APG IRU-6420 [IRU-6429] Ultrasonic Level Sensor w/ 0-2.5V /0-5V Output (5 conductor cable), 1 - 30 ft. (0.3 - 9.1 m)
The IRU-6429 series provides a non-contact method of detecting level, presence/absence detection, volume, proximity and distance. With built in technology to compensate for unpredictiable variables such as humidity, temperature and agitators the IRU-6429 is the right sensor for your application.