Propane burners

[ironman]

Hi everyone

Years ago I remember reading an ad in a model engineering magazine about a propane burner that you could run with compressed air and propane. I always wanted to copy it so I made one last week. Have a look at the video.

     

[vtsteam]

Excellent Ironman! 

I've wanted to braze with propane/air for awhile now, but wasn't sure it was possible. I hadn't tried compressed air, though, just an atmospheric burner. With the burner I built, I still needed a hearth to get enough of the flame localized on the metal -- otherwise it was too diffuse.

So I have questions about the details of your torch.

1.) Have you tried brazing with it?

2.) Is your torch an actual copy of the torch in the magazine article?

3.) What magazine was it? What issue?

4.) If it isn't a copy of the torch in the magazine, can you give the details of the tip -- dimensions etc. so I could build one?

5.) Is it just a simple cylinder, or are there mixers or ports inside?

Great work! 

The flame certainly looks concentrated enough to braze, by comparison with the usual atmospheric propane burner.

[ironman]

No I have not tried brazing with it

No it is not a copy of it because it has been so long since I have seen the article, I have forgotten what it looked like.

It was "Model Engineer" magazine and the issue was in the late 50s to mid 60s

From what I can remember the ad did not show much but I was very impressed that it could be done.

It is just a simple cylinder with a very large jet at the bottom of the cylinder. I do think that the jet size can be a lot smaller and a smaller cylinder can be used. Atmospheric propane burners are very limited in what they can do , so compressed air can force a lot more heat from a propane burner.

I will have to work out how I can post a cad drawing on mad modder.

I do have a atmospheric propane burner and it has a plate in the burner with lots of small holes drilled in it. I think they are called diffusers.

[awemawson]

Back in the days children were allowed to do proper workshop activities at school rather than just glue plastic most school workshops were equipped with a 'gas & air' brazing hearth. This comprised a circular hearth of fire brick on top of a frame that had an electric compressor below. Originally designed for 'town gas' ie coal gas, they were converted to natural gas in the 1970's

I have one of the torches somewhere. I have personally braised quite large castings with them (headstock of a 5 " swing lathe) so it is perfectly possible as I imagine propane has a similar calorific value to natural gas. They had quite a large flame.

Andrew

[lordedmond]

Andrew
would that be a large torch with a big lever to turn on the main gas and air with the burner at a say 20 degree angle to the two gas air tubes , about 2 foot long

 

looks like you got to play with the same things at school as I did metal wiring shop with Little John lathes, and a wood work shop with lathe and a free standing circular saw but no planer


one lad did cut his finger off though in metal work he was a I D Ten T , held the metal in the vice held it with his hand to stop it squealing fingers at the back and kept sawing 

it was not me

Stuart

[awemawson]

Yes Stuart that was the one !

[Meldonmech]

Hi ironman
                       This is one I want to make. I use propane in my crucible furnace which has a burner  having a 1 mm jet size, and  normal air funneled in through a venturi.  What air pressure is required to suit the burner you are using?

                             Thanks for posting such a useful item.

                                                                                            Cheers David

[ironman]

Meldonmech

It all depends on how much propane goes through the torch. 4 to 5 bar would be plenty, I had it up to 8 bar and it will blow out the flame if too much air is turned on.

Here ya go vtsteam I made a drawing of the burner.

[vtsteam]

Thank you Ironman! I will definitely try it.