1、BRITISH STANDARD BS3517:1991 ISO718:1990 Methods for Thermal shock tests on laboratory glasswareBS3517:1991 This British Standard, having been prepared under the directionof the Laboratory Apparatus Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeff
2、ect on 29 March1991 BSI10-1999 First published June1962 Second edition April1983 Third edition March1991 The following BSI references relate to the work on this standard: Committee reference LBC/8 Draft for comment89/56194DC ISBN 0 580 19489 2 Committees responsible for this British Standard The pre
3、paration of this British Standard was entrusted by the Laboratory Apparatus Standards Policy Committee (LBC/-) to Technical Committee LBC/8, upon which the following bodies were represented: British Glass Manufacturers Confederation Society of Glass Technology Amendments issued since publication Amd
4、. No. Date CommentsBS3517:1991 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Definitions 1 3 Apparatus 1 4 Sampling 1 5 Procedure 1 6 Expression of results 2 7 Test report 2 Annex A (informative) Bibliography 3 Publication(s) referred to Insid
5、e back coverBS3517:1991 ii BSI 10-1999 National foreword This British Standard has been prepared under the direction of the Laboratory Apparatus Standards Policy Committee and supersedes BS3517:1983, which is withdrawn. It is identical with ISO718:1990 “Laboratory glassware Thermal shock and thermal
6、 shock endurance Test methods” published by the International Organization for Standardization (ISO). It has been prepared by Subcommittee5, “Quality of glassware”, of Technical Committee48 “Laboratory glassware and related apparatus”, with the active participation and approval of the UK. Additional
7、 information. Reference is made in clause1 of the International Standard to ISO7459 for information only. There is no corresponding British Standard to ISO7459. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for t
8、heir 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, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see
9、copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS3517:1991 BSI 10-1999 1 1 Scope This International Standard specifies a thermal shock test and the procedure for determining the thermal shock endurance for laboratory
10、glassware in the condition received by the customer. This International Standard does not apply to fused silica ware and annealed containers made from soda-lime-silicate glass. Annealed containers made from soda-lime-silicate glass shall be tested according to ISO7459. 2 Definitions For the purposes
11、 of this International Standard, the following definitions apply. 2.1 thermal shock a sudden change in temperature applied to laboratory glassware 2.2 thermal shock endurance %t 50 a temperature difference interpolated by linear regression at which 50% of the samples will probably fail 2.3 temperatu
12、re variation the difference at any moment between the temperature at the centre of the working space and at any other point in the working space of the cold water bath or the test oven 2.4 temperature fluctuation the short term changes in temperature at any point in the working space of the cold wat
13、er bath or the test oven 3 Apparatus 3.1 Cold water bath, comprising a bath or tank capable of containing at least five times the total volume of the samples being tested at one time. It shall be fitted with a water circulator, a thermometer and a thermostatic control capable of maintaining the wate
14、r temperature to within 1 C of a specified lower temperature, t 2 , within the range0 C to27 C. NOTE 1The total volume of the samples is taken as the sum of the volume of the individual samples when each is regarded as being solid. 3.2 Test oven, preferably electrically heated with a temperature ran
15、ge up to at least300 C. It shall be fitted with an air circulating device to ensure that the temperature variation does not exceed 5 C and a thermostatic control capable of maintaining the test oven temperature fluctuation within 1 C up to180 C and within 2 C between180 C and300 C. 3.3 Tongs, with t
16、ips protected by a heat resisting material such as glass or mineral wool. 3.4 Gloves, gauntlet-type and preferably made from an asbestos-substitute material. 3.5 Basket, for testing two or more samples simultaneously. It shall be made out of or coated with a material which will not scratch or scuff
17、the samples during the test procedure. It shall be capable of holding the samples upright and separate and of allowing a free passage of water and air between them. It shall prevent the sample from floating when immersed. For the multiple testing of samples, it may be combined with an automatic devi
18、ce for placing the basket of samples in the test oven(3.2) and transferring it to the cold water bath(3.1). 4 Sampling The test shall be performed on a predetermined number of articles. The number of articles to be taken as samples from a consignment should be specified in the appropriate standard f
19、or the type of article to be tested. In default of this the number should be agreed between the interested parties. The articles used for the test shall not have been subjected to any other mechanical or thermal test procedure which could adversely affect their thermal shock endurance. The samples s
20、hall be selected to provide the information which is required from the particular test. If the selecting procedure is not specified, the samples shall be taken at random. 5 Procedure 5.1 Remove any dirt or loose debris from the samples and dry them if necessary. 5.2 Place the samples, either separat
21、ely or contained in the basket(3.5), in the test oven(3.2) which has been previously heated to the upper temperature, t 1 . Maintain the samples at that temperature for a period of time sufficient to ensure that the glass has reached temperature equilibrium;30min is normally sufficient. NOTE 2The ti
22、me required to reach temperature equilibrium depends on the maximum glass thickness and experience has shown that at least6min/mm is needed.BS3517:1991 2 BSI 10-1999 Place the cold water bath(3.1) near the test oven and achieve and maintain it at the specified lower temperature, t 2 , within the ran
23、ge0 C to27 C. 5.3 Then remove the samples from the test oven(3.2) either one at a time, holding them with the tongs(3.3) or gloves(3.4) if the samples are large, or contained in the basket(3.5). Immerse the samples which are not containers as completely as possible in the cold water bath(3.1), for a
24、 specified period of at least8s but not more than2min. Keep the tips of the tongs or the fingers of the gloves dry. Do not handle hot glassware with wet tips or gloves. Immerse containers to half the total height less the neck if any. When the rims of the articles are to be tested, immerse the sampl
25、es vertically, rim first, to a depth of about25mm and take care that entrapped air does not escape. The process of transferring the samples, timed from opening the test oven to the immersion, shall be completed in5s 1s for each sample or for the basket containing the samples. The difference in tempe
26、rature between the test oven and the cold water bath shall not be more than 3 C from the required value at the time of transference. 5.4 Then remove the samples from the cold water bath and evaluate them immediately according to6.1. 5.5 For determining the thermal shock endurance, repeat the testing
27、 according to5.2 to5.4 with increasing temperature difference values, t 1 t 2 , until all of the samples have failed. The increments of temperaturet 1 , shall be5 C for t 1 t 2 k 100 C and10 C for t 1 t 2 100 C. 6 Expression of results 6.1 Samples which do not chip, crack or break after removal from
28、 the cold water bath(3.1) are considered to have passed the thermal shock test at the temperature difference of t 1 t 2 . 6.2 For the thermal shock endurance, record the number of failures at each temperature difference and determine the %t 50value and the standard deviation s from a graph of the cu
29、mulative percentage of failures against the temperature difference at which the samples failed. 7 Test report The test report shall include: a) a reference to this International Standard; b) an identification of the article tested (e.g.shape, volume, mass, description, glass colour, surface conditio
30、n); c) the number of articles in the consignment; d) the number of samples taken for the test and sampling method; e) for the thermal shock test: the temperature difference t 1 t 2in degrees Celsius, the number of samples which passed the test; f) for the thermal shock endurance test: the temperatur
31、e difference %t 50at which50% of the samples will probably fail; the standard deviation s.BS3517:1991 BSI 10-1999 3 Annex A (informative) Bibliography 1 ISO7459:1984, Glass containers Thermal shock resistance and thermal shock endurance Test methods.4 blankBS3517:1991 BSI 10-1999 Publication(s) refe
32、rred to See national foreword.BS3517:1991 ISO718:1990 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorpor
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