Abstract: A candle for producing oxygen when ignited is mounted in the bottom of a chemical canister that is to be inserted in an open-bottom breathing apparatus receptacle provided with a depending projection. A primer for igniting the candle extends through the bottom of the canister and is exposed in the top of a firing mechanism housing secured to the canister bottom. At one side of the primer a hammer has one end pivotally connected to the housing on a transverse axis, with a spring urging the free end of the hammer into contact with the primer. Pivotally mounted in the housing on a transverse axis below the hammer is a trigger having one end engaging the bottom of the free end of the hammer in its cocked position, with the opposite end of the trigger positioned to be engaged by the receptacle projection when the canister is moved up into the receptacle, whereby to turn the trigger to disengage it from the hammer in order to release the hammer.

Abstract: The cover for a breathing apparatus canister has a body portion of substantially the same shape as the top of the canister and is provided with a skirt extending around the upper part of the canister and also with a central opening through which the neck of the canister extends. Extending from the body portion upwardly around the neck is a circular side wall closed at its upper end by a top wall above the sealing ring that encircles the upper end of the neck. The side wall is provided with inwardly projecting detents underlying the sealing ring to hold the cover in place, but the detents are sufficiently yieldable to permit the cover to be applied to the canister and removed.