Double-flange level gauge
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With double-flange level gauges, in the past when the actual liquid level reached 100%, the remote DCS would display 100%. But in recent years, when the actual liquid level reaches 100%, the remote DCS only shows a value of around 70% and doesn’t change any further. What is the reason for this? The meter technician said there was nothing wrong with the meter.
First, you need to know whether the percentage you’re referring to is one that is displayed at both ends, or a percentage calculated based on the corresponding pressure or height. It is recommended to check the range settings at both ends as well as the actual current output of the instrument
1. If the feed liquid has not changed, its density remains unchanged, and the zero point of the differential pressure gauge does not shift, then it must be that the differential pressure gauge is at its full scale – indicating a severe downward shift in its reading. 2. If neither the zero nor the full-scale reading of the differential pressure gauge shifts, then it must be that the fluid properties have changed – its density has significantly decreased. .
Over time, sediment may accumulate in the tank, the density of the medium could change, and drift may also occur. Just check it directly, that’s all. It’s something that can be done in no time. Is your meter reader also an electrician doing the job, knowing nothing at all?
I am responsible for checking the range associated with the DCS for double-flange valves, as well as recalibrating the zero point, range, and linearity of the transmitters
“Which “actual liquid level” does it refer to? Local level or other remote transmission? “If the “actual liquid level” is fine, adjust the liquid level and make comparisons; if the double-flange level gauge does not change accordingly, there is a problem with the gauge! If possible, it is necessary to regularly inspect and clean the double-flange diaphragm head.
I don’t think it must be a problem with the instruments; please determine whether everything is functioning properly based on the actual conditions on site, and check whether the instruments on site are aligned with those used for remote transmission. Factors such as whether the double flanges have been removed or whether there has been any change in the medium inside the tank can all be ruled out; in this case, it is possible to contact the instrumentation personnel for calibration with an empty tank.
For the zero position, verify the density and check the range
If there is no change in the measured medium density, it indicates zero drift; if there is a change, then the range is incorrect
Method: 1. Check the zero point； 2. Does the medium exhibit crystallization? ； 3. Check medium density