Downloaded from https://www.everyspec.com ,,/ / MIL-STD-8l,OD 19”July 1983 METHOD 501.2 HIGH TEMPERATURE !, &s.Q I-1 I-2 I-3 SECTION I PURPOSE . . . . . . . . . . . . . . . . . ...501.2-1 ENVIRONMENTAL EFFECTS . . . . . . . . . . . . . 501.2-1 GUIDELINES FOR DETERMINING TEST .2. PROCEDURES AND TEST CONDITIONS . 501.2-2 SPECIAL CONSIDERATIONS . . . . . : : : .: : : . 501.2-11 REFERENCES . . . . . .. . . . . . . . . . .501.2-12 I-4 I-5 . II-1 II-2 II-3 11-4 SECTION II,, APPARATUS.........”. . . . . . . . .501.2-13 PREPARATION FOR TEST 501.2-14 PROCEDURES.....::::: ::; :::: ;501.2-15 INFORMATION TO BE RECORDED . . . . . . . . . . 501.2-17 SECTION I I-1 lUEpilX.
High-temperature chamber tests are performed to determine if materiel can be stored and operated under hot climatic conditions without experiencing physical damage or deterioration in perfOrIIIance. @ I-2 ~. High temperatures may temporarily or permanently impair the performance of the test item by changing the physical properties or dimensions of the material(s) composing it. Examplea of some other problems that could occur as the result of high-temperature exposure are: a. Psrta binding from differential expansion of dissimilar materials. b. flow of Lubricants becoming less viscous; joints losing lubrication by outward lubricants. c.
Materials changing in dimension, either totally or selectively. d. binding, Packing, gaskets, seals, bearings and shafts becoming distorted, and failing causing mechanical or integrity failurea. e. ,s Gaskets displaying permanent set. f. Closure and sealing stri~s deteriorating. Fixed-resistance resistors changing in valuea. g. i Electronic circuit stability varying with differences in temperature gradients and differential expansion of dissimilar materials. Transformers and electromechanical components overheating. h. j. Altering of operating/releasemargins of relays @ magnetic or thermally activated devices, 501.2-1 METHOD 501,2 19 July 1983