Subject: [Q] How hot can an air-propane torch be ?

From: C++ Freak <[email-masked]>
Date: 14 May 1996 11:18:03 GMT

Is there any theoretical limit on the flame temperature of a
propane-air torch ? And any practical ?

C3H8 + 5 O2 -> 3 CO2 + 4 H2O + 2362 kJ/mol upper value

Subtract from it the heat required to heat the 20 moles of Nitrogen (drawn
with 5 M of O2) which is R [== 8.314 J/mol.K] * 20 * 1400  = 233 kJ/mol and the 
condensation heat of the H2O . Is there any theory about calculating
the flame temperature of any hydrocarbon fuel ?

Putting a Pt/PtRh10 thermocouple in the hottest part usually yields
1400-1500 degrees C.

Any other experiences ?

Klaas

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From: [email-masked] (Douglas)
Date: Wed, 15 May 1996 23:23:57 GMT

[email-masked] (James Wilkins) wrote:

>:In article <[email-masked]>, C++ Freak <[email-masked]> wrote:

>:> Is there any theoretical limit on the flame temperature of a
>:> propane-air torch ? And any practical ?
>:...
>:> Putting a Pt/PtRh10 thermocouple in the hottest part usually yields
>:> 1400-1500 degrees C.
>:> Any other experiences ?
>:> Klaas
>:The flame radiates a lot of heat to its surroundings unless it is in a hot
>:tube.  
>:In practice, my propane torch will barely melt a small bead of copper on
>:the end of a wire (conduction loss path).  
>:If the bead of molten copper falls into a can of water, it just sits on
>:the bottom glowing within a shiny steam bubble.  Wear serious protection
>:if you try this sort of thing.

I was looking at an air-propane torch a while back (I've used one for years).
The manf. claimed 2900 F.

Have not tested mine for temp, but I routinely melt 3 oz. of silver with it. 

Respectfully,

Douglas

Amulets, Talismans and Metaphysical Jewels

          http://galaxymall.com/shops/douglas.html

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From: [email-masked] (philip evans)
Date: Wed, 22 May 1996 06:30:11 GMT

>Have not tested mine for temp, but I routinely melt 3 oz. of silver with it. 

I haved a torch head sold by Canadian Tire that has some kind of vortex gizmo 
in it, it'll braze & silver solder (real silver solder) bicycle bits onto the 
frame tubes, but doesn't quite have enough heat to join the tubes together.