Issues with the process connection method of pressure transmitters
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We have a small project that is currently in the acceptance phase; the expert panel came to conduct an inspection and said that the way the pressure transmitters were connected to the main steam pipes on site was incorrect. On-site, diaphragm pressure transmitters with radiators are connected using flanges. Threaded connections should be used, along with pressure and cooling tubes, which are to be installed within a 45-degree range above and below. I checked, and indeed there is no diagram showing flange installation for 21581-2012. Is it truly not possible to use flange connections? Are there any specific specifications? I beg you. . .
You can refer to the \"Instrument Installation Manual\"; there are no mandatory regulations, but installing it in this way makes it more likely for the voltage transformer to get damaged due to high temperatures.
Is the temperature resistance of silicone oil in diaphragm pressure transmitters higher than that of steam?
There is no flange mounting option in the legend. Does that mean it’s not recommended? I contacted the design institute, and they said they have never designed anything for flanges.
The legend is the standard; its absence means it’s not recommended.
The connection diagram of diaphragm-sealed pressure transmitters in the self-control installation manual does not emphasize the state of the medium, as gas, liquid, and steam can all be measured in this way. Unlike pipeline connections, which have corresponding installation methods. Piping connections and diaphragm seal connections are on an equal footing, with no regulatory requirement specifying which connection method should be preferred. From an economic perspective, pipeline connections are generally given priority. When using diaphragm seal connections, attention should be paid to the temperature resistance of the pressure-transmitting silicone oil; high-temperature silicone oil should be used if necessary. Capillary connections should be employed rather than direct connections to prevent the electrical components of the gauge from being damaged by high temperatures, thus ensuring the gauge’s service life.
It is connected by threads, with pressure guide tubes and condensation rings – experts say that this installation method is most prone to leakage due to thermal expansion and contraction when used with steam. It is best to use a capillary flange pressure transmitter. For corrosive, toxic, flammable, and explosive chemicals, we always use capillary flange pressure transmitters.
Flange diaphragm transmitters with radiators – this is the best option, as they are leak-free and have low maintenance costs. The person doing this inspection is a bit strange