3-way control valve

[ChipFuller]

I'm trying to size a pump for a 3-way control converging flow valve setup. I have three 3-way control valves in series. The ethylene glycol either goes through a heat exchanger and across the valve (Right to Left) or goes around the heat exchanger and across the valve (Bottom to Left). I gave Samson, the valve manufactuer a flow rate of 100 gpm with a pressure differential of 15. They came back with a Cv value of 27.4 at relative travel of 86.2%. The overall Cv value is 47 at 100%. How does this work with 3 way valves and Cv? When you have a pressure differential of 15 is that across both legs of the valve overall?

Thanks