ISO 11346:2014 pdf download.Rubber, vulcanized or thermoplastic—Estimation of life-time and maximum temperature of use.
5 Selection of tests and ageing oven
The tests chosen should preferably relate to properties which are likely to be of significance in practice. Wherever possible, use shall be made of methods of test specified in International Standards,
For general evaluations, hardness, and tensile stress-strain properties are commonly used, but stress relaxation or set In compression, for example. table for sealing applications.
For the ageing of test pieces, a circulating-air oven meeting the requirements of ISO 11W shall be used,
6 Selection of threshold value
The threshold value shall be chosen as the degree of degradation that is the maximum acceptable for the property being tested and the end use. Commonly, 50% of the initial value of the property is chosen.
The test should normally be continued for a long enough period for the threshold value to be reached. Although it is possible to extrapolate to greater degrees of degradation, this is not recommended.
7 Test pieces
7.1 The dimensions and method of preparation of the test pieces shall be in accordance with the relevant Lest method standard.
7.2 The minimum total number, n, of test pieces required for a destructive test method depends on:
— the number of test pieces, a, required for a single test in accordance with the test method standard;
— the number of different ageing periods, b, necessary to obtain the property/time relationship at any one exposure temperature;
— the number of exposure temperatures, c.
The minimum number of test pieces required is given in Formula (1).
The tests chosen should preferably relate to properties which are likely to be of significance in practice. Wherever possible, use shall be made of methods of test specified in International Standards,
For general evaluations, hardness, and tensile stress-strain properties are commonly used, but stress relaxation or set In compression, for example. table for sealing applications.
For the ageing of test pieces, a circulating-air oven meeting the requirements of ISO 11W shall be used,
6 Selection of threshold value
The threshold value shall be chosen as the degree of degradation that is the maximum acceptable for the property being tested and the end use. Commonly, 50% of the initial value of the property is chosen.
The test should normally be continued for a long enough period for the threshold value to be reached. Although it is possible to extrapolate to greater degrees of degradation, this is not recommended.
7 Test pieces
7.1 The dimensions and method of preparation of the test pieces shall be in accordance with the relevant Lest method standard.
7.2 The minimum total number, n, of test pieces required for a destructive test method depends on:
— the number of test pieces, a, required for a single test in accordance with the test method standard;
— the number of different ageing periods, b, necessary to obtain the property/time relationship at any one exposure temperature;
— the number of exposure temperatures, c.
The minimum number of test pieces required is given in Formula (1).
