I'm in the design process for a cooling system. There is the need for some valves to control the flow of cooling fluid. In most machine states there's a constant fluid flow through either of two branches of the circuitry.
Initially I was working with 2/2 directional control valves with direct acting solenoid. Having low system pressure I'm forced to use direct acting valves. A power consumption of 4 W seems to be the lower boundary for a valve with ND 2mm. This is a waste of energy, since most of the time the valves stay in a constant state.
I then changed to 3/2 valves, so that only one state will consume energy. But 3/2 direct acting valves are exceptionally expensive and are available with small diameters only. I thought about ball valves, but those in turn are manufactured with diameters starting from 1/2" and have big gearboxes making them expensive as well.
So finally: Is there a possiblilty to switch a liquid between two brances of a circuit which I didn't think/know of? Tubing has mostly 8mm inner diameter, fluid is water/glycol mixture with temperatures between 10 and 90 degrees. Voltage available for controlling valves is 12V. Perhaps I'm just missing the affordable ball valve manufacturer or some tricky workaround?