Abstract: An apparatus for detecting leaks in a pipeline in a liquid dispensing system. The apparatus generally includes a tank containing a liquid, a dispenser valve disposed remote from the tank, a pipeline connected between the storage tank and the dispenser valve, a pump at the tank for supplying liquid under pressure to the pipeline and an isolation valve between the pump and the dispenser valve to isolate the pump pressure from the pressure in the pipeline between the isolation valve and the dispenser valve. The apparatus further has a pressure sensor between the isolation valve and the dispenser valve for measuring any pressure change in the pipeline between the isolation valve and the dispenser value. A leak simulation valve alternatively may be provided for draining the pipeline to simulate a leak.

Abstract: A very low differential pressure switch for detecting pressure differential across two points of a pressurized system. A flexible diaphragm divides two cavities which are exposed to fluid pressures across two points of the pressurized system, and moves a sensor actuating target axially against a compression spring relative to the sensed differential pressures. The switch has a proximity sensor responsive to the axial location of the target to produce an output indicative of a pressure differential condition between the two cavities. The switch has a selected pressure sensitivity and volumetric displacement threshold dependent in part on the cross-sectional area of the flexible diaphragm, size of the compression spring and on the distance between the diaphragm and the proximity sensor.