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Guided Wave Radar: Today’s Vanguard in Level Measurement

In 1998, the innovative engineers at Magnetrol® took the revolutionary Lawrence Livermore National Lab patent that Popular Science magazine called “Radar on a Chip”  and developed the Eclipse® – the first guided wave radar (GWR) technology transmitter for the industrial level control market. Today, most GWR devices are based on the ECLIPSE.

GWR transmitters are the preferred choice for a variety of level measurement applications because of the unique benefits they provide. Advanced GWR transmitters also provide a superior signal-to-noise ratio and overfill capacity that measures level to the face of the top of the flange. In addition, the most technologically advanced GWR transmitters have become the go-to technology for many nagging measurement problems, including remote site readings, concurrent measurement of upper and interface liquid levels and unattended echo capture.

Remote Site/Solar Power Applications

One application that has been gaining popularity is called a “solar application,” which refers to a remote, un-manned site, with a solar powered system. A fast turn-on time for low power consumption is the key to a successful solar power application.

This requires the GWR transmitter to come back from being turned off (“sleep” mode), power up and take a reliable reading within 15-30 seconds before going back to sleep to await the next measurement cycle. Magnetrol’s advanced GWR design can complete this cycle in less than 15 seconds, which makes it an ideal solution for these installations.

Upper Liquid Level – and Interface Liquid Level – Measurement

Many industries encounter interface applications that have two immiscible liquids of different specific gravities. The oil and gas industry is rife with these oil/water vessels where separation is critical. Water can be a major liquid that accompanies hydrocarbons from within their original rock formations or a minor liquid that either condenses or permeates out after long periods of rest. In many cases, it is advantageous to measure both the hydrocarbon that rises to the top and the water that settles to the bottom.

Advanced GWR transmitters are capable of effectively measuring both an upper liquid level and an interface liquid level. As only a portion of the pulse is reflected from a low dielectric upper surface, some of the transmitted energy continues down the GWR probe through the upper liquid. The remaining initial pulse is again reflected when it reaches the higher dielectric lower liquid. It is typically required that the upper liquid have a dielectric constant less than 10, and the lower liquid have a dielectric constant greater than 15.

guided wave radar
guided wave radar

Unattended Echo Capture

When a GWR transmitter experiences a process upset or other problem, the practical matter becomes how fast a user can turn around a problem and get the device back on line to minimize down time. One of the most important tools used to troubleshoot a GWR application is the echo curve.

Since an echo curve is so important in troubleshooting the device, it is critical to capture the curve at the instant a problem occurs. Too often, this means connecting a laptop and gathering information after the first signs of the problem.

The advanced ECLIPSE Model 706 GWR design has the ability to capture an echo curve based on Time (using an on-board clock) or a key Event (such as Loss of Echo or Low Echo Strength). In addition, the transmitter can store a number of these echo curves in its on-board memory.

These echo curves can then be downloaded to a laptop running software such as PACTware. The user can then email the information to the factory for expert assistance in troubleshooting. This enables the problem to be resolved much more quickly, minimizing possible downtime.