Downloaded from https://www.everyspec.com MIL-STD-810D 19 July 1983 .: c. Dehumidification, heating, and cooling of chamber test volume sfr for control of test conditions shall be achieved by methods that do not alter the chemical composition of the air, sand, or water vapor within the chamber test volume air. d. Test facility design considerations. (1) The vibratory or screw type sand feeder shall be controlled to emit the aand at the specified concentrate ions. The feeder shall be looated in such a manner as to insure that the sand.is uniformly in suspension in the air stream when it strikes the test item, to simulate the same effects as in the field. NOTE:
Uniform sand distribution is usually eaaier to obtain when the sand-air mixture is directed downward, as in figure 510.2-1. (2) Becauai of,the extrernely abrasive characteristlcs o! blowing aand at high velocity, it is not recommended that the sand be ~ recirculated through the fan or air conditioning equipment. Instead, it should : be separated Prom the air downstream from-the test chamber in a sand separator, collected in a separate receiver, and reintroduced into the sand tank or hopper. The fan should recirculate only the sand-free conditioned air. NOTE:
The sand collected,in the separator may be reused for other tests if, after snalysia, it,still Conforms to the requirements of I-3.2d(2) of this method.” 11-1.2 Q?nmQls a. ~. Unless otherwise specified in the requirements dooument, temperature and relative humidity measurements made during testing shal1 be centinuous if measurements are in analog f o r m , or .atintervala of one every 15 minutes or leas if measurements are in digital form. All instrumentation used with the test chamber shall be capable of meeting the aCCUraCfea, tolerances, etc., of General Requirements, h.4.1 and 4.4.2.
Any aignlficsnt change of the test item temperature or ohamber conditions shall result in the test item being reestablished at the required environmental conditions before continuation. b. lleja.tiveh~. Relative humidity in the te$t aeotion shall be less than 30 percent throughout the conduct of the test. , ~: The test variables (temperature, air velooity, and dust concentration) shall be continuously monitored during the test. .Humidity shall be verified just before or during’each test. . II-1.3 ~. (See General Requirements, 4.5.4.) a. =12i. The abrasion, penetration, and collection o f dust are cumulative effects that are not affected by interruption.
The test item shall be reestablished at the prescribed temperature and the test oontinued from the point of interruption. METHOD 510.2 19 July 1983 510.2-9