ZVO operates a wastewater system with 11 wastewater treatment plants in Germany. The company operates an additional 150 lift stations to transfer municipal wastewater loads to the wastewater treatment plants. One lift station is in the town of Falkenstein in the Harz district. Here, pumps raise the wastewater loads by 23 feet. The loads then flow via a pressure line along the Selke river to the local wastewater treatment plant.
At the lift station, the wastewater first collects in hoppers. Once the level reaches a specific value, or is below that level, the pumps must activate or switch off by way of a PLC. Up until now, ZVO has been using an ultrasonic sensor to detect the respective switching point using a distance measurement. Due to the increasing moisture in the shaft, however, condensation frequently builds up on the antenna of the device. In turn, the condensation has a negative impact on the acoustic measuring signal.
In addition, the measuring device proves to be extremely susceptible to large temperature fluctuations. Despite temperature compensation, spontaneously occurring, intensive sunlight leads to considerable measurement deviations. Frequently, the only way to prevent the pump from running dry is to activate the emergency off float switch. Originally, ZVO had planned to replace the sensor with a hydrostatic pressure sensor. However, this would make it necessary to install a protective tube. For this reason, the customer begins looking for a reasonably priced alternative that can install easily during operation.
ZVO is now using the OPTIWAVE 5400 for level measurement. The company sets up the non-contact radar (FMCW) level transmitter very quickly. No special knowledge is necessary thanks to the simple navigation of the level measurement device. All they need is a one-time adjustment of the tracking speed for the very quick emptying of the container.
The measuring device was originally supplied with a horizontal converter. However, the operator switches to a vertical housing position to make the values easier to read from above. Thanks to the quick coupling system, it’s possible to remove the modular converter of the OPTIWAVE 5400 under process conditions and simply rotate it 360˚.
The OPTIWAVE 5400 offers ZVO a desirable and cost-effective yet reliable distance measurement for the pump control. The radar device is perfect for measuring foaming wastewater with temperature fluctuations outside. Unlike an ultrasonic sensor or comparable radar level measuring device, the OPTIWAVE 5400 features a flat, non-peak signal feed. Thanks to the OPTIWAVE 5400’s slim antenna design, drops of condensation quickly flow off the device. Furthermore, the OPTIWAVE 5400 features a flat, non-peak signal feed. Therefore, condensation thus hardly has any effect on the measurement.
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