Downloaded from https://www.everyspec.com MIL-STD-81OD 19 July 1983 O ~THOD 511.2 - EXPLOSIVE ATMOSPHERE , ..... . . . . . ,, * ~., . m ,: SECTION I I-1 PURPOSE . . . . . . . ...... . . . ... . . . . . ... ..-. 511.2T1 I-2 ENVIRONMENTAL EFFECTS . . . . . . . . . .. . 511.,2-1. I-3 .,, .GU,IDELINESFOR DETERMINING TEST . ! . 511.2-1 .SPECIALCONSIDERATIONS .-. . . . . . . . . . . . . . .,511.2-5 I-5 REFERENCES SECTION II 11-1. APPARATUS . 11-2 PREPARATION 11-3 PROCEDURES II-4 INFORMATION .,, . . PROCEDURES AND TEST CONDITIONS . . . . . . . IL4 . . ... . . . . . . . . . . . . . . . . . . . .511.2-5. . . . .. . . . . . . . . ... . . . . . . . . 511.2-6 FOR TEST’ ... . . . . . .. .. ... . ... . .
. 511.2-6 .... . . . . . . . ... . . . . . . .. . . . . 511.2-7 TO RERECORDED . . . . . . . . . . . .511 .2-9 , ... , SECTION I . - ,. ,,- . . ,., .- .1? “This test is performed to demonstrate the ability of equipment to operate in flammable.atmospheres without causing an.explosion, or to prove that a flame reaction occurring within.an encased equipment will be contained and will not propagate outside ‘the,test item. ,, , ....- 1-2 ~. “Low levels of energy discharge or electrical arc from devices as simple as pocket transistor radios can ignite mixture.:.~f . . . 1.1 ~. 0 fuel vapor-and air.
A .,,,hot S.pOtM on the.aurface of a hermetically sealed, apparently inert equipment ease !an ignite.fuel vapor and air”mixtures. Fuel. vapors in compartments can be ignited by a low energy discharge like a spark from a shorted flashlight cell,- switch contacta, etc. . I-3 ~ AND ~TLQNS NOTE: This test method should be appli~.1at the end of the t?ilOrinS PrOcess described in section 4 of this.standard. . ,. air LQ?I. This method applies‘“toall military items designed for use ‘in or near flight vehicles,-ground vehicles; or equ tO mainta?n fuel-handling or fuel-using.Vep:’tie?. . ?. S&luacQ.
It .isqecommeridedthat the ite& used’in this test first undergo vibration arid/Ortemperature testing,, Vibration and temperature itresaes,may reduce the “effectivenessof seals, “thus.pr~du~ine fla~able ,. atmosphere’sensitivities not observable on ,un~eateditems. .:. , d. Xes t var. tie”.: The test variables are temperature, pressure, humidity, test item configuration, and fuel-vapor mixture. METHOD 511.2 19 Jtlly1983 511.2-1