Diving tanks as oxygen tanks

[Kenneth von Busenknutsch]

Someone on another board suggested a diving tank for an oxygen tank instead of a welding tank.  I had always thought diving tanks were a mixture of oxygen, nitrogen, and maybe some other gases much like what we breathe in our normal air.  Does anyone know?  Would a diver's tank work better than a welder's tank or maybe be more affordable? 

[CHfather]

You are right: Diver's tanks are compressed air, not pure O2. So, no, not an option.

[Brew]

You are correct. Compressed air is merely what we breathe on earth, which contains roughly 19% oxygen, 78% nitrogen, and 3% everything else.

[ThatHurtsMyHead]

ahhhh, let me shed more light on the SCUBA tanks.

SCUBA tanks are normally used with compressed air 21% oxygen, mostly nitrogen and some other trace gasses.  They can (and most modern divers do) use a NITROX mix which most SCUBA shops can blend.  A NITROX mix increases the O2 up to 99%.  BUT and a big BUT...  All tanks, lines and regulators have to be O2 clean.  Normal gear is only O2 clean and cerified up to 40% O2 MAX.  Therefore 99% of SCUBA shops will only fill NITROX (or commonly called EAN - Enriched Air Nitrox) up to 40%.  There's a HUGE liability if they fill greater than 40%.  (as O2 reacts violently in higher concentrations with some materials)

Also a few issues you would run into with SCUBA tanks.

#1 - You would have to be a certified EAN diver to get fills up to 40%.

#2 - You would have to be a certified Technical Diver to get blends over 40%.  SCUBA shops will not fill tanks unless you're certified

#3 - You couldn't get the tanks filled at any regular gas distributor. 

#4 - You would have to use a SCUBA regulator as the K-Valve or DIN Valve, on SCUBA tanks won't work with medical masks.

#5 - Blended SCUBA air is significantly more expensive than welding gas.  (I pay $10 for an 80 cubic foot 40% EAN mix, as opposed to $21 for a 150 cubic foot 100% O2 welding gas tank).  To get a blend from a SCUBA shop over 40% EAN is normally around $40 and up for technical gas mixes for only 80cf.

Feel free to post this on the other board.  Anyone running out and buying a SCUBA tank would be waisting their money.

PFW,

Jeff

[diamondmaker]

Amen to that. Welder's O2 is recommended because it is easy to get no questions asked... and cheapest! Don't worry about welder's tanks being in some way inferior... they are not. All O2 standards are the same across the board, just the questions, licenses and costs are different.