LIQUID FLOW SENSING DEVICE

摘要

A liquid flow sensing device which includes a control means movable between first and second positions but biassed to the first position. A valve unit is provided which has a first valve section movable in response to movement of the control means a second valve section which is fixed in relation to the first section and has first and second ports. The valve unit further includes a third section which is movable independently of the first and second sections and has means for providing communication between the first and second ports. A fluid flow passage is provided through the first and second valve sections and has a diaphragm for closing the flow passage as well as forming part of a chamber. In use the third valve section is movable so that the first and second ports are isolated but the first port is coupled to the chamber when the control means is in the first position and moves to the second position and means for coupling said first and third sections whereby as the control means reverts to said first position the first port is coupled to said second port but isolated from the chamber.