BS-6283-4-1991.pdf

BRITISH STANDARD BS 6283-4: 1991 Safety and control devices for use in hot water systems Part 4: Specification for drop-tight pressure reducing valves of nominal size up to and including DN 50 for supply pressures up to and including 12 bar Licensed Copy: London South Bank University, London South Bank University, Thu Dec 07 06:41:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6283-4:1991 This British Standard, having been prepared under the direction of the Building Services Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 28 June 1991 © BSI 06-1999 First published November 1982 Second edition June 1991 The following BSI references relate to the work on this standard: Committee reference SEB/2 Draft for comment 87/12751 DC ISBN 0 580 17941 9 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 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 Federation 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 (Property 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 Management (IWEM) 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 Authorities Association Water Companies Association Water Heater Manufacturers Association Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Thu Dec 07 06:41:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6283-4:1991 © BSI 06-1999i Contents Page Committees responsibleInside front cover Forewordii Section 1. General 1.1Scope1 1.2Definitions1 1.3Nominal size1 1.4Marking1 Section 2. Materials 2.1General2 2.2Bodies and associated parts2 2.3Sealing and diaphragm materials2 2.4Spring materials2 Section 3. Design and construction 3.1End connections and flow dimensions3 3.2Guides and moving parts3 3.3Adjustment3 3.4Springs3 3.5Strainer3 Section 4. Performance 4.1Production tests4 4.2Type tests4 Appendix A Information to be supplied by the purchaser5 Appendix B Production tests5 Appendix C Torque test5 Appendix D Drop-tight seating test6 Appendix E Flow capacity test6 Appendix F Back pressure test6 Appendix G Endurance test6 Figure 1 Drop-tight seating test rig5 Figure 2 Endurance test rig6 Table 1 Nominal size of valve1 Table 2 Flow capacity4 Table 3 Torque6 Publication(s) referred toInside back cover Licensed Copy: London South Bank University, London South Bank University, Thu Dec 07 06:41:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6283-4:1991 ii © BSI 06-1999 Foreword This Part of BS 6283 has been prepared under the direction of the Building Services Standards Policy Committee at the request of the Department of the Environment on the advice of the Standing Technical Committee on Water Regulations. It supersedes BS 6283-4:1982 which is withdrawn. Each Part of BS 6283 specifies requirements for a particular device for preventing overheating and/or excess pressures in water installations, and is intended to be suitable for citing as deemed to satisfy the relevant regulations or byelaws. This British Standard comprises the following Parts: Part 1: Specification for expansion valves for pressures up to and including 10 bar; Part 2: Specification for temperature relief valves for pressures from 1 bar to 10 bar; Part 3: Specification for combined temperature and pressure relief valves for pressures from 1 bar to 10 bar; Part 4: Specification for drop-tight pressure reducing valves of nominal size up to and including DN 50 for supply pressures up to and including 12 bar. 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. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, 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 in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Thu Dec 07 06:41:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6283-4:1991 © BSI 06-19991 Section 1. General 1.1 Scope This Part of BS 6283 specifies the design, construction and testing requirements for drop-tight pressure reducing valves (sometimes known as “pressure limiting valves”) of nominal size up to and including DN 50, suitable for use within a range of variable inlet pressures not exceeding 12 bar1) and a range of outlet pressures up to and including 6 bar. However, the valves may also be used for other water applications where appropriate. This Part of BS 6283 does not cover the application or installation of these valves. Advice on the information to be supplied by the purchaser is given in Appendix A. NOTEThe titles of the publications referred to in this Part of BS 6283 are listed on the inside back cover. 1.2 Definitions For the purposes of this Part of BS 6283 the following definitions apply. 1.2.1 drop-tight pressure reducing valve a valve which reduces the pressure of water at its outlet to a predetermined maximum value which does not increase at zero flow with the inlet pressure maintained 1.2.2 maximum inlet pressure the maximum water pressure at the inlet of a drop-tight pressure reducing valve at which the valve will function satisfactorily 1.2.3 maximum outlet pressure the maximum pressure at the outlet of a drop-tight pressure reducing valve at which the valve will function satisfactorily 1.2.4 minimum outlet pressure the minimum pressure at the outlet of a drop-tight pressure reducing valve at which the valve will function satisfactorily 1.2.5 set outlet pressure the pressure at the outlet of a non-adjustable valve at zero flow 1.3 Nominal size The nominal size of the pressure reducing valve and the nominal size of the appropriate inlet connection shall be as given in Table 1. Table 1 Nominal size of valve 1.4 Marking 1.4.1 Flow marking Each drop-tight pressure reducing valve shall be legibly and permanently marked with an arrow indicating the direction of flow to identify connections and aid correct installation of the valve. This marking shall be stamped, etched, cast or moulded on the valve. 1.4.2 Identification marking Each drop-tight pressure reducing valve shall be legibly and permanently marked with the following: a) the number of this British Standard, i.e. BS 6283-42); b) the manufacturers or agents name, trademark or symbol; c) the name or model number of the valve and its nominal size; d) the month and year of manufacture, e.g. 1291; e) the set outlet pressure in bar. NOTEAdhesive labels complying with BS 4781 are considered to be permanent for the purposes of this Part of BS 6283. 1) 1 bar = 105N/m2= 100 kPa. All pressures are gauge pressures unless otherwise stated. Nominal size of valve Nominal size of inlet connection Screwed (complying with BS 2779 or BS 21) Compression (complying with BS 864-2 and BS 864-5 Flanged (complying with BS 4504-2) Minimum clear area of strainer DN 15 20 25 32 40 50 ½ ¾ 1 1¼ 1½ 2 15/18 22 28 35 42 54 15 20 25 32 40 50 mm2 250 500 850 1 500 2 200 3 500 2) Marking BS 6283-4 on or in relation to a product 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 confused with third party certification of conformity, which may also be desirable. Licensed Copy: London South Bank University, London South Bank University, Thu Dec 07 06:41:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6283-4:1991 2 © BSI 06-1999 Section 2. Materials 2.1 General Any non-metallic materials, under the conditions for which the valve is designed, shall comply with BS 6920-1. 2.2 Bodies and associated parts The bodies and associated parts of drop-tight pressure reducing valves shall be constructed from those materials specified in clause 9 of BS 5412 and BS 5413-5:1976. Materials that are in contact with water shall be capable of complying with clause 7 of BS 2872:1989. 2.3 Sealing and diaphragm materials Sealing members and diaphragm materials shall comply with items 3) and 4) of clause 6 of BS 3457:1973. They shall also be capable of complying with the test criteria in Appendix C of BS 5412 and BS 5413-5:1976. 2.4 Spring materials Springs shall be made of one of the following: a) stainless steel complying with BS 970-4 or BS 2056; b) nickel-copper alloy (monel) complying with BS 3075; c) phosphor bronze complying with grade PB 102 of BS 2874; d) carbon steel complying with grades 094A65HS and 735A50HS of BS 2803 or grades HS2 and HS3 of BS 5216. Materials for springs in contact with water shall be a) or b) only. Materials for springs not in contact with water shall be a), b), c) or d). Licensed Copy: London South Bank University, London South Bank University, Thu Dec 07 06:41:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6283-4:1991 © BSI 06-19993 Section 3. Design and construction 3.1 End connections and flow dimensions 3.1.1 Type of connections 3.1.1.1 General End connections shall be screwed ends, compression ends or flanged ends complying with 3.1.1.2, 3.1.1.3 or 3.1.1.4 respectively. 3.1.1.2 Screwed ends Where the end connection is screwed, the thread shall be a parallel pipe thread complying with BS 2779 for internal threads and class B of BS 2779 or BS 21 for external threads of lengths given in Table 6 of BS 864-2:1983. Screwed end connections shah be designed so that when a pipe or fitting is screwed into the connection it shah not reduce the area of flow through the valve, distort any part of the valve body or adversely affect the operation of the valve. 3.1.1.3 Compression ends Where compression end connections are provided they shall comply with BS 864-2 or BS 864-5. 3.1.1.4 Flanged ends Where flanged end connections are provided they shall comply with Table 9 of BS 4504-3.3:1989. 3.1.2 Size of connections End connections shall be either the same nominal size as the valve (see Table 1) or, in the case of discharge connections only, one size larger than the nominal size of the valve. 3.2 Guides and moving parts Means shall be provided to guide the valve disc and to prevent it from being misaligned during working. 3.3 Adjustment Means for field adjustment or repair of the valve shah not be provided. 3.4 Springs Springs shall be designed in accordance with BS 1726-1. Control springs shall be protected against contact with water by membranes or seals. NOTEFor the purposes of this Part of BS 6283, a control spring is defined as being any spring with a working length that varies with movement of the main valve mechanism. 3.5 Strainer Every drop-tight pressure reducing valve shall be fitted on the inlet side with a strainer with a removable corrosion resistant element of maximum mesh size 0.7 mm. The minimum clear area of the strainer shall be as given in Table 1. Licensed Copy: London South Bank University, London South Bank University, Thu Dec 07 06:41:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6283-4:1991 4 © BSI 06-1999 Section 4. Performance NOTEFor all performance requirements, a tolerance of ± 10 % should be assumed unless otherwise specified. 4.1 Production tests When tested in accordance with B.1 each valve shall not show any visible sign of external leakage. When tested in accordance with B.2.1 the outlet pressures recorded shall not differ from the set outlet pressure declared by the manufacturer by more than 10 %. When tested in accordance with B.2.2 the outlet pressures recorded shall not differ from one another by more than 10 % of the lower limit of the outlet pressure range declared by the manufacturer. The strainer element (see 3.5) shall be fitted to the valve for all production tests. 4.2 Type tests 4.2.1 General Each drop-tight pressure reducing valve shall be capable of complying with the appropriate requirements when tested as specified in 4.2.2 to 4.2.6. These tests shall be carried out to prove the design of each type and size of valve. They shall be repeated if there is any change in design, material or manufacturing method, and in any case at intervals not exceeding 5 years. The strainer element (see 3.5) shall be fitted to the valve for all type tests. The tests shall be carried out on three valves of each type and size in the following order. a) torque test; b) drop-tight seating test; c) flow capacity test; d) back pressure test; e) endurance test. 4.2.2 Torque test When tested in accordance with Appendix C the valve shall not break or show permanent deformation or any loosening of any joint. 4.2.3 Drop-tight seating test When tested in accordance with Appendix D there shall be no increase in the reading of gauge B during the 10 min observation. 4.2.4 Flow capacity test When tested in accordance with Appendix E the flow capacity shall be not less than the appropriate value given in Table 2. Table 2 Flow capacity 4.2.5 Back pressure test When tested in accordance with Appendix F the valve shall not show any visible sign of leakage. 4.2.6 Endurance test When the valve is tested in accordance with Appendix G the following requirements shall be complied with: a) Either of the following. 1) When tested in accordance with B.2.1 the outlet pressures recorded shall not differ from the set outlet pressure declared by the manufacturer by more than 10 %. 2) When tested in accordance with B.2.2 the outlet pressures recorded shall not differ from one another by more than 10 % of the lower limit of the outlet pressure range declared by the manufacturer. b) When tested in accordance with Appendix D there shall be no increase in the reading of gauge B during the 10 min observation. c) When tested in ac