Fluctuations in double-flange level gauges – seeking advice from experts!
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The liquid level on-site is 20 percent, but the double-flange level meter keeps fluctuating – it’s very unstable, with large swings from positive values to negative values, constantly changing! Upon checking the data sheet, it turns out that the silicone oil used is a high-temperature type. Since the temperature in our environment is relatively low, electric heating elements were installed in the capillary hoses, but fluctuations still occur. The flanges were also removed for inspection, and the diaphragm boxes showed no signs of damage. Please, experts, suggest some solutions! ! !
After heating the capillary with a heat trace, the silicone oil expands due to the heat, causing the pressure readings in the positive and negative pressure chambers to be higher than the actual values. Because it is difficult for capillaries under positive and negative pressure to be heated in the same way, the deviation in the differential pressure value is not necessarily positive or negative. It is recommended to use differential pressure transmitters with low-temperature silicone oil; no heating should be applied to the capillary to avoid inaccuracies in measurements. Fluctuations may be caused by a malfunction in the transmitter, or they could result from changes in the temperature of the silicone oil due to heating
What was said upstairs makes sense; the use of electric heating may result in uneven heating of the capillaries on both sides. It is recommended to try using only ordinary insulation first
If possible, could the transmitter be removed and left to rest for a while to observe whether there are any fluctuations?
Original poster, you need to consider the temperature of the medium as well as the ambient temperature during fluctuations; it would be best if you could tell me the model of the double flange. In this way, it is possible to see the diameter and length of the capillaries, as well as the density of the silicone oil filled in, etc. The more detailed the parameters you provide, the more accurate our recommendations will be.
1. Even with electric heat tracing, as long as the temperature does not exceed the specified level and remains relatively stable, it should not affect the stable transmission of the differential pressure. 2. Is there no wave barrier? What is the pressure in the tank? 3. Reset the parameter settings by treating the empty tank as a full one again.
1. It is not recommended to provide heating for the capillary. 2. Test whether the zero point fluctuates under static conditions offline. 2. It is recommended to select a new model, providing a detailed description of the operating conditions. Avoid using silicone oil of the incorrect model.
1. Fluctuations that are consistent with the actual liquid level are normal fluctuations； 2. Those related to fluctuations and heat tracing (such as the drainage interval of steam traps, and the on/off operation of electric heaters with temperature controllers) are phenomena caused by heat tracing ； 3. Remove the flange and hang it next to the pressure tap; fluctuations indicate a transmitter fault.