FS-380P Series – Industrial Strength Inline Plastic Flow Switch. This rugged inline flow switch offers the same superior performance to non-clogging as its metal cousin (FS-380). The fixed set point and simple design make it a dependable switch. The FS-380P is an ideal choice for coolant applications requiring reliable flow detection in HVAC, semiconductor, welding, medical and other industries. 1/4˝ quick disconnect units have a host of snap-on mating adapters to fit most piping requirements.