1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-20822-6 SANS 5792:2008Edition 2 SOUTH AFRICAN NATIONAL STANDARD Resistance of crockery to crazing Published by Standards South Africa 1 dr
4、 lategan road groenkloof private bag x191 pretoria 0001 tel: 012 428 7911 fax: 012 344 1568 international code + 27 12 www.stansa.co.za Standards South Africa SANS 5792:2008 Edition 2 Table of changes Change No. Date Scope Foreword This South African standard was approved by National Committee StanS
5、A TC 5140.05, Crockery, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. This document was published in February 2008. This document supersedes SABS SM 792:1974 (edition 1). SANS 5792:2008 Edition 2 1 Resistance of crockery to crazing 1 Sc
6、ope This standard specifies a method for the determination of the resistance of crockery to crazing. 2 Apparatus Autoclave, designed for a steam pressure of at least 1,4 MPa, equipped with a safety valve, a blow-off valve, and a pressure gauge with an accuracy of 0,03 MPa, and a source of heat capab
7、le of maintaining the pressure of the steam in the autoclave at 0,70 MPa 0,03 MPa. 3 Sampling Take a laboratory sample as specified in the relevant product standard. Where no standard exists, take the laboratory sample as agreed upon between the test laboratory and the manufacturer to ensure a reaso
8、nable and acceptable reliability at a reasonable and acceptable confidence level. 4 Procedure 4.1 With the apparatus at ambient temperature, place enough distilled water (also at ambient temperature) in the autoclave to ensure that after the test some water will remain. Place the test specimens in t
9、he autoclave on supports that are at least 50 mm above the water level. Fasten the autoclave head securely in place. 4.2 Gradually heat the water in the autoclave and ensure (by keeping the blow-off valve open for several minutes after steam begins to escape) that most of the air is expelled. Then c
10、lose the blow-off valve and so increase the steam pressure (at a uniform rate) that the pressure reaches a value of 0,70 MPa within 45 min to 60 min. 4.3 Maintain the pressure at 0,70 MPa 0,03 MPa for 2 h. 4.4 Shut off the heat source, release the steam pressure immediately by opening the blow-off v
11、alve, and then loosen the autoclave head. 4.5 Allow the autoclave to cool to ambient temperature. 4.6 Remove the autoclave head and the test specimens. 4.7 Examine each specimen under oblique lighting for failure, i.e. for the presence of crazes or cracks (or both) that are visible to the unaided ey
12、e1). 1) The application of a suitable ink or dye solution to the glazed surfaces will aid the detection of failures. SANS 5792:2008 Edition 2 2 5 Test report Report the following information: a) all the data needed to identify the laboratory sample tested; b) confirmation that the test was carried out in accordance with this standard; c) any deviation from this standard; and d) the presence of crazes or cracks (or both) that are visible to the unaided eye. Standards South Africa
