Abstract: A fluid flow sensing switch device having a housing provided with a fluid flow passage therethrough defined by an inlet and an outlet separated by a valve seat controlled by a movable valve member that is operated by the pressure differential between the inlet and the outlet, the device having an electrical switch construction operatively associated with the valve member and having the switch contacts thereof actuated by the pressure differential. The switch contacts of the switch construction are disposed in the fluid flow passage so as to be exposed to fluid flow therethrough and have a part thereof carried by the valve member.

Abstract: A fluid flow sensing device having a housing provided with a fluid flow passage therethrough defined by an inlet and outlet separated by a valve seat controlled by a movable valve member that is operated by a pressure differential between the inlet and the outlet acting on a flexible diaphragm carried by the housing, the device having an electrical switch construction operatively associated with the valve member and having the switch contacts thereof disposed in the fluid flow passage so as to be exposed to fluid therethrough and being actuated by the pressure differential acting on the flexible diaphragm. The switch contacts comprise a pair of spaced apart contacts carried by the flexible diaphragm and a bridging contact member carried by the valve member and being adapted to make contact with the pair of contacts and thereby bridge the pair of contacts to close the switch construction to operate electronic switching, the electronic switching being disposed inside the housing.

Abstract: A pressure switch has a support structure on which a flexible diaphram is mounted in communication with a source of variable pressure such as a fluid conduit. A first linkage has one end operatively connected to the diaphram and the other end pivotally connected to a cradle having a mercury switch mounted therein. A second linkage is pivotally connected at one end to the support structure and pivotally connected at the other end to the cradle so that the cradle is freely pivotable in response to movements of the first linkage. A quantity of liquid mercury in the mercury switch moves into and out of contact with the mercury switch electrodes in response to pivotal movement of the cradle by the first linkage when the diaphram is moved between first and second positions corresponding to low and high pressure conditions respectively.

Abstract: In a piston actuated valve, means for determining the position of the operating piston by means of at least one insulated contact probe which is inserted through the wall of the cylinder. Two or more can be used, one in each extreme position of the piston. As the piston moves into its extreme position, contact is made with the probe and a suitable signal is sent, indicating that the piston is in that extreme position.