1、BRITISH STANDARD BS 1344-16: 1998 ISO 2747:1998 Incorporating Amendment No. 1 Methods of testing vitreous enamel finishes Part 16: Resistance to thermal shock of coatings on cooking utensils ICS 25.220.50; 97.040.60BS1344-16:1998 This British Standard, having been prepared under the directionof the
2、Sector Board forMaterials and Chemicals, waspublished under the authorityof the Standards Boardand comes into effect on 15 June1998 BSI 05-1999 ISBN 0 580 29973 2 Amendments issued since publication Amd. No. Date Comments 10220 January 1999 Indicated by a sideline in the marginBS1344-16:1998 BSI 05-
3、1999 i Contents Page National foreword ii Foreword ii 1 Scope 1 2 Definitions 1 3 Principle 1 4 Apparatus 1 5 Test specimens and sampling 1 6 Procedure 1 7 Expression of results 2 8 Test report 2 Annex A (informative) Reasons for the test conditions specified Inside back cover Table 1 Hot-plates to
4、be used to heat specimens 1BS1344-16:1998 ii BSI 05-1999 National foreword This British Standard reproduces verbatim ISO2747:1998 and implements it as the UK national standard. It supersedes BS1344-16:1975, which is withdrawn. The UK participation in its preparation was entrusted to Technical Commit
5、tee STI/36, Vitreous enamel coatings, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and
6、 European developments and promulgate them in the UK. The standard is now published in22 parts: Part 1: Determination of resistance to thermal shock of coatings on articles other than cooking utensils and fabricated sheet steel components; Part 2: Resistance to citric acid at room temperature; Part
7、3: Determination of resistance to sulphuric acid at room temperature; Part 4: Resistance to abrasion (obsolescent); Part 5: Determination of resistance to hot detergent solutions used for washing textiles; Part 6: Resistance to alkali; Part 7: Determination of resistance to heat; Part 8: Determinati
8、on of resistance to boiling citric acid; Part 9: Determination of resistance to boiling water and water vapour; Part 10: Determination of resistance to condensing hydrochloric acid vapour; Part 11: High voltage test for enamelled articles for service under highly corrosive conditions; Part 12: Produ
9、ction of specimens for testing coatings on sheet steel; Part 13: Production of specimens for testing coatings on cost iron; Part 14: Apparatus for testing with acid and neutral liquids and their vapours; Part 15: Apparatus for testing with alkaline liquids; Part 16: Resistance to thermal shock of co
10、atings on cooking utensils; Part 17: Resistance to hot sodium hydroxide solution; Part 18: Determination of fluidity behaviour Fusion flow test; Part 19: Apparatus for determination of resistance to hot detergent solutions used for washing textiles; Part 20: Low voltage test for detecting and locati
11、ng defects; Part 21: Determination of the resistance of vitreous enamelled articles to impact Pistol test; Part 22: Determination of resistance to thermal shock of coatings for fabricated sheet steel components such as burners and pan supports for cookers. A list of organizations represented on this
12、 committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or
13、 by using the “Find” facility of the BSI Standards Electronic Catalogue.BS1344-16:1998 BSI 05-1999 iii 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 Standa
14、rd does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, theISOtitle page, page ii, pages 1 and 2, an inside back cover and abackcover. This standard has been updated (see copyright date) and may have
15、had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS1344-16:1998 ii BSI 05-1999 Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepari
16、ng International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in lia
17、ison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publicati
18、on as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO2747 was prepared by Technical Committee ISO/TC107, Metallic and other inorganic coatings, Subcommittee SC6, Vitreous and porcelain enamels. This second edition cancels and
19、 replaces the first edition (ISO2747:1973), which has been technically revised. Annex A of this International Standard is for information only. Descriptors: Non-metallic coatings, protective coatings, enamels, vitreous enamels, porcelain enamels, kitchen utensils, tests, thermal shock tests, determi
20、nation, thermal shock resistance.BS1344-16:1998 BSI 05-1999 1 1 Scope This International Standard specifies a method of determining, by successive thermal shock tests, the behaviour of vitreous and porcelain enamelled cooking utensils and similar articles under sudden changes of temperature (resista
21、nce to thermal shock). 2 Definitions For the purposes of this International Standard, the following definitions apply. 2.1 thermal shock test series of operations commencing with the pouring of cold water into the heated test specimen and ending when the thermal shock temperature for the subsequent
22、thermal shock test has been reached 2.2 thermal shock temperature temperature to which the test specimen is heated before being chilled with cold water 2.3 thermal shock resistance difference between the thermal shock temperature and the water temperature at which the test specimen shows the first d
23、amage on chilling or during subsequent heating 2.4 damage chipping or tension cracks in the enamel visible at a distance of250mm by normal sight or made visible by using coloured penetrating fluids 3 Principle A series of single thermal shock tests is conducted with a temperature increase of20C betw
24、een each thermal shock obtained by heating the test specimen from the outside and then chilling it inside with water at20C. For the first test, the thermal shock temperature amounts to200C. The test ends when the first visible damage occurs. 4 Apparatus 4.1 Electric hot-plate, capable of being conti
25、nously temperature controlled, and of diameter and maximum output as giver in Table 1. Table 1 Hot-plates to be used to heat specimens For testing specimens with an uneven base, the hot-plate shall be surmounted by a ring filled with copper grit of grain size0,100mm to0,125mm. 4.2 Temperature measur
26、ing device, quickly indicating, accurate to2C. 4.3 Thermometer for measuring the temperature of the water. 4.4 Chamois leather, paper towel or laboratory tissue. 4.5 Water receptacle. 4.6 Stop-watch. 5 Test specimens and sampling 5.1 Use the utensils to be tested as test specimens without any modifi
27、cation. 5.2 The test specimens shall be representative of the entire consignment. The sampling plan shall be agreed upon between the interested parties. 5.3 At least three test specimens shall be tested. 6 Procedure 6.1 General specifications NOTEAnnex A outlines the reasons underlying the selection
28、 of the test conditions specified in this International Standard. For each thermal shock test, fill the test specimens with water at a temperature of20C 1C, to a depth of30mm if possible. If it is not possible to fill the specimens to a depth of30mm, report the actual depth in the test report. Ensur
29、e that more water is available at20C1C (see6.2.1). Heat the test specimens using the preheated electric hot-plate(4.1), operated at its maximum output. Ensure that the maximum output is such that the test temperature is achieved no earlier than5min after commencement of heating. Internal diameter of
30、 specimen Hot-plate Diameter Maximum output mm mm W Up to 180 145 1000 100 Over 180 and up to 220 180 1500 150 Over 220 220 2000 200BS1344-16:1998 2 BSI 05-1999 Measure the temperature inside at the base of the test specimen at a distance of a quarter of the internal diameter from the side of the te
31、st specimen. 6.2 First thermal shock test 6.2.1 When a temperature of200C 5C (the thermal shock temperature) is reached, fill the test specimen to a depth of30mm with the water at20C 1 C in one pouring. After5s 1 s remove the test specimen from the hot-plate, fill it completely with water at a tempe
32、rature of20C 1C and cool rapidly by placing it in water also at a temperature of20C 1C. When the test specimen reaches room temperature(23C 1C) pour out the water, dry the test specimen with the chamois leather, the paper towel or the laboratory tissue(4.4) and examine it for damage(2.4). 6.2.2 If t
33、here is no damage, heat the test specimen to220C 5C (the thermal shock temperature of the second thermal shock test). If damage occurs during heating, the test is finished. In this case, take the temperature of200C as the thermal shock temperature. For testing further test specimens, choose a temper
34、ature lower than200C for the first test and state this in the test report. 6.3 Second and further tests 6.3.1 If the test specimen comes through the first test undamaged, repeat the test at a temperature of220C 5 C. Carry out the second test as described in6.2.1. The temperature shall be now240C 5C
35、when heating up according to6.2.2. If any damage occurs, the test is finished and the thermal shock temperature is then taken as being220C. 6.3.2 If no damage occurs, carry out further tests as described with a temperature increase of20C between successive tests until damage occurs. 7 Expression of
36、results 7.1 Average thermal shock temperature Calculate the arithmetic average thermal shock temperature from the thermal shock temperatures of the individual test specimens at which the first damage is observed. If one of the individual values of three tests differs by more than50C from the average
37、 thermal shock temperature, conduct two further tests. Then calculate the arithmetic average of the five values. 7.2 Average thermal shock resistance Calculate the average thermal shock resistance by subtracting the water temperature(20C) from the average thermal shock temperature calculated in acco
38、rdance with7.1. 8 Test report The test report shall include the following information: a) reference to this International Standard, i.e.“determined in accordance with ISO2747:1998”; b) a description of the test specimen (shape, internal diameter, thickness of enamel, volume, mass, labelling); c) the
39、 sampling plan used; d) the number of test specimens tested; e) the diameter and maximum output of the hot-plate and whether a surmounting ring was used; f) the thermal shock temperature at which the enamel first showed damage (individual and average values); g) the average thermal shock resistance;
40、 h) the type of damage to the enamel and, if necessary, a photograph of the damage; i) the depth of water used for thermal shock if it was not possible to fill the test specimen to a depth of30mm.BS1344-16:1998 BSI 05-1999 Annex A (informative) Reasons for the test conditions specified A finished gl
41、ass coating is generally under a desired compressive stress. The stress is more or less altered under conditions of use; for example, cooking utensils are heated and cooled in such a way that the enamel can be subjected to tensile stress to which it is sensitive. The danger of this happening to a gi
42、ven enamelled article increases with the differences in temperature to which it is subjected during thermal shock. It is for this reason that the test for thermal shock resistance is carried out at increasing thermal shock temperatures. The tendency, however, for the occurrence of tensile stress doe
43、s not depend solely on thermal shock but also on a number of other factors, especially the coefficient of expansion of the enamel and of the metal, the thickness of the enamel coating, the modulus of elasticity and the thermal conductivity. The thermal shock test(2.1) was chosen because cracks in th
44、e enamel often are so fine that they are not visible. They can be recognized, however, during the subsequent heating because water which has remained in the cracks evaporates quickly (see6.2.1) and causes the adjacent enamel to chip. The thermal shock temperature just before the damage incurred is t
45、herefore critical to the evaluation.BS1344-16: 1998 ISO 2747:1998 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
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