Drum level – distortion in two-chamber balance measurement
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This post was last edited by liaifeng on 2020-5-17 at 10:03. Our company’s drum level gauges use dual-chamber balance containers, one on the south side and one on the north side, with a measurement range of 5.1 kPa to 1.0 kPa. I uploaded three pictures: the north side, the south side, and the schematic diagram. The side on the south side (equipped with two level transmitters) has been functioning properly throughout the 6 years since it was first put into operation, while the level on the north side is often too high (three transmitters are installed there, as shown in the diagram). Management suspects that there is a problem with the dual-chamber balance vessel; a new one was installed two years ago, and it worked normally after that. However, once the unit stops operating and is restarted, it becomes difficult to get it to function properly. After the most recent major repair and restart, the level on the north side continued to show 100%, while the level on the south side remained around 33%, which is consistent with the actual conditions. The leader believes the reason is that the two-chamber balanced container cup cannot retain water. Upon checking the liquid level gauge on the north side, it was found that on the positive pressure side (with the pressure sampling point located at the upper end), there is a boundary formed by the dual-chamber balance system and the welding joint at the base of the gauge; the temperature is higher on the side closest to the dual-chamber balance system, while it is lower on the side closest to the root valve, and it is possible to feel this temperature difference with one’s hand ； On the negative pressure side (where the pressure measurement point is located at the lower part), both sides are at high temperatures. The normal level gauges on the south side are all at high temperatures. So at that time I suspected that the root valve on the positive pressure side and the welding joint might be blocked, but after removing those parts and using wire to clear the obstruction, it seemed that the pipeline was unobstructed again. Moreover, after closing the process root valve and eliminating the dual-chamber balance, I filled the water tank (i.e., the side connected to positive pressure); with negative pressure relative to the atmosphere, the pressure displayed on the positive pressure side was correct. Even after filling the water bottle with water and putting it into use, it still shows 100% – I really can’t figure out why. I’d appreciate some advice from those who know more about this! ! !
The text is too large to read comfortably; it’s even more difficult when trying to refer to the images as well.
Has the differential pressure transmitter been calibrated? Also, is there any issue with the three-valve assembly? If conditions permit, the devices on both sides can be swapped.
The dual-chamber balance is equipped with three transmitters, so it’s impossible for all three to be faulty; therefore, there’s no need to consider swapping out the equipment in the three valve assemblies.
The dual-chamber balance is equipped with three transmitters, so it’s impossible for all three to be faulty; therefore, there’s no need to consider swapping out the equipment in the three valve assemblies.
The dual-chamber balance is equipped with three transmitters, so it’s impossible for all three to be faulty; therefore, there’s no need to consider swapping out the equipment in the three valve assemblies.
I suspect there is a problem with the pipeline; I replaced the root valve of the low-temperature gauge today, but it didn’t help
1. Take a photo to check your range settings. 2. Fill the water cup (i.e., the side connected to positive pressure); with negative pressure relative to the atmosphere, the pressure displayed as positive pressure should still be correct. But what does it mean for it to be correct? 3. A low temperature on the high-pressure side definitely indicates a blockage somewhere; has it been checked at the three-valve assembly for any leaks? Was it a blockage behind the valve?
This post was last edited by tiger2010 on 2020-4-10 at 20:16. In your picture, the same two-chamber balanced container is connected to three transmitters, but the text description in your post mentions two transmitters; it’s a bit confusing. If the range is the same, looking at the piping in your picture, it seems that the high and low pressure tubes of the three transmitters are not exactly at the same level:o
It’s definitely the same; the pressure measurement points are identical