For double-flange level gauges, what is the trend in liquid level when all of the material crystallizes in front of the primary valve on one side?

It’s hard to determine this; for example, when crystallization occurs in the lower flange, the pressure buildup is greater than that in the upper flange, and in such cases the liquid level should be higher, but logically it should be lower. So the trend can only serve as a reference

It’s hard to tell; just use 32 large bolts for the upper and lower fixing points :(

For example, when the liquid level rises normally and crystallization occurs on the negative pressure side, how will the liquid level change?

As the liquid level rises, crystallization occurs at the upper part; conversely, crystallization takes place at the lower part.

This post was last edited by FightingNow on 2015-6-23 09:06. Explain? Haha, you mean that the flanges in a double-flange design are relatively large and have many bolts that are difficult to tighten. It’s best to determine which of the upper and lower flanges has suffered crystallization, and then remove one of them – is that what you mean? ? If it were indeed the ideal situation you described, with crystal formation occurring on only one side, either on the positive or negative pressure side, it would be easier to make a judgment if there was a local level gauge available. Then, the liquid level could be raised by a fixed amount; the density of the medium could be determined based on the process parameters, and the differential pressure resulting from this rise in liquid level could be calculated. After that, the increase in differential pressure at the double-flange connection could be compared with the value calculated earlier. If there is a significant difference, it indicates that crystallization has occurred at the flange area. If crystallization occurs on the upper flange, it should have a relatively small impact on measurements; the differential pressure won’t change much ； This is because the pressure changes on the negative pressure side are relatively small; it is mainly the pressure on the positive pressure side that is greatly affected by changes in liquid level. In practice, you don’t need to be that precise; there’s no need to calculate the differential pressure in detail. Just raise the liquid level and observe the range of changes in the differential pressure, and you can make an inference.

He means to remove the flanges, right? Tell the original poster to remove both of them properly; it’s impossible to guess

This post was last edited by ylb913 on 2015-6-23 at 14:59. The crystals at the top have caused a blockage; as the liquid level rises, the display value increases accordingly； The crystals below are blocked; when the liquid level rises, the display does not change accordingly. However, the absolute value is not necessarily accurate; it is assumed that a certain amount of gas or liquid is sealed at the blocked area and the pressure measurement point. If the temperature remains constant, this pressure remains fixed and does not change with the actual pressure of the equipment. If the temperature changes, this pressure will change as well due to the temperature variation (thermal expansion and contraction).

Just measure it with a gauge, and then decide how to disassemble it. Otherwise, check everything – it’s better to be sure!

As the original poster said, the liquid level should rise normally; however, if there is a blockage due to negative pressure, the liquid level might rise very rapidly. But without actual practical experience, it’s hard to know exactly how to deal with such a blockage. . . .

Okay, let’s remove the upper and lower flanges :(