Downloaded from https://www.everyspec.com MIL-STD-81OD 19 July 1983 Step 8. Slowly increaae the air preaaure in the air into the chamber. Simulate change of altitude at meters per minute. . . .! Step 9. Stop air pressure charige’at 1500 meters ground level, whichever is reached first. test chamber by bleeding a rate no fastefithan 100 below””teataltitude or at ,. ., Step 10. Check the potential explosiveness of the aii-vaPor mixture”by attempting to ignite a sample of the mixture by a spark-gap or glow plug ignition source having sufficient energy to ignite ?
3.82-Percent hexane mixture, If ignition doee not occur, retui% the chamber to ambient atmospheric pressure, purge the chamber of the fuel-vapo~, and reinitiate the test”at the most’recent test altitude.’ :. ‘Step 11. If th6 lower limit of simulated altitude reached in steP’9 i? 3000 meters or greater above sea level, reduce the value of the test altitude ~ by 3000 meters. If the station ambient pressure altitude (i.e,, ground level) was reached. KO to ateu 13. If the station ambient Dresatirewaa not reached, ,- .- return the simulatedaltitude to station ambient“pressure, purge the chamber to remove all fuel vapor, and then evacuate the chamber to the new value of test altitude. . . . .
Step 12. Using the new value of test altitude from step 11,“conduct steps 5’through 10. .: ,, ‘“Step13. Document test results per paragraph II-4. ;:, ,. !. II-3.2 Yrocedure II - ~ent $test ... -, Step 1. Perform preparation’for the teat as given in II-2.2. Step 2. Seal the chamber with test item inside. Step 3. Raise ths ambient.air temperature inaide chamber. - Step 4. Wait until temperatures of test item and test come within 11‘C of chamber ambient air temperature. chamber inner”wal s . Step 5. Change chamber air pressure to 1500 meters of above the ‘stationambient pressure (i.e., ground level).
simulated altitude the test chamber to obtain optimum fuel-vapor/air mixture at station ambient pressure or as given in I-3.1.4bfor n-hexane. :.-’, Step 6. Inject the required quantity cf n-hexane into Step 7. Circulate the test atmosphere for at least 3 but no more than U minutes to allow for the complete vaporization of fuel and the development of a homogeneous mixture within the test item and within the test chamber. ,. .i st’eD8“( Bleed air into the chamber to return the Dressure.altitude to .-. . ..–. station ambient pressure (i.e., ground level). ,, . . ...’.’ ., ., .. M3THOD 511.2 19-July 1983., 511.2-8