ANALOG LIQUID LEVEL SENSOR

摘要

A sensor (20) for determining the location of the surface of liquid (L) in a container (23), includes: a hollow tubular stainless steel probe (21) inserted into said container, said probe having one portion (29) arranged above the surface of the liquid and having another portion (28) submerged in the liquid; a first thermocouple (TC1) operatively arranged within the probe to sense the temperature above the liquid surface; a second thermocouple (TC2) operatively arranged within the probe to sense the temperature of said liquid at a point beneath the liquid surface; a resistance wire (53) operatively arranged within the probe; a current source (60) operatively arranged to apply a constant-current to the ends of the wire; and an ohmmeter (61) for measuring the electrical resistance of the wire.