FE/FIT Symbols on a P&ID

[Sail2Sunst]

We are currently having a philosophical discussion regarding how to connect the flow meter symbol to the FE and FIT circles. I think they should both be connected to the symbol and my colleague thinks the FE should be connected to the symbol and the FIT connected to the FE. ISA shows an orifice plate with the FE and FIT connected to the symbol. My colleague feels that it is shown that way only for a orifice plate... other types of flow meters should be shown as he describes.

Any thoughts on which is correct? Are there any standards out there for this that we can refer to?

 

[FrancisL]

It is up to you, different companies do it different ways.
I agree with your proposal and it is what I have seen more often. And because the FT is not really 'downstream' of the FE, it simply uses it.
Another method is to have just one tag, in the line, and a symbol (defined in a P&ID front sheet) that represents all three. This reduced clutter on the P&ID.

 

[jsummerfield]

Touch the bubbles if they are integral. For a Micro Motion the FE is inline and the FT is remotely mounted a few foot. Two bubbles.

John

 

[controlnovice]

Jsummerfield is correct per ISA standards. If the FIT is integral to the FE, the two bubbles should touch, with the FE 'attached' to the actual meter.

Some FITs are separate from the FE and the bubbles should be separated.

That being said: We don't show the FE at all to save space on the P&ID. It's obvious that there is a flow element there (we show the different style meters per ISA). We just show the FIT and know that the FE has the same loop number.

 

[Ashereng]

On most projects that I have worked on, we usually have a philosophical discussion on such issues as well.

Some would argue that the P&ID is not the place to show installation details - the installation details is where you show how the instrument is installed. I guess they have a point - is it important to the P&ID audience how the instrument is mounted, and what happens if the P&ID differs from the installation detail?

In high temperature service, if one uses pig tails to get the instrument away from the hot element, is that still considered "integral"? I am not sure if ISA defines specifically what constitutes "integral" in all cases.

We usually end up settling on a "standard" after our discussion, and then we go and use the "standard" and "practices" that our client wants us to follow.

 

[jsummerfield]

Abreviated P&ID's are good provided that a legend sheet clarifies some of the details.

John