Originally Posted by leroy_sunset
A while back, there was a TT thread that had pics of a repressurization chamber for tennis balls using a corny keg. I wanted to try this, as I have a basket of very decent (but flat) Penn balls that I would like to use for serve practice....
Just wanted to give a shout out for the excellent photos and description. I followed your lead and am now fermenting my first batch of balls
I got a used 5-gal Cornelius keg from Beverage Elements with ball locks on the gas-input and liquid-output fittings (those shiny round "posts" on top of the keg). Also bought the necessary plastic quick-disconnect for the gas fitting.
The gas fitting internally has a spring-loaded pressure valve (a "poppet") that lets air into the keg from your air pump. Normally both the gas and liquid fittings are shut tight when there isn't a disconnect attached.
Most ball lock kegs have a manual pressure relief valve on top of the lid and this comes in handy when it's time to pull the balls out. Pin lock kegs usually don't come with that kind of lid, although they can be retrofitted easily and are sometimes sold that way.
I used the same air tank schrader valve shown in leroy_sunset's photo. Instead of using the high pressure hose (usually rated to 200+ psi) I used regular vinyl hose that's good up to 50 psi). The tip to heat the 1/4" ID hose before inserting the schrader valve is a good one since its a very tight fit. The hose clamps are stainless steel, 5/16" wide, 7/32" to 5/8" OD.
After pumping air into the keg, I attached a tire pressure gauge to the schrader valve to check the pressure, then removed the disconnect and its hose (the poppet seals the gas fitting).
I'm pressurizing at 28 psi right now (150 strokes with a bicycle floor pump). Like others, I also heard a few "popcorn popping" sounds from inside the keg when pressure went over about 25 psi.