GB757652A - Improvements in or relating to breathing apparatus - Google Patents

Abstract

757,652. Respiratory appliances. SCOTT AVIATION CORPORATION. June 14, 1954 [June 16, 1953 ; May 24, 1954], No. 17392/54. Class 81(2). Breathing apparatus for underwater use comprises a mask having an inlet chamber and a breathing chamber, exhalation valve means and means for supplying breathing fluid to the inlet chamber including a demand valve in the inlet chamber actuated by a diaphragm whose outer surface is exposed to the water pressure. Compressed air storage tanks 31, 31<SP>1</SP> mounted on a backplate 16 are connected by hoses 64, 147 with the face mask 46. The storage tanks 31, 31<SP>1</SP> are detachably secured to the back plate 16 by flexible bands 32, 32<SP>1</SP> and are provided with shut-off valves 30, 31<SP>1</SP>. Compressed air passes from the tanks 31, 31<SP>1</SP> through pipes 26, 26<SP>1</SP> to a reduction valve casing 38 which houses a spring-loaded hexagonal check valve 42, Fig. 13. The check valve 42 is normally held open by the pressure of air passing round it but on rotation of a knob 47 may be held open by a pin 48. Air then passes through a reduction valve 44 to a chamber 60 and thence leaves the casing 38 to pass through the hose 64 to the mask 46. The operation of the reduction valve 44 is controlled by a spring-urged diaphragm 68 which is subjected on one side to the pressure of the surrounding water and on the other side to the pressure in a pocket chamber 67 associated with the flow of air leaving the casing 38 by a venturi nozzle 62. Air enters the mask 46 after passing through a regulator 83 which houses a demand valve 85, Fig. 9, operated by a diaphragm 86 which is exposed on one side to the surrounding water and on the other side to air within an inlet chamber 110 in the regulator 83. Air flows from the inlet chamber 110 to the breathing chamber of the mask 46 through a check valve 111. The mask 46 is provided with a main exhalation valve 132- and a control exhalation valve, the latter having a chamber 137 connected with the inlet chamber 110 of the regulator 83 by a pipe 141. One side of the chamber 137 is constituted by a diaphragm 136 which forms the control exhalation valve, a valve seat 138 being provided. An inlet duct 113 with a cap 114 projects upwardly from the regulator 83. If desired, when not under water the user of the apparatus may open the inlet duct 113 by unscrewing the cap 114 to allow ambient air to flow directly to the mask 46. Alternatively the inlet duct 113 may be replaced by a curved inlet tube, Fig. 10 (not shown) which is closed, when desired or when the apparatus is submerged in water, by a buoyant ball. In an emergency a valve 146, associated with the reduction valve casing 38 is opened so that compressed air by-passes the reduction valve by flowing directly to the mask through hole 149 and hose 147.