P&ID help

Kind of PLC related. I am converting a process from single loop controllers to PLC controls.
My question is what are the right symbols to use? In the attachment I have included you seem the old Level controls and my attemp at the new controls. Is this correct or not? If not then what do I need to do?


I would insert an image if I could figure out how to.

I suggest you use IEC symbols - you can download these from a few places in formats suitable for immediate integration into CAD drawings.

One thing I would emphasize is using the right symbol when it exists - i.e. don't just use a simple valve symbol for hand valves, process valves and modulating valves (I have seen this done before), and where possible use symbols which allow you to guess.

I wouldn't agree with using IEC symbols unless the project is for outside the US. The ISA has standards that are more commonly used in the US http://www.isa.org/Template.cfm?Sec...stomsource/isa/Standards/StandardsListing.cfm

S5.1 is probably the most useful to you.

Regarding your diagram, the symbol for the level transmitter should be a round balloon, since it is a field device. It is common to show PLC functions separately for high and low alarms, and the PLC symbols are often included as a group in a rectangle representing the control panel.

Thanks guy.
Tom I am planning on using ISA. I have never done the prints I usually get the control side of the work. So I just looked at the Loop sheets and I don't know that I have ever paid any attention to the field sheets.

Does the 5.1 show you the basic layout for the field devices interfacing with a PLC? The stuff I found last night 5.3 and 5.5 showed some labes but it just didn't click for me. Do you know where I can some sample to use as a baseline?

S5.1 defines the symbols and abbreviations for Process and Instrumentation Diagrams. It also has some sample diagrams.