Choosing Control Valves

Control Valves are the workhorses of the process control field. As a process control guru, you should know how to select valves for all sorts of process conditions.

One of the most important resources you can have for control valve selection is the Emerson (formerly Fisher) Control Valve Handbook.

This is an incredible resource.  A complete copy of the famed Fisher Control Valve Handbook, the “Little Black Book” of Control Engineers, almost 300 pages, on-line, for free!

Click here to download the Fisher Valve Book as a pdf file

If you are new to the topic of selecting control valves, I would also recommend a series of articles by Béla Lipták. With 50+ years in the process control industry, Mr. Lipták knows his valves. This 3-part series was published in Control magazine in 2006:

Click here for part 1

Click here for part 2

Click here for part 3

This 3-part series should bring you up to speed, and help you to make an informed selection.

Do you have other great resources to suggest? Leave a comment for this post.

 

Can’t I Learn It All on Wikipedia?

There’s an incredible amount of information available on-line.  Recently, I have seen a number of newsgroup posts by engineers and students looking for “free application advice”.  Their requests elicit some responses from well-meaning engineers, replete with references to Wiki’s and other on-line information sources.

It’s tempting to think you can learn everything “on demand” by reading Wikipedia, and maybe throwing in a few searches on Google.  But you should be careful.

Let’s see how this works for some simple topics…

For PID Control, you can get this page on Wikipedia: http://en.wikipedia.org/wiki/PID_control#Loop_tuning

An impressive table of contents, a mix of theory and practice.  A few good primers.  But look a bit closer.  There is not even a mention of PLC or DCS platforms.  No actual equations for tuning.  No real discussion of algorithm selection.  In other words, all the practical aspects of process control are missing.

Here’s another topic: Control Valves.  A search on Google turns up the Emerson (formerly Fisher) Control Valve Handbook.

Click to access cvh99.pdf

This is an incredible resource.  A complete copy of the famed Fisher Control Valve Handbook, the “Little Black Book” of Control Engineers, almost 300 pages, on-line, for free!

But here’s the rub…To use this great resource, you’re looking through 300 pages of information.  I don’t know about you, but I’m old-fashioned, and like to keep a printed copy close at hand.

The point is, application of process control requires in-depth knowledge, mixed with practical experience.  Sometimes (as in Wikipedia), you only get a cursory overview.  Sometimes a Google search will turn up a real gem, like the Control Valve Handbook.  It’s up to you to dig in deeper, to sort through the theory and practical aspects.  Often, you will only develop the practical understanding by doing the work, and by learning from experienced engineers.

To become a process control guru, make sure you know how to leverage online information sources, and when to discount them.  Make sure you know when to call in someone with more experience.   Make sure you know when to invest in formal training.  You can’t find everything on the web…and what you do find can be of dubious quality.  An in-depth resource requires in-depth study.

Don’t be fooled into looking for on-line shortcuts!  If you want a simple, quick answer to a simple question, then Wiki-style resources might just work.  But if you need to solve an in-depth problem, then you need to make sure you have access to both in-depth materials AND practical advide and experience.