Thermal flow switches have many uses. One of their many uses, the thermal flow switch ensures coolant flow to several processes. Technically they operate using thermal dispersion technology. They are solid-state sensors without any moving parts, which is one of their benefits. They detect flow / no-flow conditions for a wide variety of reasons including control.
Large ships and yachts commonly use large diesel engines to propel them through oceans and seas around the world. Usually they are powered by multiple engines. As with all combustion engines they must be cooled. Ships have the luxury pf access to a great coolant, sea water.
But like any engine cooling situation the positive flow and continuous flow of engine coolant must be assured and detected. If absent, or if inadequate flow exists, cooling may not be adequate and engine overheating can occur resulting in engine shutdown or damage.
To prevent shutdown or damage due to loss of sea water coolant, most ships and yachts use a coolant system that includes a flow switch to indicate a positive flow of sea water coolant. Thermal dispersion units and paddle type units of flow switches are both used as flow detectors. Wired into the overall coolant or engine system these switches will detect flow and allow their switch contact to close or open to indicate loss of coolant flow.
Thermal dispersion flow switches operate by detecting loss of thermal energy in one internal sensor due to fluid flow, while a second thermal element is maintained at a constant temperature. These thermal flow switches have no moving parts and this makes them a long term reliable flow sensor.