How to choose the appropriate Controller output range

[hswang2]

I have a process which the feed enter from the bottom of the heat exchanger and come out from the top. And, we try to control the temperature through the inlet flow rate. If the temperature is too low, we will open the steam valve A to let more steam into the system. (Please see fig1 in the attached pdf file) . My question is that the 50% split range is appropriate for this system or not. Because we all know that the split range only has 33%, 50%, 78% options(please correct me if I am wrong), the bigger the split range, the longer the operator can react. So if we choose 25% for the process, is that means the process need shorter time to correct if something happen. Thank you very much.

 

[JLSeagull]

She split range can be any value including gaps or overlaps. Use and individual output for each valve. This permits either valve to be placed in manual if required.

 

[ajs1972]

In my experience with polymerization reactors, in the cooling-heating systems, the split range is 0 to 50% for cooling and 50 to 100% for heating.

In 50 % value, twice valves are closed.