Downloaded from https://www.everyspec.com MIL-STD-81OD 19 July 1983 METHOD 502.2 LOW TEMPERATURE SECTION II H-1 AnMHL!s 11-1.1 EaUkiWY > a. The required apparatus consists of a chamber or cabinet and auxiliary instrumentation capable of maintaining and continuously monitoring the required conditions of low temperature throughout an envelope of air surrounding the test item(s) (see General Requirements, 4.4.1a). Air velocity .inthe. vicinity of the test item shall not exceed 1.7 mls (325 ;~/min) unless justified by the test item platform environment, to prevent unrealistic cooling (heat.transfer) in the test item. 11-1.2 Ibnkch a. ~.
Unless otherwise specified in the test plani if any action other than test item operation (such as opening the chamber door) results in a significant change of the test item temperature (more than 2° C (3.6oF)) or chamber air temperature, the test item will be restabilized at the required temperature before centinuation. If the operational check is not completed within 15 minutes, reestablish the ‘testitem temperature conditions before centinuing. o b. ~. Unless otherwise specified, the rate of temperature change shall not exceed 10° C (18° F) per minute. c. ~. Temperature sensor instrumentalion is required on or in the test item to establish temperature stabilization data. d. ~.
Continuous recordings of the chamber and test item temperature shall be made if required. II-1.3 Yest int~ (See General Requirements, 4.5.4.) - ~. An interruption which allows test temperatures to fluctuate outside allowable tolerances toward ambient : conditions should be”followed by a complete physical inspection and operational check (where possible). If no problems are encountered, restabilize the test item at the test temperature and continue from the point of the interruption. Any problems should constitute test item failure, eince no extreme conditions ~ were encountered. b. ~.
Any interruption that results in more extreme exposure of the test item than required by the equipment specification should be followed by a complete physical examination and operational check (where MSTHOD 502.2 19 July 1983 502.2-9