A PFD is a Process Flow Diagram and a PID is a Piping and Instrumentation Diagram.

Milton Beychok
(Visit me at www.air-dispersion.com)
.

Hi Padovano,

PFD - Process Flow Diagram,  visit http://en.wikipedia.org/wiki/Process_flow_diagram

PID - Piping and Instrumentation Diagram, visit http://en.wikipedia.org/wiki/Piping_and_instrumentation_diagram

Regards,

Milutin

Process Flow Diagram (PFD) is the diagram where it is a macro level flow diagram of any manufacturing plant or process with indication of only material stream and not detail instrumentation,control valve tags,Piping specification etc on the line where PID means micro version of PFD , piping and instrumentation diagram which includes all instrumentation like Temperature transmiters,pressure transmitters,control valves tags etc. including safety valves ,ball valves etc. detail drawing.

Thanks & Regards,

I have always used the "&" sign in my version of the P&ID for "piping and instrumentation diagram."
We pronounced it with more of the "n" sound as in P-n-ID.

One thing to add: PID can also refer to a very common type of controller, a Proportional-Integral-Derivative controller. (http://en.wikipedia.org/wiki/PID_controller)

Therefore, it is a good idea to always write "P&ID" and to say "P-and-I-D," like pennpier mentioned, when referring to drawings. If referring to the controller, you may have to say "PID controller" to make it clear what you mean.

P.S. http://www.acronymfinder.com/ sometimes works for acronyms, although coverage of technical topics is poor.