Amy Le
National Semiconductor

Liquid-level monitoring plays an important role in today's automotive, oil, water, pressure, and gas industries, to name a few. For example, pumping oil into a storage tank requires liquid-level monitoring to prevent spillage. Draining liquid out of a silo into bottles also requires liquidlevel monitoring for volume control.

This article will explain how to automate a liquid monitoring system using a pressure sensor. Since obtaining the pressure is just one vital piece of the information, how to convert the sensor's output voltage into the liquid's height using an analog-to-digital converter (ADC) will also be explained. Details of the pressure sensor, ADC connections, system calibration and calculations, as well as an example application, are available to guide designers through the development phase.