1、BRITISH STANDARD BS 7834: 1995 ISO 9951: 1993 Specification for Turbine meters used for the measurement of gas flow in closed conduits UDC 532.575.57:681.121.4BS7834:1995 This British Standard, having been prepared under the directionof the Electrotechnical Sector Board, was published underthe autho
2、rity of the Standards Board and comes intoeffect on 15 October 1995 BSI 06-1999 The following BSI references relate to the work on this standard: Committee reference CPL/30 Draft for comment 91/20242 DC ISBN 0 580 24775 9 Committees responsible for this British Standard The preparation of this Briti
3、sh Standard was entrusted to Technical Committee CPL/30, Measurement of fluid flow in closed circuits, upon which the following bodies were represented: British Compressed Air Society British Gas plc Department of Energy (Gas and Oil Measurement Branch) Department of Trade and Industry (National Eng
4、ineering Laboratory) Electricity Industry in United Kingdom Energy Industries Council GAMBICA (BEAMA Ltd.) Institute of Measurement and Control Institute of Petroleum Institute of Trading Standards Administration Institution of Gas Engineers Institution of Mechanical Engineers Society of British Gas
5、 Industries Water Services Association of England and Wales Amendments issued since publication Amd. No. Date CommentsBS7834:1995 BSI 06-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Definitions and symbols 1 4 Principle of t
6、he method of measurement 2 5 Flowrates 2 6 Meter construction 3 7 Pressure testing 4 8 Performance characteristics 4 9 Output and readout 5 Annex A (informative) Recommendations for use 7 Annex B (informative) Other meter performance characteristics 8 Annex C (informative) Data computation and prese
7、ntation 9 Annex D (informative) Field checks 9 Annex E (informative) Perturbations 10 Figure E.1 Piping configurations for tests at low level perturbation 12 Figure E.2 Location of half-area opening for tests at high level perturbation 12 Figure E.3 Flow conditioner to damp out high level perturbati
8、on 13 Figure E.4 Alternative flow conditioner configuration to damp out highlevelperturbation 13 Figure E.5 Meter dimensions defining similarity for various size meters 13 Table 1 Symbols and subscripts 2 Table 2 Maximum flowrates and nominal sizes 3 Table 3 Strength test duration 4 Table E.1 Relati
9、onship of DN 1to DN 11 List of references Inside back coverBS7834:1995 ii BSI 06-1999 National foreword This British Stanard has been prepared by Technical Committee CPL/30 and is identical with ISO 9951:1993 Measurement of gas flow in closed conduits Turbine meters, published by the International O
10、rganization for Standardization (ISO). This is a new British Standard and no other standard has been superseded or withdrawn. This standard does not apply to turbine meters which are used for the measurement of fuel gas for fiscal purposes. Such meters are covered by different international and Brit
11、ish Standards. A related British Standard to ISO 5208:1993 is BS 6755-1:1986 Specification for production pressure testing requirements. There is no British Standard corresponding to ISO 6708. Copies of OIML Recommendations may be purchased from: BIML, 11 rue Turgot, 75009 Paris, France. A British S
12、tandard 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. Cross-references International standard Correspondin
13、g British Standard ISO 3:1973 BS 2045:1965 Preferred numbers (Technically equivalent) ISO 4006:1991 BS EN 24006:1993 Measurement of fluid flow in closed conduits. Vocabulary and symbols (Identical) ISO 5167-1:1991 BS 1042 Measurement of fluid flow in closed conduits Part 1 Pressure differential devi
14、ces Section 1.1:1992 Specification for square-edged orifice plates, nozzles and Venturi tubes inserted in circular cross-section conduits running full (Identical) ISO 5168:1978 BS 5844:1980 Methods of measurement of fluid flow: estimation of uncertainty of a flow-rate measurement (Identical) IEC 79
15、(series) BS 5501 (series) Electrical apparatus for potentially explosive atmospheres VIM:1993 PD 6461 Vocabulary of metrology Part 1:1995 Basic and general terms (international) (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 14, a
16、n inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover.ISO9951:1993(E) BSI 06-1999 1 1 Scope This International Standard specifies dimensions, ranges, c
17、onstruction, performance, calibration and output characteristics of turbine meters for gas flow measurement. It also deals with installation conditions, leakage testing and pressure testing and provides a series of informative Annex A to Annex E including recommendations for use, field checks and pe
18、rturbations of the fluid flowing. In many countries, some or all of the items covered by this International Standard are subject to mandatory regulations imposed by the laws of these countries. In cases where conflict exists between such mandatory regulations and this International Standard, the for
19、mer shall prevail. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agree
20、ments based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 3:1973, Preferred numbers Series of preferred numb
21、ers. ISO 4006:1991, Measurement of fluid flow in closed conduits Vocabulary and symbols. ISO 5167-1:1991, Measurement of fluid flow by means of pressure differential devices Part1:Orifice plates, nozzles and Venturi tubes inserted in circular cross-section conduits running full. ISO 5168:1978, Measu
22、rement of fluid flow Estimation of uncertainty of a flow-rate measurement. ISO 5208:1993, Industrial valves Pressure testing of valves. ISO 6708:1980, Pipe components Definition of nominal size. IEC 79:, Electrical apparatus for explosive gas atmospheres. OIML R 6:1989, General provisions for gas me
23、ters. OIML R 32:1989, Rotary piston gas meters and turbine gas meters. VIM:1984, International vocabulary of basic and general terms in metrology (BIPM, IEC, ISO, OIML). 3 Definitions and symbols 3.1 Definitions For the purposes of this International Standard, the definitions given in ISO 4006 and t
24、he International vocabulary of basic and general terms in metrology apply. The following definitions are given only for terms used in some special sense or for terms whose meaning it seems useful to recall. 3.1.1 flowrate actual volume of flow per unit of time 3.1.2 working range range of flowrates
25、of gas limited by the maximum flowrate q maxand the minimum flowrate q min , for which the meter error lies within specified limits (sometimes also called “rangeability”) 3.1.3 metering pressure gas pressure in a meter to which the indicated volume of gas is related 3.1.4 average velocity volume flo
26、wrate per unit of cross-sectional area 3.1.5 shell pressure-containing structure of the meter 3.1.6 metering conditions conditions, at the point of measurement, of the gas whose volume is to be measured (for example gas temperature and pressure) 3.1.7 base conditions conditions to which the measured
27、 volume of the gas is converted (for example base temperature and base pressure) 3.1.8 specified conditions conditions of the gas at which performance specifications of the meter are given NOTE 1Metering and base conditions relate only to the volume of the gas to be measured or indicated, and should
28、 not be confused with “rated operating conditions” or “reference conditions” (VIM5.05 and 5.07), which refer to influence quantities (VIM2.10). 3.2 Symbols and subscripts The symbols and subscripts used in this International Standard are given in Table 1.ISO9951:1993(E) 2 BSI 06-1999 Table 1 Symbols
29、 and subscripts 4 Principle of the method of measurement The turbine meter is a fluid measuring device in which the dynamic forces of the flowing fluid cause the turbine wheel to rotate with a speed approximately proportional to the rate of volume flow. The number of revolutions of the turbine wheel
30、 is the basis for the indication of the volume passed through the meter. 5 Flowrates The maximum and minimum flowrates shall be specified for the gas densities for which the meter will operate within the specifications of meter performance defined in clause 8. The maximum flowrate in cubic metres pe
31、r hour (m 3 /h) of the meter should preferably be a number in the set R5 of preferred numbers specified in ISO 3 (the value 63 has been rounded to 65). The unit of cubic metres per hour (m 3 /h) is preferred. Symbol Quantity Dimensions aSI unit c Pressure loss coefficient depending on meter type L 4
32、 m 4 d Relative density of the gas (d air= 1) Dimensionless D Inside diameter meter outlet/inlet L m D 1 Inside diameter pipe L m DN Nominal size meter outlet/inlet Dimensionless DN 1 Nominal size pipe Dimensionless H Height of strut L m L Length of the strut L m m Mass M kg M Molar mass M kg/mol N
33、Number of moles of gas mol p Absolute pressure ML 1T 2 Pa p m Metering pressure ML 1T 2 Pa q Flowrate L 3T 1 m 3 /s R Molar gas constant ML 2T 2G 1 J/(molK) S Chord distance between adjacent struts measured at the tip L m t Time T s T Absolute temperature of the gas G K V Volume L 3 m 3 Z Compressib
34、ility factor (deviation from ideal gas laws) Dimensionless Density of the gas ML 3 kg/m 3 Working range q max /q min Dimensionless Subscripts b Base conditions for volume or rate calculations m Metering conditions of the gas s Specified conditions for volume or rate a M = mass; L = length; T = time;
35、 G = temperature.ISO9951:1993(E) BSI 06-1999 3 6 Meter construction 6.1 General Meters shall be designed and manufacturing tolerances shall be set to allow interchangeability of meters of the same size and type. 6.2 Materials The meter body and the internal mechanism shall be manufactured of materia
36、ls suited for the service conditions and resistant to attack by the fluid which the meter is to handle. Exterior surfaces of the meter shall be protected as necessary against corrosion. 6.3 Shell The meter shell and all other parts comprising the fluid-containing structure of the meter shall be cons
37、tructed of sound materials and designed to handle the pressures and temperatures for which they are rated. 6.4 Connections and maximum flowrates The inlet and outlet connections of the meter shall conform to recognized standards. The preferred nominal sizes (DN) and corresponding maximum flowrates (
38、q max ) are given in Table 2. Table 2 Maximum flowrates and nominalsizes 6.5 Length The length of the meter between the ends of its inlet and outlet connections shall be less than or equal to5D. 6.6 Pressure tappings 6.6.1 Metering-pressure tappings At least one metering-pressure tapping shall be pr
39、ovided on the meter, to enable measurement (indirectly if necessary) of the static pressure at the turbine wheel of the meter at metering conditions. The connection of this pressure tapping shall be marked “p m ”. If more than one “p m ” tapping is provided, the difference in pressure readings shall
40、 not exceed 100 Pa at maximum flowrate with an air density of 1,2 kg/m 3 . 6.6.2 Other pressure tappings A meter may be equipped with other pressure tappings in addition to the “p m ” tapping. These may serve to determine the pressure drop over a part of the meter or for other purposes. The other pr
41、essure tappings shall be marked “p”. 6.6.3 Dimensions 6.6.3.1 Circular tappings shall conform to the requirement given in ISO 5167-1 except that they shall have a minimum bore diameter of 3 mm and a maximum bore diameter of 12 mm, and the length of the bore shall be a minimum of one bore diameter. 6
42、.6.3.2 Slit-shaped tappings shall have a minimum dimension of 2 mm and a maximum dimension of10mm in the direction of flow, and a minimum cross-sectional area of 10 mm 2 . 6.6.4 Sealing Any pressure test point or tapping connection on the meter shall be provided with a suitable means of closure, e.g
43、. a plug, and shall be capable of being sealed against unauthorized interference. 6.7 Flow direction The direction of flow or the inlet of the meter shall be clearly and permanently marked. 6.8 Meter having a removable meter mechanism 6.8.1 The construction of a meter with a removable meter mechanis
44、m shall be such that the performance characteristics of the meter as defined in 8.1 are maintained after interchange of the mechanism and/or after repeated mounting and dismounting of the same mechanism. 6.8.2 The design and method of replacement of a removable mechanism shall ensure that the constr
45、uction of the meter as specified in this clause is maintained. Maximum flowrates, q max Nominal size m 3 /h DN 40 50 65 50 100 50 160 80 250 80 400 100 650 150 1 000 150 1 600 200 2 500 250 4 000 300 6 500 400 10 000 500 16 000 600 25 000 750 40 000 1 000ISO9951:1993(E) 4 BSI 06-1999 6.8.3 Each remo
46、vable meter mechanism shall have a unique serial number marked on it. 6.8.4 Each removable meter mechanism shall be capable of being sealed against unauthorized interference. 6.9 Overloading The meter shall be designed to be capable of occasionally running 20 % above the maximum flowrate, within the
47、 range of pressure and temperature for which it is rated, for a time period of 30 min without damage or without influence on the error curve of the meter. 6.10 Marking The badge of the meter shall be marked with at least the following information: a) manufacturers name or mark; b) serial number; c)
48、maximum flowrate, q max , in actual volume units; d) maximum allowable operating pressure; e) minimum flowrate, q min , at 1,2 kg/m 3fluid density. 7 Pressure testing 7.1 General 7.1.1 The pressure testing shall be based on the shell test for industrial valves as specified in ISO5208. 7.1.2 Meters s
49、hall not be painted or otherwise coated with materials capable of sealing against leakage before leakage tests are completed. Chemical corrosion protection treatments and internal linings are permitted. If pressure tests in the presence of a representative of the purchaser are specified, painted meters from stock may be retested without removal of paint. 7.1.3 Test equipment shall not subject the meter to externally applied stress which may affect the results of the tests. 7.2 Test fluid 7.2.1 At the discretion of the
