Downloaded from https://www.everyspec.com MIL-STD-810D .19July 1983 METHOD 521.0 ICING/FREEZING RAIN ,, EaK!2 SECTION I 1-1 I-2 1-3 PURPOSE . . . . . . . . . . . . . . . . . . . . . . . ENVIRONMENTAL EFFECTS . . . . . . . . . . . . . . . . GUIDELINES FOR DETERMINING TEST 521.0-1 521.0-1 1-4 I-5 PROCEDURES AND TEST CONDITIONS . . . . . . . . . . SPECIAL CQNS3.DERATXONS . . . . . . . . . . . . . . . REFERENCES . . . . . . . . . ... . . . . . . . . . 521.0-2 521.0-4 521.0-4 SECTION II II-1 II-2 II-3 II-4 Apparatus . . . . . . . . . . . . . . . . . . . . . . PREPARATION FOR TEST . . . . .. . . . . . . . . . . PROCEDURES . . . . . . . . . . . . . . . . . . . . . INFORMATION TO BE RECORDED . . . .
. . . . . . . . . 521.0-6 521.0-6 521.0-7 521.0-8 SECTION I I-1 lURIQSE. The icing/freezing rain test is conducted to evaluate the effect of icing produced by a freezing rain, mist, or sea spray on the operational capability of materiel. This method also provides tests for evaluating the effectiveness of deicing equipment and techniques, including field expedients. 1-2 ~. A buildup of ice occurs in three principal ways: from rain falling on an item whose temperature is below freezing (O° C), from freezing rain falling on ah item at or near freezing, or from sea spray which coats equipment when temperatures are below freezing. MIL-STD-21O identifies two conditions commonly encountered:
(clear) glaze’ice and (granular) rime ice. Glaze ice occurs when rain or drizzle freezes on objects, and it is nearly as dense as pure ice. Rime ice occurs when fog droplets or drizzle falle on surfaces colder than OoC. It is white and, since it is saturated with air, is much less dense than glaze ice. Since glaze ice is more difficult to remove and has a weight approximately four times greater than rime ice, it is s more significant factor and will be the focus of this test. The ~ for ~ -- (reference f, p. 104, p. 149) identifies extremes for ice accumulation. These extremes may be used for calculating design and structural evaluations but are not suitable for establishing test conditions.
Ice formation can impede equipment operation and survival and affect the safety of operating personnel by creating the following problems: . a. Binds moving parts together. b. Adds weight.to radar antennas, helicopter rotors, etc. 19 July 1983 521.0”1 METHOD 521”.0