ANSI ASME PTC 2-2001 Definitions and Values Performance Test Codes.pdf

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1、 Intentionally left blank PERFORMANCE TEST CODESDEFINITIONS AND VALUESASME PTC 2-2001Revision of ASME PTC 2-1980 (R1985)An American National StandardDateofIssuance:December31,2002ThenexteditionofthisCodeisscheduledforpublicationin2006.Therewillbenoaddendaissuedtothisedition.ASMEissueswrittenrepliest

2、oinquiriesconcerninginterpretationsoftechnicalaspectsofthisCode.InterpretationsarepublishedontheASMEWebsiteundertheCommitteePagesathttp:/www.asme.org/codes/astheyareissued.ASMEistheregisteredtrademarkofTheAmericanSocietyofMechanicalEngineers.Thiscodeorstandardwasdevelopedunderproceduresaccreditedasm

3、eetingthecriteriaforAmericanNationalStandards.TheStandardsCommitteethatapprovedthecodeorstandardwasbalancedtoassurethat individuals from competent and concerned interests have had an opportunity to participate. Theproposedcodeorstandardwasmadeavailableforpublicreviewandcommentthatprovidesanopportuni

4、tyforadditionalpublicinputfromindustry,academia,regulatoryagencies,andthepublic-at-large.ASMEdoesnot“approve,”“rate,”or“endorse”anyitem,construction,proprietarydevice,oractivity.ASMEdoesnottakeanypositionwithrespecttothevalidityofanypatentrightsassertedinconnectionwithanyitemsmentionedinthisdocument

5、,anddoesnotundertaketoinsureanyoneutilizingastandardagainstliabilityforinfringementofanyapplicableletterspatent,norassumeanysuchliability.Usersofacodeorstandardareexpresslyadvisedthatdeterminationofthevalidityofanysuchpatentrights,andtheriskofinfringementofsuchrights,isentirelytheirownresponsibility

6、.Participationbyfederalagencyrepresentative(s)orperson(s)affiliatedwithindustryisnottobeinterpretedasgovernmentorindustryendorsementofthiscodeorstandard.ASME accepts responsibility for only those interpretations of this document issued in accordancewiththeestablishedASMEproceduresandpolicies,whichpr

7、ecludestheissuanceofinterpretationsbyindividuals.Nopartofthisdocumentmaybereproducedinanyform,inanelectronicretrievalsystemorotherwise,withoutthepriorwrittenpermissionofthepublisher.TheAmericanSocietyofMechanicalEngineersThreeParkAvenue,NewYork,NY10016-5990Copyright2002byTHEAMERICANSOCIETYOFMECHANIC

8、ALENGINEERSAllRightsReservedPrintedinU.S.A.CONTENTSForeword . vCommitteeRoster vii1 ObjectandScope. 11.1 1Object .1.2 1Scope .2 Measurement of Performance . 22.1 2Introduction 2.2 2Measurement System .2.3 2Uncertainty of Measuring Systems .2.4 3Intrinsic Accuracy 2.5 3In Situ Conditions 2.6 3Observa

9、tion Accuracy 2.7 3Sensing Accuracy .3 Definition . 53.1 5Primary Definition and Systems of Units 3.2 5Historical Definition of Units of Measure 3.3 6Definition for Use .4 Letter Symbols . 144.1 14Introduction 4.2 14Preferred Letter Symbols 4.3 14Special Principles of Letter Symbol Standardization .

10、4.4 15Description of Terms .5 Common Conversion Factors . 17Figures2.2 3Measuring System 3.3 12Enthalpy-Entropy Diagram for Water .Tables5.1 18Conversion to SI (Metric) Units 5.2 20Conversion Factors for Pressure (force/area) 5.3 21Conversion Factors for Specifi Volume (volume/mass) 5.4 Conversion F

11、actors for Specifi Enthalpy and Specifi Energy (energy/mass) 225.5 Conversion Factors for Specifi Entropy, Specifi Heat, and GasConstant (energy/massH11547temperature) 235.6 Conversion Factors for Viscosity (forceH11547time/areamass/length H11547time) 245.7 25Conversion Factors for Kinematic Viscosi

12、ty (area/time) iii5.8 Conversion Factors for Thermal Conductivity (energy/timeH11547lengthH11547temp. diff.power/lengthH11547temp. diff.) . 26Nonmandatory AppendicesA 27Sources of Fluid and Material Data B 28Units of Measure for ASME Performance Test Codes ivFOREWORDPrecise defnitions of terms and e

13、xact values of constants employed in the variousPerformance Test Codes of this Society are fundamentally important. This Code isintended to provide standard defnitions and values required by each respectivePerformance Test Code (PTC) and to supplement each of them. The principal purposeofthisCode(PT

14、C2),Definition andValues,istoprovideasourceforanyitemusedby more than one of the PTC committees reporting to the Board on Performance TestCodes. This Code is an outgrowth of fve previous codes concerning defnitions andvalues issued and adopted by the Society, and it supersedes them.A draft of the fr

15、st edition was printed in the December 1921 issue of MechanicalEngineeringandwaspresentedtotheSocietyduringthespringmeetingheldinAtlanta,Georgia the following May. On January 21, 1926, the frst such code was approvedand adopted by Council as a standard practice of the Society. The second edition oft

16、his code was approved by Council on May 14, 1931.Beginning in June 1936, a thorough review and a complete rewriting of this codewas undertaken, and the fruits of this labor were adopted by Council on June 17,1945.InJune,1969,PerformanceTestCodeCommitteeNo.2,actingunderinstructionsfrom the Standing C

17、ommittee on Performance Test Codes, proceeded to revise thisCode, the draft of which was presented to the Society as a paper during the 1970Winter Annual Meeting in New York. It was adopted in fnal form by action of thePolicy Board on Codes and Standards on February 26, 1971.The last major revision

18、of this Code began in 1972 to incorporate metrication andtheuseofSystemeInternational(SI)units.Thevaluesofmanyofthephysicalconstantsandconversionfactorswerebroughtuptodateaswell.The1980Codewasapprovedby the Performance Test Codes Supervisory Committee on February 26, 1979, and itwas approved as an A

19、merican National Standard by the ANSI Board of StandardsReview on July 21, 1980.The Code presented herein was revised by the PTC 2 Project Team and approvedby the Board on Performance Test Codes on May 29, 2001. This Performance TestCode was also approved as an American National Standard by the ANSI

20、 Board ofStandards Review on October 31, 2001.NOTICEAll Performance Test Codes MUST adhere to the requirements of PTC 1, GENERALINSTRUCTIONS.Thefollowinginformationisbasedonthatdocumentandisincludedhere for emphasis and for the convenience of the user of the Code. It is expectedthat the Code user is

21、 fully cognizant of Parts I and III of PTC 1 and has read themprior to applying this Code.ASME Performance Test Codes provide test procedures which yield results of thehighest level ofaccuracy consistent with the bestengineering knowledge and practicevcurrently available. They were developed by bala

22、nced committees representing allconcerned interests. They specify procedures, instrumentation, equipment operatingrequirements, calculation methods, and uncertainty analysis.When tests are run in accordance with a Code, the test results themselves, withoutadjustmentforuncertainty,yieldthebestavailab

23、leindicationoftheactualperformanceof the tested equipment. ASME Performance Test Codes do not specify means tocomparethoseresultstocontractualguarantees.Therefore,itisrecommendedthatthepartiestoacommercialtestagreebeforestartingthetestandpreferablybeforesigningthecontractonthemethodtobeusedforcompar

24、ingthetestresultstothecontractualguarantees. It is beyond the scope of any Code to determine or interpret how suchcomparisons shall be made.viBOARDONPERFORMANCETESTCODES(ThefollowingistherosteroftheCommitteeatthetimeofapprovalofthisCode.)OFFICERSP.M.Gerhart,ChairS.J.Korellis,ViceChairW.O.Hays, Secre

25、taryCOMMITTEEPERSONNELP.G.Albert,GeneralElectricCo.R.P.Allen,ConsultantR.L.Bannister,ConsultantD.S.Beachler,URS/Dames(b) inclusion of equipment not covered by thisCode in the PTC series; or(c) approval by the Board on Performance TestCodes of a new Code not conforming to this doc-ument.Such actions

26、will be published in MechanicalEngineering as they occur, and this Code will beamended thereafter.DEFINITIONSANDVALUESASMEPTC2-2001SECTION 2MEASUREMENT OF PERFORMANCE2.1 INTRODUCTIONThe Codes provide test procedures which yieldresults of the highest level of accuracy consistentwith the best engineer

27、ing knowledge and practice,taking into account the cost of tests and monetaryvalueofeffciencytoindustry.Performanceofequip-ment is determined in part by measurements ofphysicalquantities.Ameasurementconsistsofsens-ing a physical variable and translating this resultintodatathatiseitherindicatedorreco

28、rded.Analogdata are indicated by the position of a pointer onadialorbyapointorlineonachart.Digitaldataare indicated by a visual display of numbers orby a numerical printout. Devices used to makemeasurements are called instruments but many de-vicescalledinstrumentsmustbeusedwithadditionalcomponents t

29、o measure certain physical variablesand quantities. A millivoltmeter, for example, canmeasure voltage but a thermocouple must be usedinconjunctionwiththevoltmetertoobtainatemper-ature measurement.2.2 MEASUREMENT SYSTEMIn order to make a measurement of a physicalquantityitmustfrstbesensed,andtheinfor

30、mationabout the energy change due to sensing must betransmitted to a component that communicates thedata.Therequirementsformeasurementaremetbythe system shown in Fig. 2.2.The primary element is that part of the measure-ment system that frst senses the variable to bemeasured.Theenergychangeproducedby

31、thesens-ingmustbetransmittedtoaninformation-communi-catingunitwhereitmaybeuseddirectlyorchanged(transduced)tosomeotherformtoindicateorrecorddata. Themeasurement system may bevery simpleor very complex but the three functions appearinginFig.2.2arerequiredtomakeaphysicalmeasure-ment. The measurement s

32、ystem may be a singlecomponent such as a liquid-in-glass thermometer2wherethesensingisdonebythebulb,thetransmit-ting by the liquid column, and the data display bythe scale. On the other hand, the measurementsystemmaybemulti-componentsuchasfowmea-surement with orifces where the primary element(the or

33、ifce) causes fuid acceleration to produce apressure differential which is transmitted via tubingto a manometer where the data are displayed onthe scale.2.3 UNCERTAINTY OF MEASURING SYSTEMSMeasurementofaphysicalquantitynevercontinu-ously gives a result which is correct in an absolutesense.Thenumerica

34、lvaluedeterminednearlyalwaysdiffers by some amount from the true value, andthe extent of the deviation (called error) dependsupon the type of measurement system used. Codewritersandtestengineersmustdemonstratethatthetest measurements used will provide results suff-ciently accurate to accomplish the

35、purposes ofthe test.Theaccuracyobtainableforagivenmeasurementisdependentuponthefollowingthreecomponents:(a) the characteristics of the measured quantity,(b) the accuracy of the observation, and(c) the measurement system used.(1) The intrinsic accuracy of the measurementsystem.(2) The in-situ conditi

36、ons of its use.Item(c)(1)isgenerallywelltreatedbymostengi-neers and data concerning measurement systemcomponentsisgivenintheInstrumentsandAppara-tus Supplements. Item (c)(2)is often responsible forgross errors of measurement. Specifc analysis isnecessary for each application and installation.ASME PT

37、C 19.1, Test Uncertainty,defnes accu-racyastheclosenessofagreementbetweenamea-suredvalueandthetruevalue;errorasthedifferencebetween the true value and the measured value;anduncertaintyasanumericalestimateoftheerror.DEFINITIONSANDVALUES ASMEPTC2-2001SENSORSenses andobtains energychange fromTransmitse

38、nergyMeasuredquantityTransforms energyinto useable formfor display of dataTRANSMITTER INDICATOR and RECORDERFIG.2.2MEASURINGSYSTEM2.4 INTRINSIC ACCURACYThe intrinsic or inherent accuracy of a measure-ment system depends upon(a) materials,(b) construction, and(c) physical condition at time of use.Whi

39、letheinherentaccuracyofthefrsttwoitemscanbeestimatedfrompublisheddataconcerninganindividualmeasuringsystem component,theactualaccuracyatthetimeofusemustbedeterminedbycalibration. For this reason, all signifcant and pri-mary measuring system components must be cali-brated or checked before and after

40、PTC tests toestablish the effect of their physical condition oninherentaccuracy,unlessthereisnocausefortheircalibration to change.2.5 IN SITU CONDITIONSThe accuracy of a measurement system as useddepends upon its ability to(a) sense the variable to be measured,(b) transmit energy change,(c) apply or

41、 transduce energy, and(d) display data.The lasttwo itemsare essentiallyindependent ofuse unless environmental conditions such as vibra-tion,temperature,humidity,etc.,areofsuchmagni-tudeastopreventnormaloperation.Ifcareistakentoensureproperenvironmentalconditions,thenthecommunication function of accu

42、racy is simply theintrinsic accuracy of the components.32.6 OBSERVATION ACCURACYAccuracy of observation depends primarily uponthe following two factors:(a) accidentalmistakes,e.g.,misreadingofscales,parallax, incorrect log entries, failure to performsome required manipulation, etc.; and(b) personalc

43、haracteristics,e.g.,abilitytointerpo-late between graduations, bias in observation (ten-dency to read high or low), speed of observation.Thesetypesoferrorsmaybeminimized(butnevercompletely eliminated) by selection and training oftestpersonnel,byselectionofscaleswitheasily-readgraduations,andbyotherh

44、uman-factorengineering.Moderntechnologypermitsthedesignofinstrumentsystemsthatwillgivedigitalprintout,andtheuseoftheseshouldbeencouragedtoeliminateobservationerrorwhentheirinherentaccuracyandinsitucondi-tions permit. However, digital systems may containprogramming mistakes, and these systems must be

45、debugged thoroughly.2.7 SENSING ACCURACYTheaccuracyofsensingdependsuponthefollow-ing factors:(a) EffectofthePrimaryElementontheMeasuredQuantityForexample,aPitottubeinstalledinafowstreamto sense a local velocity must be designed so thatits presence does not change the original velocityprofle.DEFINITI

46、ONSANDVALUESASMEPTC2-2001(b) Mutual Effects of Primary Element and theMeasured QuantityWhen the temperature of a fuid fowing in apipeunderpressureistobemeasured,itisusuallynecessarytoencasetheprimaryelementinaprotec-tion tube or well. The following temperatures mustbe considered:(1) fuid temperature

47、,(2) well outer-wall temperature,(3) well inner-wall temperature, and(4) primary element temperature.Only this last temperature is sensed; that is, thesystemiscapableofmeasuringonlythetemperatureofitsprimaryelement.Aheat-transferstudyisneces-sary to estimate the fuid temperature. The factorsinvolved

48、 in such a study are(a) the physical properties of the fuid andmaterials used in the construction of the well andprimary element;(b) thenetheattransferbyradiation,conduc-tion, and convection from the well to the fuid, tothe pipe wall, and to the primary element; and(c) thefuidvelocity:forcompressibl

49、efuidsthedifferencebetweenstaticandstagnationtempera-tures may be appreciable at Mach numbers greaterthan 0.25.Mostoftheabovefactorsmayberenderednegligi-blebyproperdesignofthesystem,butunlesstheyare all investigated, serious errors may result.(c) Improper InstallationA Pitot tube designed, constructed, and installedin such manner as to cause a disturbance of the4velocity profle (for example, installed at an angletothevelocity)sensesonlyafractionofthevelocity.(d) Location of Primary ElementCaremustbetakennottol