A flow switch is a mechanical gadget used to control the flow of liquid, air or steam. The switch works by sending a trip signal to another device in the system, such as a pump, to protect it from damage and for cooling circuit protection.
The flow refers to the physical movement, or velocity, of liquid, gas or steam in a pipe that causes actuation of the switch. Liquid flow switches can be applied in air conditioning, hot water space heating systems, chlorination of swimming pools, industrial laser coolant systems, liquid transfer systems and fire sprinkler systems. A water flow switch can used in detecting water in the sprinkler system, particularly in the event of fire, to signal a local electrical fire alarm device within the building.