ISO TR 9464-2008 Guidelines for the use of ISO 5167 2003《ISO 5167-2003使用指南》.pdf

1、 Reference number ISO/TR 9464:2008(E) ISO 2008TECHNICAL REPORT ISO/TR 9464 Second edition 2008-05-15 Guidelines for the use of ISO 5167:2003 Lignes directrices pour lutilisation de lISO 5167:2003 ISO/TR 9464:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adob

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5、part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postal

6、e 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reservedISO/TR 9464:2008(E) ISO 2008 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 T

7、erms and definitions. 2 4 How the structure of this guide relates to ISO 5167:2003 (all parts). 2 5 Guidance on the use of ISO 5157:2003 (all parts) . 2 5.1 Guidance specific to the use of ISO 5167-1:2003 2 5.2 Guidance specific to the use of ISO 5167-2:2003 8 5.3 Guidance specific to the use of ISO

8、 5167-3:2003 23 5.4 Guidance specific to the use of ISO 5167-4:2003 24 6 Information of a general nature relevant to the application of ISO 5167:2003 (all parts) 25 6.1 Secondary instrumentation . 25 6.2 Measurement of pressure and differential pressure. 27 6.3 Measurement of temperature 31 6.4 Dete

9、rmination of density 35 6.5 Electrical supply and electrical installations . 40 Annex A (informative) Principles of measurement and computation. 41 Annex B (informative) Computation of compressibility factor for natural gases 57 Annex C (informative) Orifice plate assembly. 59 Bibliography . 68 ISO/

10、TR 9464:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each me

11、mber body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International E

12、lectrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards ad

13、opted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a technical committee has collected data of a different kind from that

14、 which is normally published as an International Standard (“state of the art”, for example), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed until the data it pro

15、vides are considered to be no longer valid or useful. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO/TR 9464 was prepared by Technical Committee

16、 ISO/TC 30, Measurement of fluid flow in closed conduits, Subcommittee SC 2, Pressure differential devices. This second edition cancels and replaces the first edition (ISO/TR 9464:1998), which has been technically revised. ISO/TR 9464:2008(E) ISO 2008 All rights reserved v Introduction The objective

17、 of this Technical Report is to assist users of ISO 5167, which was published in 2003 in four parts. Guidance on particular clauses of ISO 5157:2003 is given. Some clauses of ISO 5167:2003 (parts 1 to 4) are not commented upon and the corresponding clause numbers are therefore omitted from this Tech

18、nical Report, except when it has been thought to be useful to keep a continuous numbering of paragraphs. TECHNICAL REPORT ISO/TR 9464:2008(E) ISO 2008 All rights reserved 1 Guidelines for the use of ISO 5167:2003 1 Scope The objective of this Technical Report is to provide guidance on the use of ISO

19、 5167:2003 (all parts). ISO 5167:2003 is an International Standard for flow measurement based on the differential pressure generated by a constriction introduced into a circular conduit (see ISO 5167-1:2003, 5.1). It presents a set of rules and requirements based on theory and experimental work unde

20、rtaken in the field of flow measurement. For a more detailed description of the scope, reference should be made to ISO 5167-1:2003, Clause 1. Definitions and symbols applicable to this Technical Report are given in ISO 5167-1:2003, Clauses 3 and 4. Neither ISO 5167-1:2003 nor this Technical Report g

21、ive detailed theoretical background, for which reference should be made to any general textbook on fluid flow. With the application of the rules and requirements set out in ISO 5167-1:2003, it is practicable to achieve flow measurement within an uncertainty of approximately 1 % of the calculated flo

22、wrate. The constraints applicable to each of the primary devices described in ISO 5167:2003 (parts 2 to 4) need to be given consideration before determining the most suitable type for a particular application. Parts 2 to 4 can also be used to form the basis for preliminary design of a metering syste

23、m. The information necessary for detailed design, manufacture and final check is specified in the clauses and paragraphs of ISO 5167:2003 (parts 2 to 4). Secondary instrumentation is not covered by ISO 5167-1:2003, but Clause 6 of this Technical Report makes normative reference to ISO 2186. 2 Normat

24、ive references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 2186, Fluid flow in closed con

25、duits Connections for pressure signal transmissions between primary and secondary elements ISO/TR 3313:1998, Measurement of fluid flow in closed conduits Guidelines on the effects of flow pulsations on flow-measurement instruments ISO 4006, Measurement of fluid flow in closed conduits Vocabulary and

26、 symbols ISO 5167-1:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full Part 1: General principles and requirements ISO 5167-2:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular

27、 cross-section conduits running full Part 2: Orifice plates ISO 5167-3:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full Part 3: Nozzles and Venturi nozzles ISO/TR 9464:2008(E) 2 ISO 2008 All rights reservedISO 5167-4:2

28、003, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full Part 4: Venturi tubes 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 4006 apply. 4 How the structure of this guide rela

29、tes to ISO 5167:2003 (all parts) Clause 5 of this Technical Report sets out the guidance specific to each of the four parts of ISO 5167:2003: 5.1 covers part 1; 5.2 covers part 2; 5.3 covers part 3; 5.4 covers part 4. Subsequent subclause numbering relates to the clauses in each of the parts. Hence,

30、 5.1.1 covers Clause 1 in part 1; 5.4.3.1.1 covers Subclause 3.1.1 in part 4. Guidance applicable to all four parts is given in Clause 6. 5 Guidance on the use of ISO 5157:2003 (all parts) 5.1 Guidance specific to the use of ISO 5167-1:2003 5.1.1 Scope No comments on this clause. 5.1.2 Normative ref

31、erences No comments on this clause. 5.1.3 Terms and definitions No comments on this clause. 5.1.4 Symbols and subscripts No comments on this clause. 5.1.5 Principle of the method of measurement and computation 5.1.5.1 Principle of the method of measurement No comments on this subclause. ISO/TR 9464:

32、2008(E) ISO 2008 All rights reserved 3 5.1.5.2 Method of determination of the diameter ratio of the standard primary device See Annex A of this Technical Report. 5.1.5.3 Computation of flowrate The equations to be used to determine the flowrate of a measuring system are given in ISO 5167-1:2003, Cla

33、use 5. Some results of these calculations will be fixed with installation dimensions and will only need to be computed once. Other calculations will need to be repeated for every flow measurement point. Annex A gives worked examples of the iterative computations shown in ISO 5167-1:2003, Annex A. 5.

34、1.5.4 Determination of density, pressure and temperature 5.1.5.4.1 General No comments on this subclause. 5.1.5.4.2 Density For details on density measurement, see 6.4. For details on density computation, see Annex B of this Technical Report. 5.1.5.4.3 Static pressure No comments on this subclause.

35、5.1.5.4.4 Temperature The computation of temperature decrease resulting from expansion of the fluid through the primary device requires knowledge of the Joule-Thomson coefficient. The coefficient is a function of temperature, pressure and gas composition. The calculation can be carried out using an

36、equation of state (see, in Annex B, the “detailed method” using molar composition analysis) or by the use of an approximation valid for natural gas mixtures that are not too rich, and when p and T are in the range given below. In the last case, the coefficient is a function of p and T alone. Provide

37、d that, in the molar composition of the natural gas, methane is greater than 80 %, the temperature is in the range 0 C to 100 C and the absolute static pressure is in the range 100 kPa to 20 MPa (1 bar to 200 bar). () ( ) JT 22 3 0,35 0,001 42 0,231 0,002 94 0,000 0136 0,998 0,000 41 0,000 111 5 0,0

38、00 000 3 t tt ppp = + + + +(1) where JT is the Joule-Thomson coefficient, in kelvin per bar (K/bar); t is the temperature of the fluid, in degrees Celsius ( C); p is the absolute static pressure of the fluid, in bar. The uncertainty was determined from the differences between this equation and the J

39、oule-Thomson coefficient of 14 common natural gases and is given by 0,066 1 200 t U = for 70bar pu (7 MPa) (2) ISO/TR 9464:2008(E) 4 ISO 2008 All rights reservedand (290 ) 1 1 0,066 1 1 200 4 70 tt U p = for 70 bar p (7 MPa) (3) where U is the (expanded) uncertainty in the Joule-Thomson coefficient

40、K/bar). NOTE If an orifice plate with = 0,6 has a differential pressure p = 0,5 bar, the uncertainty in the Joule-Thomson coefficient corresponds to an uncertainty in flowrate in the range from 0,001 % to 0,009 %, depending on the temperature, the pressure and the gas composition. 5.1.6 General req

41、uirements for the measurements 5.1.6.1 Primary device 5.1.6.1.1 No comments on this subclause. 5.1.6.1.2 No comments on this subclause. 5.1.6.1.3 Table 1, whilst not exhaustive, lists materials most commonly used for the manufacture of primary devices. Table 1 Steels commonly used for the manufactur

42、e of primary devices AISI BS 970 AFNOR DIN 304 304-S15 Z6CN18-09 1.4301 Stainless steels 316 316-S16 Z6CND17-11 1.4401 High elastic limit stainless steel 420 420-S37 Z30C13 Table 2 gives the mean linear expansion coefficient, elasticity moduli and yield stresses for the materials of Table 1 accordin

43、g to their AISI designation. Table 2 Characteristics of commonly used steels Mean linear expansion coefficient between 0 C and 100 C Elasticity modulus Yield stress AISI designation K 1Pa Pa 304 17 10 6 193 10 9 215 10 6 316 16 10 6193 10 9230 10 6420 10 10 6200 10 9494 10 6The values given in Table

44、 2 vary with both temperature and the treatment process of the steel. For precise calculations, it is recommended that the data are obtained from the manufacturer. When the primary device under operating conditions is at a different temperature from the one at which the diameter “d” was determined (

45、this temperature is referred to as the reference or calibration temperature), the expansion or contraction of the primary device should be calculated. The corrected diameter “d” to be used in the computation of diameter ratio and flowrate should be calculated using Equation (4), assuming there is no

46、 restraint due to the mounting: ISO/TR 9464:2008(E) ISO 2008 All rights reserved 5 ( 0d0 1 ) dd TT =+ (4) where d is the primary device diameter in flowing conditions; d 0is the primary device diameter at reference temperature; dis the mean linear expansion coefficient of the primary device material

47、 T is the primary device temperature in flowing conditions; T 0is the reference or calibration temperature. Where automatic temperature correction is not required in the flow computer, the uncertainty for “d ” included in the overall uncertainty calculations should be increased for the change in “d

48、 ” due to temperature variation (see ISO 5167-1:2003, 8.2.2.4). An initial calculation may show that this additional uncertainty is small enough to be considered negligible. 5.1.6.2 Nature of the fluid No comments on this subclause. 5.1.6.3 Flow conditions 5.1.6.3.1 No comments on this subclause. 5.

49、1.6.3.2 If there is a likelihood of such a change of phase, a way of overcoming the problem is to increase the diameter ratio, so that the differential pressure is reduced. 5.1.6.3.3 No comments on this subclause. 5.1.7 Installation requirements 5.1.7.1 General The following list of inspection equipment is not exhaustive, but provides a basis for inspection control: calipers (thickness, diameters); internal micrometer (diameters);