recharge tennis balls
Yes it can be done. I have done it. My tank holds 60-68 balls. It would take 2 tanks to do some ball machines. If the ball is relatively new, a month or less, you just need to store them on 15 PSI. If you collect them from around the courts and they are unknown, you have to recharge them around 20-30 PSI. It takes about a week. Every once in a while, you find a few balls that go farther flat. I toss them out. I stated this for my friend. He coaches all ages and uses a LOT of balls. I think I have saved him about $1000 in just the last 10 months.
The tank I made him can go up to 200 PSI. I saw the green machine, nice set up. I like it. I think they should go to Nitrogen instead of CO2 though.