Industrial process control often requires the measurement of liquid inventory volume or mass. If the material is contained within a tank of known shape and dimensions, the volume can be determined accurately by measuring the level of the liquid. Various means are used to determine the liquid level. One of the simplest is the downpipe sensor, sometimes referred to as a "bubbler". King-Gage is manufacturer of industrial downpipe liquid level measuring devices. The slides provide graphic depictions of how the systems function and provide an overview of several product configurations.