There is condensate in the pressure lead tube on the negative pressure side of the differential pressure transmitter
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There is currently a differential pressure transmitter; process changes on the negative pressure side result in the presence of vapor. The pressure tap pipe on the negative pressure side is relatively long, and after pre-cooling and liquefaction, a liquid column forms within this pipe, leading to inaccurate measurements. By draining out this low liquid column, the level returns to normal. I would like to ask: in a situation like this, how should the pressure tap pipe on the negative pressure side be modified according to the standards? Thank you~~
Without knowing the specific details of the medium and piping, insulating the pressure guiding pipe can prevent inaccurate measurements caused by condensation; or, if the medium permits, an isolation fluid can be used instead.
Condensate tank. . . . . . Condensation tank. .
Install a condensate tank or gas-liquid separator
In the gas phase, first, lay horizontal thin tubes; these tubes can be placed at a distance of 3 to 5 meters apart. They must make at least one 90° turn, with no limit on the number of turns. Then, connect these horizontal thin tubes to a condenser with a diameter of around 15 centimeters. Right above the condenser, there is a lid that can be unscrewed to add water. Below the condenser, there is a thin tube – note that this tube must be connected to the high-pressure side of the differential pressure gauge! Liquid phase, horizontally arranged fine-diameter tubes, connected to the low-pressure side of the differential pressure gauge! This is called positive reverse measurement: the differential pressure gauge is always under pressure in the forward direction. The lower the liquid level in the boiler drum, the higher the reading on the differential pressure gauge; the higher the liquid level, the lower the reading. . On the pressure tapping pipeline, valves such as stop valves will be omitted here.
I agree with what was said above; it’s also possible to add an isolation tank at the point where the negative pressure is highest, and achieving negative migration can also serve the same purpose
What is a measurement attribute? What is a medium? What are the operating conditions? Nothing is clear!
No pressure guiding pipe is needed; double flanges are used instead. . .
I would like to ask how the poster determines that the gas in the pressure guiding tube liquefies to form a liquid column
Although you didn’t specify whether it’s for measuring liquid level or differential pressure, or for gas phase or liquid phase, I believe this is a design flaw – not everyone is capable of working well with instruments. In this case, the transmitter should be placed above the two pressure tapping points.