Low supply pressure alarm for gas supply

Abstract

The invention provides an in-line low supply pressure alarm device preferably housed together with a gas pressure regulator and a gas flow controller, thereby eliminating the need for the operator to monitor gas availability. The alarm device is designed to be inserted in-line and includes a hollow housing with a gas inlet, a gas outlet, and an elongate internal chamber. A piston is disposed within the chamber for axial sliding between an alarm-on and an alarm-off position. The piston includes a piston head sealed in sliding engagement with an actuating compartment of the chamber. The actuating compartment of the chamber is filled with pressurized gas in flow communication with the gas inlet in operation. The piston includes an axially extending valve stem with a lateral alarm port in flow communication with the gas inlet. The valve stem is in sliding engagement with axially spaced apart seals defining an alarm plenum within the chamber. The alarm port of the valve stem is in flow communication with the alarm plenum when the piston is in the alarm-on position. A biasing spring engages the piston to bias the piston against the pressure of gas in the actuating compartment to the alarm-on position. The low pressure alarm is activated by a gas activated alarm in communication with the alarm plenum when low pressure is detected. Preferably the alarm port is aligned with a sealed compartment within the chamber when the piston is in the alarm-off position.