Monitoring filter and dose rate - with light beam passing through dosed liquid

摘要

Dosing units for supplying filter aid has an emitter which sends light beam towards a receiver. When the plant is operating correctly, i.e. an adequate amount of filtering agent is supplied from dosing unit to liquid supply line, the passage of light beam is obstructed and no optical or acoustic signal is emitted. Sensitivity of emitter can be varied to suit the transparency of the liquid to be filtered and/or the pipe diameter.