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1、BRITISH STANDARD BS 5728-7: 1997 Incorporating Amendment No. 1 Measurement of flow of cold potable water in closed conduits Part 7: Specification for single mechanical type meters ICS 17.120.10 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:25:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
2、 BS 5728-7:1997 This British Standard, having been prepared under the direction of the Electrical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 October 1997 BSI 06-1999 The following BSI references relate to the work on this standard: Committee re
3、ference CPL/30 Draft for comment 95/210290 DC ISBN 0 580 27690 2 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee CPL/30, Measurement of fluid flow in closed conduits, upon which the following bodies were represented: Brit
4、ish Compressed Air Society British Gas Department of Trade (in preparation) Part 2: Specification for installation requirements for single meters; Part 3: Methods of test for single mechanical water meters; Part 4: Specification for combination meters; Part 5: Specification for installation requirem
5、ents for combination meters; Part 6: Test methods for combination meters. 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
6、immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 14, an 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 i
7、n the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:25:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5728-7:1997 BSI 06-19991 1 Scope This Part of BS 5728 specifies the technical, metrological and pressure loss characteristics for single mech
8、anical type water meters and establishes the nomenclature for them. It applies to water meters of various metrological classes (see clause 5) which can withstand permanent flow-rates from 0.6 m3/h to 4 000 m3/h, maximum admissible working pressures (MAP) equal to or greater than 10 bar1) and a maxim
9、um admissible temperature (MAT) of 30 C. The requirements of this Part of BS 5728 apply to water meters described as follows: self-contained integrating measuring instruments continuously determining the volume of water flowing through them, employing a direct mechanical process involving the use of
10、 volumetric chambers with mobile walls (“volumetric” water meters) or the action of the velocity of the water on the rotation rate of a moving part (“velocity” meters). 2 Normative references This British Standard incorporates, by dated or undated reference, provisions from other publications. These
11、 normative references are cited at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to, or revisions of, the cited publications apply to this Part of BS 5728 only when in
12、corporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 3 Definitions For the purposes of BS 5728, the following definitions apply. 3.1 volumetric meter a device, fitted into a closed conduit, wh
13、ich consists of chambers of known volume and a mechanism driven by the flow, whereby these chambers are successively filled with water and then emptied. By counting the number of these volumes passing through the device, the indicating device totalizes the volume flow 3.2 velocity meter a device, fi
14、tted into a closed conduit, which consists of a moving element set in motion directly by the velocity of water flow. The movement of the moving element is transmitted by mechanical or other means to the indicating device, which totalizes the volume flow 3.3 Woltmann meter a velocity meter consisting
15、 of a rotor carrying helical blades which rotates about the axis of flow in the meter 3.4 single-jet meter a velocity meter consisting of a turbine rotor rotating about the axis perpendicular to the flow of water in the meter, in which the jet impinges at a single place on the periphery of the rotor
16、 3.5 multi-jet meter a velocity meter in which the jets impinge simultaneously at several points around the periphery of the rotor 3.6 in-line meter a type of water meter, fitted directly into a closed conduit by means of the meter end connections (screwed or flanged) provided 3.7 concentric meter a
17、 type of water meter, fitted indirectly into a closed conduit by means of an intermediate fitting called a manifold. The inlet and outlet passages of the meter and manifold, at the interface between them, are coaxial 3.8 meter manifold the pipe fitting specific to the connection of a concentric mete
18、r 3.9 flow-rate the quotient of the volume of water passing through the water meter and the time taken for this volume to pass through the water meter 3.10 volume flow the volume of water passing through the water meter, irrespective of the time taken 1) 1 bar = 105 N/m2 = 100 kPa. Licensed Copy: sh
19、effieldun sheffieldun, na, Fri Dec 01 14:25:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5728-7:1997 2 BSI 06-1999 3.11 maximum permissible error2) (MPE) extreme values of the error permitted by the specification, regulations etc. for a water meter 3.12 permanent flow-rate, qp2) the flow-rate at
20、 which the meter is required to operate in a satisfactory manner under normal conditions of use, e.g. under steady and/or intermittent flow conditions 3.13 overload flow-rate, qs2) the flow-rate at which the water meter is required to operate in a satisfactory manner for a short period of time witho
21、ut deteriorating 3.14 minimum flow-rate, qmin2) the lowest flow-rate at which the meter is required to give indications within the maximum permissible error. It is determined in relation to the meter designation 3.15 transitional flow-rate, qt2) the flow-rate value, occurring between overload and mi
22、nimum flow-rates, at which the flow-rate range is divided into two zones, an “upper zone” and a “lower zone”, each characterized by a maximum permissible error 3.16 flow-rate range2) the range limited by the overload flow-rate and the minimum flow-rate in which the meter indications remain within th
23、e maximum permissible errors 3.17 indicating device a device displaying the volume flow 3.18 verification device the part of the indicating device used for the visual verification and calibration of a water meter 3.19 control element the part of the verification device formed from the indicating ele
24、ment having the lowest value decade of the indicating device 3.20 verification scale interval the lowest value scale division of the control element 3.21 nominal pressure (PN) a numerical designation which, for reference purposes, is a rounded number 3.22 maximum admissible working pressure (MAP) th
25、e maximum internal pressure that a water meter can withstand permanently at a given temperature NOTEFor temperatures between 0 C and 30 C, the MAP for materials currently used for the bodies of water meters remains constant. For cold water meters the MAP is equal to the PN. 3.23 nominal size (DN) a
26、numerical designation common to all the components of a pipe system, excluding those designated by their external diameter or by the thread dimension. It is a whole number used for reference only, approximating the constructional dimensions 3.24 pressure loss the pressure loss, at a given flow-rate,
27、 caused by the presence of a water meter in the pipeline 3.25 maximum admissible temperature (MAT) the maximum temperature that a water meter can withstand at a given internal pressure 3.26 meter designation (N) a numerical value, preceded by the capital letter N, to designate the meter in relation
28、to tabulated values of dimensions 4 Technical characteristics 4.1 Units Flow-rates for all types of water meters shall be expressed in m3/h. 4.2 In-line meters 4.2.1 Meter designations, size and overall dimensions Meter size shall be characterized either by the thread size of the end connections or
29、by the nominal size of the flange. Each meter size shall conform to the corresponding fixed set of overall dimensions (see Figure 2) which are given in Table 1 and Table 2. For threaded end connections, two minimum dimensions, a and b, shall be specified (see 4.2.5 and Figure 3). 2) The relationship
30、s between flow-rates are shown in Figure 1. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:25:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5728-7:1997 BSI 06-19993 Figure 1 Relationships of water meter metrological definitions Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:
31、25:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5728-7:1997 4 BSI 06-1999 Table 1 In-line water meters with threaded end connections: meter designation, meter sizes and dimensions Figure 2 Meter size and overall dimensions Dimensions in millimetres Meter designation Meter size (nominal size of t
32、hreaded end connection) Connection sizeMeter dimensions Threadaminbmin L1 (tolerance) Maximum values Preferred value AlternativesL2 and L3H1H2 N0.6G BG B1012134110805050180 N1G BG B10121341151301605050180 N1.5G BG B10121651901701845050180 N2.5G 1 BG 1 B12141641541901996560240 N3.5G 1 BG 1 B121619926
33、08565260 N6G 1 BG 1 Ba13182608570280 N10G 2 BG 2 B132030022534010575300 a A thread size of 1 B is acceptable as an alternative 0 2 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:25:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5728-7:1997 BSI 06-19995 Table 2 In-line water meters with
34、flanged end connections: meter designation, meter sizes and dimensions Dimensions in millimetres Meter designation (N)Size DNa Meter dimensions DNa L1 tolerances (200 # L1 # 400), Maximum values 0 (400 L1 # 1 200) L2 and L3H1H2 Volumetric, single-jet and multi-jet WoltmannVolumetricWaltmann single-j
35、et and multi-jet: Volumetric single-jet and multi-jet WoltmannVolumetric, single-jet and multi-jet WoltmannVolumetric, single-jet and multi-jet Woltmann eitheror N15N155050350300200135135115100300390 N20N256565450300200150135130110320390 N30N408080500350200180135150120320410 N50N60100100650350250225
36、135215140320440 N100125125350250135140440 N150150150500300175180500 N250200200500350190200500 N400250250600450210220500 N600300300800500240250500 N1 000400400800600290320500 N1 5005005001 000800365380520 N2 5006006001 2001 000390450600 N4 0008008001 2001 200510550700 a DN: nominal size of flanged en
37、d connections. 0 3 0 5 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:25:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5728-7:1997 6 BSI 06-1999 4.2.2 Relationship between meter designation and permanent flow-rate The numerical value of the permanent flow-rate, qp, expressed in m3/h, s
38、hall be at least equal to the meter designation. Where the value is greater than the meter designation, it shall be equal to one of the values for meter designation given in Table 1 and Table 2, provided that the relationship between meter size and meter designation is maintained in accordance with
39、4.2.4. 4.2.3 Relationship between permanent and overload flow-rates The overload flow-rate shall be twice the permanent flow-rate. 4.2.4 Relationship between meter size, connection size and meter dimensions NOTEMeter designation and meter size are, in principle, related to the connection size and me
40、ter dimensions as given in Table 1 and Table 2. For a given meter designation, it is permitted to adopt the adjacent smaller or larger connection size and/or meter dimensions. When the size of a water meter is different from that implied by the nominal designation, the meter shall be designated not
41、only by its numerical N value but also by its DN. End connections shall be the same at the water meter inlet and outlet. All meters having the same nominal size (DN) and rated to the same nominal pressure (PN) shall have compatible mating dimensions. 4.2.5 Threaded connection Thread sizes shall be a
42、s specified in Table 1 (see Figure 3). Threads shall conform to BS 2779. 4.2.6 Flanged connection Flanged end connections shall conform to BS 1560-3.2 and BS 1560-3.3, and BS 4504-3.2 and BS 4504-3.3, as appropriate, for a nominal pressure corresponding to that of the water meter. Dimensions shall b
43、e as given in Table 2. The manufacturer shall provide a clearance behind the rear face of the flange sufficient to allow access for installation and removal. 4.3 Concentric meters 4.3.1 Meter designation and overall dimensions Each meter designation shall conform to the corresponding set of overall
44、dimensions (see Figure 4). The dimensions shall be as given in Table 3. Table 3 Concentric meters: meter designation and meter dimensions Figure 3 Threaded connection Figure 4 Concentric water meter: dimensions Dimensions in millimetres Meter designation Nominal size of threaded end connection Meter
45、 dimensions LJ1J28K (maximum)(maximum)(maximum) N1G1200220 10 N1.5G1200220110 N2.5G1 or200220115 G2200220135 N3.5G2200220135 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:25:43 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5728-7:1997 BSI 06-19997 4.3.2 Relationship between meter designa
46、tion and permanent flow-rate The numerical value of the permanent flow-rate qp, shall be at least equal to the meter designation. Where the value is greater than the meter designation it shall be equal to one of the values given in the meter designation column of Table 1. 4.3.3 Relationship between
47、permanent and overload flow-rates The overload flow-rate shall be twice the permanent flow-rate. 4.3.4 Design of the meter manifold connection The design of the manifold face shall be as specified in Figure 5 or Figure 6, whichever is appropriate (see Table 3). The meter connection shall be designed
48、 to connect the meter, using the screw thread provided, to a manifold having this design of face. Suitable seals shall ensure that no leaks occur between the inlet connection and the meter/manifold exterior or between the inlet and outlet passages at the meter/manifold interface. NOTEClause 6.3 of B
49、S 5728-3:1997 refers to the additional pressure tests to be passed by this meter type before pattern approval is granted. 4.3.5 Threaded connection Thread sizes shall be as specified in Table 3. Threads shall conform to BS 2779. NOTEAll machined surfaces to be unless otherwise stated. Tolerance on all angles to be 3 Figure 5 Manifold dimensions: N1 to N2.5 concentric meters Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:25:43 GMT+00:00 2006, Uncontrolled C