Abstract: A pneumatically powered oxygen pressure loss alarm system for use in conjunction with a gas anesthesia machine having an oxygen supply circuit and a gas mixing circuit. The oxygen pressure loss alarm system comprises a volume chamber in which a pressurized volume of oxygen is maintained, an oxygen escape valve for venting the chamber when pressure within the oxygen supply circuit falls below a critical minimum level, and an audible alarm operable in response to the flow of oxygen vented from the chamber through the oxygen escape valve. In addition, a reverse flow of residual gas from the gas mixing circuit, through a master valve also used to shut off the gas anesthesia machine, is coupled to the alarm to provide an audible indication of machine shut-down.

Abstract: An assembly of isolation valves (42, 44, 46) coupled to vaporizers (54, 56, 69), and a corresponding number of valve control levers (66, 68, 70) connected by an interlock mechanism that allows only one of the levers to be in an on position at any time. The interlock mechanism includes a cable (80, 81, 82) between each unique pair of control levers, the cables being only long enough to permit one lever of each unique pair to be moved to the on position. Each lever has a camming roller (66d, 68d, 70d) that engages and rotates a forked valve cam (86) to switch the valve on or off.

Abstract: A pop-off valve (92) having a significantly improved pressure-flow characteristic and resistance to vibration or "honking." The valve includes a poppet (154) having a flat bottom end wall exposed to pressure and a peripheral lip with a frusto-conical surface (158) for engagement with a valve seat 140. A vent-hole (196) in the poppet further enhances the vibration characteristics of the valve, and a dampening chamber (186) downstream of the poppet dampens any remaining vibrations.