Temperature and pressure compensation for vortex flowmeters under negative pressure
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Question: When a vortex flow meter operates under negative pressure, is it designed for positive pressure? How should pressure compensation be carried out using a pressure transmitter, given that the transmitter measures negative pressure and the medium is gas?
I think that when selecting a flow meter, it’s sufficient to inform the manufacturer of the operating conditions; they will help you make the choice as they have considerable experience. Additionally, when performing compensation, using a gauge pressure transmitter and carrying out the compensation in the DCS under normal conditions should work fine.
When performing temperature and pressure compensation, positive or negative pressure actually doesn’t matter; they are merely different ways of representing pressure. What’s important is to use the same pressure representation method as that used during calibration. The pressure and temperature sensors are used to measure the current temperature and pressure, which are then compared with the standard conditions used during calibration, thereby determining the volumetric flow rate under standard conditions, which is equivalent to the mass flow rate.
When it’s under negative pressure, does the medium still flow? It doesn’t flow any more, so no vortices can be formed, and the vortex flow meter becomes useless.