Deflagration = Explosion propagating at subsonic velocity

Pressure/vacuum valve:

•     Prevents escape of vapors
•     Contamination of stored medium
•     Displacement of vapors
•     Environmental protection
•     Limits the storage tank pressure

The pressure/vacuum valve approved as end of line deflagration flame arrester installed at end of vent pipes prevents light-back at deflagration of potentially explosive vapor-air, and or gas-air mixtures from outside (atmospheric conditions) to the protected side (e. g. storage tank).