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Influences of torch heat



Two torch questions for anyone who doesn’t mind answering yet
another torch question…

  1. I’m confused about what influences the amount of heat produced by
    a given torch. I thought it was a function of the particular gas or
    combination of gasses used… but when I look at different
    propane-only torches, I see a wide max heat range. Of the two links
    below, one indicates 3500 F and the other 2400 F. Since they’re both
    using propane only, what accounts for the difference in heat?,8312.html

  1. I’m looking at propane because I’ve heard from my insurance
    broker that my home insurance rate will go through the roof if I have
    oxygen and / or acetylene in the basement, and I can’t currently
    justify that extra cost. I do small work and have been using a 2000 F
    butane micro torch, which I’m now growing out of. Is it a waste of
    time/effort to buy the propane-only torch? Should I just stay with a
    butane micro until I’m ready to go to a ‘real’ torch?

Thanks for any help,


The flame temperature is a function of the fuel gas used, and the
amount of oxygen it combines with. Up to a limit, more oxygen means
higher temperature.

Some torches require a supply of oxygen from a separate tank, and
others extract it from air that they “suck” in. Different torches
"suck" in different amounts of air and thus different amounts of
oxygen. This affects the flame temperature.

Regards, Gary Wooding


Sometimes you will see that the temperature claimed is the
theoretical maximum for the combustion of the specified fuel gas with
either oxygen or air depending on the type of torch. Sometimes it is
a measured value. Sometimes it is just wrong :slight_smile: The theoretical max
for propane and air is 3677 F. Torch tip design especially on
naturally aspirated torches like you mention plays a big part in max
temperature. Almost any torch will when properly adjusted work for
soldering with silver or gold solder on a certain size piece. The
size will depend on not the torch temperature but the volume of gas
burned per unit time which would be listed in BTU’s but is almost
never listed and it is by far more important than
temperature for determining suitability for a particular job.

James Binnion
James Binnion Metal Arts

I'm confused about what influences the amount of heat produced by a
given torch. 

Sue. question #2 - which torch? - is a perennial question around
here, and I’ll let others deal with that.

Interesting little page about your very question #1:

It could be that the Micromark IS hotter, some or all of it could be
PR and grabbing numbers out of thin air. Either one is hot enough to
solder with, in the end. Torches (torch handles, especially) are more
complex than they might seem.