Orifice plate flow meter
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Our company has a orifice flow meter for measuring mixed gases at a temperature of around 180 degrees, and the readings it provided were consistently on the low side. Previously, this flow meter would give lower readings only on rainy days; we used to fix it by releasing pressure through the vent valve. It is determined that the low temperature caused fluid accumulation in the flow meter, resulting in a low reading. But recently the levels have been low again and it hasn’t rained. We tried to vent the air before, but the levels remained low even after that; we’re not sure what’s causing this issue. We determine that there are 5 possible problems: (1) liquid has accumulated in the flow meter; (2) the transmitter is damaged; (3) the pressure guide tube is blocked; (4) there is an issue with the orifice plate; (5) there is a problem with the insulation. When venting the three-valve assembly, liquid was present in the vent hole for a brief moment, but not in large amounts. Also, after operation begins following the testing phase, the flow meter will gradually increase in value. But it dropped again after a while. Once the measured differential pressure stabilized, it remained at 15 KPA, but the differential pressure measured by another flow meter was 20 KPA (there are two orifice plate flow meters in this measurement pipeline, and a differential pressure of 20 KPA is normal for that meter). Is there anyone skilled enough to figure out where the problem lies?
In this case, it is recommended to install the transmitter above the orifice plate.
For mixed gas transmitters, the common installation method is to have the liquid below the orifice plate and the gas above it; try installing the transmitter on the upper side. If the orifice plate becomes clogged, drainage through the 3-valve assembly will not be smooth! If it’s a problem with the transmitter itself, replace it with a new one!
First, calibrate the transmitter; if it is still showing a low value, there might be liquid accumulation or leaks in the piping, or insulation issues could be to blame. Check each of these possibilities one by one to identify the cause. The probability of problems with the orifice plate is very low...
The transmitter is installed above the orifice plate
It’s likely due to installation issues, such as the direction, etc
It shouldn’t, it’s been running for a long time already. Problems that have emerged recently
This post was last edited by HEJIYUER on 2015-12-8 at 23:18. According to the original poster, this material will condense at room temperature. The cyclic variation in differential pressure is estimated to be caused by inconsistent condensation rates of the +/− pressure transducers. You can add heat tracing to give it a try. After draining, is the differential pressure of the two transmitters the same? For two transmitters, are the pressure tapping ports of the orifice plate separate? @jiaguoyun