOC A volatile organic compound or VOC is a carbon containing chemical which is significantly or completely vaporised at ambient temperatures What volatile organic compound VOCs are sensed by PID Most VOC s can be detected by PID Notable exceptions are low molecular weight hydrocarbons Each VOC has a characteristic threshold energy of light photon energy which when directed at the VOC causes it to fragment into ions This i
23. ly seen and also the side slot is just visible on the left hand side in the black section showing where the tool must be located in both sides to release the pellet The tool inserted here and pressed will quickly release the pellet and allow instant access to the lamp Top View LEL equivalent mechanical format Base view Outside dimensions and pin configuration as per industry standard series 4 LEL sensor Side View Pin Details 1 Positive Supply Voltage 2 Signal Output 3 OV Ground Bullet points of distinction Hazardous Locations Approvals lon Science Standard Versions e ATEX Approved Baseefa 07ATEXO060U e IECEx Approved BASO7 0030U MP3SM6FB Mini PID 3 pin ppm Ex ING ExiallC T4 3V to 3 6V certified Intertek Class 1 Div 1 Groups A B C D T4 a a sa ie 3 pin ppm Conforms to UL standard 913 3 2 certified Certified to CSA standard C22 2 No 157 ay O lt lt O O MP3SM6FN Mini PID 3 pin ppm OG aero ald BOIS enh 2010 3 6V to 18V non certified Patents MP3SB6FB Mini PID 3 pin ppb e US 7 046 012 3V to 3 6V certified e EC 1474681 MP3SB6FC Mini PID 3 pin ppb Input power 3 6 to 10V certified e 3 3 V 0 3 V 0 2 V Stable noise free 3 6 V to 10 V IS or 18 V safe zone MP3SB6FN Mini PID 3 pin ppb e 120mA max power up surge for 0 3s ifi 33mA typical under continuous operation 3 6 to 18V non certified Page 6 of 23 Mini PID Std Reg Io
24. moved but with the pellet in place to give a lamp error status in normal operation Temperature correction Increasing temperature increases slightly the PID sensitivity At 50 C the sensitivity is about 1 higher than at 20 C Likewise at 20 C sensitivity will be 3 less than at 20 C This error is negligible and temperature correction can be ignored in all but the most demanding applications Page 12 of 23 Mini PID Std Reg Ion Science Ltd Instrument Interfacing Application Notes Mechanical installation The electrical and mechanical considerations have been made simpler by designing compatibility with the standard LEL sensor configuration thus it is possible to plug the PID into a standard 20mm diameter LEL sensor position and the PID detector will operate correctly provided the OEM external signal conditioning circuit can operate under the stated output specification range of the PID Always ensure that the interconnect pins are fully seated and that the sensor is fully secure to prevent unintentional movement or removal of the sensor by those unauthorised to do so Sealing the PID The PID is designed to provide a good sealing area on the top face of the PID It is important that when measuring VOCs with a downstream pump after the MiniPID that your sampling line is well sealed to the PID Refer to the data sheet to ensure that you are sealing properly the PID without covering the gas access area The sealed cavity is define
25. multiple MiniPIDs should have the power up sequence for each module staggered by about 0 5 s to ensure that power supply current surges that may cause voltage dipping will not affect the common power rail to neighbouring modules Or select the on board regulator and supply with 5V or more to provide the local isolation of 3 3 V inside 3 It is advised that if the MiniPID has been off for a period of time to pulse the power ON for about 2 seconds then off and back on again to allow the transformer to stabilise to an ideal working state 4 For maximum repeatability in sensitivity then with ambient temperature excursions of greater than 8 C from power up state it is recommended to turn off for 0 5 seconds and then turn power back on to re set oscillator to resonant frequency Typically the MiniPID will be ready within another 0 5 seconds after application power off Often this is implicit in the applications Intrinsic Safety circuit implementation It is very important to abide by the stated temperature power voltage and current ratings This product is designed to drop into a standard LEL sensor position however LEL sensors take considerable current and are often zoned by a separate 125 mA fuse and other suitable upstream voltage limiting devices Depending upon the current required by the monitoring electronic circuits the PID may either share the same zoned 125 mA fuse or the electronics can be located in another zone whose power is suppl
26. n Science Ltd Specification Common Electrical Specifications Supply Voltage on pin 1 Ref to 0 V on pin 3 MiniPID supply Vs Current drawn at Vs 3 3 V 20 C ls Power consumption at Vs 3 3 V P Peak current at power up Im MiniPID Reg supply Vs Current drawn Is Peak current at power up IM Current Construction Drift 3 3 V 0 3 V 0 2 V stable noise free 24 mA to 33 mA at Vs 3 3V 110mW typical 120 mA for 0 3 s maximum 3 6Vto 18 V variable maximum 30 mA 3 mA independent to Vs 120 mA for 0 3 s maximum 1 5mA 10 C typical Voltage on Signal Output pin 2 Ref to 0 V on pin 3 Linear signal output Vso Stepped error states Veo Output capacitance Co Output resistance Ro Output clamp Voc Supplementary Intrinsically Safe Specifications e Approval ATEX Approved Baseefa 07ATEX0060U IECEx Approved BAS07 0030U E 111G Ex ia IIC T4 Temperature range Supply Voltage on pin 1 Ref to 0 V on pin 3 MiniPID Standard with solder blob Voltage Max Current continuous Max Power Max Current surge Max Capacitance Max Inductance Max MiniPID Regulated without solder blob Voltage Max Current continuous Max Power Max Current surge Max Capacitance Max Inductance Max Voltage Max Current continuous Max Power Max Capacitance Max Ci Inductance Max Li Pi Surge Ci Li Ui li Pi gt 50 mV to Positive Supply Voltage less 0 1V lt 40 mV 1 0 uF thro
27. ns 1to3 2kQ Pins 1to3 gt 1MQ solder joint either way around either way around set DVM to resistance Supply voltage states as circumscribed by infilling of the solder well WARNING Please also note intrinsic safety constraints on supply voltage as given elsewhere Externally regulated voltage rail Vs 3 to 3 6 V In this state the cell must be supplied a stable source of voltage between 3 0 to 3 6 V as the internal voltage rail is determined by the externally supplied voltage affecting lamp illumination and other circuits and therefore determining the sensor response thus allowing the user to trim the sensor to their particular requirements All lamps are tested to operate at a minimum supply voltage of 3 0 V before they leave the factory However as lamps age the minimum required operating voltage slowly increases until the lamp requires a voltage higher than the voltage rail supplied Therefore a lower supply voltage will curtail lamp life and deliver decreased gas sensitivity but it will extend the measuring range of the sensor and of course require less power Conversely longer lamp usage by having a higher rail voltage to assist in lamp start up from cold against the increased lamp power giving a less linear detection for high VOC concentrations In the case of the miniPID LO the lifetime of the lamp can be monitored by using the lamp out diagnostic It is recommended that the power supply is stable to wi
28. or warranty of any kind either express or implied To the extent permitted by law Ion Science shall not be liable to any person or entity for any loss or damage which may arise from the use of this manual We reserve the right at any time and without any notice to remove amend or vary any of the content which appears herein Page 4 of 23 Mini PID Std Reg Ion Science Ltd Introduction MiniPID is a miniature photoionisation sensor Sample gas freely diffusing through the filter membrane at the top of the sensor is exposed to deep ultraviolet light generated by a lamp within the sensor The emitted light ionises targeted gases in the sample so they can be detected by the gas detector and reported as a concentration eg ppb pom or mg m Chemicals such as volatile organic compounds VOCs with an ionisation potential less than or equal to 10 6 eV will be detected by the MiniPID The MiniPID can be installed in portable and stationary gas monitors that accept either Alohasense Lt or City Technology pellistor cells providing complete PID capability in a package that has the same dimensional and electrical profile as pellistors provided the electronics input circuit is designed to take the sensor s output range This opens up an incredible variety of environmental and safety applications in industrial commercial and residential markets The MiniPID sensor is offered in two models having the guaranteed range of operation below Th
29. ource lt 3 3A surge D V Supply local to other capacitor near to input Wy Differential ADCorAmp 0V Supply Resistors and capacitors chosen to suit application Version MAY 2010 Tracks should be tram lines and have ground plane close by Page 15 of 23 Mini PID Std Reg Ion Science Ltd Maintenance The electronics in the MiniPID sensor are designed to be maintenance free and not accessible Periodic sensor maintenance is required for the Mini Pellet and the lamp When does my MiniPID require maintenance Your MiniPID lamp will need cleaning from time to time How often depends pe on the environment you are measuring If you are measuring indoor air P quality where the VOC concentrations are low and there are few particulates then a monthly or even less frequent calibration may be adequate However if you are measuring high VOC concentrations and particulates are present in high concentration then check calibration frequently and when the PID has lost sensitivity or error state shows change the stack as explained below Signs when the PID needs attention e Ifthe baseline climbs after you zero the PID then the electrode stack needs replacing e lf the PID becomes sensitive to humidity then the electrode stack needs replacing e lf the baseline shifts unstable when PID moves then electrode stack needs replacing e f sensitivity has dropped too much note the change required when checking calibration then
30. ply surge current must be limited to 3 3 A under fault conditions 2 Depending upon maximum supply voltage the MiniPID may use a 125 mA fuse in the supply line for 55 C for 1 1 W T4 and a series resistor for reduced power limits for operation above 55 C ambient temperature 3 Take note of the various maximum supply voltages that may become connected to any of the pins under fault conditions Take note of the power limits of the various pins under fault conditions The capacitance is low and should not cause problems at these voltages If processing electronics are located in another zone then barrier segregation resistors are required in any signal lines 7 Competent third party assessment is required on the final product 8 MiniPID Reg Working near 10V should have signal and power rails infallibly isolated to ensure lumped capacitances on an external short circuit does not exceed the safety current limit oS Possible Intrinsically safe installations Equivalent Intrinsic Safe circuit Basic Intrinsically Safe operation Power source 125 mA lt 3 3 A surge E supply AN Signal o OHC 2x 3 Resistor bamier only required if separated Intrinsic Safety zones A y 0 to 1000 ohm value and size depends on application Link as Reg 0 Y Supply os a to meet the required intrinsically Safe specifications a a Note 4V7 diodes are Intemal and not required extemally To minimise signal noise Power s
31. s called the lonisation Potential or IP VOCs are ionised and hence detected if light of photon energy greater than the IP interacts with the gas sample The peak photon energy generated in a detector depends on the PID lamp used Xenon 9 6 eV Deuterium 10 2 eV Krypton 10 6 eV or Argon 11 7 eV Hence the use of an argon lamp leads to detection of the largest range of volatile compounds while using a Xenon lamp can increase selectivity Lamps of a particular type do not typically vary in spectral fingerprint so relative responses to a particular gas eg benzene toa particular lamp eg krypton does not vary from lamp to lamp However the intensity of lamps does vary to some extent leading to a difference in absolute response to the calibration gas Sufficient volatility of a compound is also essential for measurement by PID as with any other detector A fairly large molecule such as alpha pinene a constituent of turpentine saturates in air at about 5000 ppm at 20 C this is the maximum concentration at which the compound will usually be detected Some compounds for example machine oils and agrochemicals generate only a few ppm of vapour at ambient temperatures it is more difficult to detect these compounds in air MiniPID response factors Application Note lists VOCs by their common name and their sensitivity to a Krypton lamp the most common lamp and the lamp supplied with the Mini PID LO and Mini PID HI Page 19 of 23
32. ta sheet MSDS is available on request from lon Science Ltd Key safety issues are identified below Hazard identification Handling e May cause irritation of respiratory e Do not breathe in the powder Avoid contact with skin tract and eyes eyes and clothing e Wear suitable protective clothing Storage e Follow industrial hygiene practices Wash face and e Keep container closed to hands thoroughly with soap and water after use and prevent water adsorption and before eating drinking smoking or applying cosmetics contamination The powder carries a TVL TWA limit of 10 mg m Cleaning the Lamp Use of PID lamp cleaning kit A 31063 1 Open the container of alumina polishing compound 2 With a clean cotton bud collect a small amount of the powder 3 Use this cotton bud to polish the PID lamp window Use a circular P A action applying light pressure to clean the lamp window Do not touch the lamp window with fingers As T 4 Continue polishing until an audible squeaking is made by the cotton bud moving over the window surface usually within 15 s seconds 5 Remove the residual powder from the lamp window with a clean cotton bud Care must be taken not to touch the tips of cotton buds that are to be used to clean the lamps as this may contaminate them with finger print oil 6 Ensure the lamp is completely dry and any visible signs of contamination are removed before refitting TON eii Discarding the Mini
33. thin 10 mV high frequency spikes can be 10 times greater than this This will ensure that the digital drive circuit for the rf lamp oscillator remains in resonance maintaining a stable lamp intensity The reason for this value is that the resonant frequency may lie near a cusp of a discrete step change Internally regulated voltage rail Vs 3 6 to 18 V In this state the miniPIDs can be operated between 3 6 and 18 V The signal stability is unaffected by external supply drift as the sensor circuits are internally regulated to 3 3 V Thus the user is completely free to select the most convenient supply for their needs The internally regulated sensor is much more unaffected by power variance and can tolerate 1 V changes at low frequency Clearly the designer should guard against high frequency transient spikes as these might punch their way through the internal regulator control circuits Power up surge While the PID takes only 33 mA 7 mA under normal operation over the full voltage supply there is a power up surge of about 120 mA maximum for about 300 ms while the MiniPID seeks resonance thus consuming more current at power up Page 11 of 23 Mini PID Std Reg Ion Science Ltd Instrument Interfacing Application Notes Analogue output The output voltage range is from 0 0 V to V 0 1V for the externally regulated voltage range of V 3 0 to 3 6 V or 3 2 V when internally regulated on a supply of 3 6 V to 18 V The operating si
34. ugh 4k7 Q 0 11 uF at pin 6k3 Q 5V1 zener protected by 4k7 Q resistor Intertek Class 1 Div 1 Groups A B C D T4 Conforms to UL standard 913 Certified to CSA standard C22 2 No 157 40 C lt Ta 55 C note Pi where Ta may be taken to 65 c 5 0 V 220 mA 1 1 WO 55 C 1 0 W O 60 C 0 9 W O 65 C lt 33A 7 0 uF 0 uH 10 0 V 220 mA 1 1 W 55 C 1 0 W O 60 C 0 9 W O 65 C lt 3 3A 1 1 uF 0 uH 10 0 V 10 mA 50 mW 0 12 uF 0 uH Note Signal Output pin 3 Ci to be summed with Supply Voltage pin 1 Ci above not countable fault Schedule of Limitations The component must be mounted within apparatus which provides ingress protection of at least IP20 protection against impact and protection against possible electrostatic charging of the plastic enclosure Warning The MiniPID sensor is an Intrinsically Safe device that contains limited energy storing components An appropriate Intrinsically Safe interface must be employed for use in hazardous locations noting power limitations and temperature ranges and must be installed in strict accordance with applicable safety codes and guidance given in the Manual Failure to observe this warning can result in serious injury and or property damage Version MAY 2010 Page 7 of 23 Mini PID Std Reg Ion Science Ltd Specification Gas Detection Specifications specific Transducer Details ref Isobutylene MiniPID HI MiniPID LO Minimum Detection Level Sp 5
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