Zero adjustment for double-flange transmitters
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There is a double-flange transmitter used to measure the liquid level in a tank. The density of the medium is 0.8, the distance between the flanges is 2.1 meters, and the density of the silicone oil in the capillary is 0.94. Under normal circumstances, negative migration should occur; however, when using a 475 device to check the measurement range, it shows 0–16.8 KPa, and the displayed differential pressure value is positive at 1.38 KPa. The gauge also displays correctly, showing a value similar to that of the local magnetic flip switch; it’s around 8%, and there are variations in this value as trends change. I would like to ask whether this means that no negative migration of the gauge occurred, and instead the zero point was adjusted directly at zero. Is that why this situation is occurring, or is there a problem with the transmitter itself? Will this work properly? Everyone, please help analyze it. Automatic control instruments
Based on the density, range, transmitter settings, there are no issues with the measurement. The density of the capillaries is negligible. The table can be used normally.
Looking at the table, there is no migration.
Hello, old leader! :P I’m so happy to see you! Since, “looking at the gauge, there’s no indication of any migration,” it’s likely that after the gauge was installed, it was adjusted to zero right away when it was at the zero position. But after such a zero adjustment, it should logically be adjusted to its full scale as well; otherwise, the output slope of the gauge, that is, its sensitivity, won’t be correct. When the liquid level rises to a high level, it should be possible to compare it with the reading provided by the magnetic flap gauge; if they don’t match, then it’s likely that an incorrect \"zero adjustment\" was made. Wishing our former leader good health and endless prosperity. . . . . . .
When the liquid level rises to a high level, if the reading obtained from this device still matches the reading from the magnetic flap gauge, it is likely that the gauge was calibrated at the factory with the gas-phase flange as a reference, setting the zero and full-scale values 2.1 m higher than those based on the liquid-phase flange
Smart level transmitters do not have a zero-point shift option; one simply sets the lower and upper measurement limits (different models may have different setting options).
It’s great to see you! It’s amazing to see you still so active, helping others with their questions. I just discovered this as well – the liquid level control is set very low; when it rises a bit, the pump is used to empty it out. The maximum level allowed is around 10 percent, and it’s not permitted to go any higher. I haven’t observed it in the way you mentioned; I’m here to share it with everyone and analyze it. Thank you here, and I wish you success in your business.
This post was last edited by 1111111 on 2018-1-10 at 14:44. Differential pressure gauges are calibrated in this way. . . For example, two typical types of differential pressure gauge configurations are the insert-type remote transmission differential pressure level gauge and the insert-type remote transmission differential pressure density gauge. Since the distance between their upper and lower diaphragms is fixed, they can only be calibrated in this manner.
I’m puzzled because this device should experience negative migration, but no migration has been detected – so how is it still functioning normally?
If the liquid level is emptied, what is the gauge differential pressure?