Flow meter malfunction in Weiliba!
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The specific issue is as follows: When measuring the flow rate of medium-pressure steam, the readings have been unstable since the onset of winter. It was suspected that excessive heating was causing instability in the fluid flow. Separating the heating tubes from the pressure sensing tubes did not resolve the problem. Eventually, the pressure sensing tubes were removed altogether, and the differential pressure transmitter was connected directly to the Wilo unit; this worked for a while, but then the problem reappeared again, with the flow rate always showing as too low or not being detected at all. We have inspected and replaced the transmitter and the three-valve assembly, but the problem has not yet been resolved. I’m asking the helpful forum members to analyze what other possibilities might exist. PS: The Weiliba vertical pipe is installed with the opening facing upward, without an isolation tank.
Since there’s no problem with the transmitter part, the Wilo unit has to be removed for inspection.
Since there is no condensation tank for measuring steam, it is difficult to ensure that the liquid column heights in the two pressure transduction tubes are equal, resulting in large measurement errors. If the transmitter is installed directly on the Wilo unit, the high-temperature steam will come into direct contact with the transmitter; it is uncertain whether the transmitter can withstand this.
The current situation is that the facility is in operation, so it is not possible to remove it.
A temperature gun was used to measure the temperature at the end of the Wiliba unit; it was around 100 degrees. The temperature of the fluid inside was slightly higher, but theoretically, the transmitter diaphragm box can withstand such conditions
A condensation tank should still be added; the transmitter diaphragm won’t break in a short time, but its service life will be shortened.
The key issue now is the inaccurate measurement; are there anything else that needs to be checked?
If there is no issue with the differential pressure and the displayed value is very low, then it is still a problem with the Wilo unit; this is the root cause.
First, calibrate the transmitter; once it is confirmed that there is no issue with the transmitter, the problem may be caused by a blockage.
There are usually no problems with Weiliba; the probability of such issues is quite low. Poor readings from the flow meter are mostly caused by installation problems, such as incorrect installation of the pressure transfer pipes or the wrong orientation and position of the transmitter. You can check the transmitter; it should be possible to isolate the Wilo unit, and then remove the instrument