1、BRITISH STANDARD BS 6280:1982 Method of Vacuum (backsiphonage) test for water-using appliances UDC 621.64:620.16:532.542.7BS 6280:1982 This British Standard, having been prepared under the directionof the Building ServicesStandards Committee,was published underthe authorityof the BoardofBSI andcomes
2、 intoeffecton 30November1982 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference SEB/2 Draft for comment 79/10566 DC ISBN 0 580 12926 8 Cooperating organizations The Building Services Standards Committee, under whose direction this British Standard was p
3、repared, consists of representatives from the following: The organizations marked with an asterisk in the above list, together with the following, were directly represented on the Technical Committee entrusted with the preparation of this British Standard: Association of District Councils Greater Lo
4、ndon Council Bath Manufacturers Co-ordinating Committee Heating and Ventilating Contractors British Gas Corporation* Association British Ironfounders Association Incorporated Association of Architects and British Plastics Federation* Surveyors British Plumbing Employers Council Institute of Plumbing
5、* British Precast Concrete Federation Ltd. Institution of Environmental Health Officers Builders Merchants Federation* Institution of Gas Engineers* Building Services Research and Information Institution of Municipal Engineers Association Institution of Public Health Engineers* Chartered Institution
6、 of Building Services Institution of Water Engineers and Scientists* Clay Pipe Development Association Limited Local Authorities Organization Consumer Standards Advisory Committee of Metal Sink Manufacturers Association* BSI* National Brassfoundry Association* Convention of Scottish Local Authoritie
7、s National Coal Board Council of British Ceramic Sanitaryware National Federation of Building Trades Manufacturers* Employers Department of Health and Social Security National Water Council* Department of the Environment (PSA)* Royal Institute of British Architects* Department of the Environment (Bu
8、ilding Royal Institution of Chartered Surveyors Research Establishment)* Royal Society of Health Department of the Environment (Water Scottish Development Department Directorate)* Trades Union Congress Department of the Environment (Housing and Water Companies Association* Construction) Domestic Sol
9、id Fuel Appliances Approval Scheme Association of Manufacturers of Domestic Design Council Electrical Appliances Institute of Clerks of Works of Great Britian Association of Manufacturers of Domestic Inc. Unvented Supply Systems Equipment National Association of Plumbing, Heating and Association of
10、Water Officers Ltd. Mechanical Services Contractors British Bath Manufacturers Association Plastic Bath Manufacturers Association British Valve Manufacturers Association Ltd. Society of British Gas Industries Copper Tube Fittings Manufacturers South London Consortium Association Thames Water Authori
11、ty (Metropolitan Water Department of Trade (Metrology, Quality Division) Assurance, Safety and Standards Division) Water Research Centre Amendments issued since publication Amd. No. Date of issue CommentsBS 6280:1982 BSI 08-1999 i Contents Page Cooperating organizations Inside front cover Foreword i
12、i 1 Scope 1 2 Definitions 1 3 Apparatus 1 4 Procedure 1 5 Criterion 1 Figure 1 Arrangement of apparatus for vacuum test 2 Table 1 Recommended vacuum vessel capacities 2 Publications referred to Inside back coverBS 6280:1982 ii BSI 08-1999 Foreword This British Standard has been prepared under the di
13、rection of the Building Services Standards Committee at the request of the Department of the Environment on the advice of the Standing Technical Committee on Water Regulations. It is one of a series of standards (BS6280 to BS6282) that specify the requirements for devices and arrangements for preven
14、ting the backflow or backsiphonage of water in installations, and is intended to be suitable for citing as deemed to satisfy the relevant regulations or byelaws. This standard is based on experimental work carried out by the Building Research Establishment. A British Standard does not purport to inc
15、lude 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, page
16、si andii, pages1 and 2, 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.BS 6280:1982 BSI 08-1999 1 1 Scope This British Standard describes a me
17、thod for applying a vacuum test to water-using appliances to determine that they have an acceptable degree of protection against backflow or backsiphonage. NOTEThe titles of the publications referred to in this standard are given on the inside back cover. 2 Definitions For the purposes of this Briti
18、sh Standard the following definitions apply. 2.1 critical level the constant steady water level in a water appliance or water-using apparatus protected by a backflow prevention device when the rate of inflow of water through the feed pipework upstream of the device is the lesser of2m/s or that cause
19、d by a pressure of6bar 1)upstream of the device and with all normal outlets (with the exception of overflows) from the appliance or apparatus closed 2.2 choking flow the condition when reduction of the downstream pressure reaches a critical value at which the mass flow rate no longer increases when
20、a compressible fluid, such as air, flows through a throat or orifice at constant pressure upstream of the orifice NOTEThe critical value of the downstream pressure for air is about0.53 times the upstream pressure. 3 Apparatus 3.1 General. The test apparatus shall be arranged and constructed as shown
21、 inFigure 1 so that the absolute pressure measured near the appliance under test on its supply side remains less than0.5 bar for at least5s. NOTEThese conditions indicate the existence of choking air flow. Details of the components are given in3.2 to3.6. 3.2 Vacuum vessel and connecting pipework, of
22、 sufficient strength to support a total vacuum safely. The vacuum vessel shall be provided with a drain cock to remove any water drawn into the vessel during the test. NOTERecommended capacities of the vacuum vessel are given inTable 1. 3.3 Vacuum pump, capable of reducing the absolute pressure with
23、in the vacuum vessel to0.2 bar. 3.4 Pipes and fittings, of nominal size not less than that of the appliance under test. Any valve fitted in the test pipe shall be a full-way valve offering an unimpeded flow path. Connections to the vacuum vessel shall not unduly impede the fluid flow and shall have
24、a low loss profile when very low resistance appliances are tested. The pipe connecting the test apparatus to the appliance shall be of the same nominal size as the inlet connection on the appliance, or larger, and from0.6m to1.0m long when measured from the vacuum gauge. 3.5 Bourdon tube vacuum gaug
25、es, 0bar to1bar, complying with BS1780 or BS1780-2. The gauge connection shall be made in such a way that it does not disturb the flow in the pipework. 3.6 Water trap, provided with a cock to allow the trapped water to be drained. The trap shall not so restrict the flow that the requirement of3.1 ca
26、nnot be met. 4 Procedure 4.1 Connect the water inlet connection of the appliance under test to the test pipe as shown inFigure 1. If the appliance has more than one water inlet connection, connect the connection or connections not connected to the vacuum test apparatus to a water supply at the maxim
27、um working pressure specified for the appliance. 4.2 Establish and maintain the critical water level. 4.3 Close the full-way valve. 4.4 Evacuate the vacuum vessel to an absolute pressure of0.2bar as indicated by vacuum gauge A inFigure 1. 4.5 Open the full-way valve. 4.6 Read the vacuum gauge B. Che
28、ck that the absolute pressure does not exceed0.5bar for a period of at least5s. 4.7 Check that no water collects in the water trap. 5 Criterion If the conditions of choking flow are met (see3.1) and no water from or downstream of the appliance is drawn into the pipework upstream of the vacuum test c
29、onnection as shown by collection of water in the water trap, the appliance is deemed to have passed the test. 1) 1 bar = 10 5N/m 2= 100 kPa. All pressures are gauge pressures unless otherwise stated.BS 6280:1982 2 BSI 08-1999 Table 1 Recommended vacuum vessel capacities Nominal size of appliance inl
30、et connection Recommended minimum capacity of vacuum vessel mm m 3 u 22 0.25 22u 54 0.75 54u 76.1 2 76.1 u 108 4 108u 159 7 NOTEDrawing is diagrammatic only. Figure 1 Arrangement of apparatus for vacuum testBS 6280:1982 BSI 08-1999 Publications referred to BS 1780, Bourdon tube pressure and vacuum g
31、auges. BS 1780-2, Metric units. BS 6281, Devices without moving parts for the prevention of contamination of water by backflow 2) . BS 6282, Devices with moving parts for the prevention of contamination of water by backflow 2) . 2) Referred to in the foreword only.BS 6280:1982 BSI 389 Chiswick High
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