FED-STD-228A
4.3 After the temperature of the heating medium has been adjusted, the test tube containing the
specimen shall be placed in the medium so that the lip of the tube does not extend more than 2 inches
above the surface of the medium. Not more than three specimens shall be placed in one test tube and all
specimens in one tube shall be from a single compound. The exposure period shall start at the time the
test tube, containing the specimen, is placed in the heating, medium and shall continue for the required
time under the required conditions without opening or removing the tube.
4.4 At the end of the exposure period the specimen shall be removed from the tube and set aside on a
flat surface to rest for not less than 16 hours and not more than 96 hours at room temperature before
tests are conducted.
4.5 At the end of the rest period, unless otherwise specified in the detail specification, tensile strength
and elongation shall be determined of the aged specimen as described in methods 3021 and 3031. If
other properties are required, the specimen shall be tested as described in the specified method. The
same test shall be conducted on aged and unaged specimens for the purpose of comparison in
estimating the degree of deterioration of the aged material.
5. RESULTS
5.1 Calculation. The change in tensile strength, elongation or other characteristic of the insulation or
sheath of the inspection unit due to aging shall be calculated as follows:
Change in characteristic, percent=O-E x 100
O
where:
O=the value obtained on the unaged insulation or sheath of the inspection unit.
E=the value obtained on the aged insulation or sheath of the inspection unit.
5.2 Unless otherwise specified in the detail specification, the number of specimens tested from each
inspection unit shall be as required in the method of test, 4.2 used for determining the deterioration of the
insulation or sheath.
5.3 The change in the characteristic of the insulation or sheath of the inspection unit shall be recorded to
the nearest one percent.
5.4 The temperature and time of exposure used shall be recorded.
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