The Helical type has no moving parts and mounts from the top of the tank. Resolution is 1mm or less over a change of level up to 15ft independent of vibration, temperature, viscosity, and density up to the top of the tank. This sensor will not operate in highly aerated liquids. Materials include stainless steel and aluminum which may be fixed to the top plate via welds or O-rings. The sensor is capable of self-diagnostics and an alert in event of a fault. Entry hole diameters can be less than 2”. All standard and custom outputs are available.

Ultrasonic Helical Liquid Level Sensor

How The Helical Sensor Works

An Ultrasonic transducer sends a burst of waves down the center rod that is surrounded by a second rod in the shape of a helix. As the waves pass through the center rod its cross section expands and contracts, creating waves in anything in contact with the rod. Surrounding the center rod is another in the shape of the helix. Wave created by the center rod reach the helix and travel up the helix to the receiving transducer. The frequency of the wave is high enough that waves in air don’t reach the helix so no waves flowthrough the helix up to the receive transducer. When liquid is present, waves travel from the center rod to the helix. The time the first of the waves reach the receive transducer is linearly dependent on the liquid level. The sensor doesn’t respond to foam at the surface so the true liquid level is measured. Because acoustic losses are low, extended sensor lengths are possible. Not suitable for highly aerated fluids due to wave attenuation.


1400 Chisholm Trail Rd.
Suite F
Round Rock, Texas 78681