1、 ISO 2012 Measurement of fluid flow in closed conduits Ultrasonic meters for gas Part 2: Meters for industrial applications Mesurage de dbit des fluides dans les conduites fermes Compteurs ultrasons pour gaz Partie 2: Compteurs pour applications industrielles INTERNATIONAL STANDARD ISO 17089-2 First
2、 edition 2012-10-01 Reference number ISO 17089-2:2012(E) ISO 17089-2:2012(E) ii ISO 2012 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mec
3、hanical, 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 postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.i
4、so.org Published in Switzerland ISO 17089-2:2012(E) ISO 2012 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope 1 2 Normative references . 1 3 Terms, definitions, and symbols . 1 3.1 Terms and definitions . 1 3.2 Symbols and subscripts 6 3.3 Abbreviations . 7 4 Principles of me
5、asurement . 7 4.1 Transit time ultrasonic meters . 7 4.2 Flare or vent gas meters 8 4.3 Factors affecting performance 9 4.4 Description of generic types 9 4.5 Impact of pressure and temperature on the flowmeter geometry .14 4.6 USM measurement uncertainty determination 14 4.7 USM classification .14
6、5 Meter characteristics 15 5.1 Performance indications .15 5.2 Operating conditions 15 5.3 Meter body, materials, and construction 15 5.4 Connections 16 5.5 Dimensions .16 5.6 Ultrasonic ports .16 5.7 Pressure tapping .16 5.8 Anti-roll provision .16 5.9 Flow conditioner 17 5.10 Markings 17 5.11 Tran
7、sducers 17 5.12 Electronics 17 5.13 Firmware and software 18 5.14 Inspection and verification functions 19 5.15 Operation and installation requirements 19 5.16 Installation requirements and flow profile considerations 21 5.17 Handling and transportation 22 6 Test and calibration 23 6.1 Flow test and
8、 calibration .23 6.2 Static testing for leakage and pressure 23 6.3 Dimensional measurements .23 6.4 Dynamic testing (testing and calibration, adjustment under flowing conditions) 25 6.5 Meter diagnostics 26 6.6 In situ verification 27 Annex A (normative) Special application note on valve characteri
9、zation and noise .29 Bibliography .36 ISO 17089-2:2012(E) Foreword 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 committe
10、es. Each member 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 Inte
11、rnational Electrotechnical 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 S
12、tandards adopted 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. Attention is drawn to the possibility that some of the elements of this document may be the su
13、bject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 17089-2 was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed conduits, Subcommittee SC 5, Velocity and mass methods. ISO 17089 consists of the following parts, u
14、nder the general title Measurement of fluid flow in closed conduits Ultrasonic meters for gas: Part 1: Meters for custody transfer and allocation measurement Part 2: Meters for industrial applications iv ISO 2012 All rights reserved ISO 17089-2:2012(E) Introduction Ultrasonic meters (USMs) for gas f
15、low measurement have penetrated the market for meters rapidly since 2000 and have become one of the prime flowmeter concepts for operational use as well as custody transfer and allocation measurement. As well as offering high repeatability and high accuracy, ultrasonic technology has inherent featur
16、es like: negligible pressure loss, high rangeability and the capability to handle pulsating flows. USMs can deliver extended diagnostic information through which it may be possible to verify not only the functionality of a USM, but also several other components within the system, such as the gas chr
17、omatograph, and the pressure and temperature transmitters. Due to the extended diagnostic capabilities, this part of ISO 17089 advocates the addition and use of automated diagnostics instead of labour-intensive quality checks. This part of ISO 17089 focuses on meters for industrial gas applications
18、(class 3 and class 4). Meters for custody transfer and allocation measurement are the subject of ISO 17089-1. Typical performance factors of the classification scheme are: Class Typical applications Typical uncertainty 95 % confidence level (volume flow rate) a Reference 1 Custody transfer 0,7 % ISO
19、 17089-1 2 Allocation 1,5 % ISO 17089-1 3 Utilities and process 1,5 % to 5 % for q V q V, t b This part of ISO 17089 4 Flare gas and vent gas 5 % to 10 % for q V q V, t This part of ISO 17089 a Meter performance, inclusive of total meter uncertainty, repeatability, resolution and maximum peak-to-pea
20、k error, depends upon a number of factors which include pipe inside diameter, acoustic path length, number of acoustic paths, gas composition and speed of sound, as well as meter timing repeatability. b By specific flow conditioning or when multi-path meters are employed, lower uncertainties may be
21、achieved. The special application note(s) as presented in Clause 7 as well as information in parentheses are informative. ISO 2012 All rights reserved v Measurement of fluid flow in closed conduits Ultrasonic meters for gas Part 2: Meters for industrial applications IMPORTANT The electronic file of
22、this document contains colours which are considered to be useful for the correct understanding of the document. Users should therefore consider printing this document using a colour printer. 1 Scope This part of ISO 17089 specifies requirements and recommendations for ultrasonic gas meters (USMs), w
23、hich utilize acoustic signals to measure the flow in the gaseous phase in closed conduits. This part of ISO 17089 is applicable to transit time USMs and is focused towards industrial flow measurement. Included are meters comprising meter bodies as well as meters with field-mounted transducers. There
24、 are no limits on the size of the meter. It can be applied to the measurement of almost any type of gas; such as but not limited to air, hydrocarbon gases, and steam. This part of ISO 17089 specifies performance, calibration (when required), and output characteristics of USMs for gas flow measuremen
25、t and deals with installation conditions. NOTE It is possible that national or other regulations apply which can be more stringent than those in this part of ISO 17089. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated referen
26、ces, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. lSO 4006, Measurement of fluid flow in closed conduits Vocabulary and symbols 3 Terms, definitions, and symbols 3.1 Terms and definitions 3.1.1 General For t
27、he purposes of this document, the terms and definitions given in lSO 4006 and the following apply. 3.1.2 Quantities 3.1.2.1 volume flow rate q V q V t V d d where INTERNATIONAL STANDARD ISO 17089-2:2012(E) ISO 2012 All rights reserved 1 ISO 17089-2:2012(E) V is volume; t is time. NOTE Adapted from I
28、SO 80000-4:2006, 84-30. 3.1.2.1.1 actual flow rate volume of fluid per time at metering conditions 3.1.2.1.2 corrected flow rate volume of fluid per time measured at metering conditions, but converted to equivalent volume at base conditions 3.1.2.2 indication flow rate indicated by the meter 3.1.2.3
29、 working range set of values of quantities of the same kind that can be measured by a given measuring instrument or measuring system with specified instrumental uncertainty, under defined conditions NOTE 1 Adapted from ISO/IEC Guide 99:2007, 104.7, “working interval”. NOTE 2 For the purposes of this
30、 part of ISO 17089, the “set of values of quantities of the same kind” are volume flow rates whose values are bounded by a maximum flow rate, q V, max , and a minimum flow rate, q V, min ; the “given measuring instrument” is a meter. NOTE 3 The terms “rangeability” and “turndown” can often be found
31、in flowmeter data sheets in connection with the working range of the meter. These terms are sometimes used interchangeably although their exact meanings are different and may not mean the same as working range. For example, it is possible to find a stated flowmeter rangeability derived from the high
32、est measurable flow divided by the minimum measurable flow (typically with flow expressed in terms of flow velocity). 3.1.2.4 metering pressure p absolute gas pressure in a meter at flowing conditions to which the indicated volume of gas is related 3.1.2.5 average velocity v volume flow rate divided
33、 by the cross-sectional area 3.1.3 Meter design 3.1.3.1 meter body pressure-containing structure of the meter 3.1.3.2 acoustic path path travelled by an acoustic wave between a pair of ultrasonic transducers 3.1.3.3 axial path path travelled by an acoustic wave entirely in the direction of the main
34、pipe axis NOTE An axial path can be both on or parallel to the centre-line or long axis of the pipe. See Figure 1. 2 ISO 2012 All rights reserved ISO 17089-2:2012(E) Figure 1 Axial path 3.1.3.4 diametrical path acoustic path whereby the acoustic wave travels through the centre-line or long axis of t
35、he pipe See Figure 2. Figure 2 Diametrical paths 3.1.3.5 chordal path acoustic path whereby the acoustic wave travels parallel to the diametrical path See Figure 3. ISO 2012 All rights reserved 3 ISO 17089-2:2012(E) Figure 3 Chordal paths 3.1.4 Thermodynamic conditions 3.1.4.1 metering conditions co
36、nditions, at the point of measurement, of the fluid whose volume is to be measured NOTE 1 Metering conditions include gas composition, temperature, and pressure also known as uncorrected conditions. NOTE 2 Adapted from ISO 9951:1993, 53.1.6. 3.1.4.2 base conditions conditions to which the measured v
37、olume of the gas is converted NOTE 1 Base conditions include base temperature and base pressure. NOTE 2 Adapted from ISO 9951:1993, 53.1.7. NOTE 3 Preferred alternatives include reference conditions, standard conditions, normal conditions. NOTE 4 Metering and base conditions relate only to the volum
38、e of the gas to be measured or indicated, and should not be confused with rated operating conditions and reference operating conditions (see ISO/IEC Guide 99:2007, 104.9 and 4.11), which refer to influence quantities (see ISO/IEC Guide 99:2007, 102.52). 3.1.4.3 specified conditions conditions of the
39、 fluid at which performance specifications of the meter are given NOTE Adapted from ISO 9951:1993, 53.1.8. 3.1.5 Statistics 3.1.5.1 measurement error error of measurement error measured quantity value minus a reference quantity value ISO/IEC Guide 99:2007, 102.16 EXAMPLE Difference between the indic
40、ation of the meter under test and the indication of the reference measurement. 4 ISO 2012 All rights reserved ISO 17089-2:2012(E) 3.1.5.2 error curve interconnection of the curve (e.g. polynomial) fitted to a set of error data as a function of the flow rate of the reference meter 3.1.5.3 maximum pea
41、k-to-peak error maximum difference between any two error values 3.1.5.4 repeatability measurement precision under a set of repeatability conditions of measurement ISO/IEC Guide 99:2007, 102.21 EXAMPLE The closeness of agreement among a number of consecutive measurements of the output of the test met
42、er for the same reference flow rate under the same metering conditions. NOTE The repeatability corresponds to the 95 % confidence interval of the error. 3.1.5.5 resolution smallest difference between indications of a meter that can be meaningfully distinguished NOTE Adapted from ISO 11631:1998, 63.2
43、8. 3.1.5.6 velocity sampling interval time interval between two consecutive gas velocity measurements 3.1.5.7 zero flow reading flowmeter indication when the gas is at rest, when both axial and non-axial velocity components are essentially zero Figure 4 shows the flow rates in relation to the uncert
44、ainty budget. q V,0 Error limit (q V,0 q V,t ) Error limit (q V,t q V q V,max ) q V,max q V /(m 3 /h) q V,min q V,t 0 (q V/ q V ) / % Figure 4 Typical error curve as function of the flow rate ISO 2012 All rights reserved 5 ISO 17089-2:2012(E) 3.2 Symbols and subscripts The symbols and subscripts use
45、d in this part of ISO 17089 are given in Tables 1 and 2. Examples of uses of the volume flow rate symbol are given in Table 3. Table 1 Symbols Quantity Symbol Dimensions a SI unit Cross-sectional area A L 2 m 2 Speed of sound in fluid c LT 1 m/s Inside diameter of the meter body D L m Weighting fact
46、ors (live inputs) f i 1 b Integers (1,2,3, ) i,n 1 b Calibration factor K 1 b Flow profile correction factor k n 1 b Valve noise L p,N,v 1 b dB Path length l p L m Attenuation factor N d 1 b Valve weighting factor N v 1 b Number of samples used in the signal processing. n s 1 b Absolute pressure p M
47、L 1 T 2 Pa Emitted acoustic pressure p n ML 1 T 2 Pa Pressure difference p ML 1 T 2 Pa Mass flow rate q m MT 1 kg/s Volume flow rate q V L 3 T 1 m 3 /s Transit time t T s Average velocity v LT 1 m/s Velocity of the acoustical path i v i LT 1 m/s Weighting factors (fixed value) w i 1 b Path angle f r
48、ad Density of the fluid ML 3 kg/m 3 a M mass; L length; T time ; temperature. b ”Dimensionless” quantity. Table 2 Subscripts Subscript Meaning min minimum max maximum t transition Table 3 Examples of flow rate symbols Symbol Meaning q V, max Designed maximum flow rate q V, min Designed minimum flow
49、rate q V, t Transition flow rate for defining accuracy requirements 6 ISO 2012 All rights reserved ISO 17089-2:2012(E) 3.3 Abbreviations ES electronic system FAT factory acceptance test FC flow conditioner MSOS measured speed of sound SNR signal-to-noise ratio SOS speed of sound TSOS theoretical speed of sound USM ultrasonic flowmeter USMP USM package, including upstream pipe, flow conditioner and thermo-well when bi-directional 4
