Radar Overcomes Price Constraints for Water/Wastewater Industry

Vega is a sensor company that’s known for its radar technology, with about one in every three radar gauges around the world bearing the Vega name. But now Vega wants to make sure that people understand radar can also have all the benefits—and then some—of ultrasonic technology. That wasn’t always the case. A lot changed a few years ago when Vega began using 80 GHz technology, making its radar level measurement more accurate and more reliable because of the radar beam’s more precise focus.

But radar technology is also expensive. For this reason, Vega commonly plays in oil and gas, chemicals, and other industries that demand high-end capabilities. But not so much for water/wastewater, food and beverage, pharmaceuticals, OEMs, and other industries with low-end demands. In fact, just down the river from Vega’s headquarters in Schiltach—in the heart of Germany’s Black Forest—is a water treatment plant. You’d think the chances are good that they’d be using the sensors built by their neighboring company, but that hasn’t been the case.

The Vegapuls 11, 21, and 31 are compact 80 GHz radar sensors with an optional display.

Now Vega has added a new compact 80 GHz instrument series to its radar portfolio, making the technology especially suited to price-sensitive applications like those found in the water and wastewater industry. The new Vegapuls instruments use a new radar microchip that Vega designed to be small, with a fast startup time and low energy consumption. The microchips are considerably less expensive so that they can replace ultrasonic measurement sensors in most applications.

As it tries to make its way into new industries with this lower-price line, Vega’s message is that radar is the better ultrasonic.

Ultrasonics and radar are very similar technologies. They are both non-contact technologies; they sit at the top of a tank to measure the distance down to the product surface. For that reason, they’re installed from above; there’s no need for a hole at the bottom of a tank and therefore no possibility of causing a leak. Neither technology has to be calibrated for a specific measurement; you just have to tell the sensor where your 100% and 0% points are. With the ability to use the same devices for a lot of different measurements, both sensor types simplify project planning as well.

The Vegapuls C 11, C 21, C 22, and C 23 have fixed IP68 cable connections.

But there are several differences that set radar apart from ultrasonics, according to Greg Tischler, product manager for radar and guided wave radar at Vega Americas. Key among them is that radar is unaffected by external influences like solar heating, air temperature fluctuations, fog and mist, buildup, and condensation. In a first look of several new products offered to Vega’s sales reps and a few members of the press, Tischler demonstrated these differences:

Temperature. Radar travels at the same rate no matter what the temperature is in the atmosphere. Ultrasonic technology can be affected by changes in temperature. In a demonstration, Tischler used a heat gun to raise the air temperature in the immediate vicinity of both a radar and ultrasonic sensor. While the radar measurement stayed at 72.3%, the ultrasonic measurement was bouncing all over the place.
Gas stratification. The water/wastewater industry uses ultrasonics typically in chemical tanks. But the technology can be affected by gases that are stirred up in the tanks. In an example Tischler mentioned with an acetone tank, the ultrasonic sensor was consistent as long as the chemicals sat in the tank. But removing product from the tank stirred up gases, causing the sensor to indicate that the chemical level was rising when in fact it was dropping. In a demonstration with a fire extinguisher, Tischler showed how the ultrasonic failed but a radar sensor measured through the CO₂.
Pressure/vacuum. Ultrasonic technology is made up of mechanical waves that depend on molecules in the atmosphere. While radar can measure through any pressure level, Vega’s ultrasonic devices are limited to about 50 psi, according to Tischler.
Environmental conditions. Buildup or crystallization on the instruments can also affect ultrasonics. “It might be things like spider webs, rain—anything that can affect actual transducement,” Tischler said. He mentioned a problem water treatment plants have with the ingress of rainwater into sewage systems. “They were getting problems with buildup, and ultrasonic wouldn’t work properly.” In his demonstration, he applied peanut butter to both the ultrasonic and radar sensors. The ultrasonic measurements got pretty stuck. Although the radar reading changed slightly, it continued to track the liquid level. This ability can be useful in overfill conditions as well, where—as in Tischler’s demonstration—the submerged radar sensor indicated an overfill of 107% while the ultrasonic sensor got stuck at 85%.

Vegamet controllers work in combination with up to two radar sensors. Optimized for the water/wastewater industry, they have large graphical displays and weatherproof housing.

The new Vegapuls instruments work with both liquids and solids, and are available in a compact version with cable connection housing and in a standard version with a fixed IP68 cable connection. The sensors are also complemented by optional Vegamet controllers. Specifically designed to meet the needs of the water/wastewater industry, the controllers feature a large graphic display that can be used to visualize all measured values. The controllers enable simple implementation of pump control, flow measurement in open channels, and overfill protection according to the WHG standard.

Both the sensors and the controllers can be operated via Bluetooth with a smartphone or tablet, making setup, display, and diagnostics easier, especially in harsh or hazardous environments.