Primary door + secondary door
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Pressure gauge + primary valve + secondary valve. What are the respective functions of the primary valve and the secondary valve, and what is the order of their installation?
It’s a primary valve, and a secondary valve I guess. Doors? I don’t understand
It should be a door rather than a valve. The installation order is as follows: first, the primary valve, which is used to control the flow of the medium; then the pressure guide tube, with the lowest point of this tube connected to the drain pipe and the drain valve (which can be considered a secondary valve); and finally, a pressure gauge at the end of the pressure guide tube.
In the instrumentation field, they are referred to as primary valves and secondary valves. The one-way valve is installed near the pressure tapping point and serves to shut off the process fluid; it is not operated frequently, but needs to be closed during instrument maintenance. The secondary valve is installed near the instrument, and it generally needs to be closed when checking the instrument.
The gate serves as the boundary between the process piping and the instrument control piping, and is constructed simultaneously with the process piping； The secondary valve serves as the boundary between the instrument pipeline and the instrument itself (or the pipelines that come as part of the instrument and are supplied together with it within the instrument rack). It is installed during the construction of the instrument pipeline, and its installation comes after that of the process pipelines.
Is the answer upstairs? *Get used to the first valve, then the second valve
The primary valve is the valve at the root of the pressure guiding pipe, while the secondary valve is the valve at the root of the pressure gauge. Replace the pressure gauge; if the primary valve fails, disconnect it; if the conduit is faulty, disconnect the secondary valve.
The second half of the upper part seems to say the opposite
I’ve heard of the term ‘primary door’ and ‘secondary door’ for the first time; where did it come from?