Abstract: An improved ventilator monitor and alarm apparatus includes circuit means for actuating the apparatus in response to sensed pressure in a ventilator circuit.

Abstract: An oxygen concentrator having one or more molecular sieve beds for selectively adsorbing nitrogen from atmospheric air for increasing the oxygen concentration of a product gas, a reservoir for receiving the product gas, a surge tank, a compressor for charging atmospheric air to the sieve beds and surge tank and a valve and valve switching means for directing atmospheric air from the compressor to the sieve beds and surge tank includes means for sensing the withdrawal rate of product gas from the reservoir and a microprocessor having means for switching the valve for charging the surge tank for a miniumum time required to achieve a product gas having a selected oxygen concentration at the sensed rate of withdrawal.

Abstract: An improved percussor assembly comprises a rigid body member having gas inlet and gas outlet means, the latter including a restricted passageway and an enlarged passageway, and a vent passageway communicating with the enlarged portion adjacent the junction of the restricted passageway whereby atmospheric air is entrained into the enlarged passageway as gas flows therein from the restricted passageway thereby increasing the volume of gas supplied to a remote applicator while economizing on the amount of pressurized gas required to operate the percussor. The vent passageway also relieves gas pressure from a remote pneumatic applicator between successive bursts of gas from the percussor assembly. An improved remote applicator having means for selecting the force of the percussive bursts is also provided.