1、BRITISH STANDARD BS 2456:1990 Incorporating Amendment No. 1 Specification for Floats (plastics) for float operated valves for cold water services ICS 91.140.60 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS 2456:1990 This British Standard, having been prepared under the dir
2、ection of the Building Services Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 30 November 1990 BSI 17 September 2001 First published April 1954 Second edition October 1973 Third edition November 1990 The following BSI references relate to
3、the work on this standard: Committee reference SEB/2 Draft for comment 88/14194 DC ISBN 0 580 18965 1 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Building Services Standards Policy Committee (SEB/-) to Technical Committee SEB/2, upon
4、 which the following bodies were represented: Association of Manufacturers of Domestic Electrical Appliances Association of Manufacturers of Domestic Unvented Supply Systems Equipment (MODUSSE) Association of Water Officers Ltd. British Bathroom Council British Gas plc British Non-ferrous Metals Fed
5、eration British Plastics Federation British Plumbing Fittings Manufacturers Association British Valve and Actuator Manufacturers Association Builders Merchants Federation Consumer Policy Committee of BSI Department of the Environment (Building Research Establishment) Department of the Environment (P
6、roperty Services Agency) Department of the Environment (Water Directorate) Department of Trade and Industry (National Weights and Measures Laboratory) Institute of Clerks of Works of Great Britain Inc. Institute of Plumbing Institution of Gas Engineers Institution of Water and Environmental Manageme
7、nt Metal Sink Manufacturers Association National Association of Plumbing, Heating and Mechanical Services Contractors Royal Institute of British Architects Society of British Gas Industries South London Consortium Water Companies Association Water Services Association of England and Wales Amendments
8、 issued since publication Amd. No. Date Comments 13175 September 2001 Indicated by a sidelineBS 2456:1990 BSI 17 September 2001 i Contents Page Committees responsible Inside front cover Foreword ii Section 1. General 1 1.1 Scope 1 1.2 Definitions 1 1.3 Marking 1 1.4 Colour coding 1 Section 2. Materi
9、als 3 2.1 Effect of materials on water quality 3 2.2 Plastics materials 3 2.3 Copper alloy for boss insert 3 Section 3. Design and construction 5 3.1 Lifting efforts 5 3.2 Bosses 5 Section 4. Test requirements 7 4.1 Leakage and hot water test 7 4.2 Deflection test 7 4.3 Impact test 7 4.4 Cold embrit
10、tlement test 7 4.5 Boss distortion test 7 Appendix A Information to be supplied by the purchaser 9 Appendix B Calculation of lifting effort 9 Appendix C Method of test for leakage and determination of resistance to hot water 9 Appendix D Method of determining deflection 10 Appendix E Method of deter
11、mining resistance to cold embrittlement 11 Appendix F Method of determining resistance of the boss to distortion 12 Figure 1 Deflection test rig 11 Figure 2 Example of test bolt 12 Table 1 Minimum lifting efforts 5 Table 2 Bosses 5 Publication(s) referred to Inside back coverBS 2456:1990 ii BSI 17 S
12、eptember 2001 Foreword This British Standard has been prepared under the direction of the Building Services Standards Policy Committee and specifies the requirements for two grades of plastics floats suitable for attachment to the float operated valves specified in BS 1212. This revision supersedes
13、BS 2456:1973 which is withdrawn. The principal change in this revision is the inclusion of two grades of float: grade C for use in cold water cisterns only; and grade H for use in either cold water cisterns or cisterns with a limited exposure to hot water. For information regarding the correct size
14、of float to use with a particular size of float operated valve, reference should be made to BS 1212-1, BS 1212-2 or BS 1212-3. 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. Complian
15、ce with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 12, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates whe
16、n the document was last issued. Sidelining in this document indicates the most recent changes by amendment.BS 2456:1990 BSI 17 September 2001 1 Section 1. General 1 1.1 Scope This British Standard specifies requirements for two grades of float, with or without boss inserts. Grade C for use in cold w
17、ater cisterns only, where they may be exposed to temperatures not exceeding 38 C. Grade H for use in cold water cisterns or systems that may subject the float to hot water not exceeding 93 C for a limited period, e.g. from a vent pipe arrangement in a feed and expansion cistern. The standard specifi
18、es plastics spherical floats of 102 mm, 114 mm, 127 mm and 152 mm diameter, and non-spherical floats having equivalent lifting efforts, suitable for attachment to the float operated valves specified in BS 1212-1, BS 1212-2 and BS 1212-3, except when otherwise specified by the purchaser in accordance
19、 with Appendix A of this standard. Appendix A lists the information to be provided by the purchaser at the time of enquiry or order. NOTE The titles of the publications referred to in this standard are listed on the inside back cover. 1.2 Definitions For the purposes of this British Standard the fol
20、lowing definitions apply. 1.2.1 diameter of spherical float the average outside diameter of the float measured along two axes at right angles to each other and clear of the joining seam (if any) 1.2.2 lifting effort the net upward force acting on the float when immersed in water so that half of its
21、volume is below the surface 1.3 Marking Floats shall be legibly and permanently marked with the following information, in such a manner as not to damage or distort the float: a) the number of this British Standard, i.e. BS 2456 1) ; b) the manufacturers name or identification mark; c) the BS type re
22、ference in the form 102 NS and the reference letter L as appropriate (see 3.2); d) in the case of non-spherical floats having a surface intended to be uppermost in operating conditions, the word “top” on the uppermost surface. 1.4 Colour coding Floats shall be colour coded as follows: a) red for gra
23、de H intended for use where they may occasionally be exposed to hot water at temperatures not exceeding 93 C; and b) blue for grade C intended for use in cisterns where they may occasionally be exposed to hot water at temperatures not exceeding 38 C. 1) Marking BS 2456:1990 on or in relation to a pr
24、oduct represents a manufacturers declaration of conformity, i.e. a claim by or on behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of the claim is therefore solely the responsibility of the person making the claim. Such a declaration is not to be confu
25、sed with third party certification of conformity, which may also be desirable.2 blankBS 2456:1990 BSI 17 September 2001 3 Section 2. Materials 2 2.1 Effect of materials on water quality 2.1.1 General No part of a float shall be made of, or contain, any substance capable of promoting microbial growth
26、 or of affecting in any way the physical, chemical or bacteriological quality of the water with which it will be in contact in service. 2.1.2 Non-metallic materials When used under the conditions for which they are designed, non-metallic materials in contact with or likely to come into contact with
27、potable water shall comply with BS 6920-1. 2.2 Plastics materials Floats shall be manufactured from one or more plastics material(s) containing, if required, the addition of not more than 15 % of the manufacturers own clean reworked material complying with this standard. No other reworked material s
28、hall be used. 2.3 Copper alloy for boss insert Boss inserts shall be manufactured from copper alloy complying with CZ 121 as specified in BS EN 12163, BS EN 12164 and BS EN 12167.4 blankBS 2456:1990 BSI 17 September 2001 5 Section 3. Design and construction 3 3.1 Lifting efforts Floats shall have a
29、lifting effort of not less than that shown in Table 1 for the appropriate BS type reference, when calculated immediately following the leakage test (see 4.1) as described in Appendix B. NOTE The shape and dimensions of non-spherical floats are not specified. Table 1 Minimum lifting efforts 3.2 Bosse
30、s 3.2.1 General Floats shall be supplied in either of the following conditions: a) with a boss integral with the float and screwed in accordance with Table 2; b) with the size of the screw thread in the boss varied to suit special conditions specified by the purchaser in accordance with Appendix A,
31、and identified by the reference letter “L” (see 1.3) provided that the other requirements of this standard are complied with. NOTE Unless otherwise specified by the purchaser at the time of enquiry or order (see Appendix A) the float will be supplied complying with item a). 3.2.2 Boss face The face
32、of the boss shall be flat and at right angles to the axis of the boss. 3.2.3 Axis For spherical floats only, the axis of the boss shall be radial to the float. Table 2 Bosses 123 BS type reference Diameter or float if spherical, subject to a tolerance of 2.5 mm Minimum lifting effort mm N 102 S 102
33、2 102 NS 2 114 S 114 2.9 114 NS 2.9 127 S 127 4.2 127 NS 4.2 152 S 152 7.1 152 NS 7.1 Key to column 1 a) the number corresponds to the diameter of the float in millimetres; b) the letter “S” refers to a spherical float; c) the letters “NS” refer to a non-spherical float. 123 BS type reference for fl
34、oats Minimum length of screw thread in boss Designation of BS 84 screw thread in boss mm in 102 S 13 5/16 18 BSW 102 NS 13 5/16 18 BSW 114 S 13 5/16 18 BSW 114 NS 13 5/16 18 BSW 127 S 13 5/16 18 BSW 127 NS 13 5/16 18 BSW 152 S 19 7/16 14 BSW 152 NS 19 7/16 14 BSW6 blankBS 2456:1990 BSI 17 September
35、2001 7 Section 4. Test requirements 4 4.1 Leakage and hot water test When tested in accordance with Appendix C, as appropriate, for grade H or grade C, floats shall show no signs of deterioration or leakage. 4.2 Deflection test Immediately following the leakage test (see 4.1) when tested in accordan
36、ce with Appendix D floats shall not deflect more than 7 mm. 4.3 Impact test When dropped from a height of 1 500 mm onto a concrete floor, there shall be no visible indication of damage and the float shall subsequently meet the requirements of 3.1. 4.4 Cold embrittlement test When tested in accordanc
37、e with Appendix E, floats shall exhibit no visible damage. 4.5 Boss distortion test When tested in accordance with Appendix F, the float boss shall not be visibly distorted or damaged and the float shall subsequently meet the requirements of 3.1.8 blankBS 2456:1990 BSI 17 September 2001 9 Appendix A
38、 Information to be supplied by the purchaser The purchaser should supply the following information at the time of enquiry or order: a) the BS number, type reference and grade followed by the word “Float” (see Table 1) in the form “BS 2456:Type 102 NS:Grade C Float”; b) for special conditions the req
39、uired screw thread of the boss (see 3.2.1). Appendix B Calculation of lifting effort Calculate the lifting effort developed by floats, whether spherical or non-spherical, using the following formula: NOTE The factor 10 6converts the half-volume of the float to the mass in kilograms of an equal volum
40、e of water. The factor 9.8 converts mass in kilograms to force in newtons. Appendix C Method of test for leakage and determination of resistance to hot water C.1 Apparatus C.1.1 A vessel, having cross-sectional dimensions of not less than 50 mm greater in each direction than the longest and widest p
41、arts of the float to be tested, and having a depth able to contain sufficient water, in addition to the float under test, to ensure that for the period of test the float is covered by at least 50 mm of water. Alternatively, a hot water supply capable of maintaining the water level 50 mm above the fl
42、oat may be used in preference. C.1.2 A means where applicable, of heating the water in the vessel of C.1.1 and maintaining it at 93 2 C. C.1.3 A weight, capable of being attached to the float under test, and of keeping the float submerged to a depth of 50 mm. C.2 Procedure C.2.1 For grade H (red) fl
43、oats, immerse the weighted float in water in the vessel for a period of 30 days at a temperature of 93 2 C, maintaining the water at a height of not less than 50 mm above the top of the float. C.2.2 For grade C (blue) floats, immerse the weighted float in water in the vessel for a period of 100 h at
44、 a temperature of 38 2 C, maintaining the water at a height of not less than 50 mm above the top of the float. C.2.3 During the test observe the float for leakage and after 100 h or 500 h as appropriate, remove the float, immediately examine it, and record any signs of deterioration and/or leakage.
45、where E L is the lifting effort, measured in newtons; V is the volume of the float, excluding any part of the boss which projects outside the surface, measured in cubic millimetres; M is the mass of the float, including the boss, in kilograms, immediately after passing the hot water test in 4.1. E L
46、 9.8 V10 6 2 - M =BS 2456:1990 10 BSI 17 September 2001 Appendix D Method of determining deflection D.1 Principle The principle of the deflection test is to determine whether or not the material of the float, in association with the design adopted for the float, is capable of resisting deformation u
47、nder a load relevant to the operating conditions in service at the upper limit of temperature likely to be reached in service. D.2 Apparatus D.2.1 A straight sided vessel, not less than 300 mm deep internally and capable of containing hot water. D.2.2 A means of heating the water, and maintaining it
48、s temperature at 93 2 C for grade H (red) or 38 2 C for grade C (blue). D.2.3 A substantial beam, fixed to the top of the straight-sided vessel of D.2.1 and carrying two guide bushes at least 150 mm apart and having their axes in the same vertical line. D.2.4 A rod, of at least 10 mm diameter to sli
49、de between the bushes. D.2.5 Rigid mountings, for fixing to the rod and supporting: a) the float to be tested at the lower end of the rod, using the threaded boss as a means of attachment (standard spherical floats have their boss axis horizontal); b) a dial indicator gauge having its plunger vertical and touching the float and positioned so that it is directly above the centre of buoyancy of the float; c) detachable weights at the top of the rod. The apparatus is shown in Figure 1.
