Air operated liquid level sensor. Intrinsically safe because it uses no electronics, so it can be operated in hazardous areas. The sensor probe sits in the tank and sends an air signal to a valve when the liquid level is too low or too high.
For example, to fill a daily-use ink or adhesive container from a 55 gallon drum or tote tank, the sensor can be set up to operate a double diaphragm or peristaltic pump when the daily tank runs low, filling it without any expensive or large explosionproof electronics.
Setup instructions: Link. Schematic setup: Link. Parts breakdown: Link
