Abstract: A pressure switch comprising a housing and a movable pressure responsive diaphragm in the housing cooperating therewith to define a sensing chamber. The housing has an inlet passage leading to the sensing chamber and a vent passage leading from the sensing chamber. A check valve allows fluid to flow through the inlet passage into the sensing chamber and prevents flow through the inlet passage in the reverse direction. A pressure relief valve at least partially vents the sensing chamber through the outlet passage in response to the differential pressure across the pressure relief valve reaching about a predetermined magnitude. At least a portion of the diaphragm is movable along a path in response to pressure changes in the sensing chamber and an actuator is carried by the movable portion of the diaphragm. A switch is mounted on the housing in a position to be actuated by the movement of the actuator.

Abstract: A dispenser for flowable material comprising a pump, a dispensing head coupled to the outlet of the pump, a control valve for controlling pump operation, and a manually operable valve carried by the dispensing head for controlling the control valve. The pump includes a rolling diaphragm which is moved on the discharge stroke by fluid under pressure supplied from the control valve and is moved on the intake stroke by a spring. None of the controls for the dispenser are electrical.