1、Designation: D3195/D3195M 10Standard Practice forRotameter Calibration1This standard is issued under the fixed designation D3195/D3195M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revision. A number in parenth
2、eses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the calibration of variable-areaflowmeters (rotameters) used to determine air sample volumesat or close to ambient conditions of pr
3、essure and temperature,in the analysis of atmospheres for pollutant content.1.2 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalues stated in each system may not be exact equivalents;therefore, each system shall be used independently of
4、the other.Combining values from the two systems may result in non-conformance with the standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health p
5、ractices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1071 Test Methods for Volumetric Measurement of Gas-eous Fuel SamplesD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD3631 Test Methods for Measuring Surface
6、AtmosphericPressureE1 Specification for ASTM Liquid-in-Glass ThermometersE337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E1137/E1137M Specification for Industrial Platinum Resis-tance ThermometersE2251 Specification for Liquid-in-Glass
7、 ASTM Thermom-eters with Low-Hazard Precision Liquids3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, refer toTerminology D1356.3.1.2 Standard conditions are taken as 25C 77F and101.3 kPa (760 mm Hg) at existing ambient humidity. Thisconforms to most of the ASTM me
8、thods for atmosphericsampling and analysis that involve volumetric corrections.Absolute temperature scales are to be used when substitutingvalues into the formulae used in this procedure.4. Summary of Practice4.1 Two alternative methods of performing the requiredvolume determinations for rotameter c
9、alibration are described:4.1.1 Using the water-sealed rotating drum meter (wet testmeter). See Section 7.4.1.2 Using the volumetric gasometer (bell prover). SeeSection 8.5. Significance and Use5.1 Choice of method depends primarily on which equip-ment is available. Higher accuracy is possible with t
10、he gasom-eter. The accuracies of the methods of atmospheric analysis, forwhich the calibration procedure is intended, do not warrant thevery highest possible accuracy in flow measurement.6. Apparatus6.1 Wet Test Meter, or Volumetric Gasometer, with waterseal and equipped with a water manometer on th
11、e inlet.6.2 Counter Balance Weights, for gasometer.1This practice is under the jurisdiction of ASTM Committee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.01 on Quality Control.Current edition approved June 15, 2010. Published July 2010. Originallyapproved in 1973. Last pre
12、vious edition approved in 2004 as D3195 - 90 (2004).DOI: 10.1520/D3195-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe
13、ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 Mercury BarometerSee Test Methods D3631.6.4 Psychrometer, (if room air is used for calibration gas).See Test Method E337.6.5 Thermometer, to measure ambient temperature
14、. SeeSpecifications E1, E1137/E1137M, and E2251.6.6 Stopwatch.6.7 Air Supply, either a cylinder of compressed air or adiaphragm type pump of adequate capacity and a ballastvolume or restrictor to eliminate pulsations.6.8 Needle Valve.7. Procedure Using Wet Test Meter7.1 Unless it was already calibra
15、ted within the previousthree months, calibrate the wet test meter by Test MethodsD1071. The method described in Section 19 is recommendedfor highest accuracy.7.2 Set up the apparatus as shown in Fig. 1, makingconnections as short as possible and large enough insidediameter to avoid any appreciable p
16、ressure drops.7.3 Before and after the complete calibration run, recordroom temperature, barometric pressure in accordance with TestMethods D3631, and relative humidity (when room air is usedfor calibrating gas) in accordance with Test Method E337. Useaverage values for subsequent calculations.7.4 S
17、tart air flowing through the rotameter and wet testmeter.Adjust the flow to the desired rate with the needle valve.Take a pair of timed readings on the wet test meter, understeady flow, for each of five or more uniformly spaced pointson the rotameter scale, going from low values to high values.Repea
18、t, going from high to low. Note the manometer readingand meter water temperature for each meter reading.8. Procedure Using Gasometer8.1 Unless it was already calibrated within the previous sixmonths, in the same location, calibrate the gasometer by TestMethods D1071.8.2 Set up the apparatus as shown
19、 in Fig. 2, makingconnections as short as possible and large enough insidediameter to avoid any appreciable pressure drops.8.3 Before and after the complete calibration run, record theroom temperature, barometric pressure, and relative humidity(when room air is used for calibrating gas). Use average
20、 valuesfor subsequent calculations.8.4 Start air flowing through the rotameter and into thegasometer. Adjust the flow to the desired value with the needlevalve.8.5 Adjust eight counterbalance weights on the gasometeras required to maintain no greater than 2 in. of water back-pressure when operating.
21、 (It is pertinent to leave the units innon-SI units as this calibration is in accordance with theprocedure of manufacturer specifications for testing, thus noequivalent SI units given.)8.6 Take a pair of timed readings on the gasometer scale,under steady flow, for each of five or more uniformly spac
22、edpoints on the rotameter scale going from low values to highvalues. Repeat, going from high to low.9. Calculations9.1 Convert all temperature and pressure readings to abso-lute units, as follows:F 1 460 5 R (1)C 1 273 5 Kin. of water 3 0.249 5 kPain. of water 3 0.0737 5 in. Hgin. of water 3 1.87 5
23、mm Hg9.2 Calculate the indicated flow readings for all recordedrotameter points by dividing the indicated delta volumes by thetime.9.3 Using the following equation, convert these indicatedflow readings to actual flows that would be indicated by therotameter if it were calibrated for air at the stand
24、ard conditionsstated in 3.1.2:Q15 QPm2 D!Ta/PmTm=Ta/Ts(2)FIG. 1 Calibration Assembly Using Wet Test MeterD3195/D3195M 102where: (see Appendix)Q1= flow rate rotameter should indicate,Q = flow rate indicated by wet test meter or gasometer,Ts= standard temperature, absolute units (298 K or537R),Tm= met
25、er temperature, absolute units (water temperaturefor wet test meter; room temperature for gasometer),Ta= room temperature, absolute unitsPm= gas pressure during calibration (inlet pressure for wettest meter; barometric pressure for gasometer) (kPa,in. water, mm Hg), andD = vapor pressure of water in
26、 the calibrating gas (kPa,in. water, mm Hg).9.4 Prepare the calibration curve by best fit to all points. Itshould be labeled “. at 25C 77F and 101.3 kPa (760 mmHg).”10. Keywords10.1 calibration; flowmeter; rotameterAPPENDIX(Nonmandatory Information)X1. DERIVATION OF FLOWMETER EQUATIONX1.1 The equati
27、on is based on the premise that thecalibrated rotameter should read air flow correctly at standardconditions, as defined. Therefore, in order to prepare thecalibration curve it is first necessary to convert the wet testmeter or gasometer readings to the values that would beindicated by the rotameter
28、 if it had been calibrated understandard conditions. This can be done logically in several steps.First, the indicated values are corrected for the water vaporadded by the wet test meter or gasometer, assuming saturation,by operating with the factor:Pm2 D/Pm(X1.1)where:FIG. 2 Calibration Assembly Usi
29、ng GasometerD3195/D3195M 103Pm= gas pressure during calibration (inlet pressure for wettest meter; barometric pressure for gasometer), andD = vapor pressure of water at 100 % R.H. and tempera-ture Tm, minus the vapor pressure of water in thecalibrating gas.X1.2 Next, the volume measured in the wet t
30、est meter orgasometer is corrected to what it was in the rotameter. Thisfactor is:Ta/Tm(X1.2)where:Ta= room temperature, absolute units andTm= meter temperature, absolute units (water temperaturefor wet test meter; room temperature for gasometer).X1.3 This is what the rotameter should read but if it
31、 werecalibrated with air at standard temperature and used to measureair at this different temperature, the viscosity effect wouldcause a slightly different reading. Since viscosity is propor-tional to the square root of absolute temperature (independentof pressure up to 10 atmospheres), the indicate
32、d flow woulddiffer from actual flow by the factor:=Ta/Ts(X1.3)where:Ts= standard temperature, absolute units (298 K or 537R)X1.4 Putting these elements all together gives us theequation indicated in the body of the method.X1.5 Subsequent use of the rotameter normally involvestaking the indicated flo
33、w off the curve and correcting it tostandard conditions. The factor for this correction is:TsPr/TaPs=Ts/Ta(X1.4)where:Pr= rotameter pressure, kPa (mm Hg) andPs= standard pressure 101.3 kPa (760 mm Hg)NOTE X1.1In many cases, Pris, or can be assumed to be, the same asbarometric pressure. However, when
34、 any question exists, and for highestaccuracy, a water manometer should be used, just downstream of therotameter.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advi
35、sed that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either
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37、 you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individ
38、ual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D3195/D3195M 104
