1、BRITISH STANDARD BS7431:1991 ISO9808:1990 Method for Assessing solar water heaters Elastomeric materials for absorbers, connecting pipes and fittingsBS7431:1991 This BritishStandard, having been prepared under the directionof the Refrigeration Heating and Air Conditioning Standards Policy Committee,
2、 waspublished under the authorityof the Standards Boardand comes into effect on 29March1991 BSI01-2000 The following BSI references relate to the work on this standard: Committee reference RHE/25 Draft for comment88/77913 DC ISBN 0 580 19480 9 Committees responsible for this BritishStandard The prep
3、aration of this BritishStandard was entrusted by the Refrigeration Heating and Air Conditioning Standards Policy Committee (RHE/-) to Technical Committee RHE/25, upon which the following bodies were represented: Association for Consumer Research (ACRE) Association of Consulting Engineers British Gas
4、 plc British Precast Concrete Federation Ltd Chartered Institution of Building Services Engineers Copper Development Association Cranfield Institute of Technology Department of the Environment Department of the Environment (Building Research Establishment) Design Council Institution of Gas Engineers
5、 International Solar Energy Society National Centre for Alternative Technology Royal Institute of British Architects Solar Trade Association Swimming Pool and Allied Trades Association Ltd University College Cardiff Water Byelaws Advisory Service Amendments issued since publication Amd. No. Date Com
6、mentsBS7431:1991 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Test pieces 1 4 Qualification tests 1 5 Ageing tests 2 6 Immersion in heat-exchange fluids 2 7 Test report 2 Table 1 Test temperature for ageing tests 2 Ta
7、ble 2 Test report 3 Publication(s) referred to Inside back coverBS7431:1991 ii BSI 01-2000 National foreword This BritishStandard has been prepared under the direction of the Refrigeration Heating and Air Conditioning Standards Policy Committee and implements a corresponding International Standard i
8、n the development of which the UK has played an active part. This BritishStandard is identical with ISO9808:1990 “Solar water heaters Elastomeric materials for absorbers, connecting pipes and fittings Method of assessment”, published by the International Organization for Standardization (ISO) and pr
9、epared by Technical Committee ISO/TC180, Solar heating. The Technical Committee has reviewed the provisions of ISO4632-1 to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. Related BritishStandards to ISO34-1 1)and ISO4632-1 are
10、 BS903-A3:1982 and BS5176:1975 respectively. 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 obligatio
11、ns. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, 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 insid
12、e front cover. Cross-references International Standard Corresponding BritishStandard ISO48:1979 BS903 Methods of testing vulcanized rubber Part A26:1969 Determination of hardness (Technically equivalent) ISO188:1982 Part A19:1986 Heat resistance and accelerated ageing tests (Identical) ISO471:1983 P
13、art A35:1985 Temperatures, humidities and times for conditioning and testing of test pieces (Identical) BS5173 Methods of test for rubber and plastics hoses and hose assemblies ISO1402:1984 Section102.1:1985 Hydrostatic tests (Identical) ISO1431-1:1989 Part A43:1990 Determination of resistance to oz
14、one cracking (static strain test) (Identical) ISO1653:1975 Part A39:1980 Determination of compression set under constant deflection at low temperatures (Identical) ISO1817:1985 Part A16:1987 Determination of the effect of liquids (Identical) ISO4661-1:1986 Part A36:1987 Preparation of samples and te
15、st pieces (Identical) BS5173 Methods of test for rubber and plastics hoses and hose assemblies ISO7326:1984 Section106.3:1986 Determination of ozone resistance (Identical) 1) In preparation.BS7431:1991 BSI 01-2000 1 1 Scope This International Standard specifies a means of assessing elastomeric mater
16、ials for use in the manufacture of absorbers, connecting piping and fittings for use in solar water heaters. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the
17、editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of curre
18、ntly valid International Standards. ISO34-1:, Rubber, vulcanized Determination of tear strength Part1: Trouser, angle and crescent test pieces 2) . ISO37:1977, Rubber, vulcanized Determination of tensile stress-strain properties. ISO48:1979, Vulcanized rubbers Determination of hardness (Hardness bet
19、ween30 and85IRHD). ISO188:1982, Rubber, vulcanized Accelerated ageing or heat-resistance tests. ISO471:1983, Rubber Standard temperatures, humidities and times for the conditioning and testing of test pieces. ISO1402:1984, Rubber and plastics hoses and hose assemblies Hydrostatic testing. ISO1431-1:
20、1989, Rubber, vulcanized or thermoplastic Resistance to ozone cracking Part1: Static strain test. ISO1653:1975, Vulcanized rubbers Determination of compression set under constant deflection at low temperatures. ISO1817:1985, Rubber, vulcanized Determination of the effect of liquids. ISO4661-1:1986,
21、Rubber, vulcanized Preparation of samples and test pieces Part1:Physical tests. ISO7326:1984, Rubber and plastics hoses Assessment of ozone resistance under static conditions. 3 Test pieces The test pieces shall be as specified in the relevant test method. The test pieces required for the tests spec
22、ified in4.3 and4.7 should preferably be cut from samples of the finished product. Where this is not practicable test pieces may be cut from sheet material. If it is required to separate a section of fluid passage from a finished absorber, the test piece shall be prepared in accordance with ISO4661-1
23、. 4 Qualification tests 4.1 Hardness Hardness shall preferably be tested using the normal test set out in ISO48. The test may also be performed using the micro-test set out in ISO48, on a test piece of thickness not less than2mm, but it should be noted that the two methods may give a different resul
24、t on a particular test piece. In case of doubt, the results of the normal test shall be considered as definitive. 4.2 Compression set at low temperature Compression set shall be tested in accordance with ISO1653, using a small-type test piece maintained under a compression of25% for24h ata temperatu
25、re of40 C. 4.3 Resistance to ozone Resistance to ozone shall be tested in accordance with ISO1431-1, procedure A, for test pieces other than hose or absorber fluid passages. The test period shall be7days, and the ozone concentration shall be200pphm 20pphm. The temperature of test shall be40 C 2 C an
26、d the elongation of the test piece shall be20%. For hose or absorber fluid passages, the test shall be carried out in accordance with ISO7326. 4.4 Tear strength Tear strength shall be tested in accordance with ISO34-1, method C, using a crescent test piece. 4.5 Tensile strength Tensile strength shal
27、l be tested in accordance with ISO37, using a type2 dumb-bell test piece. 2) To be published.BS7431:1991 2 BSI 01-2000 4.6 Elongation at break Elongation at break shall be tested in accordance with ISO37, using a type2 dumb-bell test piece. 4.7 Burst pressure Burst pressure of hose or absorber fluid
28、 passages shall be tested in accordance with the relevant requirements of ISO1402. The test piece shall beatleast450mm long for items of internal diameter76mm or smaller, and at least600mm long for larger items. NOTE 1Burst pressure tests carried out at ambient temperature cannot be taken as indicat
29、ive of the burst pressure at elevated temperatures. 5 Ageing tests 5.1 Artificial ageing The test pieces required for the tests specified in5.2 shall be subjected to an ageing test in an air-oven in accordance with ISO188, for a period of14days at a test temperature related to the maximum service te
30、mperature as listed in Table 1. Upon being removed from the oven, the test pieces shall be conditioned for24h in a standard atmosphere at23 C and50% humidity, in accordance with ISO471. Table 1 Test temperature for ageing tests 5.2 Properties after ageing The following properties of the material sha
31、ll be determined upon completion of the artificial ageing: a) hardness, in accordance with4.1; b) resistance to ozone, in accordance with4.3; c) tensile strength, in accordance with4.5; d) elongation at break, in accordance with4.6; e) burst pressure, in accordance with4.7. 6 Immersion in heat-excha
32、nge fluids 6.1 Immersion in propylene glycol If the material is to be used in conjunction with propylene glycol, the test pieces required for the tests specified in6.3 shall be immersed in propylene glycol at the appropriate test temperature given inTable 1 for a period of7days in accordance with IS
33、O1817:1985, clause11. 6.2 Immersion in other heat-exchange fluids If the material is to be used in conjunction with aheat-exchange fluid other than propylene glycol,theimmersion shall be performed using theheat-exchange fluid proposed. The test pieces required for the tests specified in6.3 shall be
34、immersed in the heat-exchange fluid at the appropriate test temperature given in Table 1 for a period of7days in accordance with ISO1817:1985, clause11. 6.3 Properties after immersion The following properties of the material shall be determined upon completion of the immersion specified in6.1 or, if
35、 appropriate,6.2: a) hardness, in accordance with4.1; b) tensile strength, in accordance with4.5; c) elongation at break, in accordance with4.6; d) burst pressure, in accordance with4.7. 7 Test report The results of the tests described in clauses4, 5 and6 shall be presented as shown in Table 2. Type
36、 a Test temperature bMaximum service temperature C C B C D E F G H 100 125 150 175 200 225 250 70 100 125 150 175 200 225 a Type (heat resistance) classification in accordance with ISO4632-1:1982, Rubber, vulcanized Classification Part1: Description of the classification system. b The test temperatu
37、res are one step higher than the maximum service temperature to which the material may be subjected.BS7431:1991 BSI 01-2000 3 Table 2 Test report Property of material Results a Qualification test (clause4) After ageing (clause5) After immersion in propylene glycol (clause6) After immersion in other
38、fluid (to be specified) (clause6) Hardness IRHD b Tensile strength (MPa) Elongation at break (%) Burst pressure of hose (MPa) Compression set at low temperature (%) NR NR NR Resistance to ozone (condition of test piece andany cracking) NR NR Tear strength crescent test piece (kN/m) NR NR NR a NR, no
39、t required. b IRHD, International Rubber Hardness Degrees.4 blankBS7431:1991 BSI 01-2000 Publication(s) referred to See national foreword.BS7431:1991 ISO9808:1990 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing Br
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