Cecil, take a look here: http://www.stcvalve.com/Normall-Open-Solenoid-Valve-Specifications_2SO040.htm

I would contact the valve manufacturer and run your plans by them. A continuous valve is intended to be powered, well, continuously, but I agree that it will get hot during normal operation. If a solution could be found that did not involve a continuous flow of current, I would definitely check it out. I'm not familiar with the electrically actuated ball valves, but I would certainly explore that possibility in greater detail if I were you.

Ask a manufacturer about continuous duty in the manner you envision. They should be able to provide you with the duty cycle for the solenoid.

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.