I've been at a few auctions where oxygen bottles for medical use were up for grabs. Can these be used for oxy cutting/welding purposes (are the fittings the same)? Also, should I be looking for a test date on these bottles - how long between required test intervals? Thanks for being such a great, informative group!
AFAIK, hydro testing is 5 years (for everything), and the (small) medical bottles I've personally seen have different fittings than welding bottles do. Don't know if that's true in all sizes. As always, there's also the question of whether the bottles for sale are actually owned bottles that can be sold, or leased bottles.
Is pressure an issue? I suspect the pressure of the oxygen in these cylinders is way less than cylinders used for oxy/fuel welding/cutting. These little breath-babies are very mobile and, hence, prone to dropping and getting knocked over. There is no form of mechanical damage protection--no shielding whatsoever. I'd guess that if you busted the valve off one of these the consequences from the pressure would not be catastrophic. But bust the valve off a welding oxy cylinder and you've got a rocket.
(BTW, I sure miss Jason Headly. Wish he'd start posting again. )
For typical cutting, you want about 30 or 40 psi. The cylinder would need to have that as a minimum. I assume a standard oxy/fuel regulator would deliver 40psi if the source cylinder had 40psi.
I think another question--assuming I am correct about pressure--is would you have enough volume to make the use of such a cylinder worth while?
"David Todtman" wrote: (clip) I suspect the pressure of the oxygen in these cylinders is way less than cylinders used for oxy/fuel welding/cutting.(clip) ^^^^^^^^^^^^^^^ We have had these around the house at times, but I do not know for a fact what their fill pressure is. Logically, I would expect it to be the same as welding cylinder pressure, since the person using the portable cylinder wants to have the maximum time between cylinder changes. Dropping the pressure to a "safe" level would seriously limit the content, unless the cylinders were made unduly large, which is also not an attractive option.
The regulator attachment on these medical oxygen tanks is different, and the regulators are different also--they are set up similar to MIG regulators, to deliver known volume flow rates rather than pressure.
This has been thrashed out in several of the aviation newsgroups in regards to oxygen systems for flight above 15,000'. Long & short is that whether medical or industrial cylinders are being filled the oxy all comes outta the same machine.