Can a valve be connected at the junction of the differential pressure transmitter and the tank?
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Can a valve be connected at the junction of the differential pressure transmitter and the tank?
If connected using capillaries, no valves can be used; if connected via piping, a check valve can be installed.
Based on the properties of the material, the process engineering team decides whether valves should be installed. 1. If there is a valve, the instrument can be removed and maintained after the valve is closed ； 2、a) If the instrument itself is of high quality and not prone to damage ； b) Instrument failures have little impact on process operation ； c) Process media do not allow the addition of valves between pipeline equipment and instruments (e.g., media that tend to crystallize) ； Then the valve cannot be installed.
Why can’t those with capillaries be used? Please explain the reason.
A valve can be connected at the junction of the differential pressure transmitter and the tank! Valves for capillaries? Could you take a look? I don’t even know how to operate it! Some double-flange differential pressure transmitters have special conductive fluid filled in the capillary tubes; they cannot be disconnected, otherwise they will be ruined!
I agree with what was said on the third floor: whether to install valves depends not only on whether the process allows it, but also on the convenience of maintaining the instruments; no generalization can be made regarding this issue.
In capillary differential pressure transmitters, the capillary end is usually connected using flanges; therefore, no valves can be installed at the root section. Moreover, the flange and the capillary portion beyond it form a single unit, so valves cannot be added there either. Other types of differential pressure transmitters can be equipped with a valve for maintenance purposes.
This issue needs to be determined based on the actual conditions of the process medium and the type of differential pressure transmitter. If the process medium has a high viscosity, tends to crystallize, becomes viscous at low temperatures, and a double-flange transmitter is used, then there is no need to install valves ； If a conventional differential transmitter that requires a pressure tap is used, valves should be installed, and heat tracing also needs to be considered. If the medium does not fall into any of the above categories, a double-flange differential pressure transmitter can be used, with or without a valve ；
In the case of a capillary type, a shut-off valve is installed at the device’s outlet, and then the flange of the differential pressure transmitter is connected. If pressure guiding tubes are required for installation, the method is the same as that for the diaphragm flange type: a shut-off valve is placed at the device’s outlet, followed by the installation of the instrument flange, with the pressure being led to the differential pressure transmitter through the pressure guiding tubes. From the perspective of instruments, root valves should be installed in all cases, except for those that are plug-in type.
Why isn’t anyone giving me points for this title of mine? Also, if there’s a problem with the pressure transmitter, it needs to be taken apart for repair; if there’s no intermediate valve, the storage tank has to be emptied, and sometimes the tank even has to be cleaned, which is quite troublesome. If an intermediate valve is available, things are much simpler – the valve can be closed to allow for disassembly. As a precaution, a blind flange can be used, but in practice, intermediate valves are used very rarely. That’s why I asked this question.
In which factory does the original poster work? Among the transmitters I’ve seen, there is one type that doesn’t have a valve; it’s an insert-type double-flange transmitter designed for use in high-temperature environments where the fluid is viscous and prone to clogging, as well as in corrosive conditions. All the other transmitters come equipped with valves, and having a valve is only beneficial – there are no disadvantages to it. Besides, transmitters need to be calibrated once a year, and without a valve, it would be difficult to disassemble them
Previously at a large company, only half of the units were equipped with intermediate valves; now at a small company, they don’t exist at all.
No problem, then the capillary can’t be connected to a valve? What should I do if I need to carry out maintenance?
It’s best for everyone to go and take a look in person and ask the experienced workers. To be honest, I don’t know why either. Maybe it’s not that it’s impossible to add it; rather, adding an intermediate valve would increase the cost.