Ultrasonic Level Sensors use a pulsing sound generator and receiver to read sound echoes between the sensor and liquid level to provide a continuous level measurement. Ultrasonic Level Sensors work well in tanks that have a perpendicular unobstructed view directly to the non-turbulent surface of a liquid. Please note that the sensors should never be mounted in the center of a domed top tank. The EchoSpan® family is designed for more difficult applications with options available to read heights up to 32.8'. The sensor has an integral push button display that allows you to calibrate and program the range directly from the sensor when it is installed on the tank. They also included a patented software technology that allows the sensor to ignore echoes generated by internal obstructions in the tank such as mixers and ladders as long as they are not within a 3" diameter beam area directly below the sensor. Range: 8" to 18'. Accuracy: 0.2% of range. Resolution: 0.039". Dead band: 8". Beam width: 3". Configuration: push button. Memory: non-volatile. Display type: LCD, 6-digit. Display units: Inch, cm and percent. Supply voltage: 12-28 VDC. Loop resist: 500 Ohms @ 24 VDC. Signal output: 4-20 mA, two-wire. Signal invert: 4-20 mA, 20-4 mA. Signal fail-safe: 4 mA, 20 mA, 21 mA, 22mA or hold last. Precess temperature: -7°F to 140°F. Temperature comp.: automatic. Ambient temperature: -40°F to 160°F. Pressure: MWP = 30 psi. Enclosure rating: NEMA 4X (IP65). Enclosure material: polycarbonate. enclosure hardware: brass & stainless. Enclosure vent: water tight membrane. Conduit entrance: dual, 1/2" NPT. Trans material: PVDF. Process mount: 2" NPT. Mounting gasket: Viton™. Classification: general purpose. Compliance: CE & RoHS.