Vortex flowmeter fluctuations
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The customer has installed a DN65 vortex flow meter on-site, one that includes temperature and pressure compensation and is designed for measuring steam. Even with the valve closed, there are fluctuations in flow rate, with the magnitude of these fluctuations being around 0.1 T/h; the frequency also keeps changing. What could be the cause? Is it because the valve isn’t fully closed, or is it because there’s always air in the pipeline? Logically, shouldn’t the presence of a frequency indicate that there’s always air in the pipeline?
The fluctuation problems encountered by customers with vortex flowmeters can be caused by several factors: 1. **Valve not fully closed** – If the valve is not completely closed, even a small gap can lead to minor leaks of steam or gas, which causes the flowmeter to indicate flow. It is possible to check and test the sealing performance of the valve to determine whether there are any leaks. 2. **Gas present in the pipeline** – Even if the valve is closed, if there is gas remaining inside the pipeline before it is closed, this gas may move within the pipeline due to changes in pressure or temperature, resulting in fluctuations detected by the flow meter. In this case, the presence of gas can be indirectly confirmed through fluctuations in frequency. 3. **Sensitivity of the flow meter itself** – Vortex flow meters are highly sensitive to hydrodynamics; even slight flow variations can be detected. Furthermore, if the flow meter is installed in an improper location or in an incorrect manner, it can also lead to unstable readings. Recommended actions include: - Checking the closed state of the valve to ensure it is fully sealed. - Empty and recalibrate the flow meter to ensure that no external factors affect the readings. - If the problem persists, it may be necessary to consider checking the location and method of installing the flow meter, or to consult the equipment manufacturer for technical support. .
See what happens when the valve is closed and slowly opened back to its previous state. Having a frequency does not necessarily mean there is traffic
Check whether the leakage from the valve is a bit excessive, causing vibration in the pipeline； Check whether the pipeline is vibrating or if there is electromagnetic interference, etc.
The current reason is the movement of gas within the pipeline, which causes fluctuations in flow rate
Thank you for your answer. The issue at the site was due to residual gas in the pipes