The instantaneous value of Emerson’s mass flow meter is 0 – help!
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The nameplate is as shown in the diagram; the medium being measured is ethylene oxide. Recently, we have encountered a problem: sometimes the instantaneous value of the flow meter suddenly drops to 0, even though the flow rate is at its maximum – it’s not due to a low-flow condition. This has happened four or five times this year; sometimes the issue resolves on its own within a few hours, but yesterday it took almost ten hours for the flow meter to return to normal. The trend curve displayed on the control panel also showed a sudden upward jump. What’s also strange is that both the cumulative value indicated by the field gauge and that shown on the control panel kept increasing, even though the instantaneous value was 0; the cumulative values remained basically normal. We are seeking advice from those who have encountered similar problems.
Based on your description, where the instantaneous value of the flow meter suddenly becomes 0 while the cumulative value continues to increase normally, there could be several possible reasons: 1. Flow meter failure: It may be that there is a defect in the flow meter itself or an issue with the sensor. It is recommended that you check whether the flow meter’s power supply is functioning properly and whether the connections are in good condition, and try restarting or replacing the flow meter. 2. Environmental impact: Ethylene oxide, as the measuring medium, may affect the flow meter, resulting in occasional instantaneous values of 0. Consider using a flow meter that is more suitable for this type of medium, and keep the environment around the equipment clean. 3. Signal transmission interruption: There may be a problem with the signal transmission line, preventing the instantaneous values from being transmitted properly. You can check the connection of the signal transmission cable and reconnect it, or replace the signal transmission cable. 4. Issues with the data collection system: If you are using a central control system for data collection and display, the problem may lie with that system. You can try resetting or updating the software of the central control system, and ensure that its communication with the flow meter is functioning properly. In summary, it is recommended that you first check whether there is a fault with the flow meter itself, and then verify that the signal transmission and data acquisition systems are functioning properly. If the problem persists, it is recommended that you consult a professional technical support staff for further diagnosis and solutions. .
The supply voltage is 20.3V, which is within the normal range; signal transmission should also be normal, as when the value at the field site is 0, the value at the control center is also 0, with no errors reported. Perhaps more analysis is still needed.
This post was last edited by tiger2010 on 2023-8-15 at 10:57. From the alarm message in your picture, it seems that the power supply isn’t providing enough power; it would be best to use a separate 24VDC switching power supply and give it a try.
It’s the gas-liquid two-phase flow meter that has been zeroed out
The quality of Gaozhun’s mass flow meters is really excellent. Based on the situation described by the poster and the additional information provided, I suspect that one possible issue is related to the power supply voltage; since mass flow meters have relatively high power consumption, the voltage supplied to these instruments might be too low, or the load in the power supply circuit may not be sufficient. Second, there may be electrical interference at the moment, causing an instantaneous interruption of the excitation signal to the mass flow detector. Another issue is the presence of a large number of bubbles in the medium, which results in a two-phase flow; such a large number of bubbles cannot be measured by flow meters. This situation generally does not affect the accumulation calculation; it’s just that the integration value when the signal is zero is zero and is not included in the accumulation.
When it is momentarily zero, check what density the flow meter detects; it is most likely caused by bubbles or particles