Abstract: Breathing apparatus supplies air or oxygen to a patient and comprises a hand-held housing (10), a gas inlet on the housing, a gas outlet (12) on the housing (10), and a manual/automatic switch (16) on the housing for supplying gas either to a manually operable valve (40) or to a main valve (48) which delivers gas to the outlet on a cyclic basis. A trigger (22) on the housing (10) controls the supply of gas to the outlet through the manually operable valve (40).

Abstract: Apparatus for detecting combustible gases and vapors, and comprises catalytic sensors selectively sensitive to the presence in a given environment of a potentially dangerous constituent such as a hydrocarbon gas and arranged to produce a signal representative of the presence of the constituent, a normally deactivated transducer responsive on activation to the output of the sensors and effective to produce an output signal indicative of the presence of the constituent in a concentration above a predetermined level, a pulse generating circuit arranged automatically and periodically to activate the sensors for a selected relatively short interval during which detection but not poisoning can occur and subsequently to deactivate the sensors for a relatively long period, fault detecting circuits for producing a fault signal in the event of circuit failure or impending power failure, and alarm circuitry for providing a differentiated warning in response to the fault signal and in response to the output signal.