3 replies to this topic

[sineadi]

What is the exact difference between Flow sheet, Process flow diagram and Block diagram

[Art Montemayor]

Sineadi:

There is no "language police force" in the English language. You can pretty well do with it as you please. Just look at the difference between British, Canadian, USA, and Austalian versions. In fact, just look at what some of our member write! It's very difficult to understand some of it.

Consequently, people call the generic Process Flow Diagram (PFD) what they want to call it - often employing poetic license to the point where you often don't know what they mean. I'm presently dealing with clients who have proven that they don't know the difference or logic between a PFD and a Piping & Instrumentation Diagram (P&ID) - no matter what you/they call it.

A PFD (that's what I've called it for 50 years) serves a logical and important function in any process-dependent project. It's a document intended to display and explain the basic material and energy balance taking place in a process. It basically illustrates the principal steps, flows, or equipment employed to bring about a Unit Operation or a Unit Process - together with a table detailing the main flowstreams, their composition, and properties. It does not enter into the details of process control or piping design and requirements.

With a PFD as a pre-requisite, you can generate a P&ID - and those are the classical steps in defining a process. You can employ "blocks", Icons, or detailed outlines of equipment in the PFD. It really doesn't matter, as long as you accurately and clearly title the objects. Hence, the variation of "block diagram".

I would not worry nor spend time trying to understand or study the different titles for this diagram. The time wasted is not worth it.

[Radionise]

Don't worry pal.

Process flow sheet (PFS) and PFD are the same thing.

[Profe]

Sineadi:

In addition to the valuable information already mentioned, it is advisable to review the following direction:
http://www.roymech.c.../Flow_Diag.html

of the British Standards.

Profe.