How butterfly valves will perform as good as DRVs ( double regulating valves) in flow balancing through parallel chiller(er) water circuits.The butterfly valve I had is 10 diameter, and propose to replace Oventhop Double regulating valve, as the later is more expensive.Butterfly valves are commonly used in such an application and frequently they are the most utilitarian, rubber-lined valves such as the Keystone AR2.  A double-offset valve WOULD be more suited particularly for modulating because of less torque and less friction, but a bit more pricey.  Google does not find any mention of "Oventhop Double regulating valve", which is kind of remarkable even if it is mis-spelled.  Here will be your problem when balancing the system.  This is not always true, but from experience of such systems.  Everyone in the plant will want to adjust the valves and water flow.  Pretty soon you'l see a slow decline in performance of the cooling system.  What you will find is all the valve will be at some partial closed state.  You need to find the loop with the least resistance (shortest line or smallest exchanger, whatever.) and make sure that vale is 100% open, then adjust the other three, do not ever close the that valve.

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