Gas shutoff valve having a positive open indicator

Abstract

An improved manually-operable outlet valve for a tank of pressurized gas, especially a tank in a pressurized breathing oxygen system in an aircraft. The valve has a valve body conventionally attachable to a standard oxygen tank. A rotatable valve stem is disposed within a threaded port in the valve body to open and close a poppet valve that mates with a seat machined in the valve body. A torque limiter comprising a stack of Belville washers is disposed between the valve stem and the poppet to prevent over-torque of the valve upon closing of the poppet against the seat. A collar surrounds the stem and rides axially with the valve stem during actuation of the valve. A lever and an electrical microswitch are mounted on the valve body. The collar intercepts and actuates the lever during axial travel of the collar, and the lever actuates the microswitch from an open to closed position or the reverse, the switch being in a first state at one extreme of collar travel and in the opposite state at the opposite extreme of collar travel. The microswitch is attached to an electrical connector for connection to a circuit including an annunciator in the cockpit of the aircraft, the microswitch and annunciator being wired such that the annunciator preferably is energized when the valve is open.