Flow alarms type GIR for Platon NG-LG series
Flow alarm for glass tube flowmeter
Floscan GIR flow alarms use an infra-red beam across the glass tube of a variable flowmeter.
More details:
Passage of the float between the sensor arms is detected and a logic within the electronics determines whether the float is above or below the sensor position. The sensor is 12 VDC powered with a transistor switch output to drive external logic circuits.