Air Lock Purge Requirements .Air Changes Per Hour Air Lock Room equals 5 x 8 x 9 = 360 cu. ft. CFM Rate = 6cm/air change per hour Mixing Factor = 1 in all cases Note: The above graph is calculated using a mixing factor of 1. Though this is rarely the case with larger rooms, airlocks can have mixing factors very close to one because of the heavy degree of air saturation they are designed for, normally having very large air changes. If tests show that the room actually has a larger mixing factor you must multiply the time factor determined form the above graph by the actual mixing factor to arrive at the actual time to reach the required purge amount. Therefore, if you are supplying the above air lock with 110 air changes and the above graph indicates that purge would be completed in 2 minutes, if the actual mixing factor is tested to be a value of 2 then the actual time to purge will be four minutes not the two minutes as shown above, since the above graph is calculated based on a mixing factor of one. See our publication #31 for a good analysis of this type of situation. Click here to email this page to a friend
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