Deflagration Flame Arrester, Endurance Burning Proof. Function and Description For many years the PROTEGO®® BE/HR BE/HR end-of-line deflagration flame arrester has been successfully used to protect vessels and process engineering apparatus which are not pressurized. The device provides protection against flame transmission through atmospheric deflagration and stabilized flames which can burn for very long time on the flame arrester element surface, so called endurance burning. Main application area is on in - and out breathing and vent lines, with the goal to prevent flame transmission caused by endurance burning or atmospheric deflagration from propagating into the vessel or plant.