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WHat does this P&ID symbol mean?

WHat does this P&ID symbol mean?

RE: WHat does this P&ID symbol mean?

Do you think you can find another set of drawings around the same age that has the legend sheet? If you can describe what that pressure control loop is meant to do and what type of process this is, maybe someone that has worked with something similar can give their thoughts.

My guess is that the PIC has an interlock at some defined low pressure, so therefore an "L" is shown. But again, complete guess.

RE: WHat does this P&ID symbol mean?

you should show more than the symbols. Show a good portion of the drawing with the title block and notations, the we may have a better idea to the meaning of the symbols.

RE: WHat does this P&ID symbol mean?

That is local a pneumatic controller and valve, with an instrument air suppliy for the controller to directly modulate the valve.

Common symbols in the older plants.

RE: WHat does this P&ID symbol mean?

The "L" is for "LOW" and is related to the "PCV" (Low Pressure Control Valve) and the "PIC" (Low Pressure Indicating Controller).

Sometimes its possible to do all the right things and still get bad results

RE: WHat does this P&ID symbol mean?

So does it mean that it is a symbol for "LOW" alarm/trip?

RE: WHat does this P&ID symbol mean?

@OP i think the conclusion is that it can mean a lot of things and that you will need to look at a legend or some other P&ID where its also used (and not used).

My best guess would be as hacksaw, self actuating valve but i would guess that the L symbol could mean that the SP is adjustable - maybe remotely adjustable? Maybe its a hacksaw says that its a plant air supply, if you have a high presure and a low pressure plant air system then the L would support this (meaning air from the low pressure system).

RE: WHat does this P&ID symbol mean?

I always though it just indicates a supply of instrument air.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: WHat does this P&ID symbol mean?

I am happy that you found the actual definition for the actual symbol for that specific Project.
I assume you found the actual P&ID Legend Sheet for that specific Project.
Having that symbol and using it for that specific purpose does not mean that some other Project, by a different Process Engineer, might use that symbol and the letter "L" for some other purpose.

Make sure that all your projects have a "P&ID Legend Sheet" with all Symbols identified.

Sometimes its possible to do all the right things and still get bad results

RE: WHat does this P&ID symbol mean?

smile So its a very good example that a symbol can have many meanings and that they will all make sense even though they can be very different!

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