Contacting and non-contacting types are familiar to most users from their widespread application in liquid level measurement. The most common are radar (contacting and non-contacting), ultrasonic.

    

Radar Level Measurement - for solids applications, radar provides the greatest versatility:

 

•    It delivers very fast response to changes in level, making it suitable for real-time closed-loop process control and safety applications

•    The speed of radar is unaffected by changes in the vapor space—such as humidity, temperature, composition, or pressure/vacuum—providing better accuracy than speed-of-sound technologies.

•    With appropriate heating or purging, radar can resist condensation and dusty environments.

•    Contacting radar (guided wave) focuses the radar energy within the waveguide to maximize signal strength in difficult applications. Where contacting radar cannot be applied, for example where blocked by an agitator or vessel internals, non-contacting radar can often be used effectively.

•    Radar waveguides and antennas are available in alloys able to withstand corrosive elements along with very high pressures and temperatures.

•    Radar is rarely affected by interference because it uses a frequency range largely immune to noise from motors, conveyers, or other equipment.

 

 

 Ultrasonic is appropriate in applications where the vapor space is consistent in composition, and where the temperature remains relatively stable or is controlled. Temperature is critical because it affects the speed of sound. While ultrasonic devices don’t have the broad operating temperature range or pressure range of radar (ultrasonic doesn’t work at all in a vacuum), it is suitable for many applications, even those with corrosive atmospheres.