Welding O2. Would you?

[Woz]

As an engineering company I have lots of O2 knocking about at work. It is, of course, industrial stuff. Now with the current increase in O2 costs I am looking at using the stuff at work for blending low % nitrox- say up to 32% with occasionally some 50%.

Also for trips, I am looking at getting a 15L cyl, O2 cleaning it then filling it up before I leave then decanting from this.

Anyone see any problems?

[Mark Chase]

Yes. Why not??

Because its not batch tested???? Not a big enough reasion for me.

What do you think they put the pure 02 to 250 bar into dirty tanks

BANG


I dont think so

ATB

Mark Chase

[colinicky]

Originally Posted by Mark Chase

What do you think they put the pure 02 to 250 bar into dirty tanks

Surprising as it seems they don't clean welding grade cylinders ,according to BOC & Air Products if a diving grade cylinder is returned part full it is emptied via vacuum ,due to them having a non return valve fitted this keeps impurities out anway .they are then refilled .
With welding grade there is no non return valve to stop any impurities so in theory it is possible that feedback of acetalyne or propane could occur ,this is then left in the cylinder as they are not emptied on return just 'topped off'
Please note I said in theory nobody I have spoken to has ever had it happen but on a rebreather I supose it could be more of an issue due to rebreathing any impurities & then adding from the O2 injection as well were as on oc it would be exhaled & gone so no build up .
We recently had this discussion within our club & decided to get the account with Air Products

[Alan Gough]

I've used 99.5 O2 £25 quid for 50l 200bar for several years without trouble.
Alan

[Woz]

With oxy sets, though, the O2 cylinder is connected directly to the regulator then the O2 is fed down it's own hose to the torch. Unless the acetylene can turn a corner, jump up a nozzle, swim upstream through a valve, repressurise itself to 200 bar and squirt itself through a regulator I can't see how it would be contaminated. Unless it was an "acetylene salmon".

And it is unlikely to get contaminated at the gas filling place as they will only pump O2 into cylinders with the correct paint job. So the only way you could get acetylene into an O2 cylinder is if you connect a full acetylene cyl to an empty O2 cyl directly and open the valves. Which you can't do without making a special adapter. Even the most foolhardy welder would not attempt that. Hmmmm. Or maybe they would.

[Mark Chase]

Originally Posted by colinicky

Surprising as it seems they don't clean welding grade cylinders ,according to BOC & Air Products if a diving grade cylinder is returned part full it is emptied via vacuum ,due to them having a non return valve fitted this keeps impurities out anway .they are then refilled .
With welding grade there is no non return valve to stop any impurities so in theory it is possible that feedback of acetalyne or propane could occur ,this is then left in the cylinder as they are not emptied on return just 'topped off'
Please note I said in theory nobody I have spoken to has ever had it happen but on a rebreather I supose it could be more of an issue due to rebreathing any impurities & then adding from the O2 injection as well were as on oc it would be exhaled & gone so no build up .
We recently had this discussion within our club & decided to get the account with Air Products

This is absolutly hilarious

Why do you need a non return valve on a positive presure tank? Even once the tanlk is at ambient presure you would still need a compresor to force gas into it or you would have to leve the valve open during some significant temperature changes.

You have obviously no idea how they do welding. I would love to see the result of some ascetalane getting back into the 02 tank that would be some fireworks show I would also be facinated to know how the acetalain goes down the acetalain hose to the mix nozel. Jumps across the nozel and runs back up the 02 hose and into the tank without the aid of a compreser.

ATB

Mark Chase

[Mark Chase]

Dam you woz you beet me to it

ATB

Mark Chase

Must type faster.

[Alan Gough]

No it is true, honest.
But you have to keep the cylinder upright so the acetylene quickly settles to the bottom and you can just decant the oxygen off the top !
Alan

[colinicky]

I did say in THEORY as told to me by BOC & Air Products that doesn't mean I agree ! I've actually got my own oxy/propane cutting gear plus a welding set oxycetalene & I couldn't see it either But you've got to admit it's a good marketing ploy by them
If you can't blind them with science then baffle them with bull***t .

[dry suit diver]

I 'borrowed' an analyser from a friend and checked the O2 cylinders at the engineeering shop next door to our offices, 99.2%, the owner is amiable to a O2 top off to give me nitrox so yes I would but only into an O2 clean tank,
am looking to get a 3 litre pony as an O2 cylinder for emergency use just need to get a trickle mask etc and get the engineering shop to fabricate the bits required to manufacture.


As for the comments about acetylene contamination , as Scotty from Star Trek never said " Ye canna change the laws of physics".