Gas welding

Indeed - though I might use a Fomblin perfluoroperether oil here, in Monel K-400 cylinders with definitely-not-silicon- tin bronze (or possibly inconel) pistons and viton seals, to make things easier.

Also, and my hobby is building LOX-kero rocket engines which operate high-speed (120 krpm) turbines in dirty 90% oxygen at 5,000 psi and 750 C.

No Fomblin there though.

As you say, not for the faint-heated - but far more important, not for the the unknowing.

-- Peter Fairbrother

How useful is oxy-propane? Can you eg weld steel with it?

I know it's great for brazing, but for welding?

Available generally? lpm?

ta,

-- Peter

Dunno - but I use oxy-'Turbogas' which goes to 3,600° C IIRC. I'd guess that the major component would be acetylene, with a more modern method of dissolving or making safe the pressurised acetylene.

I expect Adamsgas would be selling a similar product.

Apparently not due to hydrogen levels being a problem but then I don't need to weld steel with OA as I have other methods.

That's mainly what I'll be using it for.

The ones a friend bought were from Tuffnells IIRC and Devilbiss 5lpm units. Here

I guess she got a discount as she runs a glass school and uses them for running lampworking torches or she was mistaken, I'll check when I see her next but that's what she mentioned before when asked.

[...] [.]

I paid £220 for a 5lpm Devilbiss (however it's capitalised), so in line. Might go another £150 for a second one, if available.

More interesting perhaps, there do exist homeuser medical compressors which take concentrator output and put it into cylinders - might your friend (or anyone) be able to get any of those?

-- Peter

I'll ask as when she had a tutor running a course the tutor's husband mentioned people in the US doing things of that sort with the concentrator output to get higher pressure or higher flows than achievable directly from the concentrator.

Peter,

I guess you'll be after one of these

I see from the spec that it produces 93% +/- 3% oxygen, so the question is, at the lower limit is 90% oxygen ok for welding. I'd imagine it is but presumably the BOC bottles are much closer to 100%

AWEM

I've seen it mentioned elsewhere that industrial oxygen is significantly purer than medical welding, the main thing with medical being the cleanliness. It may be that welding or at least cutting oxygen needs the purity, I don't know for sure.

I don't know either - but for everyday work, the output from my concentrator works fine. That's supposed to be 96% at 3 lpm and 94% at 5 lpm, mostly I use it at around 3 lpm.

-- Peter

I had a quick look earlier and found many threads discussing it and details that the European spec for medical O2 was 99.5% pure minimum and industrial higher but that is for bottled oxygen, apparently a spec exists for aviation oxygen as well which is drier to prevent equipment icing at low temperature. One thread mentioned a US supplier Praxair as stating that it all came from the same tank and filled on the same rigs but the difference was the end use as there was a small possibility of oxygen bottle contamination by acetylene in industrial applications, I presume any fuel gas, if flashback arrestors weren't used.

I don't have any experience yet of the oxy concentrator and propane in actual use but may do soon. Having been injured a couple of years ago and suffered suspected lung bruising I was given oxygen at the minimum flow the system would allow to bump the blood oxygen from from around

93% IIRC to more acceptable levels but I doubt 90% or 95% would have made that much difference in that application compared to 99.5%.

Ouch.

Roughly speaking, when they give you oxygen in hospitals it's either at

30% (technically 20% to 40%) concentration in the breathed gas, or at 60% (technically 40% to 70%) if there is a bag on the mask - no bag, it's 30%, the oxygen is diluted by the surrounding air.

It is very rare that they give anybody more than 60%. When they do there is a bag in the specially wide airline, not on the mask.

The 93% will be a blood oxygen level, not the concentration of oxygen in the breathing gas or oxygen supply.

-- Peter

Peter,

I don't know the details just one of those things they clip into your nostrils for extra oxygen input and no bag as far as I can remember just plugged into the wall and adjusted for minimum flow, so they told me, to top up the levels from normal respiration so maybe you're right and no where near pure required I expect. After my incident 19/10/2011 I spent 1.5 weeks in RUH ITU and I think the day I was let go, after a month stay with the NHS, this happened

or search for "ruh itu oxygen fire" in November 2011.

(a) £150, (b) £66 quoted at my local Faversham Hobbyweld outlet

Regards, Alan

acetylene. My Argon comes from these people. > >

k/ > > Charles > > > ------------------------------------------------------

--------------------------------------- > > What do they charge for (a) the cylinder, and (b) the gas? > (a) £150, (b) £66 quoted at my local Fave rsham Hobbyweld outlet

73850372 Regards, Alan

I've ended up with Allbee acetylene as it was twice the quantity of the Hob byweld gas and cheaper. The Allbee cylinder including 10 litres of gas was £178.80. The Hobbyweld agent quoted £160.00 for the cylinder plus £60 .00 for the gas.

The price quoted from Albee agents varied from what I paid to over £220.0

1. The price from Hobbyweld agents was more or less the same. My cylinder c ame from Portable Gas Supplies of Finchampstead.

Thanks for the helpful replies.