Re-breathing apparatus
First Claim
1. Rebreathing apparatus of the closed circuit type comprising a first gas supply for providing a breathable gas mixture, a second gas supply for providing oxygen alone, a gas circuit, and an electrical circuit,the gas circuit comprising gas flow control valves coupled to the respective gas supplies and a solenoid valve coupled to the oxygen supply and means for interconnecting the solenoid valve to the breathable gas mixture,the electrical circuit comprising a pair of transducers in the gas circuit, one said transducer being sensitive to oxygen partial pressure, the other said transducer being sensitive to total pressure, amplifiers controlled by the output of respective said transducers and arranged to amplify respective said outputs, an analogue divider coupling the outputs of said amplifiers, the output of the divider being indicative of percentage of oxygen in the breathable gas mixture, and solenoid driving means coupled to the output of said analogue divider to the winding of the solenoid valve to energise the solenoid valve upon drop in the percentage of oxygen in the gas circuit so as to open the solenoid valve and thereby introduce oxygen from the oxygen supply to the breathable gas mixture.
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Accused Products
Abstract
This invention relates to a diver'"'"'s re-breathing apparatus of a closed circuit type. The gas circuit is provided with a solenoid valve coupled to an oxygen cylinder and arranged to be energised to introduce oxygen into the breathable atmosphere when the oxygen content therein drops below a certain proportion.
The electrical circuit comprises a pair of transducers in the gas circuit, one of which is sensitive to oxygen partial pressure and the other sensitive to total pressure, the outputs of the two transducers being amplified and fed into an analogue divider, the output of the divider being responsive to percentage of oxygen in the breathable atmosphere and being effective to energise the solenoid to thereby maintain the oxygen content of the breathable atmosphere within limits of percentage, rather than within limits of partial pressure.
36 Citations
10 Claims
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1. Rebreathing apparatus of the closed circuit type comprising a first gas supply for providing a breathable gas mixture, a second gas supply for providing oxygen alone, a gas circuit, and an electrical circuit,
the gas circuit comprising gas flow control valves coupled to the respective gas supplies and a solenoid valve coupled to the oxygen supply and means for interconnecting the solenoid valve to the breathable gas mixture, the electrical circuit comprising a pair of transducers in the gas circuit, one said transducer being sensitive to oxygen partial pressure, the other said transducer being sensitive to total pressure, amplifiers controlled by the output of respective said transducers and arranged to amplify respective said outputs, an analogue divider coupling the outputs of said amplifiers, the output of the divider being indicative of percentage of oxygen in the breathable gas mixture, and solenoid driving means coupled to the output of said analogue divider to the winding of the solenoid valve to energise the solenoid valve upon drop in the percentage of oxygen in the gas circuit so as to open the solenoid valve and thereby introduce oxygen from the oxygen supply to the breathable gas mixture.
Specification