| abstract |
816,874. Respiratory appliances. NORMALAIR Ltd., and MINISTER OF FUEL & POWER. April 26, 1956 [June 6, 1955], No. 16181/55. Class 81 (2). A closed-circuit breathing apparatus, primarily for use in mine rescue work, and including a liquid-oxygen cartridge in a vacuum-jacketed container in Fig. 1, is provided with inspiration and exhalation valves disposed upstream and downstream respectively of the mouthpiece and a vent valve for excess gas located between the exhalation valve and the CO 2 absorber. The oxygen cartridge a is carried in a vacuum-jacket b and at least part of the exhaled air passes around the cartridge to assist evaporation. To prevent the temperature of the circulating, gas from falling too low, part may by-pass the cartridge container, if desired, under the control of a manually-actuated flap valve. In another arrangement, a perforated plate is fitted over the inlet to the cartridge container and in this case, moisture in the gas is deposited as snow on the plate so that the gas is forced to flow entirely through the by-pass but when the temperature of the gas reaches a sufficiently high value, the snow melts and the gas again passes through the container. In yet another arrangement the perforated plate is disposed in the inlet pipe to the cartridge container, and the flow through the by-pass is additionally controlled by a manually-actuated butterfly-valve. |