Background 
Earlier this year, our radar product manager, along with members of our service group tested the performance of the VEGAPULS 64, its 80 GHz radar sensor for liquid level measurement, mounted on ball valves and gate valves. The tests occurred in the VEGA Americas Learning Center Lab and in each instance the product measured was oil with a dielectric constant of 2.1. 

Method
Four different valve sizes were tested: 1.5”, 2”, 3”, and 4”, and in each case, an empty vessel was filled and emptied again. We used stainless steel process connections and measured at empty, half-full, and full. As a point of comparison, VEGAPULS 64 radar sensors with corresponding process connections to each valve were tested without a valve in the process. For example, a sensor with a 1.5” process connection was installed directly on a test vessel with measurements taken at empty, half-full, and full. 

Results 
The VEGAPULS 64 performed well with each size and style of valve tested. Using standard false signal suppression with no special parameters or adjustments, the 80 GHz sensor delivered a clear signal every time with all four valve types and sizes. 

Conclusions
The results of these tests represent a significant shift in the way operators think about liquid level measurement, particularly of hazardous chemicals and other volatile substances. It is common for users to separate instruments from the process with valves to keep personnel safe and to preserve the life of the instrument. This separation made it difficult to use a radar sensor. The VEGAPULS 64 erases that difficulty.

The high-frequency instrument emits a radar beam as narrow as 3° based on selected antenna, so fewer signals are reflected by a valve’s interior. This minimized noise creates a clear picture of the level inside a tank without installing a costly, special-ordered valve. It is easy to imagine a future where all users separate the volatile liquids in their storage tanks and reactors with a ball valve or gate valve and an 80 GHz radar sensor.