BS 3457-1973 Specification for materials for water tap and stopvalve seat washers
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76C5528190344E4C8434E8B3D88CDBAD |
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文件大小(MB)： |
0.17 |
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页数： |
5 |
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日期： |
2010-10-4 |
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文本摘录（文本识别可能有误，但文件阅览显示及打印正常，pdf文件可进行文字搜索定位）：
BS 3457 : October 1973,UDC 621.646.6-762.4,Specification for,Materials for water,tap and stopvalve,seat washers,Amendments issued since publication,Amd. No. Date of issue Text affected,British Standards Institution - 2 Park Street - London W1A 2BS,Telephone 01-629 9000,Telex 266933,BS 3457 ： 1973,Contents,Co-operating organizations,Foreword,Specification,Page,Inside front cover,2,1. Scope 3,2. Definitions 3,3. Effect on water 3,4. Effect on metals 3,5. Marking 3,6. Rubber for washers for hot and cold water 4,7. Leather for washers for cold water only 4,8, Flexible vulcanized fibre for washers for,hot water only 4,Foreword,BS 3457 was first prepared in 1962 under the authority of the Sanitary Appliances Industry Standards,Committee, to provide standard tests and performance requirements for materials for water tap seat washers.,Although this present British Standard contains specifications for rubber and leather and fibre, the majority,of the committee responsible for its preparation strongly recommends rubber washers because they are suitable,for use with both hot and cold water. The presence in the standard of the specifications for leather and fibre is,explained by the suitability of washers of these materials for certain applications, namely, leather for cold water,only and fibre for hot water only.,The other principal changes between this and the previous edition of the standard are:,(1) the introduction of the term 'seat washer to distinguish such washers from head washers and joint,washers.,*,(2) the use of more realistic criteria in Clause 3 for determining the effect of washer materials on water.,(3) more precise reference in Clause 7 to BS 1309 and BS 3144 for testing leather washers.,(4) the deletion from Clause 7 of the moisture content requirement and stearine base requirements.,(5) the deletion from Clause 8 of hard vulcanized fibre and the replacement of BS 1737 and F.64 by,BS 3964 as the testing criterion.,As part of BSPs programme of metrication, this standard is expressed in metric terms. The metric values are,given in SI units: for further information reference should be made to BS 3763「The International System of units,(*SI) and PD 5686, The use of SI units5.,2,BS 3457 ： 1973,British Standard Specification for,Materials for water tap and stopvalve,seat washers,1. Scope,This British Standard specifies requirements for physical and some chemical properties for materials for water tap,and stopvalve seat washers of the type defined in Clause 2, and made of rubber or leather or fibre.,NOTE. The titles of the British Standards referred to in this standard are listed on the inside back cover.,2. Definitions,For the purposes of this British Standard the following definitions apply:,(1) Seat washer. The disc of material fitted to the washer plate of a water tap or st op valve in such a manner,that, on closing the tap or valve, it is brought into contact with the seat and closes the orifice against further flow.,(2) Cold water. Water at a temperature not exceeding 35 °C.,(3) Hot water. Water at a temperature exceeding 35 0C and not exceeding 100 °C.,3. Effect on water,3.1 Material used for seat washers shall be immersed for a period of 24 hours in a glass containing 0.25 litre of,normal potable water at 20 ± 2 °C having a residual chlorine content of 0.5 ± 0.1 mg/1. This first portion of,water shall then be rejected and replaced by a second similar portion. Immersion for 24 hours of the same sample,of material in this second portion of water shall neither impart any appreciable or objectionable taste to the,water, nor produce any toxic effect, nor foster the growth of bacteria, nor impart colour discernible to the,unaided eye.,3.2 To assess the compliance of the material with the requirements stated in 3.1, one tap washer having the,following dimensions shall be used:,outside diameter 60 mm min.,inside diameter 10 mm max.,thickness (when new) 6 mm min.,Alternatively, a number of smaller washers of total equivalent surface area may be used.,4. Effect on metals,The material of the washer shall not corrode the metal seat or the washer plate sufficiently to impair the,performance and life of a tap or stopvalve.,5. Marking,Sheet materials supplied as complying with the requirements of this British Standard shall bear the following,marks.,(1) The number of this British Standard, i.e. BS 3457.,(2) An identification mark of the manufacturer.,NOTE. Attention is drawn to the certification facilities offered by BSI; see the inside back cover of this standard.,3,BS 3457 ： 1973,6. Rubber for washers for *hot and *cold water,Rubber for washers to be used with *hot and c*old wate……
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