Gas welding

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The bottles get used for heating and cutting mainly for my occasional use, but I resist going to propane as it's just not as hot :(
As for tungsten sharpening, I spotted a dedicated sharpener on eBay the other day - looked like a glorified angle grinder with a fitting that took the electrode at the right angle, but I think that you still had to twiddle it. Absolute bargain at 450 :) Little Wrongs with that :)
Andrew
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On 08/10/13 19:11, Andrew Mawson wrote:

I handed my BOC acetylene back in recently as I used it so little I couldn't justify the imminent rental renewal. I'll use oxy propane instead. It has been years since I did any OA welding as I have other equipment I can weld with so mainly used it for heating, brazing and silver soldering. I doubt my house insurers would like it either what with the paranoia with acetylene. I know a local workshop has a specific exclusion on acetylene, oxygen can be kept inside, and propane has to be stored outside when not in use. I'll see how I get on with the oxy propane and have the opportunity to try an oxygen concentrator and if that is OK then I may return the oxygen bottle when it's empty. I can get a refurbished ex medical oxygen concentrator for 150 so that's about a years BOC rental, gas fill, and surcharge. The oxygen concentrator should handle my needs and I can use/borrow a big bottle if need be. I don't know when BOC barcoded their bottles but my acetylene bottle didn't have one.
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On 08/10/13 20:21, David Billington wrote:

Hi Charles too :)

If you have a water-cooled torch, or are using low amps, maybe just use a size smaller electrode and don't bother sharpening it? I haven't tried that ..
BTW, do not of sharpen thoriated electrodes on a bench grinder. Nasty. You probably shouldn't sharpen any tungstens on a bench grinder, but it really matters with thoriated tungstens.
Alpha emitters with a 20+ year biological half-life .. are to be avoided.

I have a 4 lpm concentrator, which runs a small torch quite well - but by itself it isn't enough for larger work.
At the moment I use a wheelie-bin full of balloons as an oxygen store (yes, it works well), but I am working on a small oxygen compressor - not a project for the faint-hearted or unknowing - to fill cylinders to about 1,000 psi. That's low enough that they are most unlikely to break, but high enough for decent mass storage,
-- Peter
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On 08/10/2013 21:55, Peter Fairbrother wrote:

I'd be petrified if there was any oil contamination in the compressor, as you say, not for the faint hearted.
--
Mike Perkins
Video Solutions Ltd
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On 08/10/13 22:03, Mike Perkins wrote:

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
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On 08/10/13 20:21, David Billington wrote:

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
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On 08/10/13 23:34, Peter Fairbrother wrote:

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 http://www.tuffnellglass.com/contents/en-uk/d103.html 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.

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On 09/10/13 00:23, David Billington wrote:
[...]

[.]

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
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On 09/10/13 00:49, Peter Fairbrother wrote:

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.
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On 09/10/13 00:49, Peter Fairbrother wrote:

Peter,
I guess you'll be after one of these http://www.devilbisshc.com/products/oxygen_conservers/ifill/
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"David Billington" wrote in message

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
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On 09/10/13 10:49, Andrew Mawson wrote:

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.
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On 09/10/13 10:55, David Billington wrote:

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
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On 09/10/13 19:52, Peter Fairbrother wrote:

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%.
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On 09/10/13 22:55, David Billington wrote:

[...]

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
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On 09/10/13 23:39, Peter Fairbrother wrote:

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 http://www.aagbi.org/sites/default/files/April_ANews_Web_0.pdf or search for "ruh itu oxygen fire" in November 2011.
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