Refilling other oxygen cylinders from a larger welding cylinder is common among scuba divers and general aviation pilots. Transfill adapters (Google "transfill adapters" for pics) are sold for the purpose.

While browsing the Petrogen oxy-gasoline torch site I noticed their little rescue torch that used medical O2 cylinders so the responders can use their cylinder pool if required. It uses a CGA 540 valve but comes with a CGA 370 adapter.

http://www.petrogen.com/page.asp?id=...tting%20System

"The PCS will cut 1/4-inch steel for 25 minutes; 1-inch steel for 13minutes; 4-inch steel for five minutes. The fuel tank holds 1.5 quarts of fuel, which will last for about 1.5 hours of non-stop cutting. Cutting time is limited by oxygen supply."

So....I bought an adapter "Oxygen Cylinder Refill Yoke Adapter~CGA 540 to CGA 870" via Ebay, a 48" Western Enterprises pigtail, and the separate CGA 540 nipples and nuts. (You can just get a complete CGA 540 to CGA 540 pigtail with crimped ends, but I prefer separate parts.) Awaiting a CGA 540 tee so I can monitor (but of course not regulate due to regulator type and location) refilled pressure with my welding regulator's gauge.

Why medical cylinders? Because they are small.light, easy to get for free (I have a couple of full E's) and the adapter was cheap. If I had a conventional small oxygen cylinder I'd transfill it too.

http://www.catalinacylinders.com/markmed.html

Fuel:

I want this setup specifically for periodic trips to a salvage yard where truck space is limited, so I don't want the hazards of bouncing around an acetylene cylinder or drawing too much acetylene when cutting. I'll use the 20lb propane tanks until I can find a reasonably priced or free 5lb tank, or ideally a mountaineering propane tank ($$$).

It works fine but I haven't cut heavy stock for long enough to time how long an oxygen cylinder lasts.

Usual cautions about servicing high pressure oxygen and proper familiarity with equipment apply. Protect your medical cylinder from external damage as they are lightweight compared to industrial cylinders.

Top view of CGA 370 cylinder to CGA 540 regulator adapter:

Propane cutting tips, Victor GPN two-piece style

Complete setup:

 

Update:
One oxygen cylinder was sufficient to clip a '97 F150 cab in half.

 

Thanks for shareing. Great way to recycle materials. Love the little oxygen dolly. I am imaginig some little 'ol man with his oxygen tank in the indian casino suddenly getting tired of losing and pulling a torch out to retreive his coins!

We switched from acetylene to propane in our cutting rig at work. The three of us that use it really like it. We paired it up with a new Harris Pipeliner torch. The complete pipeliner rig cost the same as the needed replacement of our Victor cutting attachment alone! We are very pleased with the Harris.

 

Propane and CNG torches can be great, as long as you get ALL propane or CNG equipment. I know the tips are quite different from acetylene tips, and of course pressures are a bit different as well. I ran a couple different types of torches like that, and have to admit my ultimate system is a natural gas torch paired with an oxygen generator, on drop-down reels in the shop. Never run out of gas, never have to cart bottles, and it's cheaper to operate.

 

"my ultimate system is a natural gas torch paired with an oxygen generator,"

Invacare and DeVilbiss make "home fill" medical oxygen systems that refill medical oxygen cylinders. They are too expensive new, but you might score one at an estate sale or similar.

"Propane and CNG torches can be great, as long as you get ALL propane or CNG equipment."

The cutting tips are easy to tell apart (I only buy two-piece propane tips because I like the ease of cleaning).

Very good thread on regulator interchange etc:

http://weldingweb.com/showthread.php?p=304615

 

Likewise. I like the two piece tips on the Harris because the outer tip is chromed. Protects the inside orifice tip and resists fouling with slag if you get sloppy.

Didn't quite get the consensus on which regulator is best in the link. But we use the same regulator you'd use for acetylene and that's what our LWS recommended.

 

I was under the impression you need a different regulator for propane, possibly a different hose. I know the pressures tend to be lower, but the volume higher with propane and CNG, and have heard that the hose material is different, maybe to handle either the propane or the oderant.

 

Grade T hose is preferable and high-quality. It is heavy duty, rated for both fuels and what to get if in doubt.

In practice, other grades work OK for many people. I wouldn't buy a new non-Grade T welding hose for any gas welding purpose since T holds up much better, but if I had some R for personal use I'd use it up taking due care of it. (Hose shown in pic is not T-grade, but was new, free, and is thus disposable.)

When you see T and lesser hose side-by-side T's tougher construction is obvious. Serious professional welding outfits come with T as standard.

Industry standards are "T-only" for non-acetylene. Can't go wrong with that:
http://weldingmag.com/processes/news/wdf_45963/

Acetylene regulators will work with propane, but not the reverse. Permissible acetylene outlet pressures are lower than propane.

Example propane regulator from the Airgas site. It's a handy site for finding equipment, but don't forget to comparison shop online. Find out what brands your local welding supplier carries. Some of their stuff may be higher than online, but it pays to have a friendly relationship with your local supplier.

http://www.airgas.com/browse/product...&recIds=313083

With any hose, if it's worn/cracked/burned/damaged either shorten and repair with a correctly crimped fitting (if just a section is bad) or replace it. Crimp kits are used professionally for making custom hoses and safe if you cut out the damaged section and only crimp good hose, but for the casual use the hose is cheaper than the kit.

Oetiker-style kits are MUCH nicer and quicker to use than the traditional brass ferrules. (I build and repair lots of hoses at work.) Pic is an example, they are widely available:

http://www.drillspot.com/products/33...ose_Repair_Kit

Bottom line is if you want to comply with standards, the differences are T-rated hose if you don't already have that, and a propane regulator plus of course propane tips for your torch.

 

The easiest way to update this post was to link to this thread:

Very portable propane cutting. - WeldingWeb™ - Welding forum for pros and enthusiasts

I've now cut a bit using both style "small cylinder" adapters. Works great for utility cuts and solved my problem of dragging the BBQ jug. I could have bought a 5lb jug instead for about the same money, but I wanted the lightest portable option and so far this is it.

You can choose between the "regulator style" or the "denrep" style which is slimmer and lighter. He has more cutting time with his and burning out 4" pins is ample testimonial to it being effective. I haven't had anything that thick to slay for a while.

I haven't maxed out the flow yet when cutting, but you can see the turned-down bolt replacing the orifice tube in this pic. Instead of the little orifice with a slit cut across it, the bolt is through-drilled to meet a hole drilled perpendicular to the bolt axis. When screwed down, small LP adapters depress the Schrader valve pin with the end of the tube where the orifice is normally drilled. My way there is less restriction.

I haven't used the "fill" adapter shown yet but it should work much better with the larger bore.

Play safe, study how cutting equipment works because "theory of operation matters", leak check everything you assemble,