GB1086471A - Diver's breathing system - Google Patents

Abstract

1,086,471. Diver's breathing system with safety valve. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. May 3, 1965, No. 18557/65. Heading AST. A diver's breathing system comprises a mask, a gas inlet connected to a high pressure source, a gas outlet connected to a low pressure source, and a safety valve which is normally open but which blocks the. outlet at a certain predetermined pressure in the diver's breathing system which is preferably not more than 0.2 atmospheres lower than the pressure at the exterior of the breathing system. As illustrated with reference to Fig. 1, the system may comprise a mask 1, an inlet 6, an outlet 26, a membrane 12, a membrane operated valve 12, a housing cover 13 with water openings 14, a safety valve 17 operated by membrane 22 and held open by valve spring 23. In operation, the diver lowers the pressure inside space 10 on inhaling, whereby valve 9 opens and gas under pressure flows from conduit 6 through space 10 and into conduit 2 leading to the mask. On exhaling, the diver raises the pressure in space 10 and valve 9 is closed. Further, valve 25 is opened and exhaled gas is exhausted from 10 under the action of the low pressure source. If the pressure in the space 10 falls to an undesired level, the safety valve 17 closes under the influence of the pressure difference operating on membrane 22, and thus protects the diver. A simplified and alternative safety valve is illustrated with reference to Fig. 2 and comprises a conduit 32 of which part 33 has been removed and over which a flexible conduit 34 has been slid. The flexibility of conduit 34 is chosen so that it collapses at a predetermined pressure difference across the wall 34.