Revitalizing old tennis balls

[Number]

*Originally posted by Ethilrist *
If you really want to pressurize your balls, you could find a homebrewer with a kegging system and try to sweet-talk him into using one of his spare soda kegs as a ball-pressurizer, so instead of force-carbonating beer he’s force-carbonating tennis balls.

Hmm, I do have a CO[sub]2[/sub] system left over from my more active homebrewing days. That might be an interesting experiment.

[choosybeggar]

*Originally posted by ryoushi *
**Okay, how do they get nitrogen into the balls? I can’t think of any compounds off-hand that will give off nitrogen when heated like they do with CO[sub]2[/sub] balls… Liquid nitrogen would work, but then we run into problems with it’s temperature as it expands… **

Same way nitrogen is used to fill the safety air bag of your car, perhaps.

From thehistoryofcars.com:

During the airbag’s deployment, a series of chemical reactions take place between highly toxic sodium azide (NaN3), potassium nitrate (KNO3), and sodium dioxide (SiO2) to inflate the bag. After the crash sensor has triggered an electric circuit, it creates a high-temperature condition necessary for NaN3 to decompose. During it’s decomposition, NaN3 produces sodium metal (Na) and nitrogen gas (N2). A rapid pulse of the hot nitrogen gas (N2) is released from a gas generator at up to 200 miles per hour, filling the airbag, which is made of thin nylon fabric. The nitrogen gas then converts the highly toxic NaN3 to harmless gas. The KNO3 and SiO2 are present to remove the highly reactive and potentially explosive sodium metal (Na) by converting it to a harmless material. This whole process happens in approximately 1/25th of a second.

The line about the nitrogen gas converting the NaN3 into harmless gas is BS (the NaN3 turns into harmless nitrogen and sodium), but the rest is accurate.

[DougC]

• • • The cheap one I remember was a little mutant can-thing that held three balls at a time, and had a built-in pump. The instructions said you pumped it up and left the balls inside overnight. I still can’t find it tho’…
      ~

[Shalmanese]

If you started off with fresh balls and kept them in a pressurized can whenever you wern’t using them, it should maintain the life of the balls forever theoretically.

[Q.E.D]

*Originally posted by Shalmanese *
**If you started off with fresh balls and kept them in a pressurized can whenever you wern’t using them, it should maintain the life of the balls forever theoretically. **

Well, no, because there’s more to ball life that merely internal pressure. The felt wears off and degrades, and eventually the rubber will degrade as well, and lose its elasticity.

[DesertDog]

*Originally posted by Ethilrist *
More of a supply-and-demand kind of thing–there are many more uses for CO[sub]2[/sub] out there, so it’s cheaper.

Actually, after water and crude oil, LN[sub]2[/sub] is the cheapest liquid on the market. It’s probably, as ** Ethilrist** quessed, more expensive to assemble them in a pressurized chamber rather than drop in a pellet that emits the gas upon heating.

Or, (this just occurred to me) it’s simply the snob appeal. ("I’ve got a can of nitrogen-filled tennis balls – same as the pros use.)

DD