I think people have different choices of fuel gasses because they are
doing different sorts of work. Putting a ramp on a gun is different
from making a boiler. For one you want to get a lot of heat in a small
area quickly so the whole gun does not heat up. For a boiler you want
to get a pretty big thing hot maybe with a particular area a bit hotter
than the rest.

For the A/C manufacturer the speed of O/A saves time and therefore
money. If it costs say $60 an hour to pay salary, benefits, shop
overhead etc, you save money by spending a bit more on fuel and oxygen.

But I disagree that air/propane isn't hot enough for any silver
brazing. According to the " Brazing Handbook " put out by the AWS,
BAg23 has the highest brazing temp and it is 970 to 1038 C. That is
possible with air/propane. Just not if the heat is escaping.


Dan