ASHRAE 41 3-2014 Standard Methods for Pressure Measurement.pdf

1、ANSI/ASHRAE Standard 41.3-2014(Supersedes ASHRAE Standard 41.3-1989)Standard Methods forPressure MeasurementApproved by the ASHRAE Standards Committee on June 28, 2014; by the ASHRAE Board of Directors on July 2, 2014; and by theAmerican National Standards Institute on July 3, 2014.ASHRAE Standards

2、are scheduled to be updated on a five-year cycle; the date following the standard number is the year ofASHRAE Board of Directors 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,

3、 GA 30329-2305. E-mail:ordersashrae.org. Fax: 678-539-2129. Telephone: 404-636-8400 (worldwide) or toll free 1-800-527-4723 (for orders in US andCanada). For reprint permission, go to www.ashrae.org/permissions. 2014 ASHRAE ISSN 1041-2336SPECIAL NOTEThis American National Standard (ANS) is a nationa

4、l voluntary consensus standard developed under the auspices of ASHRAE.Consensus is defined by the American National Standards Institute (ANSI), of which ASHRAE is a member and which has approved thisstandard as an ANS, as “substantial agreement reached by directly and materially affected interest ca

5、tegories. This signifies the concurrenceof more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that aneffort be made toward their resolution.” Compliance with this standard is voluntary until and unless a legal jurisdiction

6、makes compliancemandatory through legislation.ASHRAE obtains consensus through 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 Pro

7、jectCommittee Chair and Vice-Chair must be members of ASHRAE; while other committee 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 ProjectCommittees.The Manager of Standard

8、s of ASHRAE should be contacted for:a. interpretation of the contents 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 prom

9、ulgate Standards and Guidelines for the benefit of the public in light of available information andaccepted industry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of any products, components,or systems tested, installed, or operated in accordance with AS

10、HRAEs Standards or Guidelines or that any tests conducted under itsStandards or Guidelines will 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

11、 for ratingpurposes,bysuggestingsafepracticesindesigningandinstallingequipment,byprovidingproperdefinitionsofthisequipment,andbyprovidingother information that may serve to guide the industry.The creation of ASHRAE Standards and Guidelines is determined by the need for them,and conformance to them i

12、s completely voluntary.In referring to this Standard 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 41CognizantTC:TC 1.2, Instruments and Measurement

13、SPLS Liaison: John F. DunlapFrank J. Spevak, Chair* James L. Douglas* James SchaeferErik S. Anderson* Richard L. Hall* John P. Scott*Shane J. Angle* Mark Kedzierski* Michael Wegenka*B. Terry Beck* Alexander Leyderman* Charles C. Wright*Patrick E. Collins* Kevin Brent Peck* David Yuill*Denotes member

14、s of voting status when the document was approved for publicationASHRAE STANDARDS COMMITTEE 20132014William F. Walter, Chair David R. Conover Malcolm D. KnightRichard L. Hall, Vice-Chair John F. Dunlap Rick A. LarsonKarim Amrane James W. Earley, Jr. Mark P. ModeraJoseph R. Anderson Steven J. Emmeric

15、h Cyrus H. NasseriJames Dale Aswegan Julie M. Ferguson Janice C. PetersonCharles S. Barnaby Krishnan Gowri Heather L. PlattSteven F. Bruning Cecily M. Grzywacz Douglas T. ReindlJohn A. Clark Rita M. Harrold Julia A. Keen, BOD ExOWaller S. Clements Adam W. Hinge Thomas E. Werkema, Jr., CODebra H. Ken

16、noyStephanie C. Reiniche, Manager of StandardsCONTENTSANSI/ASHRAE Standard 41.3-2014,Standard Methods for Pressure MeasurementSECTION PAGEForeword .21 Purpose.22 Scope23 Definitions .24 Classifications .35 Requirements36 Instrument Types (Informative) .47 Uncertainty Calculations .98 Test Report .99

17、 References9Informative Annex A: Informative References and Bibliography.10Informative Annex B: Methods for Uncertainty .11Informative Annex C: Example of an Uncertainty Calculation for a Pressure Measurement 12Informative Annex D: Pressure Units Conversion Table.13NOTEApproved addenda, errata, or i

18、nterpretations for this standard can be downloaded free of charge from the ASHRAEWeb site at www.ashrae.org/technology. 2014 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-Con

19、ditioning Engineers, Inc.ANSI is a registered trademark of the American National Standards Institute.2 ANSI/ASHRAE Standard 41.3-2014(This foreword is not part of this standard. It is merelyinformative and does not contain requirements necessaryfor conformance to the standard. It has not been pro-ce

20、ssed 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 material are not offered the right toappeal at ASHRAE or ANSI.)FOREWORDFirst published in 1989, Standard 41.3 is inten

21、ded to helpusers select and apply suitable pressure measurement instru-ments. This revision of the standard updates the descriptionsof pressure measurement instruments and provides tables ofinformation to help users quickly identify the specific types ofinstruments that best suit their applications.

22、 New sectionshave been added regarding the test requirements, measure-ment uncertainty calculations, and test report. Additionally,this revision meets ASHRAEs mandatory language require-ments.1. PURPOSEThe purpose of this standard is to prescribe methods for mea-suring pressure.2. SCOPEThe pressure

23、measurement methods described herein areintended for use in testing heating, refrigerating, and air-con-ditioning equipment and components.3. DEFINITIONSThe following definitions apply to terms used in this standard:absolute pressure: normal force per unit area exerted by afluid on a containing wall

24、 with respect to zero absolute pres-sure (a perfect vacuum). Absolute pressure can be positiveonly (see Figure 3-1).accuracy: the degree of conformity of an indicated value toan accepted standard value, or true value. The degree of inac-curacy is known as the total measurement error and is the sumof

25、 bias error and precision error.ambient pressure: the pressure in which a device operates.barometric pressure: the pressure of the atmosphere relativeto zero absolute pressure (a perfect vacuum). Standard atmo-spheric reference pressure (assumed at sea level) is defined bythe International Civil Aer

26、onautics Organization (ICAO) as101.325 kPa, 1013.25 millibars, 14.696 psia, 29.921 in. Hg at0C (32F).bias, fixed, or systematic error: a persistent differencebetween the true or actual value to be measured and the indi-cated value from the measuring system, usually due to theparticular instrument or

27、 technique of measurement. An errorof this type can be corrected by calibration.calibration: correcting or determining the error of an existingscale, or of evaluating one quantity in terms of readings fromanother.differential pressure: difference in pressure between any twopoints in a system (see Fi

28、gure 3-1).error: the difference between the true value of the quantitymeasured and the measured value. All errors in experimentaldata can be classified as one of two types: systematic (fixed)errors or random (precision) errors. The terms accuracy andprecision are often used to distinguish between sy

29、stematicand random errors. A measurement with small systematicerrors is said to be unbiased. A measurement with small ran-dom errors is said to have high precision. A measurement thatis unbiased and precise is said to be accurate.fixed error: same as systematic error.gage (or gauge) pressure: pressu

30、re above or below ambientpressure (see Figure 3-1).hysteresis: in control systems, the difference between theresponse of a system to increasing and decreasing signals.precision: the closeness of agreement among repeated mea-surements of the same characteristic by the same methodunder the same condit

31、ions. Compare to accuracy.precision error: same as random error.pressure: normal force per unit area exerted by a fluid on acontaining wall with respect to a reference.pressure transducer or pressure sensor: a device that con-verts mechanical energy into an electrical output that is pro-portional to

32、 the mechanical stimulus.pressure transmitter: a device that translates low-level elec-trical outputs from sensors into high-level electrical signalsfor transmission and processing.pulsating pressure: random or oscillating pressure variationsthat are more frequent than 1 Hz. Pulsations less than or

33、equalto 1 Hz are considered to be steady state.random error: a statistical error that is caused by chance andis not recurring. Random errors cannot be corrected throughcalibration. There are two types of random errors: (a) additiveerrors that are independent of the magnitude of the observa-tions and

34、 (b) multiplicative errors that are dependent on themagnitude of the observations.resolution: the smallest change a sensor is able to detect inthe quantity that it is measuring.sensitivity: the ratio of the change in indicated value to thechange in measured variable.snubber: a device used to suppres

35、s pressure pulsations orfluctuations, or to protect internal gage mechanisms.static pressure: pressure at a point where the fluid element isin equilibrium. Static pressure would be indicated by a pres-sure-sensing instrument at rest with respect to the fluid.surroundings pressure: same as ambient pr

36、essure.total pressure: the pressure on a plane normal to the localflow direction. It is the maximum value of pressure as a func-tion of direction at a point, and it is equal to the summation ofstatic pressure and velocity pressure: pt= ps+ pv. Total pres-ANSI/ASHRAE Standard 41.3-2014 3sure is indic

37、ated when the fluid is brought to rest at a pres-sure-sensing instrument.uncertainty: an estimated value for the error in a measure-ment, which may be the result of both systematic and randomerror. Because only random errors can be treated by statisticalmethods, and only systematic errors can be cor

38、rected throughcalibration, uncertainty computed using this standard willresult from random errors.velocity pressure: Velocity pressure is the net pressure increasethat can be derived from the complete conversion of the veloc-ity to pressure in a reversible process, expressed as (V2/2),where is the f

39、luid density and V is the fluid velocity.4. CLASSIFICATIONSInstruments that are within the scope of this standard are sep-arated into the following categories.4.1 Pressure Measurement Instruments. These instru-ments are described in Section 6.1.4.2 Low Absolute Pressure (Vacuum) Instruments. Thesein

40、struments are described in Section 6.2.4.3 Pressure Calibration Instruments. These instrumentsare described in Section 6.3.5. REQUIREMENTS5.1 Test Plan. A test plan is a document or other form ofcommunication that specifies the tests to be performed andthe required measurement accuracy for each test

41、. Sources ofthe test plan include, but are not limited to, (a) the person orthe organization that authorized the tests to be performed, (b)a method of test standard, (c) a rating standard, or (d) a regu-lation or code.5.2 Values to be Determined5.2.1 Pressure (gage, absolute, or differential) as spe

42、cifiedin the test plan.5.2.2 The uncertainty in each pressure measurement shallbe estimated using the methods in Section 7 for every run.Alternatively, the worst-case uncertainty for all runs may beestimated and reported for every run.5.3 Test Requirements5.3.1 Unless otherwise specified in the test

43、 plan, pressuremeasurement errors shall be less than 1.0% of the full scale.If absolute pressure sensors are not used, the pressure mea-surement uncertainty calculations shall include the baromet-ric pressure correction to obtain absolute pressure values.5.3.2 Unless otherwise specified in the test

44、plan, maximumresolution interval shall be 1% of full scale.5.3.3 Measurements from the instruments shall be trace-able to primary or secondary standards calibrated by theNational Institute of Standards and Technology (NIST). Theindicated corrections shall be applied to meet the requirederror limits

45、given in subsequent sections. Instruments shall berecalibrated on a regular schedule that is appropriate for eachinstrument, and calibration records shall be maintained. Allinstruments shall be applied in a manner that ensures compli-ance with the specified error limits.FIGURE 3-1 Pressure terminolo

46、gy illustration.(Reprinted by permission of the American Society of Mechanical Engineers. All rights reserved.)4 ANSI/ASHRAE Standard 41.3-20146. INSTRUMENT TYPES (INFORMATIVE)6.1 Pressure Measurement Instruments. Pressure mea-surement instruments that can be applied within the scope ofthis standard

47、 include, but are not limited to, the types that aresummarized in Table 6-1. Sections 6.1.1 through 6.1.13 con-tain a brief description of each of the types listed in Table 6-1.6.1.1 Bourdon Tube Gage. Bourdon tube gages feature anelastic tube closed at one end that deflects under pressure toprovide

48、 a direct pressure reading on the face of the gage (seeFigure 6-1). Variations of the elastic tube include C-shaped,helical, and spiral.6.1.2 Bellows Gage. The bellows gage uses a thin-walledconvoluted pressure sensing element to provide a direct pres-sure reading (see Figure 6-2). Applications incl

49、ude measuringgage pressure with a reference to atmospheric pressure, mea-suring differential pressure, and measuring barometric pres-sure with a reference to vacuum.6.1.3 Diaphragm Gage. A slack diaphragm gage uses aflexible diaphragm (see Figure 6-3). The motion of the dia-phragm under pressure is amplified by linkages to provide adirect indication of pressure. The diaphragm gage is suitablefor measuring low pressures.6.1.4 U-Tube Manometer. The U-tube manometer is a U-shaped tube with vertical legs. The liquid in this device is nor-mally water, or a liquid with a de