Successful Retrofit of a Wastewater Treatment Plant with a Clamp-On Ultrasonic Flow Meter
Without modifying the existing piping, the Aken Wastewater Association was able to save significant costs in optimizing the inflow measurements at its wastewater treatment plant thanks to the successful installation of the KATflow150 dual-channel flow measurement system
AZV Aken Saves a Five-Figure Amount Through Non-Invasive Flow Measurement
Since 2021, all wastewater treatment plants in Saxony-Anhalt that meet a certain size requirement have been required to provide evidence of continuous inflow measurements. However, the Aken Wastewater Association previously lacked a measurement system to monitor the main inflow from the northwestern part and the secondary inflow from the southern part of its service area. With the goal of installing stationary flow meters at two locations within the plant without having to “modify the old cast-iron pipes with a diameter of DN 500 or the manhole structure,” Mr. Thomas Heppner, the plant manager and person in charge, contacted Katronic.
After initially clarifying technical details, a cost estimate for the KATflow 150 two-channel flow measurement system was submitted to the association. This system, designed for permanent installation with two analog current outputs (4 … 20 mA) and two digital relay outputs, is a non-invasive ultrasonic flowmeter particularly well-suited for retrofitting existing facilities.
After Mr. Heppner received approval for the project’s funding, a test measurement was to be conducted at the wastewater treatment plant. This would allow for a more accurate assessment of the future technical feasibility of the measurements and the scope of the commissioning process.
Since the conditions for a test measurement on the two DN 500 cast-iron pipes located in a shaft structure proved insufficient for acoustic sensor coupling due to rust, several measures had to be taken in advance to ensure a functional measurement. In addition to tension straps for securing the sensors to the large-diameter pipes, these measures included the use of a cordless angle grinder and a ‘K0’ transducer with higher signal strength.
After the “main inlet” measurement point was properly prepared, a signal was immediately detected and measurement values were demonstrated. Nothing stood in the way of installing the KATflow 150 evaluation unit.
At the second location, “secondary inlet,” no signal was initially detectable. As it turned out later, during excavation work near the wastewater treatment plant, a DN 200 PE supply line had been encountered that appeared to merge a few meters further into the DN 500 cast iron pipe, where the test measurements had failed. Using a portable clamp-on flow meter, a strong measurement signal was then generated, and volumetric flow rates were confirmed.
The Katronic employees tasked with completing the project checked the new measuring point on-site at the start of their assignment using the portable KATflow 200 clamp-on flow meter. A measurement signal was present, and flow rates could be detected. A K1L transducer compatible with the KATflow 150 was then clamped onto the 200-mm pipe and wired to the data acquisition unit, located approximately 35 m away, via an extension cable. The successfully retrofitted KATflow 150 two-channel flow measurement system has been fully operational ever since and is used for simultaneous flow monitoring on two inlet pipes at the wastewater treatment plant.
The AZV Aken was able to save a mid-five-figure amount on the retrofit of the system—costs that would otherwise have been incurred by constructing a second shaft and equipping it with expensive measuring instruments.
