Linear Design Fluid Level Sensor Utilizing New Material Technology

For many years, fluid level measurement in fuel tanks has been accomplished using a float and lever arm to operate a variable resistor. The resistance reading is translated by any of several gauge designs. The float and lever arm sensor requires a significant amount of tank space and has accuracy and reliability problems.

A new family of linear sensors utilizing various thick film materials is discussed. The devices utilize conductive plastic or cermet resistors on various substrates and may be operated as a 2-wire variable resistor or 3-wire potentiometer. Significantly less space is required and the shape of the signal output curve can be adjusted to fit a variety of tank designs. The linear sensors are adaptable to the modular reservoir fuel delivery systems now in use.