P&ID instrument Abbreviations

In that context, and without sight of the document, AFS could mean "Air Flow Switch", though the abbreviation itself can sometimes refer to an adjustable spanner - "Any F&£$%@ Size" - which would be out of context. That's the problem with abbreviations -particularly in CR4 - they need definition before they are used so that all readers have a point of reference.

So there should be a standard list of instrument tag abbreviations, which the P&ID originator should have used to populate the drawing. If the reference is not on the drawing then ask the originator for the route to this list in the first instance. It might turn out to be an international standard, in which case once known about it can be found using any internet search engine.

That's what I have notices on a lot of p&id drawings..... No legends.

It's not unusual to find that the 'scribes' who generate P&ID's adapt common terminology without necessarily providing a legend, in many cases because they're unaware that there's deviation from the standard.

I would guess that given the functions, air flow switch for AFS sounds reasonable.

Although first letter H is officially designated 'hand', could HTT be Humidity-Temperature Transmitter ?

thank You very Much.

As PW said -this may be a good time to submit an RFI (request for information) to the engineer/system designer/drawing draftsperson.

Your know whats ironic, besides "PID" standing for Proportional Integral Derivative, "PID" also stands for Process Identification.ha ha

Also this ISA reference may be use in the future...

http://www.isa.org/Content/Microsites165/SP18,_Instrument_Signals_and_Alarms/Home163/ISA_Standards_for_Committee_Use/S_55.pdf

Useful related sources ...

http://www.smartdefine.org

http://www.acronymgeek.com/