FED-STD-228A
Method 4041.1
18 APRIL 2014
TEST TUBE HEAT-AGING, INSULATION AND SHEATH
1. SCOPE
1.1 This method is intended for use in determining the effect of high temperatures and a controlled
circulation of air on rubber and rubber-like insulation and sheaths of insulated wire and cable. The
selection of suitable periods of aging depends upon the rate of deterioration of the particular compound
being tested. Temperatures that have been used vary from 120°C to 149°C (250° ± 300°F). Exposure
periods frequently used are 10, 20, 40, 70, and 166 hours. In any case the conditions selected should be
such that the deterioration will not be so great as to prevent the determination of the final physical
properties.
2. SPECIMEN
2.1 The specimen should be as described in methods 3021 and 3031 or other method of test required for
determining the amount of deterioration, 4.2.
3. APPARATUS
3.1 The apparatus shall be as follows:
3.1.1 An aluminum or glass test tube 38 for holding the specimens. The test tube shall be provided with
a cork stopper fitted with two glass tubes 9 ±0.6 millimeters in outside diameter and a wall thickness of
1.0 millimeter. The inlet tube shall extend 4 ½ inches above the top of the stopper and to within ½ inch of
the bottom of the test tube. The outlet tube shall extend 12 inches above the top of the stopper and the
lower opening of the tube shall extend 1 ½ inches below the bottom surface of the stopper.
3.1.2 Provisions for vertically suspending the specimens as near the bottom of the test tube as possible
without touching each other or the sides or bottom of the tube.
3.1.3 A liquid bath or other apparatus as an aluminum block equipped with thermostatic control which will
control the temperature within ±1°C (2°F) of the required temperature.
3.1.4 Equipment for rapid circulation of the liquid heating medium if used so as to keep the temperature
throughout the liquid within ± 1°C (2°F).
3.1.5 Recording thermometers to record the temperature in various parts of the heating medium during
the test.
4. PROCEDURE
4.1 Unless otherwise specified in the detail specification, the test shall be carried out at a temperature of
120° ± 1°C (248° ± 2°F) for a period of 20 hours ± ¼ hour.
4.2 Unless otherwise specified in the detail specification, tensile strength and elongation tests, methods
3021 and 3031, respectively, shall be used to determine the deterioration of the insulation or sheath, due
to aging.
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