P&ID questions 1

[ProcessEngineer1]

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,

 

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.

 

[JLSeagull]

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.

 

[GL431]

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.

 

[ProcessEngineer1]

Thanks GL431,

It was so nice to get the answer.

Thanks a lot once again.