Radar Replaces Displacer Level Sensors
Radar level sensors use microwave pulses above 2 GHz which travel at the speed of light. The wave travels a distance of one meter in 3.4 nanoseconds. The speed remains essentially the same in a vacuum or any type of gas. The advantage is obvious, namely precision, non-contact detection for almost any medium. However, radar does have one crucial disadvantage. Objects inside the container or changes in the container cross-section create “false” echoes which interfere with detection.
There is one variant which sidesteps these problems: On guided wave radar systems, the pulses are sent down a metal probe. At the boundary surface, sufficient energy is reflected back to determine the level in the container. The signal travels through vapor clouds and past any objects. Agitators pose the only remaining problems. However, even for that problem the company has a solution. “We can supply a curved probe on our latest guided wave radar systems,” reported Baert. This feature is very welcome in the pharmaceutical and biotechnology industries.
Two Sides of the Same Coin
Magnetrol delivers around 20,000 sensors a year, particularly to customers in the oil, gas and petrochemical industry. However, demand also exists for the Belgian company’s sensors in other industries where there is a need for maximum precision. As detection becomes increasingly accurate, rugged and versatile, development efforts are now focused on data evaluation.
Other trends such as wireless data transmission are not a significant factor at the moment, reported Annick Halterman, Global Service and Technical Support Manager. “Many customers actually insist on the two-wire standard.” Non-contact and guided wave sensors are two sides of the same coin, said Halterman. Rather than deciding on one standard, the important thing is to know which technology is better for any given application. The sensors complement each other very well, sometimes even in the same system.