Fuel filter unit with water content indicator

摘要

Corrosion of a water sensor resulting from the passage of considerable electric current through it while it is in contact with water is prevented in a motor fuel filter equipped for water separation by interrupting or greatly reducing the current passing through the sensor after the sensor has given a signal indicating the presence of water in sufficient quantity to require draining soon. The warning provided to the vehicle driver is maintained thereafter either by a signal storage circuit (flipflop) or by causing current diverted from the sensor to flow through a substitution resistor or a shunt transistor.