Abstract: A pipe probe is installed downward into the liquid contained in the tank and is connected pneumatically to a remote reporting unit located in the operator's area. An air pump pressurizes the probe, increasing the pressure up to the point at which the liquid is completely displaced from the probe and bubbles of air evolve from the end of the probe. At that point the pressure is proportional to the height of the liquid in the tank. A pneumatic connection from the probe to the reporting unit refers the pressure to a piezoresistive pressure transducer working in concert with an electronic process controller. The controller produces a voltage output which is reported as a digital numeric readout, reading in volts or in programmed engineering units. Jittery variations in the least significant figure of the numeric readout, which are associated with the evolution of air bubbles from the end of the probe, are eliminated by adding an air tank buffer to the pneumatic system.