Why does the transmitter on the Aliba flow meter show that the pressure on the positive pressure side is lower than that on the negative pressure side?
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Recently, I encountered such a problem during construction: an Aliba flow meter was installed on-site. Its positive pressure side was facing the direction of flow, in line with the direction of the process medium, and the pressure guide tube was connected to the positive pressure side of the transmitter. The negative pressure side of the transmitter was connected to the negative pressure side of the Aliba flow meter. Yet why did the transmitter keep showing that the pressure on the negative pressure side was higher than that on the positive pressure side? After checking the transmitter, there are no issues with it. How should this be resolved? I would appreciate it if experts could provide some analysis.
Generally, the differential pressure transmitters used in Willyba flowmeters are of the micro-differential type; it is essential to ensure that the diaphragm box of the transmitter remains vertical during installation, with no deviation allowed.
If the wiring of your VeriBa flow meter and transmitter is correct, you can check whether the above errors are present. I hope this helps you.
I’ll go to the site tomorrow to check whether the transmitter diaphragm box is vertical. Thank you for your help.
What was said on the 2nd floor makes a lot of sense. As an additional point, it’s best to keep the pressure lead for Anubas flow meters as short as possible, in order to minimize deviations caused by static pressure differences; it’s ideal to install them directly on the pipeline itself :)
If the problem is resolved, please let me know, thanks. If it can’t be solved, let’s think of another way.
We have encountered this situation while driving as well; it was a leak in the pressure tap connector. The pressure difference here is only 1 KPa. Another point is the view from the 2nd floor.
If there is not enough straight pipe section, it will lead to an uneven flow velocity distribution within the pipeline, as well as backflow, resulting in such consequences. Our company has been at the site, so this phenomenon must be occurring.
I’m not sure if this happens when there is no data flow; it’s possible to adjust the transmitter’s negative offset first. However, I still agree with what was said on the second floor – this is a fundamental issue that will lead to inaccurate measurements in the future
This is a common issue when the system is first put into operation after construction: there is a blockage on the positive pressure side
Everyone has raised many questions, all of which are worth considering. But I’m not sure what exactly the problem is that the original poster encountered
Yes. At this time, the operating conditions are unstable and the medium is not clean. It is usually a problem with the pressure measurement pipeline; problems with the transmitter are rare. Try to operate the valves in your three/five valve assemblies following the procedure of zeroing them and observing the trend in their values; also open the exhaust and drain valves on the pressure lead lines. The vent and drain screws on the transmitter flange valve assembly can also be opened, to remove water in the case of gas measurement, and to remove air in the case of liquid measurement – all while ensuring safety. If that still doesn’t work, close the pressure tapping line connected to the throttle element, and reopen it once the operating conditions have stabilized. Strictly speaking, the issue raised by the poster is not during construction (unless it involves joint testing with media), but rather during commissioning. This post was last edited by emir001 on 2008-1-2 14:37.]
On-site, once the instrument readings are inaccurate, it is often assumed that the problem lies with the instrument itself. At such times, after ruling out issues with the instrument, it is necessary to consider whether there might be problems related to the manufacturing process. This situation can occur if the process conditions are unstable at the start of operation, or if the process parameters do not meet the design requirements, among other things.