Level measurement using 'through-the-wall' principles
For many years, process industries have widely used ultrasonic ‘through-the-air’ principles as a preferred method of level measurement. This can have limitations with regard to some applications, as pressurised vessels, varying gas densities and surface foam can all cause loss of the echo signal.
Hycontrol’s new non-contact ultrasonic instruments are capable of monitoring levels with novel ‘through-the-wall’ techniques which overcome these fundamental problems.
This enables level measurement in totally enclosed vessels without the need to enter or cut into the tank or silo. These systems can provide a wide range of control options, from single point level switching to continuous level measurement and can be installed on a wide range of applications including hazardous and aggressive media.
The instrument transmits a pulse of high-frequency sound from the transducer attached to the outside of the tank or vessel. This pulse passes through the tank wall and through the fluid until it reaches the fluid surface. It is then reflected back to the transducer and is received as a transit echo. The microcontroller times this reflection and, with the aid of patented window technology, calculates the distance accurately and reliably.
The principle is simple, with an ultrasonic sensor being mounted to the outside of the vessel and ‘coupled’ to the tank with a transmission gel. This enables the ultrasonic sound to travel from the transducer through the wall of the tank and into the liquid. Using this technology Hycontrol can obtain either a level measurement or a simple switch point depending upon what is required. This is particularly advantageous if the vessel is pressurised or has no process connections. Please note this technology has to be used with clean liquids only with no sidewall contamination such as rust or scale.
A modified version of this non-intrusive technology can be used on cylinders for determining piston positions and pig detection in oil lines.
Long measuring ranges up to 15 m
Non-contact measurement principle
Hazardous area options ATEX
Simple to install on outside of vessel
Fixed and portable units available
Will detect under a foam layer
Hygienic mounting available
Ideal for aggressive applications
No interruption of process