5.4 cu. ft. spare air

[SurprisedOutlet]

Got a used spare air for cheap and read here (somewhere) that paintball tanks have the same neck. So I got a used paintball tank with a hydro date of 10/2012 for $25. I figure it would be fun to play around with at the lake. Anyway, I dropped an LED down the neck of the paintball tank and there was a bunch of black residue or something on the inside. I don't want to breathe that so I rigged up a tank tumbler with my drill. I used rock tumbler grit with some steel shot and hot soapy water and tumbled it for a couple hours. The results were great, no more residue and nice sparkly aluminum on the inside. Here's the 5.4 cu. ft. spare air next to the original tank.

 

[knotical]

Thread sizes should work: 5/8" 18 UNF-2B for both Spare Air and most paintball cylinders.
sources:
http://www.aberdeenwatersports.com/.../Regulators/Spare Air Service Manual 2003.pdf
and (for example):
http://www.ninjapaintball.com/documents/Regulator Installation Guide.pdf
also:
SP Screws and Threads [ZDSPB Tech]

caveat: keep the cylinder pressure within the Spare Air regulator rating. At least some Guerrilla Air cylinders are rated to 4500 psi. The Spare Air regulator is not. (Older ones 1800psi, newer ones 3000 psi).

Breathing compressed air from a cylinder not previously used for that purpose is a personal choice. Was the tumbling as described by SurprisedOutlet sufficient? Your decision. I’d be OK with it.

 

[SurprisedOutlet]

Thanks. Just thought I would share in case others were wondering if it was possible. I would only be filling from another tank so pressure would be < = 3000 psi

 

[OtherHalf]

Did you just use soapy water, or did you use a proper cleaning solution? There are certain cleaning solutions for breathing devices that are engineered to be safer. Consider doing a good tumble with diluted simple green or blue gold, then double rinsing with distilled water, and using a proper lubricant on the threads. That dirty substance on the inside of the cylinder was oil, not something you want coating your lungs.

And be careful tumbling with media, especially on aluminum. It can weaken the metal and cause it to fail hydro.

 

[SurprisedOutlet]

I used lightly soapy water with some fine grit ruck tumbler media. Looks like fine black sand. I added some round steel shot to push the grit around. The inside of the tank looked like finely sanded aluminum afterwards. No visible scratches or swirl marks. No trace of any residue left.

Edit:
I rinsed the tank several times and lubricated the threads with silicone spray I got at the LDS.

 

[scubastingray]

Very cool thread and it's awesome to have the service manuals!
5.4 cu ft is just about useful, but seems unobtrusive enough to just tuck away.

 

[SurprisedOutlet]

Yes, I downloaded and printed the service manual and installed a new service kit in my spare air. It works great and doesn't leak. I initially had a small leak that I traced to the burst disk plug. The surface of the plug that contacts the disk was a little corroded. I removed the corrosion and reinstalled it and the leak was gone.

 

[RJP]

Great, now you'll have enough gas in that tank that you can run out of air TWICE on the same dive!

:d

 

[knotical]

Another caveat (should have mentioned this before).

DO NOT do this with anything other than an all-metal cylinder. The only wrapped cylinder I know of that is authorized for in-water use is not a paintball cylinder.