Radar Level Measurement New Radar Sensor for Liquids — with 80 GHz in the Spotlight

| Author / Editor: Sabine Mühlenkamp / Dr. Jörg Kempf

Vega is sending to the starting line a real “game changer” in radar level measurement — the first 80-GHz sensor for liquids characterized especially by extremely good focusing. This feature will make level measurement more reliable than ever before. Measuring points that were previously considered problematic, such as vessels with internal installations, will benefit most from this “world first”.

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The Vegapuls 64 is ideal for installation in smaller processing systems and filling vessels, e.g. in the pharmaceutical and food industry, but also in pilot plants.
The Vegapuls 64 is ideal for installation in smaller processing systems and filling vessels, e.g. in the pharmaceutical and food industry, but also in pilot plants.
(Picture: Vega)

After the resounding success of the bulk solids radar level transmitter Vegapuls 69 one and a half years ago, Vega is making big news again. In May 2016 the Schiltach instrumentation expert was launching a new series of radar level transmitters for liquids that also operate at a frequency of 80 GHz. “We are sure that Vegapuls 64 will be a game changer,” said Managing Director Günter Kech in early March, announcing the market launch to the trade press. “All difficulties that have hindered the progress of radar measurement technology until now are history.”

The new radar sensor features better focusing and a very wide dynamic range. This is illustrated by a simple calculation: A radar sensor with 26 GHz transmission frequency and an antenna of size DN 80 has a beam angle of approximately 10°. Vegapuls 64 has a beam angle of only 3°. For example, this benefits the food industry, where agitators, heating coils or spray heads usually complicate radar level measurement inside vessels. Now the radar beam simply passes right by these obstacles.

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Until now there was no radar sensor for liquid applications on the market with a dynamic range as large as that of the new Vegapuls 64. This means that media with poor reflective properties — i.e. low dielectric constants — can now be measured considerably better than with previous radar sensors. A great advantage with foam, extremely turbulent product surfaces, condensate or buildup on the antenna! “There are applications in which the antenna has to be cleaned of deposits every two months. After we installed a sensor from the pilot series in one such case, the operator didn’t have to do that any more. The higher measuring certainty ensures a reliable measurement,” explains Clemens Hengstler, Product Manager for radar/ultrasonics at Vega.

Simple Installation and Setup

Setup and commissioning is also many times easier because the need for false echo suppression is largely eliminated. The smart plics concept makes setup even easier (see box). And another feature makes the installation safe and reliable: the very narrow measuring beam allows Vegapuls 64 to be mounted on existing gauge sockets. This is interesting for all applications where the whole vessel has been approved by a pressure test and may no longer be changed.

Normally, a socket causes interfering signals. Not so with Vegapuls 64: its narrow measuring beam just goes right past the edges of the socket. Dismantling or changing the socket is therefore not necessary for reliable operation of the instrument. This makes things a lot easier for the oil/gas industry. There, it is now standard practice to install a ball valve between the tank and the measuring instrument, so that the instrument can be safely removed, just in case.

This configuration is now also common in nylon production. The problem: ball valves used to cause strong interfering reflections — the new Vegapuls 64 avoids this, ensuring reliable measuring results. Vegapuls 64 comes with different antenna systems in different sizes. At the moment, the thread sizes on offer are ¾ inch (beam angle 14°), 1½ inch (7°), DN 50 (6°) and DN 80 (3°). For hygienic applications there are other process fittings available, e.g. those complying with 3A and EHEDG, where only PTFE serves as the wetted material. The smaller beam angle has other implications as well. “Thanks to the good focusing you can select a smaller antenna,” says Hengstler. The process fitting of the smallest antenna is no larger than a 1-euro coin.