Does the pressure difference resulting from the height difference of the pressure taps when a venturi flow meter is installed vertically have an impact?
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For a vertically installed Venturi flow meter, if the liquid inside is at rest and the flow rate is 0, the differential pressure transmitter should still give a reading—this reading corresponds to the height difference between the pressure tapping points. This is also the principle behind level measurement. When actually measuring the flow rate, this differential pressure will surely have an impact. However, it seems that manufacturers of throttling elements do not take this situation into account in their calculations. Or, before the device is turned on, fill the venturi with liquid, and perform a calibration of the transmitter reading at that time?
Yes, when a venturi flow meter is installed vertically, the height difference between the pressure tapping points does create a pressure difference, which affects the measurement results. Before measurement, zero calibration is usually required to ensure that the reading of the differential pressure transmitter is zero when the liquid is at rest. This can eliminate the effect of the initial pressure difference caused by height differences. When the flow meter begins to operate, the measured differential pressure will more accurately reflect changes in flow velocity. Therefore, proper calibration and installation are key steps to ensuring measurement accuracy. .
As long as the pressure guide tube is filled with liquid, the hydrostatic pressure remains the same
Firstly, when the liquid is installed vertically, it can only flow from bottom to top. In a Venturi flow meter, due to the height difference between the pressure sensing tubes on the positive and negative sides, it is necessary to zero the differential pressure transmitter after installation; alternatively, the pressure sensing tubes on both sides can be brought to the same level, and then a three-valve assembly can be used to connect them to the transmitter.