GB850557A - Improvements in breathing apparatus - Google Patents

Abstract

850,557. Respiratory appliances. ROBERTSHAW-FULTON CONTROLS CO. June 17, 1958 [June 17, 1957], No. 19388/58. Class 81(2) [Also in Group XXIX] A servo-actuated control valve assembly for high altitude use has means for applying fluid pressure, derived from the oxygen source, to the outer face of the control diaphragm. Oxygen is received into the body of the assembly through a union 22, Fig. 3, and duct 30, and is fed to a valve chamber 32 which is closed by a flexible member 40, Both sides of the member 40 are, however, connected through ducts 44, 46, Fig. 4, which are restricted by a metering choke 48, and consequently the valve normally remains closed. The user's mask is connected to the outlet 26 and, on inhalation, the drop in pressure is communicated through orifice 54, Fig. 3, to the diaphragm 56 and, when this is drawn downwards, it bears against a lever 62, Fig. 4, pivoted on a spring 74, and so lifts a block 64 and sealing member 66 away from the valve seat 58 so that the lower side of valve 40 is vented through duct 50. This causes the member 40 to be deflected downwards by the supply pressure and oxygen flows round the seating 38, Fig. 3 to the pipe 26. The upper face of the diaphragm 56 is adjacent to a perforated plate 95 forming the lower wall of a cup-shaped chamber, the upper rim 80 of which may be engaged by a plate 88 when the latter is lowered by a spring-loaded aneroid 97. The enclosed space 92 is supplied with oxygen received from the duct 30 through a communicating conduit 94 and, according to the position of the plate 88, this builds up a pressure which bears on the diaphragm 56 and tends to open the pilot valve to assist the flow of oxygen to the mask.