SF52 User`s Manual
Contents
1. 97224 Issue 02 November 2011 8 Michell Instruments SF52 User s Manual e The readings given by some types of hygrometer are sensitive to gas type For any Instrument which reads in terms of mass per unit volume e g in grams per cubic metre it must be confirmed whether the calibration is valid for the gas in use e Avoid using instruments in direct sunlight or near any other source of heat unless they are suitably shielded to prevent measurement errors Sampling in general e Relative humidity measurements should be carried out at a representative temperature Failure to allow temperature equilibration will lead to a false indication of the relative humidity e Variations in vapor pressure from place to place can occur where an environment is subject to any addition or removal of water If so care must be taken over where to make a measurement in order to obtain a representative result e Sources and sinks of water vapor should be avoided in any sampling system Invasion of stray water can be minimised by attention to leaks hygroscopic materials droplets and condensation The lower the humidity the more critical these precautions are e Hygroscopic materials should be avoided Many materials contain moisture as part of their structure particularly organic materials whether natural or synthetic salts or anything which contains them and anything which has small pores Temperature changes can increase the tendency of the2. 353 scfs Tighten the sensor finger tight ensuring the cable does not snag Then using a 24mm A F spanner wrench tighten to fully compress bonded seal 30 5 Nm 22 5 ft Ibs a A MK u I zz 97224 Issue 02 November 2011 2 Michell Instruments SF52 User s Manual 3 OPERATION Operation is very simple assuming the following installation techniques are adhered to Sampling Hints Be Sure the Sample is Representative of the Gas Under Test The sample point should be as close to the critical measurement point as possible Also never sample from the bottom of a pipe as entrained liquids may be drawn into the sensing element Av Figure 4 1 Installation location Minimize Dead Space in Sample Lines Dead space causes moisture entrapment points increased system response times and measurement errors as a result of the trapped moisture being released into the passing sample gas and causing an increase in partial vapor pressure Deadspace Figure 4 2 Indication of dead space Remove Any Particulate Matter or Oil from the Gas Sample Particulate matter at high velocity can damage the sensing element and similarly at low velocity they may blind the sensing element and reduce its response speed If particulate such as degraded desiccant pipe scale or rust is present in the sample gas use an in line filter Use High Quality Sample Tube and Fittings Michell In
3. 10 20148 Milano Italy Tel 39 02 4047194 Fax 39 02 40010565 E mail it info michell com Web www michell com it Japan Michell Japan KK Musashino Center Building 1 19 18 Nakacho Musashino Tokyo 180 0006 Japan Tel 81 422 502600 Fax 81 422 521700 E mail info michell japan co jp Web www michell japan co jp Middle East Michell Instruments Middle East P 06 097 Sharjah Airport Int l free zone Sharjah United Arab Emirates Tel 971 6 5575028 Fax 971 6 5575029 E mail me info michell com North America Michell Instruments Inc 319 Newburyport Turnpike Suite 207 Rowley MA 01969 USA Tel 01 978 484 0005 Fax 01 978 843 7669 E mail us info michell com Web www michell com us United Kingdom Michell Instruments Ltd 48 Lancaster Way Business Park Ely CB6 3NW Cambridgeshire England Tel 44 1353 658000 Fax 44 1353 658199 E mail info michell com Web www michell com uk Michell Instruments 13 97224 Issue 02 November 2011 SF52 User s Manual NOTES 97224 Issue 02 November 2011 14 Michell Instruments SF52 User s Manual NOTES Michell Instruments 15 97224 Issue 02 November 2011 SF52 User s Manual NOTES 97224 Issue 02 November 2011 16 Michell Instruments 1 5 MICHELL Instruments http www michell com
4. in temperature pressure or gas flow rate relative to the process being sampled results may need to be converted or interpreted For example pressure dew point will differ from the value found after expanding the gas sample to atmospheric pressure Care should be taken to distinguish between gauge and absolute values of pressure Dew point in general e The measuring environment and all parts of the sampling pathway must be kept above the dew point if condensation is to be avoided Electrical trace heating or other heating methods should be used if necessary An excess temperature of 10 C above the dew point is usually a safe margin e For measurements in the region below 0 C it must be clear whether the condensate is dew or frost Failure to distinguish between these can result in errors of about 1 C for every 10 C below zero Michell Instruments 9 97224 Issue 02 November 2011 SF52 User s Manual Relative humidity in general e Due care must be taken of temperature The effect of temperature on humidity is highly significant Failure to take this into account can sometimes lead to errors so large that the measurement is meaningless In many situations the largest single source of uncertainty in a humidity measurement is the effect of temperature differences from place to place in the process room or chamber The importance of considering the temperature effects carefully cannot be overstated when relative humidity is the par
5. place rules upon European manufacturers of electrical and electronic equipment The directives aim is to reduce the impact that electronic devices have on the environment Michell products are currently exempt from the RoHS directive however all future products will be developed entirely using compliant materials Furthermore Michell is taking active steps to remove non compliant materials and components from existing products wherever possible Michell is in full compliance with the WEEE Directive Registration No WEE JB0235YW Customers may be required to return certain instruments for treatment at the end of their working life June 2010 97224 Issue 02 November 2011 vi Michell Instruments SF52 User s Manual Warranty Unless otherwise agreed the Supplier warrants that as from the date of delivery for a period of 12 months the goods and all their component parts where applicable are free from any defects in design workmanship construction or materials The Supplier warrants that the services undertaken shall be performed using reasonable skill and care and of a quality conforming to generally accepted industry standards and practices Except as expressly stated all warranties whether express or implied by operation of law or otherwise are hereby excluded in relation to the goods and services to be provided by the Supplier All warranty services are provided on a return to base basis Any transportation costs for t
6. SF52 Dew Point Transmitter User s Manual i 97224 Issue 02 November 2011 Michell Instruments Inside front cover blank SF52 User s Manual MICHELL Instruments SF52 2011 Michell Instruments This document is the property of Michell Instruments Ltd and may not be copied or otherwise reproduced communicated in any way to third parties nor stored in any Data Processing System without the express written authorization of Michell Instruments Ltd 97224 Issue 02 November 2011 iii Michell Instruments SF52 User s Manual Contents SIE V Electrical Safety irnar aaa ir uk aco Exdg pecus pU LUE xu ae FARA UA CAR VARI OMA DRU LAM rod MR ERO V Pressure Safety i issetesadkuta tuc inex uud us onu anra RAE RA RR dedu e tud g Da ru Rn NEAR RANK RG cane A RARE XE PARAR BRIT V Toxic Materials 5 cetero trap t haue ca ame V Repair and Maintenamee szsar nina ea a a tad de a na a a ER aa EEE a nahe V Cali DFAQION TRIER V AbbteviatiOris casei oo p rito pana ba o Rud aaa R a nap dE a Fan Ru Fu RUD AR aa ERA D xc S Rara dE vi Recycling PONGCY f EET vi WEEE And ROHS ComiplignGe ire konnien seen penal snceasa E eux deca dno sue oxM mash eR Ke RC ENEE vi luc vii suelo rS vii 1 ol inelo U cle rere Tern rer ttre E ITI 1 1 1 gclct 1 2 Preparation Tor USO ss cc eet sxeoee Octa he
7. ameter of interest e Care must be taken when expressing uncertainties changes or fractional differences in relative humidity For example the difference between 50 RH and 52 RH is 2 RH This can also be expressed as a difference of 4 of value It is important to distinguish clearly between these two kinds of statement Recommendations specific to ranges of measurements e Ambient humidity Avoid using hygrometers near the body which is a source of heat and moisture Do not breathe close to the measurement e High humidity above the ambient range Ample lines should be maintained above the dew point of the gas being measured to avoid condensation Electrical trace heating is often the most practical method Low humidity and very dry gases If possible prepare for measurements by flushing sample lines and hygrometers with dry gas or by evacuating to low pressure Drive off stray residual water by baking assemblies if possible but not instruments unless designed for this The lower the moisture content to be measured the more dramatically the required drying time multiplies e Avoid hygroscopic materials At low humidity anything much below a dew point of 0 C the amounts of water given off by organic and porous materials can dramatically affect the value of humidity The lower the level of moisture the more significant the effects e Choose impermeable materials to avoid inward diffusion of moisture through sampling tub
8. d to maintain the equipment in a safe condition The safety instructions are either warnings or cautions issued to protect the user and the equipment from injury or damage Use competent personnel using good engineering practice for all procedures in this Manual Electrical Safety The instrument is designed to be completely safe when used with options and accessories supplied by the manufacturer for use with the instrument Pressure Safety DO NOT permit pressures greater than the safe working pressure to be applied to the instrument The specified safe working pressure is up to 20 bar 290 psi maximum Toxic Materials The use of hazardous materials in the construction of this instrument has been minimized During normal operation it is not possible for the user to come into contact with any hazardous substance which might be employed in the construction of the instrument Care should however be exercised during maintenance and the disposal of certain parts Repair and Maintenance The instrument must be maintained either by the manufacturer or an accredited service agent Refer to Appendix C for details of Michell Instruments worldwide offices contact information Calibration The recommended calibration interval for this instrument is 12 months unless it is to be used in a mission critical application or in a dirty or contaminated environment in which case the calibration interval should be reduced accordingly The instrument sh
9. eed routine cleaning or other maintenance Before using any solvent cleaner check with Michell Instruments that this will not harm the sensor or other materials of construction e Wherever possible ensure that hygrometers are calibrated under the conditions of use i e at similar values of humidity and temperature and if relevant in similar conditions of pressure airflow etc e Keep a record of calibrations and any adjustments to the hygrometer This will show the long term stability of the instrument and allow the associated uncertainty to be assessed e Check instruments if possible at intervals between calibrations by comparison with another stable instrument to monitor for long term drift Routine checks are also useful before and after subjecting an instrument to transportation or other stress which might lead to a shift in its performance Where the check is against two or more instruments this is even better not only does this add confidence but in the event of one instrument drifting among a set of three it can be seen which reading is most suspect Cleanliness of the environment will affect different hygrometers in different ways Dust and airborne droplets should be avoided or filtered out if possible Contaminants can come from the most surprising sources ordinary urban pollution for example FEB BGBG GG GG gt t jz p pj gt z z 6 eree90 _ LS S os z
10. es and enclosures Steel and other metals are practically impermeable PTFE Teflon is only slightly permeable and will usually be satisfactory for dew points above 20 C and sometimes below this level Materials such as PVC and rubber are relatively permeable and so totally unsuitable at low humidity and not really satisfactory in any humidity range e Surface finish of pipework is important for very dry gases Even the tiny quantities of water adsorbed on the surfaces of non hygroscopic materials can have significant effect Polished or electropolished steel is recommended for the best results e Clean environments are always best for humidity measurements but this is especially critical at very low humidity Even fingerprints harbour water High purity cleaning agents are recommended Analytical Reagent AR quality solvents for oil based contaminants and purified water distilled or de ionised for salts Cleaning should be followed by thorough drying by a clean method e Sample tubing should be as short in length as possible The surface area should be minimised by using the narrowest tubing that the flow conditions will permit e Avoid leaks Minimising the number of connections elbows tees valves etc helps with this e Adequate flow of the gas sample should be ensured to minimise the influence of sources of stray water in the flow path e Dead ends should be avoided as they cannot easily be flushed e Back diffusi
11. g temperature Probe Housing 30 to 85 C 22 to 185 F Storage 40 to 85 C 40 to 185 F Operating pressure 20 bar 290 psi maximum Temperature coefficient Temperature compensated across operating temperature range Mechanical specification Ingress protection IP65 Housing material Nickel coated brass Dimensions L 85mm 824mm L 3 34 80 94 max Filter HDPE front filter Weight 320g 11 290z Mechanical connections G 1 2 BSP DIN ISO 228 or Y2 NPT Cable 2m 6 5 Michell Instruments 5 97224 Issue 02 November 2011 SF52 User s Manual A1 Dimensions 85 0 17 0 3 3 ins 0 7 ins 15 0 20 0 0 6 ins 0 8 ins a mm Y o c we c9 G 1 2 BSP babes or 1 2 NPT Q Figure A1 Dimensions of the SF52 26 5 1 0 ins Te NPT 17 1 8 NPT r F AT G 1 2 BSP pe or 1 2 NPT p 35 0 14ins Figure A2 Dimensions of the Sample Block lip E 97224 Issue 02 November 2011 6 Michell Instruments SF52 User s Manual Appendix B Recommended Practices in Humidity Measurements e_O O u C i o c n Michell Instruments 7 97224 Issue 02 November 2011 SF52 User s Manual Appendix B Recommended Practices in Humidity Measurements The following text is reproduced with kind permission from the National Physical Laboratory It is originally pub
12. he return of a warranty claim shall reside with the Customer Return Policy If a Michell Instruments product malfunctions within the warranty period the following procedure must be completed Notify a Michell Instruments representative giving full details of the problem the model variant and the serial number of the product If the nature of the problem indicates the need for factory service then the instrument should be returned to Michell Instruments carriage prepaid preferably in the original packaging with a full description of the fault and the customer contact information Upon receipt Michell Instruments will evaluate the product to determine the cause of the malfunction Then one of the following courses of action will be taken e If the fault is covered under the terms of the warranty the instrument will be repaired at no cost to the owner and returned If Michell Instruments determines that the fault is not covered under the terms of the warranty or if the warranty has expired an estimate for the cost of the repairs at standard rates will be provided Upon receipt of the owner s approval to proceed the product will be repaired and returned Michell Instruments vii 97224 Issue 02 November 2011 SF52 User s Manual 1 Introduction The SF52 dew point transmitter from Michell Instruments can provide 4 20mA or voltage signal for either dew point or absolute humidity with excellent accuracy and linear
13. ity The robust housing together with an operating pressure of up to 20 bar 290 psi makes the SF52 ideal for many dew point and moisture measurement applications 1 1 Features Dew point or absolute humidity outputs Current or voltage output signals Excellent linearity and temperature compensation IP65 Excellent sensor protection Fast response Small size Digital recalibration ask local distributor for more details Michell Instruments T 97224 Issue 02 November 2011 SF52 User s Manual 2 Preparation for use 2 1 Electrical Connections mA output Supply V gt _ ve power Signal 4 20 mA Dp load max 500 2 Brown Common Ground Yellow Not used Cable Voltage output White ve power Green Signal Voltage Dp Brown Common Ground Yellow Not used Figure 2 1 Electrical Connections 2 2 Installation Prior to installation of the sensor ensure that hands are clean in order to prevent contamination NOTE DO NOT TOUCH THE FILTER DISC The SF52 can be mounted into either a flow through sensor sampling block optional extra or directly inserted into a pipe or duct and can be operated at pressures of up to 2 MPa 20 bar 290 psi when fitted with the bonded seal provided The recommended gas flow rate when mounted in the optional sampling block is 1 to 5 I min 2 1 to 10 6 scfh However for direct insertion applications gas flow can be from static to 10 m sec
14. les etna delen Sen ce dics auda ah eae seco Gece ce duse nuts Ute RR RUE EET ds 2 21 Electrical Connections PRETIUM 2 2 2 115 7 u 0 1 IERTERERFERTPRETTEFTERFEUEEPEFPPEPRTEUHERTFELETTTLRLTENUFEDENEVERFIORELTEFERTLTFETLLOTEETLEILTESPERDFEUFTELFETETLTEN 2 Bi SORER ATION RE IRI EIU L S 3 Figures Figure 2 1 ElectriGal Golpe H ER 2 Figure 4 1 Installation lOCatlON nassen exe eh exta DENER NAE EA AO APEERE 3 Figure 4 2 Indication Wofelcz eEcin lacum EEE 3 Figure A1 Dimensions OF the SE52 s isis 200000 klgn kv Duk ER opa E RRARNERRR a RR ahnen 6 Figure A2 DIMENSIONS OF the Sample BIOGK suat a sh asesoria sas diea Eua g Rada K Ru sk ARTE EEE TEA 6 Appendices AppendbcA Technical Sp cifications encor ag eng nen 5 A1 BI 6 Appendix B Recommended Practices in Humidity Measurements uunnsssnsnennnnnnnnnnnnnnn nenn nnnnnnnnnnnnnnnn 8 Appendix C List of Worldwide Michell Instruments Offices sse 13 R 97224 Issue 02 November 2011 iv Michell Instruments SF52 User s Manual Safety The manufacturer has designed this equipment to be safe when operated using the procedures detailed in this manual The user must not use this equipment for any other purpose than that stated Do not apply values greater than the maximum value stated This manual contains operating and safety instructions which must be followed to ensure the safe operation an
15. lished in the booklet A Guide to the Measurement of Humidity Definition of Relative Humidity Relative Humidity The ratio of the actual vapor pressure to the saturation vapor pressure over a plane liquid water surface at the same temperature expressed as a percentage This is commonly understood when the term X percent relative humidity is used For actual vapor pressure e and saturation vapor pressure e e relative humidity in x 100 e S USAGE The phrase relative humidity is commonly abbreviated RH although this is not a recognized abbreviation Values of relative humidity are commonly expressed in units of percent relative humidity RH Recommended practices in humidity measurements General practical recommendations e Where relative humidity is of interest a direct measurement of relative humidity is usually best Where an absolute measure of humidity is needed choose dew point vapor pressure or similar measurements e Establish the measurement requirements at the purchasing stage in order to have the right instrument for the job e Allow hygrometers to equilibrate in any new environment This is particularly necessary after changes in temperature due to transportation or storage Depending on the instrument and on how great the change in conditions this may require from only a few minutes to many hours e Follow Michell Instruments care instructions for the instrument Some instruments n
16. on of moisture should be minimised e g by fast flow rates of gas long exhaust tubes after the sensor or by valves which isolate the low humidity region from ambient air 97224 Issue 02 November 2011 10 Michell Instruments SF52 User s Manual Practical recommendations for specific types of hygrometer Relative humidity capacitive sensor e Care should be taken to avoid mechanical shock impact or thermal shock sudden temperature changes Sensors should be protected from steam or water sprays and from direct sunlight e Where a sensor is at risk of exposure to dust droplets or the occasional knock during handling the appropriate guard or filters for the sensor head should be used e Any temptation to breathe on the sensor or to wave it over cups of tea etc should be resisted Filters and saturation guarding may protect the sensor but these actions carry a risk of damage by condensation or other contamination e Protective filters can slow the response time of sensors This can be avoided by removing any filter but the benefit must be weighed against the risk of damage to the sensor e Sensors should not normally be submerged in liquids In the case of a resistive electrolytic sensor water or other liquids would certainly damage the sensor beyond repair e Salt solutions are especially commonly used for calibration of electrical sensors and should be provided with traceability directly or via a calibrated hygrometer P
17. ould be returned to the manufacturer Michell Instruments Benelux BV for re calibration Safety Conformity This product meets the essential protection requirements of the relevant EU directives Further details of applied standards may be found in the product specification Michell Instruments V 97224 Issue 02 November 2011 SF52 User s Manual Abbreviations The following abbreviations are used in this manual bar pressure unit 100 kP or 0 987 atm C degrees Celsius F degrees Fahrenheit DC direct current Dp Dew point grams g m grams per cubic meter gr fe grains per cubic foot m meter s mA milliampere mm millimetres psi pounds per square inch 9o percentage OZ ounces RH relative humidity V Volts ve positive 2 inches feet Recycling Policy ue Michell Instruments is concerned with the protection of the environment It is our commitment to reduce and eliminate from our operations wherever possible the use of substances which may be harmful to the environment Similarly we are increasingly using recyclable and or recycled material in our business and products wherever it is practical to do so The product that you have purchased may contain recyclable and or recycled parts and we will be happy to provide you with information on these components if required WEEE And RoHS Compliance The Waste Electronic and Electrical Equipment WEEE Directive and the Restriction of Hazardous Substances ROHS Directive
18. rotection of sensors from direct contact with salt or solution is most important as contamination would destroy or seriously impair the sensing element Michell Instruments 11 97224 Issue 02 November 2011 SF52 User s Manual Appendix C List of Worldwide Michell Instruments Offices liue SSS SSS SSS SSS eee al 97224 Issue 02 November 2011 12 Michell Instruments SF52 User s Manual Appendix C List of Worldwide Michell Instruments Offices Asia Michell Asia PO Box 3149 Joondalup WA 6027 Australia Tel 61 893 046587 E mail au info michell com Web www michell com au Benelux Michell Instruments Benelux BV Krombraak 11 4906 CR Oosterhout The Netherlands Tel 31 162 680 471 Fax 31 162 437 566 E mail nl info michell com Web www michell com nl China Michell Instruments Shanghai Ltd Room 505 Qilai Building 889 Yishan Road Shanghai 200233 P R China Tel 86 21 5401 2255 Fax 86 21 5401 2085 E mail cn info michell com Web www michell com cn Germany Austria Switzerland Michell Instruments GmbH Industriestrasse 27 D 61381 Friedrichsdorf Germany Tel 49 6172 591700 Fax 49 6172 591799 E mail de info michell com Web www michell com de France Michell Instruments SAS 2 4 rue Jean Desparmet 69008 Lyon France Tel 33 437 53 88 20 Fax 33 437 53 88 21 E mail fr info michell com Web www michell com fr Italy Michell Italia Srl Via Capecelatro
19. se materials to affect the humidity of the surrounding air e Condensation in a sampling process can invalidate humidity measurements by reducing the water content of the gas being measured What is more condensed liquid may alter the humidity elsewhere by dripping or running to other locations and evaporating there In these circumstances measurement results may be misleading if hygrometer location is not considered carefully e Water droplets or mist must be avoided These can result in overestimates of the humidity of the air between the droplets Such results may exceed 100 RH or may be impossible to interpret meaningfully Droplets of liquid also damage some electrical types of humidity sensor Filtering the air sample can eliminate droplets e If pumps are used for sampling gas these should be located after the hygrometer to avoid contaminating the measurement environment Where possible oil free pumps should be used or filters employed Oscillations in pressure due to pumping can sometimes be reduced or buffered using a needle valve or a reservoir of large volume e Special treatments such as filtration can change the amount of moisture in a gas Some drying agents take out other gases too e When sealing any sensor or probe into a port or manifold in a duct or chamber leaks through the probe or electrical cable should be considered These are not always sealed against passage of ambient air Where sampling involves a step change
20. struments recommends that wherever possible stainless steel tubing and fittings should be used This is particularly important at low dew points since other materials have hygroscopic characteristics and adsorb moisture on the tube walls slowing down response and in extreme circumstances giving false readings For temporary applications or where stainless steel tubing is not practical use high quality thick walled PTFE tubing J Se Michell Instruments 3 97224 Issue 02 November 2011 SF52 User s Manual Appendix A Technical Specifications E 97224 Issue 02 November 2011 4 Michell Instruments SF52 User s Manual Appendix A Technical Specifications Performance Measurement range dew point 40 to 60 C 40 to 140 F dew point temperature a range absolute 5 200 g m 0 to 87 4 gr f amp Accuracy dew point 2 C 3 6 F dew point Accuracy absolute humidity 0 4 to 3 g m 0 175 to 1 311 gr ft on value of absolute humidity Stability lt 1 C year lt 1 8 F year Response time lt 10 sec typical for 90 of the step change Electrical output input Output signal 0 1 0 5 0 10 V or 4 20 mA Supply voltage 14 30 V DC for 0 10 V output 8 30 V DC for 0 1 0 5 V 4 20 mA output Current consumption 9 mA load current Supply voltage influence 0 005 RH V Operating conditions Operatin
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