5 replies to this topic

[vnilla_gorilla]

I've heard it said that you only include certain ones, but I'm not sure what the defining criteria is. I know you don't want every block valve shown, but you do want those that allow you to do a bypass. 

 

Not sure about check valves.

[Bobby Strain]

Show no valves of any kind. Just connector lines and equipment symbols.

 

Bobby

[xavio]

vnilla,

 

Bobby is right, PFD should only show concept, not details.

You may include some important control valves but usually not the manual ones.

 

There are some guidelines for drawing PFD, but there is no such must-obey criterion.

Anyway, every drawing should serve its purpose: to explain thousand words with one sketch.

If you feel that particular manual bypass/check valves are very important, you can always choose to show them on your PFD.

 

For example, in our plant we have two large check valves at inlet and outlet of reactor, these two check valves are critical safety items.

We opt to show them on the PFD.

On the contrary, check valves on pumps discharge are so common, we don't need to show them on the PFD.

 

Hope it helps.

 

xavio

[fallah]

vnilla,

 

PFD is nothing to do with piping; then in which generally no valve is required to be shown, but critical valves are as exceptions which are to be selected as per the nature of each individual plant. Showing control valves that function among control loops is another story and they, along with the relevant loops, have to be shown as important guidelines to proceed in subsequent PID preparation...

[vnilla_gorilla]

Thank you for the responses. 

 

The PFDs I inherited went as far as showing them on tank inlets so it made me question what I had known up until then. 

 

I believe the check valves they included were Class 1.

 

I will proceed with your input as my default method unless specific project requests something different.

[shan]

PFDs are used to demonstrate process engineer's design concepts.  Valves may be included to make some ideas across, such as flow directions, temperature set philosophies and level control methods.