BS ISO 14511-2002 Measurement of fluid flow in closed conduits Thermal mass flowmeters《封闭管道流体流量测量 热质量流量计》.pdf

1、BRITISH STANDARD BS ISO 14511:2001 Measurement of fluid flow in closed conduits Thermal mass flowmeters ICS 17.120.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 14511:2001 This British Standard, having been prepared under the direction of the Sector Policy and Strat

2、egy Committee for Materials and Chemicals, was published under the authority of the Standards Policy and Strategy Committee on 15 January 2002 BSI 15 January 2002 ISBN 0 580 38845 X National foreword This British Standard reproduces verbatim ISO 14511:2001 and implements it as the UK national standa

3、rd. The UK participation in its preparation was entrusted by Technical Committee CPI/30, Measurement of fluid flow in closed conduits, to Subcommittee CPI/30/5, Velocity based methods, which has the responsibility to: A list of organizations represented on this committee can be obtained on request t

4、o its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BS

5、I Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enq

6、uirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This do

7、cument comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 31 and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsReference n

8、umber ISO 14511:2001(E) OSI 1002 INTERNATIONAL STANDARD ISO 14511 First edition 2001-10-15 Measurement of fluid flow in closed conduits Thermal mass flowmeters Mesure de dbit des fluides dans les conduites fermes Dbitmtres massiques par effet thermiqueii ISO 11541:(1002)Eiii Contents Page Foreword.i

9、v Introduction.v 1 Scope 1 2 Normative references 1 3 Terms and definitions .1 3.1 General terms.1 3.2 Specific terms 2 4 Selection of thermal mass flowmeters 4 5 Capillary thermal mass flowmeter (CTMF meter).5 5.1 Principles of measurement.5 5.2 Typical design7 5.3 Applications and limitations of u

10、se .8 5.4 Meter selection.10 5.5 Installation and commissioning.12 6 Insertion and/or in-line thermal mass flowmeter (ITMF meter).13 6.1 Principles of measurement.13 6.2 Typical design16 6.3 Applications and limitations of use .18 6.4 Meter selection.20 6.5 Installation and commissioning.22 7 Instru

11、ment specification sheet and marking 24 7.1 User specification sheet .24 7.2 Manufacturers data sheet 24 7.3 Marking .25 8 Calibration 27 8.1 General considerations.27 8.2 Use of the desired gas under process conditions .27 8.3 Use of a surrogate gas 27 8.4 In-situ calibration.27 8.5 Insertion-ITMF

12、meter .27 8.6 Calibration frequency28 8.7 Calibration certificate 28 9 Pre-installation inspection and testing .29 10 Maintenance .29 10.1 General29 10.2 Visual inspection .29 10.3 Functional test .30 10.4 Record keeping (maintenance audit trail) .30 Bibliography31 Page3 ISO14511:2001 15January2002I

13、SO 11541:(1002)E iv 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 committees. Each member body interested in a s

14、ubject 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 Electrotechnical Commission

15、(IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Inte

16、rnational 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 International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent righ

17、ts. International Standard ISO 14511 was prepared by Technical Committee ISO/TC 30, Measurement of fluid flow in closed conduits, Subcommittee SC 5, Velocity and mass methods. Page4 ISO14511:2001 15January2002ISO 11541:(1002)Ev Introduction This International Standard has been prepared to guide thos

18、e concerned with the specification, testing, inspection, installation, operation and calibration of thermal mass gas flowmeters. A list of standards related to ISO 14511 is given in the bibliography. Page5 ISO14511:2001 15January2002blank 6egaP 1002:11541OSI 2002yraunaJ51INTENRATIONAL TSANDADR ISO 1

19、1541:(1002)E1 Measurement of fluid flow in closed conduits Thermal mass flowmeters 1 Scope This International Standard gives guidelines for the specification, testing, inspection, installation, operation and calibration of thermal mass gas flowmeters for the metering of gases and gas mixtures. It is

20、 not applicable to measuring liquid mass flowrates using thermal mass flowmeters. This International Standard is not applicable to hot wire and other hot film anemometers, also used in making point velocity measurements. 2 Normative references The following normative documents contain provisions whi

21、ch, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the pos

22、sibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 4006, Measurement of fluid flo

23、w in closed conduits Vocabulary and symbols ISO 7066-2, Assessment of uncertainty in the calibration and use of flow measurement devices Part 2: Non- linear calibration relationships Guide to the expression of uncertainty in measurement (GUM). BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML, 1st edition, c

24、orrected and reprinted in 1995 IEC 61000-4, Electromagnetic compatibility (EMC) Part 4: Testing and measurement techniques 3 Terms and definitions For the purposes of this International Standard, the terms and definitions given in ISO 4006 and the following apply. NOTE The term “gas” is used as a sy

25、nonym for single gases, gas mixtures and vapours. 3.1 General terms 3.1.1 flowrate quotient of the quantity of fluid passing through the cross-section of a conduit and the time taken for this quantity to pass through this section NOTE In this International Standard, the term “flowrate” is used as a

26、synonym for mass flowrate, unless otherwise stated. Page7 ISO14511:2001 15January2002ISO 11541:(1002)E 2 3.1.2 mass flowrate flowrate in which the quantity of fluid is expressed as a mass NOTE The term “flowrate” is used as a synonym for mass flowrate in this International Standard, unless otherwise

27、 stated. 3.1.3 accuracy of measurement closeness of the agreement between the result of a measurement and a true value of the measurand NOTE Accuracy is a qualitative concept. 3.1.4 uncertainty of measurement parameter, associated with the result of a measurement, that characterizes the dispersion o

28、f the values that can reasonably be attributed to the measurand 3.1.5 repeatability measuring instrument ability of a measuring instrument to provide closely similar indications for repeated applications of the same measurand under the same conditions of measurement NOTE These conditions include: mi

29、nimized variations resulting from the observer; the same measurement procedure; the same observer; the same measuring equipment, used under the same conditions; the same location; repeated measurements within a short period of time. 3.1.6 flow profile graphic representation of the velocity distribut

30、ion NOTE The point flow velocity across the cross-section of a conduit is not constant. It varies as a consequence of upstream and downstream disturbances and with the Reynolds number of the flow stream. For a fully developed flow, the point flow velocity varies from 0 m/s at the pipe wall to a maxi

31、mum value at the conduit centre. The flow profile describes the variation of the flow velocity across the conduit cross-section and may be expressed mathematically or graphically. 3.2 Specific terms 3.2.1 sensor element of a measuring instrument or measuring chain that is directly affected by the me

32、asurand 3.2.2 laminar flow element element inserted into the gas stream to establish a constant ratio between the main flow stream and the bypass flow through the sensor Page8 ISO14511:2001 15January2002ISO 11541:(1002)E3 3.2.3 thermal mass flowmeter TMF meter flow-measuring device which uses heat t

33、ransfer to measure and indicate mass flowrate NOTE The term thermal mass flowmeter also applies to the measuring portion of a thermal mass flow controller and not the control function. 3.2.4 capillary thermal mass flowmeter CTMF meter TMF meter normally consisting of a laminar flow element, bypass t

34、ube (capillary), temperature sensors (some designs include a separate heater) with supporting electronics and housing 3.2.5 insertion and/or in-line thermal mass flowmeter ITMF meter TMF meter normally consisting of one or two temperature sensing sensors (some designs have a separate heater) with su

35、pporting structure, electronics and housing, of which the sensors are exposed to the full gas stream 3.2.5.1 insertion-ITMF meter ITMF meter with the sensors mounted on a probe, inserted through the process conduit wall, into the gas stream 3.2.5.2 in-line ITMF meter ITMF meter with the sensors moun

36、ted in a flow body which serves as an integral part of the conduit 3.2.6 thermal mass flow controller flow controlling device that comprises a TMF meter, a valve and controlling electronics NOTE The output of the TMF meter is compared against an adjustable setpoint and the valve is correspondingly o

37、pened or closed to maintain the measured flowrate at the setpoint value. 3.2.7 transmitter associated electronics providing the heater with electrical power and transforming the signals from the temperature sensors to give output(s) of the measured parameters NOTE The transmitter can be integrally m

38、ounted to a TMF meter. However, for some applications the transmitter can be remotely installed away from the flow sensor. 3.2.8 retractor mechanism insertion-ITMF meters mechanical arrangement including an isolation valve that allows the positioning and/or extraction of the flow sensor within the c

39、onduit 3.2.9 rangeability statement of the minimum and maximum limits of which an individual sensor can measure and indicate EXAMPLE For a maximum flowrate 1 000 kg/h and a minimum flowrate 10 kg/h, the rangeability 10 kg/h to 1 000 kg/h. Page9 ISO14511:2001 15January2002ISO 11541:(1002)E 4 3.2.9.1

40、turndown numerical ratio of the maximum to minimum limits of which an individual sensor can measure EXAMPLE For a maximum flowrate 1 000 kg/h and a minimum flowrate 10 kg/h, the turndown ratio 1 000/10 100:1. NOTE In practice, the terms rangeability and turndown are used interchangeably and can be a

41、ssociated with an uncertainty statement. 3.2.10 k-factor numerical factor unique to each TMF meter which is associated with the mass flowrate derived during the calibration and when programmed into the transmitter ensures that the meter performs to its stated specification NOTE When a surrogate gas

42、has been used for calibration purposes, the manufacturers gas factor list or database has been applied for conversion to the desired gas under process conditions. 3.2.11 normalized volumetric flowrate (GB) standardized volumetric flowrate (US) flowrate for which the quantity of fluid is expressed in

43、 terms of volume, with the fluid density calculated at a known and fixed pressure and temperature condition NOTE 1 The values used to define these reference conditions (also known as “standard reference conditions”) are industry and country specific and therefore shall always be specified when these

44、 units are used. Typical reference conditions are 0 C and 101,325 kPa. NOTE 2 Normalized volumetric units or volumetric units specified to standard reference conditions, such as “Nm 3 /h”,a r e commonly used with CTMF and ITMF meters, however this practice is not recommended as they are neither SI u

45、nits nor symbols and their use without knowledge of the reference conditions will lead to significant errors. In this International Standard, volumetric units specified to standard reference conditions are followed by the expression “(normalized)”,e . g .m 3 /h (normalized). 3.2.12 normalized veloci

46、ty (GB) standardized velocity (US) flowrate for which the quantity of fluid is expressed in terms of the speed of flow, with the fluid density calculated at a known and fixed pressure and temperature condition NOTE 1 The values used to define these reference conditions (also known as “standard refer

47、ence conditions”) are industry and country specific and therefore shall always be specified when these units are used. Typical reference conditions are 0 C and 101,325 kPa. NOTE 2 Normalized volumetric units or volumetric units specified to standard reference conditions, such as “Nm/s”,a r e commonl

48、y used with CTMF and ITMF meters, however this practice is not recommended as they are neither SI units or symbols and their use without knowledge of the reference conditions will lead to significant errors. In this International Standard, volumetric units specified to standard reference conditions

49、are followed by the expression “(normalized)”, e.g. m/s (normalized). 4 Selection of thermal mass flowmeters TMF meters fall into two basic design categories: a) capillary TMF meters (CTMF meters); b) full bore TMF meters, consisting of the following two types (ITMF meter): 1) insertion type; 2) in-line type. Page10 ISO14511:2001 15January2002ISO 11541:(1002)E5 The choice of appropriate design for a particular application is primarily dependent on: the required flowrate and range;