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Will Bubbles in the Liquid Affect Measurement of Magnetic Flow Meters?

December 09, 2022

As one of the most popular flow monitoring devices in the industrial fields, electromagnetic flow meter is an ideal solution for flow detection. While you may note that during the measurement, there are bubbles in the liquids, so will it affect its measurement?

First we may have to know why air bubbles in liquids. This is because that the inhalation of gas by the medium from the outside or the transformation of dissolved gas in the medium into free bubbles can generate air bubbles in liquids.

If the air bubbles in magnetic flow meters are evenly distributed, it will generally not affect the measurement; however, if large air bubbles cover the entire electrode, it will cause instantaneous open circuit of the flow signal input and fluctuation of the output signal!

magnetic flow meter

 

How to Deal With Bubbles?

If it is judged that the error is caused by the installation position, for example, when the signal fluctuates because the gas in the magnetic flow meter installed at a high point of the pipe system, or the air inhaled from the outside, changing the installation position is the best solution.

However, in some cases, when the magnetic flow meter has large DN size or it is not easy to change the installation position, we can solve the problem by installing a gas collecting device and an exhaust valve upstream of the flow meter.

You may ask how to judge whether the measurement error is caused by the bubbles? When the measurement signal fluctuates, immediately cut off the excitation circuit current of the magnetic field. If the meter still displays the flow and the signal is unstable at this time, it is mostly caused by the air bubbles.