The Problem.

I hate quoting inaccurate numbers, but I'm going to do it anyway. I've heard 2 different estimates in the last couple weeks that either 100 million or 300 million tennis balls are produced each year.  Those are big numbers any way you look at it and like a lot of people, I'm becoming more and more concerned about my impact on how much waste is going into landfills.

So,,, I was thinking, "What if we an recycle, or renew and reuse, tennis balls so that we can cut the number demanded in new ball production?" Wouldn't that be great? Yeah, I think it will be great!

I started googling for ideas on how to recharge tennis balls and found several articles or forum postings that suggest that tennis balls go flat because they contain 14.7 lbs psi of pressure when new but once they are released from their can, they begin to slowly leak this pressure through the rubber membrane. If you could put the ball into a container and put it under pressure at 14.7 lbs psi for a while, the air would leak back into the ball until the pressure was equal inside and out. This seems simple so I set out to build a contraption to test this hypothesis.

The Solution (Attempt #1).

Here is a the original prototype I made from 4" tubing. It will hold 26 tennis balls.

It hooks up to an air compressor with an air regulator set at 14.7 lbs psi.  Balls are put into the container where the removable red plug is. The plug is put in and tightened, and the container is hooked up to an air compressor. Viola! Ball recharger!
No problem!

I hooked this up to a compressor in my garage, and left it there by my dog's bed. That one worked well for about 30 minutes and then I heard a huge, 'BOOOM'. The plug blew out of the end scaring the hell out of my dog and shooting about 15 tennis balls straight at him in his bed. When I got to the door and looked out, he was standing out in the driveway looking scared as hell.

Thinking I may have not tighened the plug enough, I set it up again, but it lasted about 20-30 minutes and blew out the plug again. Man that is loud!

Upgrade to prototype

My friend John suggested I try a ball valve, which I had not seen for 4 inch pipe, but I found one for 4" pipe at the local plumbing supply specialty store. This works well.

(I promise I'll get a picture up of the upgrade here.)

I haven't performed any valid tests yet of whether this actually works in practice to recharge a tennis ball. I think it will, but I need to test it.