Repressurizing used Balls

#51
I'm working on a simple homemade invention/solution. Will post
pictures once I finish making it. A little busy right now, but home to
finish it by Jan 1st. I'll post instructions on how to make it also.
 
F

fenman

Guest
#52
I built one using a 4 foot section of 3 inch PVC pipe (PW Pipe IPS 100 psi). I glued a cap on one end and put a "QWIK" pressure test cap on the other end. A tire valve stem installed near the top allows me to pump it up to about 25 lbs. It holds 22 balls and has served me well for 10 years. It takes over a year to repressurize really flat balls.
 
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#53
The PVC pipe idea sounds great. I was thinking of using a large jar and
an old basketball (using the step cutting the basketball to make a lid).
 
F

fenman

Guest
#54
You could pick up an old pressure cooker at a garage sale, thrift store, or e bay. Put a valve stem in the pressure release hole. Fill it up with balls.

Plus you could use it to cook up something.
 

Nuke

Hall of Fame
#55
Get a large garden sprayer from the hardware store. Dump a bunch of balls in the tank and pump it up to store the balls between playing. No modifications needed. And you can use it to spray insecticide or fertilizer in the garden..
 
#57
Ha! That's the best repressurizer yet. I think I'm going to go get one.
I wonder how long it takes for the balls to get repressurized...
 
F

fenman

Guest
#58
All of the sprayers I've looked at were unsuitable for 2 reasons: The hole was too small for a ball. When filled with solid objects it would not be possible to insert the pump-cap assembly. A simple redesign by the manufacturer could fix those problems and provide an affordable device for tennis.
 
#59
Nuke's idea is brilliant.

Just add a moderately accurate pressure gauge, so you don't over pressurize, an instruction sheet, and you could make a fortue selling them on ****.
 
#60
converted pressure sprayer

Actually, the converted pressure sprayer is already available here, about US$200 per unit:

http://www.smartitems.com/ballcharger.htm

and I will try to post the image here:



I'm not sure how good a seller this item will be, because most players that I play with couldn't be bothered to repressure old balls, and also new balls are not all that expensive. Plus people just like to play with new balls, and for practice, many players don't mind playing with softer balls, or don't need the feel of the bounce of a new ball. Only the real fanatics and purists appreciate the feel of a new ball bounce from an old ball.
 
#62
My first comment is on using heat to repressurize balls. That only adds pressure to the balls as long as the heat is still present in the entrapped air within the ball. Hot air spreads out more and has less density than cool air, so it presses out on the sides of the ball more. Once it cools off, it will have the same lack of bounce. You need to actually put air into the ball for it to be truely pressurized.

As for the ball charger, I bought a Tennis Ball Saver for $10 a while ago at MC Sporting Goods. I tried it on old balls, but it didn't seem to do much. I now use it on new balls. i keep them in it whenever not in use. Since then, I have never had to quit using any balls due to lack of bounce. They all go bald, but still have brand new bounciness. I would say it was well worth the $10.
Where did you buy it ? and what brand is it ? I live in Europe and I'd really like to purchase one... Can you get some for me ? and then ship them ?i dont know if that's too much for asking...

I don't know if this also works... I own a pressurized machine, actually a couple, since my dad deals with cars and everything... If I get a large container with enough thickness (like those gasoline containers that pretty much everyone has) and then make a cap to fit the container and just pump the air inside with the machine would that work ?
 
#64
Freezing the balls might work!

According to the gas laws pressure decreases as temperature decreases, so freezing the ball would decrease the pressure inside. Before you freeze it a completely flat ball should have a pressure inside equal to the atmospheric pressure.
The pressure inside the refrigerator would be the regular atmospheric pressure. Once the ball is frozen, the pressure inside the ball would be lower than the atmospheric pressure that it was at prior to freezing, and the pressure inside the refrigerator would be higher than the pressure inside the ball.
Well, in the same way that pressure would escape a ball when it was new, pressure will go back into the ball since the pressure outside is higher than the pressure inside. I believe that's how these "rechargers" are supposed to work.
Take the ball out after some time (probably quite a while...) and let them regain room temperature, and the balls should now be at a higher pressure than they were before freezing. Sounds like it might work...
well your theory fails because the pressure inside the refrigerator won't be the same as a normal atmospheric pressure... if the air is inside it will be "freezed" also... so technically if you put a tennis ball inside it won't do anything because once the ball gets "frozen" it will have the same pressure as in the rest of the refrigerator... the solution here would be to get a frozen ball and to maintain it really cold without influencing the surrounding atmosphere but that seems quite hard for a common person to do at home
 
#65
what's the value of a repressurizer like the gamma pressure cap?

What is your opinion of a reasonable retail price of a repressurizer unit like the gamma pressure cap, which had a sleeve, screw on cap with indicator/valve, and a hand pump? I have found a factory in China which could produce a similar unit, and possible enhancements. What enhancements might you suggest?

One enhancement would be an easier way to attach the cap to the sleeve instead of a screw on thread which required some strength to get airtight. Another would be some indication of approximate air pressure inside the container. And finally include different size containers, like 3-ball, 4-ball, up to maybe 8 or 10 balls.

Just thinking...
 
#66
Voila, I have found a retailer in Italy that carries the Gamma pressure cap (but without the Gamma logo), and as well the address printed on the package of the cap's inventor, Mr. Thoma Kunststoffe. It was a bit difficult contact the retailer, communicate with him on the shipping and mailing cost, and making payment to him, but eventually everything got done and I got the product. If anyone wants the contact of the retailer or Kunststoffe, pm me and I'll pass along the info.
 
#67
No big deal. It's just that the store owner is a difficult person to deal with. His store has lots of old products, and happened to have about 3 of these units. But because the product is old, the one I bought wouldn't hold a seal, so I had to go back to the store to exchange for another unit, which also didn't work. Each unit has 3 components -- the sleeve, cap and pump, and I made him let me try different components from the units he had until I had a set that worked in its entirety. This got him really upset that I just wouldn't go away and be satisfied with an unworkable product.

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#68
???

DSM: why did you quote my comments about the difficulties with the store owner in Causeway Bay in Hong Kong? Since then, I've looked for another retail store that still had this Gamma Pressure Cap, and as I said in my last post, I found a retail store in Italy that has the original inventor's product, called only the Pressure Cap (without the Gamma logo). They are two different stores in two different locations. So what's with your merely quoting my earlier comments? I'm not advertising or trying to sell the product, just passing on info to others who may want to buy the product.
 
#69
DSM: why did you quote my comments about the difficulties with the store owner in Causeway Bay in Hong Kong? Since then, I've looked for another retail store that still had this Gamma Pressure Cap, and as I said in my last post, I found a retail store in Italy that has the original inventor's product, called only the Pressure Cap (without the Gamma logo). They are two different stores in two different locations. So what's with your merely quoting my earlier comments? I'm not advertising or trying to sell the product, just passing on info to others who may want to buy the product.
since i couldn't pm you i dont know why...can you get me the contact in italy ? I live in Europe and I'd like very much to have some of those pressure caps... so let me know something if you see this thanks
 
A

aroddick

Guest
#70
ive found a cheaper way to repressurize balls....well, what happened was there was a time where i left all my stuff inside my hatchback....and it would get hot, cuz in socal, it's getting up around 95-100 degrees...i took a tennisball out after leaving them for a couple weeks and they were bouncing as high as, if not higher, than new tennisballs...so the heat from the car pretty much repressurizes balls...so i can get new bouncy balls w/o spending money for a repressurizer that only repressurizes three balls...i can repressurize a whole hopper

I second that, they are good again for like 2 or 3 matches.

IT WORKS
 
#71
SalvadorVeiga, the contact person is Stefano Mezzadri in Pero, outside of Milano, Italy. His email is <xtennis@xtennis.it> He has the Pressure Cap for sale on his website at euro 10,60 <http://www.xtennis.it>
 
#72
SalvadorVeiga, the contact person is Stefano Mezzadri in Pero, outside of Milano, Italy. His email is <xtennis@xtennis.it> He has the Pressure Cap for sale on his website at euro 10,60 <http://www.xtennis.it>
thank you so much for the reply... Do you have one ? Does it really work out for you ? I think 2 of these caps will work out for me... but I am wondering if I get a ball machine if I can "build" a solution...

I have a compressor machine...if I put the balls in a container and just pump air at 14lbs pis will it work the same ?
 
#73
works

Salvador, the pressure cap works on same principle as you mention: pumping air to greater than general air pressure into a sealed container with the balls. The key points are: making sure that there's an airtight seal and a way to see that air has not leaked out.

I have been using the pressure cap for about a year and a half, and it works for me. I like playing with balls that have close to new ball bounce. I use a 4 ball plastic container. For some reason, the pressure cap works only with plastic and not metal containers.
 
#77
well your theory fails because the pressure inside the refrigerator won't be the same as a normal atmospheric pressure... if the air is inside it will be "freezed" also... so technically if you put a tennis ball inside it won't do anything because once the ball gets "frozen" it will have the same pressure as in the rest of the refrigerator... the solution here would be to get a frozen ball and to maintain it really cold without influencing the surrounding atmosphere but that seems quite hard for a common person to do at home
no, it's not a closed system in the fridge. Cold air is circulated, so the pressure in the fridge should be at atmospheric pressure else you won't be able to open the door. Theoretically, I would think freezing balls would repressurize them for a longer time than heating. Freezing balls would equilibrate the internal pressure to atmospheric pressure at low temperature. upon returning to room temperature, the internal pressure would then be higher than atmospheric pressure, thus repressurised. Pressure in heated balls would only be elevated while they are still hot.

I've just placed some in the fridge. Will try them out his weekend.
 
#78
Freezing the balls might work!

According to the gas laws pressure decreases as temperature decreases, so freezing the ball would decrease the pressure inside. Before you freeze it a completely flat ball should have a pressure inside equal to the atmospheric pressure.
The pressure inside the refrigerator would be the regular atmospheric pressure. Once the ball is frozen, the pressure inside the ball would be lower than the atmospheric pressure that it was at prior to freezing, and the pressure inside the refrigerator would be higher than the pressure inside the ball.
Well, in the same way that pressure would escape a ball when it was new, pressure will go back into the ball since the pressure outside is higher than the pressure inside. I believe that's how these "rechargers" are supposed to work.
Take the ball out after some time (probably quite a while...) and let them regain room temperature, and the balls should now be at a higher pressure than they were before freezing. Sounds like it might work...
Actually, the main problem is not the cold air in the freezer, but the initial condition that the ball must be "Before you freeze it a completely flat ball should have a pressure inside equal to the atmospheric pressure." Pressurized balls have way more pressure than diffusion of gas along the temperature gradient would allow.

Even if it was possible (supercooling perhaps), it is way more economical and environmentally friendly (freezing = electricity = coal/gas most of the time) to get another can of balls and wholesale/donate the old balls to dog owners.
 
#79
I went to the store in Causeway Bay in Hong Kong where I got my Gamma Pressure Cap. The owner said he doesn't carry them anymore because of the difficulties with me on the last purchase. He also said he doesn't want my business. So I don't know if he really got rid of his old stock, or if he was just saying that he won't sell to me even if he does have any left in stock. So that's that...

So now I have to be careful that the one I do have will not explode or develop a leak.
Why does this story remind me of Maxline/Eagnas?

Rod
 
#80
I made a ball reviver that works well. Using a 4' section of 3" PVC pipe (rated at 200psi), an end cap (sealed) and a 3 inch valve (ordered off ****). connected to a valve w/pressure gauge*. I attach it to my air compressor, driving it up to 40psi. leave it till I need them. usually overnight they come out strong, like new.
holds about 24 balls. works well.


*pressure gauge is available at Homedepot in the air compressor section. it has a hose fitting, shut off valve and gauge built in. around $7
 
#81
I made a ball reviver that works well. Using a 4' section of 3" PVC pipe (rated at 200psi), an end cap (sealed) and a 3 inch valve (ordered off ****). connected to a valve w/pressure gauge*. I attach it to my air compressor, driving it up to 40psi. leave it till I need them. usually overnight they come out strong, like new.
holds about 24 balls. works well.


*pressure gauge is available at Homedepot in the air compressor section. it has a hose fitting, shut off valve and gauge built in. around $7
Can you post some pics, especially the end opposite the sealed end cap?
 
#83
the end (other than the sealed end) is the big 3 inch valve I won (the bid on for $20). the air valve is screwed in near the closed off cap (put air valve in, with nut inside pipe, then pvc cement/seal the end cap) you need to put the valve as close to the end as possible.
I stand it up on the valve end (when full) and strapped it to a shelf in the garage. (near my air hose). when I need them, I open the valve and out comes the recharged balls. works well. (the key is finding at least a 3" valve- any smaller and the balls won't fit through it!)
 
#84
the end (other than the sealed end) is the big 3 inch valve I won (the bid on for $20). the air valve is screwed in near the closed off cap (put air valve in, with nut inside pipe, then pvc cement/seal the end cap) you need to put the valve as close to the end as possible.
I stand it up on the valve end (when full) and strapped it to a shelf in the garage. (near my air hose). when I need them, I open the valve and out comes the recharged balls. works well. (the key is finding at least a 3" valve- any smaller and the balls won't fit through it!)
Thanks for the detailed description but I still have no idea what it should look like. Do you have a link to the valve you won? But really pics would be even better.
 
#89
Are you guys sure that some of those gizmos don't double penis enlargement devices? :) Pressureless balls are the way to go IMO; they supposedly are good for a year of regular use.
 
#90
sorry for the delay in responding, I've been out of the country.
basically, the thing looks like a shoulder mounted bazooka.
just do an image search on google for 3" valve. the other end of the 4 foot pipe has a cap on it. (at that end I put an air fitting and pressure valve)
very simple, but it works well.
 
#91
I've used my company's chemical tank to built a repressurize tank for the flat tennis ball. Took me a month to repressurize flat (no super flat thou). I pumped in about 30PSI into the tank. Too bad the tank could not take in more than 30PSI (air starts leaking above 30PSI due to sealing problem). Finally i councluded that these repressurizer tank helps in preventing the tennis ball from getting flat due to atmospheric pressure but not exactly very effective in repressurizing tennis ball due to the time involved.

Check this pics of my tank.

http://server5.ihostphotos.com/show.php?id=153843
http://server5.ihostphotos.com/show.php?id=153844

Cheers,
Ryan
I find it very hard to believe that tennis balls can be repressutized. Has anyone ever done it? I have been following forums on this topic and have yet to hear of anyone actually doing it. Here’s why I don’t think it’s possible.
A ball in a pressurized tank will immediately collapse in on itself until the pressure inside the ball equals the pressure outside the ball. Without a pressure differential there is no reason for air to cross the rubber barrier. My brother years ago built me a ball pressurizer out of steel that I could put 100 psi into. It worked fine for keeping fresh balls pressurized but did not pressurize flat balls. I see devices on the market claiming to be able to repressurize balls...I don’t believe they work.
 

LGQ7

Hall of Fame
#92
From 20 years of experience, it works. It won't re-pressurize dead balls, that takes too long. It does keep new balls new. You will also need a Craftsman Strap Wrench. I saw a Bob Vila commercial and I put 2 and 2 together.

 
#93
I find it very hard to believe that tennis balls can be repressutized. Has anyone ever done it? I have been following forums on this topic and have yet to hear of anyone actually doing it. Here’s why I don’t think it’s possible.
A ball in a pressurized tank will immediately collapse in on itself until the pressure inside the ball equals the pressure outside the ball. Without a pressure differential there is no reason for air to cross the rubber barrier. My brother years ago built me a ball pressurizer out of steel that I could put 100 psi into. It worked fine for keeping fresh balls pressurized but did not pressurize flat balls. I see devices on the market claiming to be able to repressurize balls...I don’t believe they work.
Yes, it works. I can make any ball hard as long as it has no holes and I have time. Corny keg pressurizer.
 
#94
You can use a small water accumulator tank.
No modifications necessary. Unscrew the lid. Put the balls in. Put the lid back. Use bicycle pump to pressurise it throught the valve on the back side. Until you start hearing popping sound from the inside.
( Balls collapse. That is the max pressure you can make . typically it is 3x of atmospheric pressure for a half deal balls.)
Dead balls restore in about 1 months under pressure of 3x ( 1.5 times higher than in a regular can when you by them)

https://www.pumpvendor.com/Accumulator_Tanks_Pressure_Tanks.html
Look for SF 3400-002 on this page ( down below)


Check Home Depot. They have cheap tanks.
 
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