1、ASME MFC-3Ma2007Addenda to ASME MFC-3M2004Measurement of Fluid Flow in PipesUsing Orifice, Nozzle, and VenturiThree Park Avenue New York, NY 10016AN AMERICAN NATIONAL STANDARDK0113ADate of Issuance: March 24, 2008ASME is the registered trademark of The American Society of Mechanical Engineers.This c
2、ode or standard was developed under procedures accredited as meeting the criteria for American National Stan-dards. The Standards Committee that approved the code or standard was balanced to assure that individuals from com-petent and concerned interests have had an opportunity to participate. The p
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7、of this document may be reproduced in any form,in an electronic retrieval system or otherwise, without the prior written permission of the publisher.The American Society of Mechanical EngineersThree Park Avenue, New York, NY 10016-5990Copyright 2008 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll
8、rights reservedPrinted in U.S.A.MFC-3Ma2007Following approval by the ASME MFC Standards Committee and ASME, and after public re-view, MFC-3Ma2007 was approved by the American National Standards Institute on October11, 2007.Addenda to the 2004 edition of ASME MFC-3M2004 are issued in the form of repl
9、acement pages.Revisions, additions, and deletions are incorporated directly into the affected pages. It is advis-able, however, that this page, the Addenda title and copyright pages, and all replaced pages beretained for reference.SUMMARY OF CHANGESThis is the first Addenda to be published to ASME M
10、FC-3M2004.Replace or insert the pages listed. Changes given below are identified on the pages by a marginnote, (a07), placed next to the affected area. The pages not listed are the reverse sides of the listedpages and contain no changes.Page Location Change7 1-5.3.1 Equations and nomenclature revise
11、d9 1-6.4.1(e) Metric values for Dsmalland Dlargein subparas. (1) and (2) revised11 Table 1A-1 In the fifth column, sixth and eighth entries are revised14, 14.1 Fig. 1C-1 General Note added20 2-4.1.5 Revised21 2-4.2.1(b)(2) Revised22 Fig. 2-3 Note (1) revised25 2-4.3.2.1 In Eq. (2-5), values for U.S.
12、 Customary units revised2-4.3.2.1(c) (1) Penultimate paragraph added(2) Last paragraph revised26, 26.1 2-5.1 First sentence revised27 Table 2-3 Sixth column head revised28 2-5.2(h)(1)(b) Third line revised29 2-5.2(i) First line revised2-5.2(i)(2) Second line editorially revised33 2-5.3.2.4 Fifth lin
13、e revised34 2-5.3.3.1 Last line of first paragraph revised48.1 Nonmandatory AddedAppendix 2B49 3-1 Last sentence of the third paragraph revisedPage Location Change5152.1 3-4.1.1 Last sentence added53 3-4.1.7.2 Equation (3-8) revised in its entirety55 3-4.2.5(b) Last sentence of the last paragraph re
14、vised3-4.2.6.1 New subpara. (c) added and subsequent subparagraph redesignated as (d)56 3-4.2.7.2 Equation (3-14) revised in its entirety61 3-5.2(h)(2)(b) Last line of second paragraph revised3-5.2(i) First line revised63, 64 3-5.4(c) In the last paragraph, “10%” revised to read “6%”71, 72 4-4.2.8 S
15、econd and third paragraphs revised73 4-4.5.3(c) Revised75, 76 4-5.2(h)(1)(b) Last sentence of the second paragraph revised4-5.2(i) (1) Last sentence revised(2) In Examples (1) and (2), fifth line revisedcient can occur over a period of time and can lead tovalues outside the uncertainties given in th
16、is Standard.(c) The primary device shall be manufactured from ma-terials for which the coefficient of expansion is known.1-5.2 Nature of the Fluid(a) The fluid can be either compressible or incom-pressible.(b) The fluid shall be such that it can be considered asbeing physically and thermally homogen
17、eous and single-phase. Colloidal solutions with a high degree of disper-sion can be considered to behave as single-phase fluids.(c) For measurement, it is necessary to know the den-sity and viscosity of the fluid at the working conditions.In the case of a compressible fluid it is also necessary tokn
18、ow the isentropic exponent of the fluid at the work-ing conditions.1-5.3 Flow Conditions1-5.3.1 Pulsating Flow. This Standard does notprovide for the measurement of pulsating flow (see ISO3313 for reference). The flow is considered sufficientlysteady for this Standard to apply when(SI Units)H11349 0
19、.10 (1-10)(U.S. Customary Units)H11349 0.10whereH9004H33526pH33526 (hH33526wH33526) H11005 time-mean value of the differentialpressureH9004pH11032rm (hH11032w) H11005 root-mean-square value of H9004pH11032 (hH11032w), the fluctuating component of the pressureH9004pH11032rm (hH11032w) can be measured
20、 accurately only by usinga differential pressure sensor with sufficiently fast re-sponse (see ISO 3313 for reference). Furthermore, thewhole secondary system should conform to the designrecommendations specified in ASME MFC-8M.1-5.3.2 Phase Change of Metered Fluid. The uncer-tainties specified in th
21、is Standard are valid only whenthere is no change of phase through the primary device.Increasing the bore or throat of the primary element willreduce the differential pressure and may prevent achange of phase. For liquids, the pressure in the throatsection must not fall below the vapor pressure of t
22、he liq-uid (otherwise, cavitation will result). For gases, it isonly necessary to calculate the temperature at the throatif the gas is in the vicinity of its dew point. The tem-perature in the throat can be calculated assuming anisentropic expansion from the upstream conditions (thehH11032wH5007hH33
23、526wH33526H9004pH11032rmH5007H9004H33526pH33526upstream temperature may need to be calculated in ac-cordance with the Eq. (1-8) such that the fluid is in thesingle-phase region.1-5.3.3 Pressure Ratio. If the line fluid is a gas, thepressure ratio (throat pressure to upstream pressure ra-tio, P2/P1)
24、shall be between 0.80 and 1.00. If the fluid isa liquid, there is no limit to the pressure ratio, providedthere is no phase change in the process fluid, and theprimary element does not deform or deflect excessively.For detailed information, refer to Parts 2, 3, or 4 of thisStandard as appropriate fo
25、r specific primary devices.1-6 INSTALLATION REQUIREMENTS1-6.1 General(a) The method of measurement applies only to flu-ids flowing through a pipeline of circular cross section.(b) The pipe shall run full at the measurement section.(c) The primary device shall be fitted between twostraight sections o
26、f cylindrical pipe of constant diame-ter and of specified minimum lengths in which there isno obstruction or branch connection other than thosespecified in Parts 2, 3, or 4 of this Standard as appro-priate for specific primary devices.The pipe is considered to be straight when the devi-ation from a
27、straight line does not exceed 0.4% over itslength. Flanges in the straight sections of pipe upstreamand downstream of the primary device shall be at 90deg (H110061/2deg) to the pipe itself. The minimum straightlengths of pipe conforming to the above requirementnecessary for a particular installation
28、 vary with the typeand specification of the primary device and the natureof the pipe fittings involved.(d) The pipe bore shall be circular over the entire min-imum length of straight pipe required. The cross sectioncan be considered circular if it appears so by visual in-spection. The circularity of
29、 the outside of the pipe canbe used as a guide, except in the immediate vicinity (2D)of the primary device where special requirements shallapply according to the type of primary device used.Seamed pipe can be used, provided the internal weldbead is parallel to the pipe axis throughout the entireleng
30、th of the pipe required to satisfy the installation re-quirements for the primary device being used. The seammust not be situated within 30 deg of any pressure tapused in conjunction with the primary device; no weldbead shall have a height greater than the permitted stepin diameter according to the
31、requirements of the pri-mary device used. If spirally wound pipe is used thenit must be honed or machined smooth.(e) The interior of the pipe shall be clean at all times.Dirt that can readily detach from the pipe shall be re-moved. Any metallic pipe defects must be removed.The acceptable value of pi
32、pe roughness depends onthe primary device. In each case there are limits on thevalue of the arithmetic mean deviation of the roughnessMEASUREMENT OF FLUID FLOW IN PIPES USING ORIFICE, NOZZLE, AND VENTURI ASME MFC-3Ma20077(a07)profile, Rasee paras. 2-4.3.1, 3-4.1.2(i), 3-4.1.6.1, 3-4.2.2(f),3-4.2.6.1
33、, and 3-4.3.4.1 or para. 4-5.4.2). The internal sur-face roughness of the pipe shall be measured at ap-proximately the same axial locations as those used todetermine and verify the pipe internal diameter. A min-imum of four roughness measurements shall be madeto define the pipe internal surface roug
34、hness. In meas-uring Ra, an averaging-type surface roughness instru-ment with a cut-off value of not less than 0.75 mm (0.03in.) shall be used. The roughness can change with timeas stated in para. 1-5.1(b), and this should be taken intoaccount in establishing the frequency of cleaning thepipe or che
35、cking the value of Ra.An approximate value of Racan be obtained by as-suming that Rais equal to k/H9266, where k is the uniformequivalent roughness as given in a Moody diagram. Thevalue of k is given directly by a pressure loss test of a sam-ple length of pipe, using the Colebrook-White Equationgive
36、n in para. 1-6.4.1(e) to calculate the value of k fromthe measured value of friction factor, H9261. Approximate val-ues of k for different materials can also be obtained fromthe various tables given in reference literature, and Table1B-1 gives values of k for a variety of materials.(f ) The pipe can
37、 be provided with drain holes and/orvent holes to permit the removal of solid deposits andentrained fluids. There shall be no flow through eitherdrain holes or vent holes, however, during the flow meas-urement process. In many custody transfer applications,drain holes or vent holes are explicitly pr
38、ohibited.Drain and vent holes should not be located at the pri-mary device. When it is not possible to conform to thisrequirement, the diameter of the vent or drain hole shallbe less than 8% of the pipe inside diameter. The center-line of a pressure tap and the centerline of a drain orvent hole shal
39、l be offset from each other by at least 30deg azimuthally (i.e., in the plane perpendicular to theaxis of the pipe) and they shall be located no closer than0.5D from each other.(g) Insulation of the meter may be required if the tem-perature difference between ambient conditions and theflowing fluid
40、are significant given the desired measure-ment uncertainty. This is particularly important if thefluid being metered is near its critical point: small tem-perature changes result in major density changes. It canbe important at low flow rates, where heat transfer ef-fects can cause distorted temperat
41、ure profiles, and achange in the mean temperature value from the upstreamto the downstream side of the meter run, as well as strat-ification of temperature layers from top to bottom. A tem-perature difference between the upstream and the down-stream sides of the meter run can also occur.1-6.2 Minimu
42、m Upstream and Downstream StraightLengths of Pipe(a) The primary device shall be installed in thepipeline at a position such that the flow conditions im-mediately upstream of the primary device approximatethose of swirl-free, fully developed pipe flow. Conditionsmeeting this requirement are specifie
43、d in para. 1-6.3.(b) The required minimum upstream and down-stream straight lengths required for installation betweenvarious fittings and the primary device depend on theprimary device. For some commonly used fittings asspecified in paras. 2-5, 3-5, and 4-5 of this Standard, theminimum straight leng
44、ths of pipe indicated can be used.Flow conditioners, such as those described in para. 1-6.4, however, often permit the use of shorter upstreampipe lengths. Such flow conditioners must be installedupstream of the primary device for fittings not coveredby paras. 2-5, 3-5, and 4-5 of this Standard, or
45、where suf-ficient straight lengths to achieve the desired level of un-certainty are not available.1-6.3 General Requirement for Flow Conditions at thePrimary Device1-6.3.1 Requirement. If the specified conditionsgiven in paras. 2-5, 3-5, and 4-5 of this Standard cannotbe met, but the flow conditions
46、 immediately upstreamof the primary device can be demonstrated to conformto swirl-free fully developed flow (as defined in paras.1-6.3.2 and 1-6.3.3) over the entire Reynolds numberrange of the flow measurement application, the appli-cable sections of this Standard remain valid.1-6.3.2 Swirl-Free Co
47、nditions. Swirl-free conditionscan be taken to exist when the swirl angle at all pointsover the pipe cross-section is less than 2 deg.1-6.3.3 Acceptable Flow Conditions. Acceptable ve-locity profile conditions can be presumed to exist when,at each point across the pipe cross-section, the ratio ofthe
48、 local axial velocity to the maximum axial velocity atthe cross-section is within 5% of that which would beachieved in swirl-free flow at the same radial positionat a cross-section located at the end of a very long (over100D) straight length of similar pipe with fully devel-oped flow.1-6.4 Flow Cond
49、itionersSome additional material regarding flow conditionersis given in Nonmandatory Appendix 1C.1-6.4.1 Compliance Testing(a) If a given flow conditioner passes the compliancetests outlined in paras. 1-6.4.1(b) to 1-6.4.1(f) for a par-ticular primary device, the flow conditioner can be usedwith the same type of primary device with any value ofdiameter ratio up to 0.67 downstream of any fitting. Ifthe distance between the flow conditioner and the pri-mary device, and that between the upstream installa-tion and the flow conditioner, are in accordance withpara. 1-6.4.1(e), and the d
