What is the buffer device between the pressure gauge and the pressure vessel it is attached to?
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Recently, while studying the relevant standards, I came across Article 9.2.1.3 of TSG21-2016 \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\". As shown in the figure above, what is the buffer device mentioned in item (4), and how does it enable isolation of the medium? I used to only know that there was a trap on the pressure gauge of the steam pipeline; other than that trap, I wasn’t aware of anything else
bg4.png The buffer tube is also known as a trap: In pressure vessels where the boiler or working medium consists of high-temperature steam, a trap must be installed on the connection pipe of the pressure gauge. Its function is to allow the steam to condense within this curved section, thereby preventing high-temperature steam from entering the gauge’s spring tube directly and causing the components inside to overheat and deform, which would affect the accuracy of the pressure gauge. It can even lead to damage; when steel pipes are used for trap pipes, their inner diameter should not be less than 10 mm. A three-way stopcock should be installed between the pressure gauge and the trap, to allow for flushing of the pipeline, replacement, and calibration of the pressure gauge.
It’s the isolation container. By applying an isolation fluid, it separates the medium from the instrument sensing elements. Actually, there’s no need for such hassle; diaphragm pressure gauges or transmitters with single-flange isolation provide the same level of isolation. Personally, I think many aspects of the TSG standards are simply made up arbitrarily; they force one to refer to other standards in order to come up with some nonsensical descriptions.
The fifth floor is the right choice. This is a professional explanation!
Is that all? Item (3) of this article has already mentioned the trap, so won’t item (4) repeat it?
The condenser tube, commonly known as a bell bend, is used in part for cooling purposes to prevent excessive temperatures.
Use a Bourdon tube for high temperatures; use an isolation tank for dirty media; use diaphragm pressure gauges or transmitters for extremely dirty conditions or those prone to clogging
It seems to be a dedicated pressure gauge with its own isolation device?
Yes, you just need to search for diaphragm pressure gauges and diaphragm pressure transmitters