SpudFiles

Umm I have a 9 oz tank with a half inch fitting on it now, granted it wont depress the pin, but it does seal. So I don't know what your talking about.

You need to think much bigger. I used size "e" medical oxygen tank which is about 4" diameter and about 26" long. Mine is very, very simple and VERY cheap. Tank cost was only 10 bucks (ebay is your fiend). This thing is a beast that weights in at about 20 pounds all up which actually works well when launching large/heavy projectiles.

It took me all of 15 minutes to screw everything together using teflon tape on the threads. To eliminate leaks the fittings are very, very tight. As it has already been said all I had to do was put the tank in a vice and unscrew the unwanted regular. It was in very, very tight. Let me repeat . . .it was in super tight.

Should be NPT threads on that c02 tank. My oxygen tank is 1/2" NPT. I wish it was larger, but it still makes for a sweet tank. Here is a picture showing how I put it together. No wise cracks on my paint colors.

In have multiple barrels ranging from 1" to 3" diameter. I have a 1.5" barrel that is 10 ft long. Launches whatever I want very, very far despite the inefficient ball valve.

I did the same thing with scba tanks that firefighters use...I wasnt satisfied with the small tank outlet threads so I had them drilled and tapped to 1"NPT....They are even larger than your oxygen tank but lighter since they are fibre wrapped aluminum......They work very nicely but I would definitely go with a faster valve when you get the chance....Even a modded sprinkler valve @ 150psi will out perform that ball valve @ higher pressure....Nice set up .

EGOed wrote:I did the same thing with scba tanks that firefighters use...I wasnt satisfied with the small tank outlet threads so I had them drilled and tapped to 1"NPT....They are even larger than your oxygen tank but lighter since they are fibre wrapped aluminum......They work very nicely but I would definitely go with a faster valve when you get the chance....Even a modded sprinkler valve @ 150psi will out perform that ball valve @ higher pressure....Nice set up .

Thanks. I'm not to excited about my small outlet either. I'm not convinced that a faster valve would make much difference because I think the air flow constraint in the system is size of the outlet and not the ball valve.

I wanted to drill and tap larger threads but I don't have heavy enough equipment or a large enough tap. My buddy has the same basic set up but he cut off the bottle where it necks down and welded a 1.5" coupling. He has a HUGE opening.

Yes , I was thinking about cutting the neck also since I still have another 12 tanks to play around with....I could easily go 2" NPT if I did that and coupled to a metal piston valve would give me extreme power and range at high pressure.....Right now I am limited to 150psi max with the 1" sprinkler valve setups and hose that I am using....I hate to let those tanks go to waste , but the small outlet porting really limits you as far as making large bore cannons...I am going to have to go with 2" steel pipe for chambers until I can get those tanks modified I guess.

nz-cannon Hi,

The threads on the paint ball valve on the tank are,

Internal threads 5/8 -18

External threads 1/2 -14 NPS The gas conpany name 320 asa.

The pin that stick out of the 320 end is about 0.100 of an inch. The next peace is an UHM flat washer which seals the Co2. The pin is a brass 1/4 hex about .625 to .75 on an inch long. It inside the valve.

Ah, should be able to get something to work. Cheers for the replies.

Killjoy wrote:Frankrede used a paintball tank on his hybrid, not sure what size he used but you could check.

Edit: he used a 3/8" nipple, so I guess that what works

Indeed.
But I used a 3/8" npt tap too make new threads for an even better fit.
A 3/8" npt tap should only run you less than 10$

Ah ok, glad you mentioned that...

Hmm, ok things are getting complicated.
There seems to be conflicting reports of different sizes. On this web site http://www.teamonslaught.fsnet.co.uk/co2_info.htm, it says that the cylinder thread is 5/8 inch UNF which is Unified National Fine.

All the fittings I can get here are BSP, British Standard Pipe (I'm pretty sure they are, I will check soon though). Now, I cant get 5/8 inch fittings, they just aren't used here, but even if I could they wouldn't fit because of the different types of threads.

The UNF and BSP threads have a different number of TPI (threads per an inch) I think BSP is 14 for a 3/4inch fitting and UNF is 18 for a 5/8inch fitting.

When the sizes are converted to metric, a 3/4 inch size is only about 3mm over the 5/8 inch size. If it was a BSP thread in the tank I could probably just tap it out to 3/4inch because both 5/8 BSP and 3/4BSP have 14TPI.

Maybe I shouldn't use a paintball tank, I don't want to spend 50$ buying it to find out I cant thread anything into it.