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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 6920 : Subsection 2.2.
2、3 : 1996 ICS 13.060.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Suitability of non-metallic products for use in contact with water intended for human consumption with regard to their effect on the quality of the water Part 2. Methods of test Section 2.2 Taste of water S
3、ubsection 2.2.3 Method of testing tastes imparted to water by hoses for conveying water for food and drink preparation Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:51 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having been prepared under the direction of the Hea
4、lth and Environment Sector Board, was published under the authority of the Standards Board and comes into effect on 15 December 1996 BSI 1996 First published June 1990 Second edition December 1996 The following BSI references relate to the work on this standard: Committee reference EH/3/7 Draft for
5、comment 95/521399 DC ISBN 0 580 26287 1 BS 6920 : Subsection 2.2.3 : 1996 Amendments issued since publication Amd. No.DateText affected Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee EH/3, Water quality, to Subcommittee
6、EH/3/7, Effects of materials on water quality, upon which the following bodies were represented: Association of Manufacturers of Domestic Electrical Appliances Automatic Vending Association of Britain British Adhesives and Sealants Association British Bathroom Council British Cement Association Brit
7、ish Iron and Steel Producers Association British Malleable Tube Fittings Association British Non-ferrous Metals Federation British Plastics Federation British Plumbing Fittings Manufacturers Association British Rubber Manufacturers Association Limited British Valve and Actuator Manufacturers Associa
8、tion British Water Cadmium Association Department of the Environment (Drinking Water Inspectorate) Department of the Environment for Northern Ireland Department of Trade and Industry (Laboratory of the Government Chemist) Ductile Iron Producers Association Galvanizers Association Institute of Plumbi
9、ng Lead Development Association Pipeline Industries Guild Pipeline Protection Association Scottish Association of Directors of Water and Sewerage Services UK Water Byelaws Scheme Water Research Centre Water Services Association of England and Wales Zinc Development Association Licensed Copy: sheffie
10、ldun sheffieldun, na, Tue Dec 05 01:30:51 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6920 : Subsection 2.2.3 : 1996 BSI 1996i Contents Page Committees responsibleInside front cover Forewordii Method Introduction1 1Scope1 2References1 3Definitions1 4Principle1 5Reagents1 6Apparatus1 7Samples1 8Tes
11、t procedure1 9Expression of results2 10Test report2 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:51 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii BSI 1996 BS 6920 : Subsection 2.2.3 : 1996 Foreword This Subsection of BS 6920 has been prepared by Su
12、bcommittee EH/3/7 under the direction of the Health and Environment Sector Board. This Subsection of BS 6920 supersedes BS 6920 : Subsection 2.2.3 : 1990, which is withdrawn. This edition introduces technical changes but it does not reflect a full review or revision of the standard, which will be un
13、dertaken in due course. Minor modifications have been introduced to clarify the test method. BS 6920 is published in several Parts, namely Part 1 Specification, Part 2 Methods of test and Part 3 High temperature tests. Part 2 is further subdivided into a number of Sections and Subsections as follows
14、: Section 2.1Samples for testing Section 2.2Taste of water Subsection 2.2.1General method of test Subsection 2.2.2Method of testing tastes imparted to water by hoses Subsection 2.2.3Method of testing tastes imparted to water by hoses for conveying water for food and drink preparation Section 2.3Appe
15、arance of water Section 2.4Growth of aquatic micro-organisms Section 2.5The extraction of substances that may be of concern to public health Section 2.6The extraction of metals Compliance with a British Standard does not of itself confer immunity from legal obligations. Licensed Copy: sheffieldun sh
16、effieldun, na, Tue Dec 05 01:30:51 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 19961 BS 6920 : Subsection 2.2.3 : 1996 Method Introduction Flexible hoses are used for conveying water in equipment for food and drink preparation. Overnight, during shut-downs and at various other times, the water ma
17、y be static in these hoses for varying periods of time. With a high surface area of the material of the hose exposed to a relatively small volume of water, the water may readily pick up substances from the hose capable of producing a discernible taste. Additionally, the hose may react with any resid
18、ual chlorine in the water to produce a disinfectant-type taste. Experience has shown that, even when the water-contact material does not produce a taste in water, when fabricated into a complete hose, substances from the outer material may interact with the water-contact material in such a way as to
19、 produce a taste in the water. For these applications, it is therefore important not only to test the complete hose, including any reinforcements and outer layers, but to use a ratio of surface area of water-contact material to volume of water representative of the worst situation likely to be encou
20、ntered in practice. 1 Scope This Subsection of BS 6920 describes a method designed to assess the ability of flexible hoses (including reinforcements) to impart a discernible taste to water intended for use in the preparation of food and drinks. It is applicable only to the testing of hoses intended
21、for installation in equipment used for food and drink preparation. 2 References 2.1 Normative references This Subsection of BS 6920 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited
22、 publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this Subsection of BS 6920 only when incorporated in the reference by amendment or revision. For undated references, th
23、e latest edition of the cited publication applies, together with any amendments. 2.2 Informative references This Subsection of BS 6920 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the ins
24、ide back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this Subsection of BS 6920, the definitions given in BS 6920 : Subsection 2.2.1 apply. 4 Principle Lengths of hose are filled with test water for 24 h. This water is then diluted and assessed for t
25、he presence of any discernible taste, compared to the test water blank, by taste panellists. If a taste is detected then the same hoses are refilled with fresh test water for a further 24 h period. The water from this final soaking period is diluted and assessed by the taste panellists. The test pro
26、cedure is repeated using chlorinated test water. NOTE 1. The procedures for assessing the water samples for taste are described in full in BS 6920 : Subsection 2.2.1. NOTE 2. The procedures do not involve any testing of the outer layers of reinforced hoses on their own, but only as part of the compl
27、ete hoses. 5 Reagents The reagents shall be as given in BS 6920 : Subsection 2.2.1 : 1996. 6 Apparatus The apparatus shall be as given in BS 6920 : Subsection 2.2.1 : 1996. 7 Samples Samples of hoses shall conform to 5.2.9 of BS 6920 : Section 2.1 : 1996. If samples are taken from a reel of hose, tw
28、o samples shall be taken from one end of the reel, and two samples from the other end. 8 Test procedure WARNING. Conduct this test with due regard to the possible presence of substances in the extracts that may be hazardous to the health of the taste panellists. Only products found to conform to the
29、 microbial growth test requirement in clause 6 of BS 6920 : Part 1 and deemed suitable for contact with water intended for human consumption in accordance with clause 7 (toxicological test) of BS 6920 : Part 1 may be assessed in this test, unless details of the chemical composition and process of ma
30、nufacture of the sample(s) are known, and any possible hazard can be assessed. Instruct the taste panellists not to swallow any test extract under any circumstances Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:51 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 BSI 1996 BS 6920 : Subsect
31、ion 2.2.3 : 1996 8.1 Extraction procedures 8.1.1 Chlorine-free water 8.1.1.1 Extraction On the same day as testing is to start, rinse the inner surface of four 1 m lengths of the hose (see clause 7) using a minimum of 10 l of chlorine-free test water for each (see 6.2 of BS 6920 : Subsection 2.2.1 :
32、 1996) Clamp a 1 m length of hose from each end of the reel in a U bend configuration. Completely fill each length of hose using chlorine-free test water. Cover each end of the hoses with a fresh piece of aluminium foil. In addition, fill an empty 1 l test container conforming to 7.1 of BS 6920 : Su
33、bsection 2.2.1 : 1996 with chlorine-free test water; this constitutes the blank test. Seal the containers with fresh pieces of aluminium foil. Store the hose under test and the containers of water at either (232) C for (241) h for cold water testing, or at the selected temperature in the case of hig
34、h temperature tests in accordance with Part 3 of BS 6920. 8.1.1.2 Dilution At the end of the storage period, unclamp the hoses and transfer the contents of the hose to separate appropriately sized clean glass graduated measuring cylinders conforming to BS 604 and determine and record the volume of t
35、he water. To the water samples from the hoses add equal volumes of fresh chlorine-free test water (6.2 of BS 6920 : Subsection 2.2.1 : 1996). Instruct the taste panellists to assess these samples in accordance with 8.2. 8.1.2 Chlorinated water Repeat the procedure described in 8.1.1.1 using the othe
36、r two lengths of hose (see clause 7) and chlorinated test water (6.3 of BS 6920 : Subsection 2.2.1 : 1996) instead of chlorine-free water. After the extraction period, neutralize any free residual chlorine in the water from the hoses in accordance with 10.4.2 of BS 6920 : Subsection 2.2.1 : 1996, pr
37、epare the dilution (see 8.1.1.2) and instruct the taste panellists to taste the dilution prepared using chlorine-free water (see 8.2). 8.2 Tasting procedure Adjust the temperature of the diluted extracts and blank test water to (251) C by placing the containers in a temperature-controlled water bath
38、 conforming to 7.3 of BS 6920 : Subsection 2.2.1 : 1996. Remove the blank test from the water bath and pour off (305) ml of the water into a clean tasting glass conforming to 7.4 of BS 6920 : Subsection 2.2.1 : 1996. Instruct the taste panellists to take into the mouth whatever volume of water is co
39、mfortable and to hold it in the mouth for several seconds before discharging it without swallowing. If a taste is detected in the blank test water, then start the complete test again using fresh hose samples, fresh water and fresh test containers. Repeat this tasting procedure for each of the two di
40、luted extracts. If no taste is detected in either extract, record this result and discontinue the test. If a taste is detected record a description of the taste and, using the same two hose samples and the same type of test water, follow again the procedure in 8.1.1 or 8.1.2, as appropriate, ending
41、with the testing of the final diluted extracts. NOTE. A list of tastes commonly encountered is given in annex A of BS 6920 : Subsection 2.2.1 : 1996. 9 Expression of results Express the results in accordance with clause 11 of BS 6920 : Subsection 2.2.1 : 1996. 10 Test report In addition to the requi
42、rements for the test report given in items (a) to (j) of clause 12 of BS 6920 : Subsection 2.2.1 : 1996, the report shall include the following particulars: a) a description of the hose, including details of reinforcements and outer coverings; b) that extracts were prepared by filling lengths of hos
43、e with test water and subsequently diluting this with an equal quantity of test water; c) the length of the test sample; d) the internal diameter of the test sample; e) the surface area of the material in contact with the test water; f) the volume of test water contained within the test sample durin
44、g extraction; g) whether a taste was detected in the dilutions of either the first or second extracts from the hose samples; h) a statement as to whether or not the results obtained conform to clause 4 of BS 6920 : Part 1 : 1996. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:51 GMT+00
45、:00 2006, Uncontrolled Copy, (c) BSI BSI 1996 BS 6920 : Subsection 2.2.3 : 1996 List of references(see clause 2) Normative references BSI standards publications BRITISH STANDARDS INSTITUTION, London BS 604 : 1982Specification for graduated glass measuring cylinders BS 6920Suitability of non-metallic
46、 products for use in contact with water intended for human consumption with regard to their effect on the quality of the water BS 6920 : Part 2Methods of test BS 6920 : Section 2.1 : 1996Samples for testing BS 6920 : Section 2.2Taste of water BS 6920 : Subsection 2.2.1 : 1996General method of test B
47、S 6920 : Section 2.4 : 1996Growth of aquatic micro-organisms BS 6920 : Section 2.5 : 1996The extraction of substances that may be of concern to public health Informative references BSI standards publications BRITISH STANDARDS INSTITUTION, London BS 6920Suitability of non-metallic products for use in
48、 contact with water intended for human consumption with regard to their effect on the quality of the water BS 6920 : Part 1 : 1996Specification BS 6920 : Part 2Methods of test BS 6920 : Section 2.2Taste of water BS 6920 : Subsection 2.2.2 : 1996Method of testing tastes imparted to water by hoses BS
49、6920 : Section 2.3 : 1996Appearance of water BS 6920 : Section 2.6 : 1996The extraction of metals BS 6920 : Part 3 : 1990High temperature tests Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:51 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 389 Chiswick High Road London W4 4AL | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BSI British Standards Instit
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