ASHRAE 41 7-2015 Standard Methods for Gas Flow Measurement.pdf

1、ANSI/ASHRAE Standard 41.7-2015(Supersedes ANSI/ASHRAE Standard 41.7-1984)Standard Methods forGas Flow MeasurementApproved by ASHRAE on September 30, 2015, and by the American National Standards Institute on October 1, 2015.ASHRAE Standards are scheduled to be updated on a five-year cycle; the date f

2、ollowing the Standard number is the year ofASHRAE approval. The latest edition of an ASHRAE Standard may be purchased on the ASHRAE website (www.ashrae.org)or from ASHRAE Customer Service, 1791 Tullie Circle, NE, Atlanta, GA 30329-2305. E-mail: ordersashrae.org. Fax: 678-539-2129. Telephone: 404-636

3、-8400 (worldwide) or toll free 1-800-527-4723 (for orders in US and Canada). For reprintpermission, go to www.ashrae.org/permissions. 2015 ASHRAE ISSN 1041-2336SPECIAL NOTEThis American National Standard (ANS) is a national voluntary consensus Standard developed under the auspices of ASHRAE. Consens

4、us is definedby the American National Standards Institute (ANSI), of which ASHRAE is a member and which has approved this Standard as an ANS, as“substantial agreement reached by directly and materially affected interest categories. This signifies the concurrence of more than a simple majority,but no

5、t necessarily unanimity. Consensus requires that all views and objections be considered, and that an effort be made toward their resolution.”Compliance with this Standard is voluntary until and unless a legal jurisdiction makes compliance mandatory through legislation. ASHRAE obtains consensus throu

6、gh participation of its national and international members, associated societies, and public review.ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard. The ProjectCommittee Chair and Vice-Chair must be members of ASHRAE; while other co

7、mmittee members may or may not be ASHRAE members, allmust be technically qualified in the subject area of the Standard. Every effort is made to balance the concerned interests on all Project Committees. The Senior Manager of Standards of ASHRAE should be contacted fora. interpretation of the content

8、s of this Standard,b. participation in the next review of the Standard,c. offering constructive criticism for improving the Standard, ord. permission to reprint portions of the Standard.DISCLAIMERASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in lig

9、ht of available information and acceptedindustry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of any products, components, or systemstested, installed, or operated in accordance with ASHRAEs Standards or Guidelines or that any tests conducted under its

10、Standards or Guidelineswill be nonhazardous or free from risk.ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDSASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testing for rating purposes, bysuggesting safe practices in designing and i

11、nstalling equipment, by providing proper definitions of this equipment, and by providing other informationthat may serve to guide the industry. The creation of ASHRAE Standards and Guidelines is determined by the need for them, and conformanceto them is completely voluntary.In referring to this Stan

12、dard or Guideline and in marking of equipment and in advertising, no claim shall be made, either stated or implied,that the product has been approved by ASHRAE.ASHRAE Standing Standard Project Committee 41Cognizant TC: 1.2, Instruments and MeasurementsSPLS Liaison: John F. DunlapJohn P. Scott, Chair

13、*Richard L. Hall*Michael Perevozchikov*Kevin L. Amende* Mark Kedzierski* Frank J. Spevak*Erik S. Anderson*Lloyd Le* Christopher G. Stone*B. Terry Beck* Alexander Leyderman* Michael Wegenka*Patrick E. Collins* Hongmei Liang*James L. Douglas*Kevin B. Peck* * Denotes members of voting status when the d

14、ocument was approved for publication Denotes members of Subcommittee 41.7ASHRAE STANDARDS COMMITTEE 20152016Douglass T. Reindl, Chair Keith I. Emerson Heather L. PlattRita M. Harrold, Vice-Chair Steven J. Emmerich David RobinJoseph R. Anderson Julie M. Ferguson Peter SimmondsJames D. Aswegan Roger L

15、. Hedrick Dennis A. StankeNiels Bidstrup Srinivas Katipamula Wayne H. Stoppelmoor, Jr.Donald M. Brundage Rick A. Larson Jack H. ZarourJohn A. Clark Lawrence C. Markel Julia A. Keen, BOD ExOWaller S. Clements Arsen K. Melikov James K. Vallort, COJohn F. Dunlap Mark P. ModeraJames W. Earley, Jr. Cyrus

16、 H. NasseriStephanie C. Reiniche, Senior Manager of Standards ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.CONTENTSANSI/ASHRAE Standard 41.7-2015,Standa

17、rd Methods for Gas Flow MeasurementSECTION PAGEForeword .21 Purpose.22 Scope23 Definitions .24 Classifications .25 Requirements36 Instruments .47 Gas Flow Rate Measurement Methods.48 Uncertainty Requirements.129 Test Report .1210 Normative References.12Informative Annex A: Informative References and

18、 Bibliography.13Informative Annex B: An Uncertainty Analysis Example for a Coriolis Flowmeter14Informative Annex C: An Uncertainty Analysis Example for a Differential Pressure Flowmeter .18NOTEApproved addenda, errata, or interpretations for this standard can be downloaded free of charge from the AS

19、HRAE Web site at www.ashrae.org/technology. 2015 ASHRAE1791 Tullie Circle NE Atlanta, GA 30329 www.ashrae.org All rights reserved.ASHRAE is a registered trademark of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.ANSI is a registered trademark of the American Nati

20、onal Standards Institute. ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.2 ANSI/ASHRAE Standard 41.7-2015(This foreword is not part of this standard. It i

21、s merelyinformative and does not contain requirements necessaryfor conformance to the standard. It has not been pro-cessed according to the ANSI requirements for a standardand may contain material that has not been subject topublic review or a consensus process. Unresolved objec-tors on informative

22、material are not offered the right toappeal at ASHRAE or ANSI.)FOREWORDThe 1984 edition of Standard 41.7 was limited to square-edged orifice meters. In the 2015 edition, the scope has beenexpanded to cover the breadth of gas flow measurementdevices used for testing heating, ventilating, air-conditio

23、ning,and refrigerating systems and components, and to includefield gas flow measurements in addition to laboratory gasflow measurements. This standard meets ASHRAEs manda-tory language requirements.Selecting an appropriate gas flow flowmeter can be adaunting task given the wide variety of operating

24、principles,measurement precision, and costs of commercial products.Whether gas flow measurements are to be taken in a labora-tory or in the field, selecting the appropriate meter should bebased on the required measurement accuracy. Once a gasflowmeter has been selected, the user may need to consultw

25、ith the meter manufacturer regarding installation specifics,operating range limits, calibration limits, and other similarspecifics in order to obtain the expected measurement accu-racy. Safety is an important consideration for all proceduresinvolving gases, particularly regarding flammability, toxic

26、ity,and corrosiveness. Safety glasses and other personal protec-tion equipment should be worn.1. PURPOSEThis standard prescribes methods for gas flow measurement.2. SCOPEThis standard applies to laboratory and field gas flow mea-surement for testing heating, ventilating, air-conditioning,and refrige

27、rating systems and components. This standard isrestricted to applications where the entire flow stream of gasenters and exits the gas flowmeter in a gas-only state duringdata recording with the following exceptions:a. This standard does not apply to airflow measurements atpressures within this range

28、: 25 kPa to +25kPa (100 in.H2O to +100 in. H2O) referenced to ambient pressure.Those measurements are within the scope of ASHRAEStandard 41.2.b. This standard does not apply to fan performance ratingairflow measurements. Those measurements are withinthe scope of ASHRAE Standard 51.c. This standard d

29、oes not apply to gaseous-phase refrigerantmass flow measurements where the gas flow includes cir-culating lubricant. Those measurements are within thescope of ASHRAE Standard 41.10.3. DEFINITIONSThe following definitions apply to the terms used in this stan-dard. accuracy: the degree of conformity o

30、f an indicated value tothe corresponding true value. equivalent diameter: the diameter of a circle having the samearea as a rectangular area. error: the difference between the test result and its corre-sponding true value.mean, : the arithmetic average of N readings.measurement system: the instrumen

31、ts, signal conditioningsystems (if any), and data acquisition system (if any).precision: the closeness of agreement among repeated mea-surements of the same characteristic by the same methodunder the same conditions. random error, : the portion of total error that varies ran-domly in repeated measur

32、ements throughout a test process.sample size, N: the number of individual values in a sample.systematic error, : the portion of total error that remainsconstant in repeated measurements throughout a test process.test point: a specific set of test operating conditions and toler-ances for recording da

33、ta.true value: the unknown, error-free value of a test result.uncertainty: a measure of the potential error in a measure-ment or experimental result that reflects the lack of confi-dence in the result to a specified level. unit under test: equipment that is the subject of the gas flowrates measureme

34、nts using this standard.4. CLASSIFICATIONS4.1 Gas Flow Operating State. Gas flow measurement meth-ods shall be restricted to applications where the entire gas flowstream enters and exits the flowmeter in the vapor-only stateduring data recording. Trace amounts of liquids shall be lessthan 1% by mass

35、 unless otherwise specified by the flowmetermanufacturer or by the test plan in Section 5.1.4.2 Gas Flow Measurement Applications. Gas flow mea-surement applications that are within the scope of this stan-dard shall be classified as one of the following types.4.2.1 Laboratory Applications. Gas flow

36、measurementsunder laboratory conditions are engineering developmenttests or tests to determine product ratings.Informative Note: Laboratory gas flow measurementstend to use more accurate instruments than field measurementsdo and tend to meet the instrument manufacturers installationrequirements.4.2.

37、2 Field Applications. Gas flow measurements underfield conditions are tests to determine installed system gasflow rates.Informative Note: Field gas flow measurements tend touse less accurate instruments than laboratory measurementsdo and often do not to meet the instrument manufacturersinstallation

38、requirements. 4.3 Gas Flowmeters4.3.1 Mass Flowmeters. Gas flowmeters in this categoryperform direct measurement of gas mass flow rates.Xm ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without A

39、SHRAEs prior written permission.ANSI/ASHRAE Standard 41.7-2015 34.3.2 Volumetric Flowmeters. Gas flowmeters in this cat-egory perform direct measurement of volumetric gas flowrates. If gas mass flow rates are required, each volumetric gasflow measurement shall be multiplied by the inlet gas densitya

40、t the flow measurement location to obtain the gas mass flowrate measurement.Informative Note: Ultrasonic flowmeters, vortex-sheddingflowmeters, and drag-force flowmeters are examples of veloc-ity measuring devices that can be used to determine volumetricflow rates.4.4 Gas Flow Measurement Methods. G

41、as flow measure-ment methods that are within the scope of this standard areshown in the following list. Each of these gas flow measure-ment methods is described in Section 7.5:a. Coriolis flowmetersb. Thermal flowmetersc. Orifice metersd. Flow nozzlese. Venturi tubesf. Turbine flowmetersg. Variable-

42、area flowmetersh. Ultrasonic flowmetersi. Pitot-static tube methodsj. Vortex-shedding flowmetersk. Drag-force flowmeters5. REQUIREMENTS5.1 Test Plan. A test plan is a requirement. The test planshall specify the test points and the required measurementsystem accuracy at each test point. A test plan i

43、s a documentor other form of communication that specifies the tests to beperformed and the required measurement accuracy for eachtest. Sources of the test plan are (a) the person or the organi-zation that authorized the tests to be performed, (b) a methodof test standard, (c) a rating standard, or (

44、d) a regulation orcode.5.2 Values to be Determined and Reported. The test valuesto be determined and reported shall be as shown in Table 5-1.Use the unit of measure in Table 5-1 unless otherwise speci-fied in the test plan in Section 5.1.5.3 Test Requirements5.3.1 Accuracy. A selected gas flowmeter

45、shall meet orexceed the required gas flow measurement system accuracyspecified in the test plan in Section 5.1 over the full range ofoperating conditions.5.3.2 Uncertainty. The uncertainty in each gas flow mea-surement shall be calculated using the method in Section 8 foreach test point. Alternative

46、ly, the worst-case uncertainty forall test points shall be estimated and the same value reportedfor each test point.5.3.3 Gas Mass Flow Rate Steady-State Tests. If the testplan in Section 5.1 requires gas mass flow rate data points tobe recorded at steady-state test conditions but does not specifyth

47、e steady-state criteria, each set of steady-state test conditionsshall meet the criteria specified by Equations 5-1 through 5-5.(5-1)(5-2)where= gas mass flow rate, kg/s (lbm/h) = standard deviation of measurement samplesn = number of measurement samples(5-3)(5-4)If the test plan in Section 5.1 spec

48、ifies a target gas massflow rate for the steady-state test conditions, , then thecriterion in Equation 5-5 shall be met unless otherwise speci-fied in the test plan.(5-5)5.3.4 Airflow Dynamic Tests. If required by the test planin Section 5.1, gas mass flow rate measurements shall bemade at the dynam

49、ic operating conditions and test conditionlimits specified in the test plan. Data points shall be recordedat time intervals specified in the test plan.Informative Note: Dynamic tests need to address theresponse time of the selected instruments to ensure that theresponse time is appropriate for the test plan requirements. Takeinto consideration dampening features that are commonly usedin air flowmeter electronics and signal conditioning. Dynamicmeasurements of velocity would be needed if quantities liketurbulence intensity were to be measured.TABLE 5-1 Mea