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 978-0-626-21854-6 SANS 5872:2008Edition 2SOUTH AFRICAN NATIONAL STANDARD Compression set of vulcanized rubbers under constant deflection Published b
4、y SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001 Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 5872:2008 Edition 2 Table of changes Change No. Date Scope Foreword This South African standard was approved by National Committee SABS TC 45, Rubb
5、er and rubber products, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in November 2008. This document supersedes SABS SM 872:1976 (first edition). This document is based on ISO 815. SANS 5872:2008 Editio
6、n 2 1 Contents Page Foreword 1 Scope . 3 2 Normative references . 3 3 Apparatus . 3 4 Preparation of test specimens 4 5 Procedure . 4 6 Calculations 4 SANS 5872:2008 Edition 2 2 This page is intentionally left blank SANS 5872:2008 Edition 2 3 Compression set of vulcanized rubbers under constant defl
7、ection 1 Scope This standard specifies the procedure for testing a compression set of vulcanized rubbers under constant deflection. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies.
8、For undated references, the latest edition of the referenced document (including any amendments) applies. Information on currently valid national and international standards can be obtained from the SABS Standards Division. SANS 5867 (SABS SM 867), Preparation of samples of vulcanized rubbers for te
9、sting. SANS 5868 (SABS SM 868), Conditioning of vulcanized rubbers. 3 Apparatus 3.1 Compression apparatus A jig consisting of two or more clean, rigid, parallel, flat, highly polished plates, chromium plated or of stainless steel, each of size approximately 200 mm 75 mm and bolted together. 3.2 Spac
10、ers Steel spacers of such a size that contact with the compressed test specimens is avoided, and of thickness 75 % of that of the specimens under test. 3.3 Oven A uniformly-heated air circulating oven maintained at a temperature of (70 1) C. 3.4 Thickness gauge A micrometer dial type gauge capable o
11、f measuring accurately to 0,01 mm. 3.5 Cutter A rotating circular die type cutter suitable for cutting discs of diameter (29,0 0,5) mm and lubricated with soapy water. SANS 5872:2008 Edition 2 4 4 Preparation of test specimens From each test sample after, when relevant, preparing it in accordance wi
12、th SANS 5867 cut, by means of the cutter, enough discs to provide three specimens each of thickness (12,5 0,5) mm and condition them in accordance with SANS 5868. NOTE Not more than seven layers of rubber may be used to achieve the required thickness. 5 Procedure 5.1 Using the thickness gauge, deter
13、mine the thickness of each specimen. So place the specimens between the plates that they do not contact each other, or the bolts, or the spacers, and that the flat surfaces are in contact with the plates. 5.2 Using the spacers, tighten the bolts until the distance between the plates is such that the
14、 specimens are compressed to 75 % of their original thickness. 5.3 Immediately place the assembly in the oven for a period of (22-24) h. 5.4 Remove the assembly and while still hot remove the test specimens and condition them in accordance with SANS 5868 on a wooden surface for a period of (30 3) mi
15、n. Remeasure the thickness of each test specimen. 6 Calculations Calculate the compression set ( s ) of each test specimen as follows: oo1ss%= 10ttCttwhere tois the initial thickness of the test specimen, measured in millimeters. t1is the thickness of the test specimen after recovery, measured in mi
16、llimeters. tsis the thickness of the spacer, measured in millimeters. Calculate and record the average of the three results as the compression set of the test sample, except that, if a result differs from the mean by more than 5 % regard the test as invalid, discard all three results, and repeat the test. SABS
