Wastewater pipe flow measurement
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The inflow flow rate to the sewage tank is 600 mm in diameter; the fluid contains bubbles and particles, and it is not possible to ensure full pipe filling. The pipeline is mostly buried underground, with the flow meter installed on the vertical pipe that leads into the tank from above; the outlet is at atmospheric pressure. With the plug-in ultrasonic flow-free display, the signal strength value is highly unstable. Insertion-type electromagnetic flowmeters exhibit large measurement fluctuations and cannot meet the requirements. I am considering installing a vent valve below the pipeline (upstream of the flow meter) to exhaust air at a pressure higher than that at the outlet; I wonder if this could improve the measurement performance of the electromagnetic flow meter.
From top to bottom? To ensure a full pipeline, it’s necessary to measure from bottom to top. 1. If there are bubbles and particles present, do not use an ultrasonic flow meter based on the time difference method; your insert-type ultrasonic flow meter operates using this method, so it certainly won’t work well ； 2. Assuming a flow from bottom to top, it is theoretically possible to maintain a full pipe, but bubbles can affect the electrodes, causing large fluctuations in the electromagnetic flowmeter ； 3. Assuming that an exhaust valve is installed from bottom to top in the lower part of the pipeline (upstream of the flow meter) to exhaust air at a pressure higher than that at the outlet, it is estimated that this approach will not completely resolve the fluctuation problem associated with the electromagnetic flow meter, as the resistance of the exhaust valve is much greater than that of a DN600 pipeline, and the majority of the bubbles flow towards the DN600 pipeline. 4. It is recommended to install submersible multi-functional Doppler flow meters in the upstream horizontal pipes; these meters are designed for use with fluids containing bubble impurities. They can measure flow rates when the pipe is not completely filled, and they can display the flow rate, liquid level, and temperature. Feel free to ask for more details.
The opinion is similar to that on the 2nd floor: first, confirm whether the ultrasonic system selected is a Doppler type, as the time-difference method won’t work.
It’s best to meet all the conditions to achieve a full pipe. Insertion-type electromagnetic vortex flow meters should be used as little as possible.