Downloaded from https://www.everyspec.com MIL-STD-81OC 10 March 1975 METHOD 501.1 HIGH TEMPERATURE 1. PURPOSE. The high temperature test is conducted to determine the resistance of “e-t to elevated temperatures that may be encountered during service life either in storage (withoutprotective packaging) or under service conditions. 1.1. General effects. In equipment, high temperature conditions may cause the permanent set of packings and gaskets. In items of complex construction, binding of parts may also result due to differential expansion of dissimilar materials. Rubber, plastic, and plywood may tend to discolor, crack, bulge, check, or craze.
Closure and sealing strips may partially melt and adhere to contacting parts. 1.2 Procedure I is intended to approximate the exposure of equipment to a high temperature storage condition for a period of time prior to operation. 1.3 Procedure II is intended to approximate the cyclic high temperature stresses that equipment is exposed to during storage and operation. 2. APPARATUS. Temperature chamber. 3. PROCEDURES 3.1 Procedure I Step 1 - Pre’parethe test item in accordance with General Requirements, 3.2. Step 2 - Raise the internal chamber temperature to 71° C (160”F) or as specified in the equipment specification.
Step 3 - Maintain the internal chamber temperature for a period of 48 hours or as specified in the equipment specificationwhile insuring the relative humidity is not in excess of 15 percent. Step 4 - Adjust the internal chamber temperature to the highest operating temperature for which the test item is designed tO OPerate and maintain until temperature stabilizationof the test item is reached. 501.1-1 METHOD 501.1 10 March 1975