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P&ID questions

P&ID questions

P&ID questions

(OP)
I have a difficulty in understanding this convention. Please let me know, what I can infer from the below convention.

PIS-+A-+

and  LS++A++

and so on.

Thank you,


RE: P&ID questions

P&ID slang is not as generic as you might think. P is Pressure, I is usually Indicator, S is usually Switch, but I have no idea about the pluses.
But relax, if you look at page 1 in your P&ID book you should find a legend that tells you everything you need.

RE: P&ID questions

Refer to ISA 5.1 for the instrumentation symbology.  A P&ID legend is a good thing.  Some include with the process flow diagrams.

LS is level switch.  A is alarm.

PIS is unusual but would be pressure indicating switch.  For example, Mercoid makes a bourdon tube pressure gauge switch. The alarms often include an associated suffix like H for high and L for low.

RE: P&ID questions

PIS-+A-+ --> switch at low pressure and high pressure, alarm at low pressure and high pressure

LS++A++ switch at high-high level, alarm at high-high level

Often you will find a "slang" written and the signs are not fully conforming to ISA.

RE: P&ID questions

(OP)
Thanks GL431,

It was so nice to get the answer.

Thanks a lot once again.

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