Discussion on liquid level measurement issues
Thread Content
The liquid level at the bottom of our aviation fuel fractionation tower has a set of measuring instruments, a double flange and a differential pressure transmitter. Recently, the process has reported that the instrument measurement is inaccurate. On-site inspection, the indications of the double flange and the differential pressure transmitter are about 79%, and the glass plate is full when inspected on-site. However, when the valve is opened in the process to increase the external discharge, the bottom pump of the tower quickly appears to be evacuated. It was later confirmed that the liquid level at the bottom of the tower was indeed full and had reached a very high level. As the components at the bottom of the tower became lighter, the pump at the bottom of the tower was evacuated. However, I couldn't figure it out. As the components became lighter, the measurement range would increase, but why did the two liquid level measuring instruments end when the maximum indication reaches 79%, and could no longer indicate any higher?
This phenomenon is normal, because the density of the measurement medium becomes smaller, and the differential pressure generated at the same full scale (height) will become smaller. The maximum differential pressure range of the meter when setting is a certain value. The percentage is displayed after dividing the two, so the display becomes smaller at full scale.
The density becomes smaller and the static pressure decreases. Of course, the indication cannot reach the original maximum value of the measuring range.
i see! thanks
Medium density and temperature will all be affected.
I agree with the opinion above. In fact, the density has become smaller, causing the pressure on the membrane box to become smaller, causing the meter display value to not reach the maximum.
The density decreases, the pressure difference decreases, and the measuring range becomes larger.
The second floor said it very well, that’s it
As the components at the bottom of the tower become lighter, the pump at the bottom of the tower is evacuated, and the density of the measurement medium becomes smaller, resulting in a smaller pressure on the membrane box. The differential pressure generated at the same full scale (height) will become smaller, and the maximum differential pressure range of the meter when setting is a certain value. After dividing the two, the display becomes a percentage, so the display becomes smaller at full scale.