GB514366A - Improvements in or relating to respiratory appliances - Google Patents

Abstract

514,366. Fluid-pressure servomotors. DRAGER, O. H. Feb. 1, 1938, No. 3099. Void. Convention date, Feb. 6, 1937. [Class 135] [Also in Group VI] In respiratory appliances, wherein continuous, and intermittent lung-operated, supplies of oxygen are provided, the lung-operated member is arranged to interrupt the continuous supply, the static pressure of which thereupon opens the valve of the intermittent supply. As shown the continuous supply, controlled by a valve 1, is led through a nozzle 2 and a passage 16 to a chamber 12 beneath a diaphragm 3, and thence through a passage 16a and an open valve 5 to the respiratory circuit at 14. The valve 5 is connected to a plate 8 on the breathing bag and is biassed open by a spring 15. On collapse of the bag, valve 5 is closed, and the pressure built up raises diaphragm 3 and opens the intermittent supply valve 4, connected to conduit 14 by a passage 16b. To avoid excessive pressure, which would oppose the re-opening of valve 5, a pressure relief valve 9 is provided which opens the continuous supply at a pressure slightly above that required to operate diaphragm 3, for example, 0.6 atmospheres. Instead of valve 9 a nozzle may be arranged and dimensioned to byepass valve 5 and to build up 0.6 atmospheres in passage 16a. The nozzle may be mounted in the valve 5. In a modified arrangement the diaphragm chamber 12 is normally byepassed but is opened to the pressure when the valve 5 is closed. Valve 4 may be opened manually on emergency by a knob 13 on an elastic diaphragm 19, or by a spring- held lever engageable with the stem 6 of valve 5 to close the valve. The valve stem 6 may have a terminal button detachably engaging a forked member on the plate 8, or may be secured to a diaphragm closing one end of the breathing bag and clamped between the bag fittings and the valve casing. The invention is applicable both to closed circuit and open breathing apparatus.