The test described in this part of ISO 5925 determines the rate of leakage of ambient (cold) and medium (warm) temperature smoke from one side of door and shutter assemblies to the other under the specified test conditions. The test is applicable to door and shutter assemblies of different configurations intended for purposes of controlling the passage of smoke in case of fire. The acceptable leakage rates for different situations are not addressed in this part of ISO 5925, but rather are specified by the regulations of the controlling authorities. The principle of the test is explained briefly in Annex A.