DIY building a PVC Pipe pressurizer

neilers

New User
I'm curious on the subject of building a PVC pipe tennis ball pressurizer. I just haven't found any tutorials on doing this, so I'm writing out my plan of attack and I hope that someone smart tells me if it's a no-go, or if I'm all good to go ahead.

So my apparatus would be:

- 40inch pvc pipe. 1 meter long. (according to my calculation, this can hold about 100+/- balls).
- 2 pvc ends.
- tire valve

Here are my questions:
- How would I attach the PVC ends, what would I use to glue it? Would I tape it? Or glue it, what is better?
- How do I secure the tire gauge in one of the PVC ends, without any air-leaks? Is there any information on this?

Here is a really crappy diagram I made in sketchup, will it look like this?

 

Dags

Hall of Fame
There have been a few attempts to build pressurisers. The biggest obstacle is clearly creating a container that can both withstand pressure and not leak: the most popular designs appear to convert pressure cookers and beer kegs. A recently updated thread is here:

http://tt.tennis-warehouse.com/index.php?threads/how-to-pressurize-revive-old-tennis-balls.397853/

There are more if you search for them.

At the end of the linked thread, a few of us are discussing Zombie Tube. A couple of posters have bought from them. I sent an email query a week ago, and haven't heard back... I do get the feeling that it's someone's hobby rather than a bonafide business at the moment. Still, you could consider using their parts rather than building your own cap:

http://savethetennisballs.com/zt1-install/

Or potentially buy their product for 24 or 76 balls:

http://savethetennisballs.com/zt-elite-series/

I'm not sure how much faith I have in them. We've had no reports of people being burnt by them yet, but communication clearly isn't a strong point, and that always makes me a touch nervous.
 

kcmiser

Rookie
A few years ago, I built something almost exactly like you've diagrammed. Bought replacement tire valves, drilled a hole in the PVC and epoxy'd one in. That part was no trouble. The problem came in the end pieces. I think even the permanent end cap leaked until I epoxy'ed the seams (spray bottle full of water with a few drops of dish soap came in handy. Pressurize, then spray seams and look for bubbling as sign of leaking air.)

The big trouble was how to seal the other end. I started with a rubber friction cap over the top of the open end. Major disaster- big leakage. Also, being impatient, I tried the pressure up to about 25 psi to speed diffusion into the ball and offset some of the leakage that would occur. Once, when doing this, the friction gave out, there was a monster "pop", and the cap flew off at high speed. It only destroyed a cardboard box and sent tennis ball flying all over my garage, but had the timing been worse, it could have hit and injured me. Lesson learned- friction cap under high pressure is dangerous. Don't do it or you risk winning a "Darwin Award".

I then went to a threaded end cap instead, using high pressure thread tape. Much more of a pain to seal, because the threads have to be sealed very tight. I had to put the cap end in a vise and use a huge wrench to rotate the pipe. Even with all this, it still leaked. Air under pressure is really, really sneaky stuff. I could get it to hold well enough that I could just pump it up a bit every 24 hours or so to maintain acceptable pressure, but it really takes time for air to diffuse, so you have to remember to re-pump every night for a couple of weeks or so. With the design that you/I have means that you need unless your pipe is really long, you're only doing a few balls at a time (this suddenly sounds really dirty, doesn't it?), so it's not worth the effort.

If I could have modified the design so that I used a PVC pipe/threaded cap as just the entrance to a large container that held fifty or sixty balls (I have a ball machine and would love my old ball machine balls all to have decent pressure), it might have been worth messing with. For doing eight or ten at a time like this design will do, it wasn't worth the headache.
 

onehandbh

Legend
If you use something with threads on the ends, you can try wrapping the threads with a few layers of teflon tape. You can get it at most hardware stores.

I use it when doing any kind of plumbing work.
 

neilers

New User
I'm really curious how ball factories such as Wilson pressurize their cans, so their porus balls stay at a constant 14psi.

Would it just be easier to drill a hole onto the lid of a wilsons can, put a tire valve in and pump it?
 

Javi

New User
I am going to give this a go with 6" pvc schedule 40 (non-dwv which has thinner walls) w/a rated operating psi of 140 for my ball machine balls. I would end up storing them at 10-20% of that so should be fine. You have to use the right pipe glue (there are different kinds) for the pipe ends which melts the pipe/fitting together and results in a higher psi rating then the pipe. One side will be capped the other will have a threaded plug with Teflon tape.
 

Chotobaka

Hall of Fame
I'm really curious how ball factories such as Wilson pressurize their cans, so their porus balls stay at a constant 14psi.

Would it just be easier to drill a hole onto the lid of a wilsons can, put a tire valve in and pump it?
Two completely different applications. The OEM tubes are single use designs -- it is the opening/closing function that is most difficult to deal with. That is why pressure cookers work, since the lids are purpose-built apparatus designed to hold a great amount of pressure.
 

esantoro

Rookie
A few years ago, I built something almost exactly like you've diagrammed. Bought replacement tire valves, drilled a hole in the PVC and epoxy'd one in. That part was no trouble. The problem came in the end pieces. I think even the permanent end cap leaked until I epoxy'ed the seams (spray bottle full of water with a few drops of dish soap came in handy. Pressurize, then spray seams and look for bubbling as sign of leaking air.)

The big trouble was how to seal the other end. I started with a rubber friction cap over the top of the open end. Major disaster- big leakage. Also, being impatient, I tried the pressure up to about 25 psi to speed diffusion into the ball and offset some of the leakage that would occur. Once, when doing this, the friction gave out, there was a monster "pop", and the cap flew off at high speed. It only destroyed a cardboard box and sent tennis ball flying all over my garage, but had the timing been worse, it could have hit and injured me. Lesson learned- friction cap under high pressure is dangerous. Don't do it or you risk winning a "Darwin Award".

I then went to a threaded end cap instead, using high pressure thread tape. Much more of a pain to seal, because the threads have to be sealed very tight. I had to put the cap end in a vise and use a huge wrench to rotate the pipe. Even with all this, it still leaked. Air under pressure is really, really sneaky stuff. I could get it to hold well enough that I could just pump it up a bit every 24 hours or so to maintain acceptable pressure, but it really takes time for air to diffuse, so you have to remember to re-pump every night for a couple of weeks or so. With the design that you/I have means that you need unless your pipe is really long, you're only doing a few balls at a time (this suddenly sounds really dirty, doesn't it?), so it's not worth the effort.

If I could have modified the design so that I used a PVC pipe/threaded cap as just the entrance to a large container that held fifty or sixty balls (I have a ball machine and would love my old ball machine balls all to have decent pressure), it might have been worth messing with. For doing eight or ten at a time like this design will do, it wasn't worth the headache.

Good critique of the tutorial I referenced. I hadn't thought that the threads would be the weak link.
 
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