For liquid low flow or flow failure alarm on cooling systems, water heaters or lubrication systems, the Platon LF flow switch is a rugged sensor with simple electrical reed switch output. Installed in a vertical line with flow upwards, normal flows lift the float in the sensor. A magnet encapsulated in the float then actuates a reed switch, giving contact closure. Should the flow drop to below the preset alarm level, the float falls to the rest position and the contacts open to give an alarm output.