The Gast 4AM motor is the best choice, it has more torque at lower speed than the Gast 2AM. A Gast 2AM will work also, just. In both cases they work better if you pay attention to not restricting the exhaust and keep the inlet line 1/2" and choose a regulator for higher flow. Gast has the specs for both on their website.
I got a 15 gallon tank at Surplus Center. They are out of those now.
https://www.surpluscenter.com/sort.asp?catname=air&keyword=ATT1The trouble with air is leaks. The check valves are NOT gas tight, likewise pilot valves, etc. So if you use a compressor with a motor, yóu'll have to add a ball valve after the check valve.
Solenoid or motorized ball valves will not leak.
My reserve tank is now manually operated; it started out on a check valve which leaked, and then a soft seated check valve which eventually also leaked.
Pilot valves also leak, though special soft seal ones leak less.
Pressure relief valves typically don't leak.
Compressed air is a great power source, and the actuators are powerful and cheap. The only drawback is coping with the slow, weeping leaks. Manageable if you know what to expect in advance, or you can learn the hard way as I tend to.
Best Wishes,
Bruce M
