Oxy - Propane

[waggy]

Hello peeps,

Reading the thread in the tooling section re use of oxy - propane has made me think. (Dangerous!) I've got Oxy - Actylene which I use a lot on boilers and for fabricating parts.
The question - Can the Oxy - Acetylene regulator, pipe, Sapphire Lite torch and nozzles be used for Oxy - Propane? Are there any special nozzles, etc required?

Regards,

Waggy.

[Steve M. W]

Good question Waggy if any one in the know could confirm what should be used. As I understand BOC do not recognise oxe propane for use through the Sapphire type gun as it is not a hot enough gas to weld with but they do not seem to appreciate that we only want it for silver soldering or brazing, there stance to me is that you can only use propane for cutting and for that purpose they do supply a propane mixing jet for cutting torch. (That’s the line I got from my local BOC supplier. Or could it all be a myth to make us rent the more expensive accet bottle) But I know people that use oxy propane for silver soldering using the propane regulator and Sapphire gun and standard oxygen bottle and regulator.
If using oxe propane what sort of flame are you going to get or should you aim for is it similar to an oxy accet flame or a Sivert type flame or a propane and air type flame as on Flame Fast type unit.
Any one who can answer Waggys question will be helping a lot more of us.

Steve

[Malcolm]

I've used a standard oxy-acet torch with propane for years. it seems to work OK with an ordinary propane regulator. It's sometimes a bit difficult to light, and of course not nearly so hot as acet. Much hotter than propane/air though. The flame looks much the same as an oxy/acet flame. Its fine for brazing and silver soldering, and the advantage is that you can't do as much damage if you lack skill, like me.

[chris vine]

Hi Waggy,

I am the same as malcolm. I have used an oxy acetylene torch with a propane cylinder and regulator for years now. Works fine.

I have a nozzle a bit like a small pepper pot with 6 holes in it. This give a useful larger flame for larger items where you are using the torch for extra heat as opposed to precision

chris.

[waggy]

Hello peeps,

Thanks for your help. I've just coupled the propane up in place of the acetylene and had a go at getting a decent flame.
I started with a No1 nozzle, very difficult to light. The propane flame is fairly large and fierce to begin with but dies away after a couple of seconds. When a decent flame is held and the oxygen added I found it very easy to blow the flame out. After playing with the propane pressure I got a fair flame.
I then tried a No10 nozzle, far easier to control the flame although it still dies away after lighting but adding the oxygen didn't blow it out.
In both cases the propane flame burnt away from the nozzle until the flow was reduced by nearly turning off the gas. After I got the flame against the nozzle I could increase the gas and add the oxygen.
I tried braizing a couple of bits together, no problem! Further experimentation required, methinks!
I get the impression nozzle size is the key, possibly using larger sizes with propane, thus giving an equivalent heat out put of the smaller sizes when used with acetylene?
The other advantage of propane - no little black smuts stuck to everything!

Regards,

Waggy.

[AndrewP]

You've hit the nail on the head with tip sizes Waggy. I don't know the orifice diameters of the Saffire tips but I use a Little Torch (that is is it's name, honest) on oxy propane for fine work and the smallest tip I can keep alight reliably is a no4 which is 20 thou. The next size down is 11 thou and a right b*****r to set up on oxy/propane but a doddle on oxy/acetylene. I am sure I heard somewhere this had to do with the molecular size of the fuel gas? - whatever!
I doubt that not being able to use the smallest tips will be a problem if we are talking about soldering boilers.
The pure propane flame burning away from the tip is a sure sign of too high a pressure for that tip, the initial surge almost certainly a slightly leaky regulator allowing a higher pressure to build up in the hoses while the torch is off. I habitually open both torch taps for a couple of seconds before lighting to remove that surge.
Yes - it is nice and clean isn't it ;D I hate that black snow that falls all over the workshop when I use Acetylene.

Cheers, Andy

[waggy]

Thanks Andy,

Never gave it a thought the reg could be at fault. Strip down and clean may do the trick, I might do the reg as well! Hee hee.

Waggy.

[mmaidnz]

I was under the impression propane burners had left handed threads on the bottles,to prevent confusion with acetylene.

[waggy]

Hello mmaidnz,

You are correct when you say the threads are left hand, however so are the threads on acetylene gear, at least in the UK.

Waggy.

[tcase]

The problem with the flame blowing off the tip with propane is due to the much lower flame speed of Propane, 3.3 M/s compared with 7.4 M/s for Acetylene. If the nozzle velocity gets too high, away goes your flame. If you look into the nozzle of a normal self blowing Propane torch, they often have a ring of small jets around the outside of the larger main jet, these are low velocity flame jets that maintain the flame on the large jet as it is being constantly blown off.
Back in the days when I was involved in bottled gas, all combustible gasses came in cylinders with left hand threads an right hand threads on non-combustibles. I assume this is still the norm in the UK.