2 replies to this topic

[jprocess]

Dear All,
What does the term "Split Range Control" mean?
In which situations we should consider it?
Thanks in advance.
Cheers.

[pleckner]

You are splitting the range of controll between two different control valves.

Look at these resources and if you have any specific questions after reviewing them, just post them.

 Split__range_controllers.pdf   38.75KB   256 downloads

http://www.controlgl...s/2005/580.html

[latexman]

jprocess,

A CV has about a 10:1 turndown. Let's say you need 50:1. Pipe two CVs in parallel. For example, say one is 1" with 1" piping and the other is 2" with 2" piping. The main pipe run these parallel pipe runs tee into may be 3". Run a 4-20 ma signal from one controller to both valves. Set up the 1" CV to be closed at 4 ma and 100% open at 14 ma and set up the 2" CV to be closed at 10 ma and 100% open at 20 ma. Notice the overlap. Depending on the demands of your system, you may or may not want an overlap. You may want a smaller or larger overlap. You can also customize to your requirements by specifing the CV trim as linear, equal percentage, quick opening, etc. to get exactly what you want. You can make one CV linear and the other can be equal percentage. Whatever serves your needs best.