Abstract: The invention provides an in-line low supply pressure alarm device preferably housed together with a gas pressure regulator and a gas flow controller, thereby eliminating the need for the operator to monitor gas availability. The alarm device is designed to be inserted in-line and includes a hollow housing with a gas inlet, a gas outlet, and an elongate internal chamber. A piston is disposed within the chamber for axial sliding between an alarm-on and an alarm-off position. The piston includes a piston head sealed in sliding engagement with an actuating compartment of the chamber. The actuating compartment of the chamber is filled with pressurized gas in flow communication with the gas inlet in operation. The piston includes an axially extending valve stem with a lateral alarm port in flow communication with the gas inlet. The valve stem is in sliding engagement with axially spaced apart seals defining an alarm plenum within the chamber.

Abstract: The personal emergency breathing system includes a canister carrying a layered filtration unit, a mouthpiece, a hood, a cover and a lid at opposite ends. Upon removal of the cover, the mouthpiece and hood are deployed. By placing the mouthpiece in the user's mouth and donning the hood, the user may breathe filtered ambient air. At the opposite end of the canister is a demand valve having an oxygen supply line. Upon removal of the lid at the opposite end of the canister and coupling the supply line to an oxygen bottle, oxygen may be supplied the user, augmenting the supply of ambient filtered air. Thus, the user may clip the oxygen bottle along with the canister to his/her belt and escape from toxic gases and smoke-filled environments. The demand valve supplies oxygen to the user only upon inspiratory effort and closes upon exhalation, thereby extending a given supply of oxygen up to 150% as compared to a continuous supply of oxygen.