Non-resettable, pressure-actuated switch

Abstract

A general-purpose, pressure-sensitive electrical switch, having a frangible electrically conductive path that is irreversibly broken by an excessive applied pressure differential, The switch includes a pressure-deflectable diaphragm and an interior chamber. The diaphragm forms an interface between the internal chamber and the external environment. As the pressure differential across the diaphragm exceeds a specified level, the diaphragm deflects. The internal chamber can also be sealed with an internal pressure P.sub.1 so that the diaphragm deflects for a specified absolute external pressure P.sub.2. The force of the deflection is transmitted to brittle, inelastic structure within the switch through an intermediate load transmission element. The electrical path, which is along the brittle structure, terminates in a pair of externally-accessible terminals. The force of deflection stresses the brittle structure beyond its fracture stress level, causing it to break and opening the electrical path between the terminals. A ceramic bar traversing the switch through the sealed chamber or the base itself can serve as the frangible structure. The electrical terminals can be connected into an external alarm circuit for positive indication of the occurrence of a preselected pressure condition.