Calculate the individual flow rate - based on the pressure drop?

Hi

I have to calculate the flow rate inside two systems, which got water from the same “source”.

It is for a project with a pressure vessel with heat transfer arrangements, cooling coils inside the pressure vessel, and “jacket” system outside the pressure vessel.

Something like the one on this picture: http://www.postmixing.com/mixing%20f...ly%20large.jpg and the jacket system: http://www.cheresources.com/jacketed..._design3.shtml

I can calculate the pressure drop for every jacket- and coil-module, and it must be the only factor that “set” the individual flow rate, or what?