ASTM D3195-1990(2004) Standard Practice for Rotameter Calibration《转子流量计校准的标准实施规程》.pdf

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1、Designation: D 3195 90 (Reapproved 2004)Standard Practice forRotameter Calibration1This standard is issued under the fixed designation D 3195; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p

2、arentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 condition

3、s of pressure and temperature,in the analysis of atmospheres for pollutant content.1.2 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 practices and

4、determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1071 Test Methods for Volumetric Measurement of Gas-eous Fuel SamplesD 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 3631 Test Methods for Measuring Surface Atmospheri

5、cPressureE1 Specification for ASTM Liquid-in-Glass ThermometersE 337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, refer toTerminology D 1356.3.1.2 standa

6、rd conditions are taken as 25C and 101.3 kPa(760 mm Hg) at existing ambient humidity. This conforms tomost of the ASTM methods for atmospheric sampling andanalysis that involve volumetric corrections.Absolute tempera-ture scales are to be used when substituting values into theformulae used in this p

7、rocedure.4. Summary of Practice4.1 Two alternative methods of performing the requiredvolume determinations for rotameter calibration 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. Signi

8、ficance and Use5.1 Choice of method depends primarily on which equip-ment is available. Higher accuracy is possible with the 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 mea

9、surement.6. Apparatus6.1 Wet Test Meter, or Volumetric Gasometer, with waterseal and equipped with a water manometer on the inlet.6.2 Counter Balance Weights, for gasometer.6.3 Mercury BarometerSee Test Methods D 3631.6.4 Psychrometer, (if room air is used for calibration gas).See Test Method E 337.

10、6.5 Thermometer, to measure ambient temperature. SeeSpecification E1.6.6 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 i

11、t was already calibrated within the previous 3months, calibrate the wet test meter by Test Methods D 1071.The method described in Section 19 is recommended forhighest accuracy.7.2 Set up the apparatus as shown in Fig. 1, makingconnections as short as possible and large enough insidediameter to avoid

12、 any appreciable pressure drops.7.3 Before and after the complete calibration run, recordroom temperature, barometric pressure in accordance with TestMethods D 3631, and relative humidity (when room air is usedfor calibrating gas) in accordance with Test Method E 337. Useaverage values for subsequen

13、t calculations.1This practice is under the jurisdiction of ASTM Committee D22 on Samplingand Analysis of Atmospheres and is the direct responsibility of SubcommitteeD22.01 on Quality Control.Current edition approved October 1, 2004. Published December 2004. Originallyapproved in 1973. Last previous

14、edition approved in 1998 as D 3195 - 90 (1998)e1.2For 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 ASTM website.1Copyright A

15、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.4 Start 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 ea

16、ch of five or more uniformly spaced pointson the rotameter scale, going from low values to high values.Repeat, 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 six

17、months, in the same location, calibrate the gasometer by TestMethods D 1071.8.2 Set up the apparatus as shown 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 te

18、mperature, barometric pressure, and relative humidity(when room air is used for calibrating gas). Use average 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

19、 weights on the gasometeras required to maintain no greater than 2 in. of water back-pressure when operating.FIG. 1 Calibration Assembly Using Wet Test MeterFIG. 2 Calibration Assembly Using GasometerD 3195 90 (2004)28.6 Take a pair of timed readings on the gasometer scale,under steady flow, for eac

20、h of five or more uniformly spacedpoints 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 0.073

21、7 5 in. Hgin. of water 3 1.87 5 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

22、 calibrated for air at the standard conditionsstated in 5.2:Q15 QPm2 D!Ta/PmTm=Ta/Ts(2)where: (see Appendix)Q1= flow rate rotameter should indicate,Q = flow rate indicated by wet test meter or gasometer,Ts= standard temperature (298 K or 537R),Tm= meter temperature (water temperature for wet testmet

23、er; room temperature for gasometer),Ta= room temperature,Pm= gas pressure during calibration (inlet pressure for wettest meter; barometric pressure for gasometer) (kPa,in water, mm Hg), andD = vapor pressure of water in the calibrating gas (kPa, inwater, mm Hg).9.4 Prepare the calibration curve by b

24、est fit to all points. Itshould be labeled “. at 25C and 101.3 kPa (760 mm Hg).”10. Keywords10.1 calibration; flowmeter; rotameterAPPENDIX(Nonmandatory Information)X1. DERIVATION OF FLOWMETER EQUATIONX1.1 The equation is based on the premise that thecalibrated rotameter should read air flow correctl

25、y 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 if it had been calibrated understandard conditions. This can be done logically in se

26、veral 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:Pm= gas pressure during calibration (inlet pressure for wettest meter; barometric pressure for gasometer), andD = va

27、por 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 test meter orgasometer is corrected to what it was in the rotameter. Thisfactor is:Ta/Tm(X1.2)where:Ta= room temperature, andTm= meter temperatur

28、e (water temperature for wet testmeter; room temperature for gasometer).X1.3 This is what the rotameter should read but if it werecalibrated with air at standard temperature and used to measureair at this different temperature, the viscosity effect wouldcause a slightly different reading. Since visc

29、osity is propor-tional to the square root of absolute temperature (independentof pressure up to 10 atmospheres), the indicated flow woulddiffer from actual flow by the factor:=Ta/Ts(X1.3)where:Ts= standard temperature (298 K or 537R)X1.4 Putting these elements all together gives us theequation indic

30、ated in the body of the method.X1.5 Subsequent use of the rotameter normally involvestaking the indicated flow off the curve and correcting it tostandard conditions. The factor for this correction is:TsPr/TaPs=Ts/Ta(X1.4)where:Pr= rotameter pressure, andPs= standard pressure (760 mm Hg or 101.3 kPa)

31、D 3195 90 (2004)3NOTE X1.1In many cases, Pris, or can be assumed to be, the same asbarometric pressure. However, when 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 pa

32、tent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised 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 revisio

33、n at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your com

34、ments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If 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 copyright

35、ed by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual 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).D 3195 90 (2004)4