Author Topic: Atmospheric Propane Brazing Torch Experiments  (Read 14347 times)

Offline dranoel58

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Re: Atmospheric Propane Brazing Torch Experiments
« Reply #25 on: July 07, 2013, 08:10:33 PM »
Hi     
            Love challenges too, especially when it is said that something cant be done.


         So true that in some material you read i.e. specifications, flame temperature capabillities, verry high figures are quoted.
In practice it is a different story, no ideal labority style conditions, gives other results.
Here is some material I borrowed from Wiki, Just to make the point.
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The maximum adiabatic flame temperature a propane torch can achieve with air is 1,995 C (3,623 F). Some propane torches are also used with a tank of pure oxygen to achieve a flame temperature nearing 2,820 C (5,110 F).
The temperature in these flames is lower because of incomplete combustion, heat loss in combustion, oxygen quantity etc.
A large factor in the temperature of the flame is the percent of oxygen mixing with the propane. With air/fuel torches, since air contains about 21% oxygen, to obtain the maximum flame temperature with air, you must use a very large ratio of air/fuel. Even glass bead-making torches, which are essentially bunsen burners with an added air pump, can only achieve temperatures of 1,100 C (2,010 F).
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The further losses that occur while transfering heat to the workpiece, are very big, on just a brazing hearth.
That is why a higher temperature fuel is needed for brazing (bronze welding ) , or insulate with fire brick type forge.

Have made a few attempts at brazing on a hearth, it is just too hard with a brush type flame, temperature is getting close and it just melts the brazing rod.
But no control, and cant make a strong joint.
Close but no cigar.

Regards

Offline mattinker

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Re: Atmospheric Propane Brazing Torch Experiments
« Reply #26 on: July 08, 2013, 10:35:51 AM »
First of all, what kind of brazing are you talking about? At the temperatures you are talking about, you should be able to silver braze. Mikey Porter, suggests making his half-inch burner first to be able to silver braze some of the parts of the larger sized burners. The Porter burners are the current favourite for a lot of home foundries.

I haven't finished my 3/4" Porter burner yet so I cannot speak from personal experience.

Regards, Matthew
« Last Edit: July 08, 2013, 02:48:20 PM by mattinker »

Offline vtsteam

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Re: Atmospheric Propane Brazing Torch Experiments
« Reply #27 on: July 08, 2013, 09:16:23 PM »
Mattinker, I'm shooting for brass/bronze braze. Won't be able to work on this until the cupola is done, though.  :poke:
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline dranoel58

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Re: Atmospheric Propane Brazing Torch Experiments
« Reply #28 on: July 09, 2013, 02:52:55 AM »
Here some pictures to show that the turbulation slots help to create a smaller, concentrated, primary flame.
It has consumed a lot of time, but it is rewarding to see the result.

Hope it inspires you, P.M. me if you like more information.
 
Cheers, Regards.



Offline vtsteam

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Re: Atmospheric Propane Brazing Torch Experiments
« Reply #29 on: January 17, 2018, 07:51:52 PM »
My photos in this thread restored after Photobcket broke the links
I love it when a Plan B comes together!
Steve
www.sredmond.com