Ultrasonic level sensors work by emitting an ultrasonic sound pulse several times per second from the base of the transducer. The pulse travels through air, reflects against the process medium below and returns to the transducer. The sensor measures the pulse time of flight between sound generation and receipt, and translates this into distance or liquid level height within the vessel.
Ultrasonic technology is inherently non-contact and is therefore impervious to challenging application factors that can negatively impact level sensor performance such as corrosive & ultra pure liquids, coating, scaling, dirt, density, dielectric or conductivity.
The factors to avoid with ultrasonic are extreme foam, vapour, turbulence and installations in flange fittings with tall risers. Foam, vapour and turbulence can absorb and / or deflect away a substantial portion of the return signal. Tall installation fittings can disrupt the acoustic signal path.