I would love to get my hands on a propane torch that would use pressurized air (reguires an air compressor) to create more heat as to be able to bend heavier iron bars. So...
All ideas and links appreciated
Thanks in advance
Why would compressing the air increase heat? That's a property of the fuel/oxygen/inert-gas ratio.
A good normally aspirated burner should produce all the heat you need. look up Ron Reil's site, especailly his Mongo burners. Simple and work well. Otherwise a fan will do for the air supply. There is still a limit to the heat output - 80% of the combustion air is effectively inert, sucking up heat and volume. This lowers the flame temperature and heat output. You need air volume, not pressure. You need 25 times as much air as LPG, so the volumes can be a lot. With the flamespread testing machine we have just finished building at Uni, it uses a pilot burner. This initially was set with a pressure regulator, but this was incredibly touchy - the needle wasn't off the stop. We ended up using a $5000 mass flow controller - dial up the airflow to 6l/min +- 0.01% :) If the air velocity is higher than the flame velocity, then it will blow the flame off the end of the burner. It doesn't take much. Geoff
If you want lots of heat....
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
Most any jewelry supply will sell you an air-propane torch head. They aren't really designed for heating and bending big steel bars. For that you can buy a 3,000,000 btu weedburner for about $50. It runs directly off the tank pressure without a regulator. No air line required. Bugs
In Glass blowing we commonly use a National 3A blow pipe. It's a hand torch. Although they are rated for use with Oxy, they were originally a gas / air torch. They still offer gas / air tips for them. The link below should take you to the torch itself. The second link should take you to the gas /air tips.
If you should get such a set up and have any grief from you local fire marshal because you're not using welding hose, or have the crimp fitting rated for 300 psi, or the tip & torch are not UL listed as a welding torch. Please tell em to KISS YOUR ASS. NFPA 51 does not apply to Gas/ air torches. Only when oxygen is used does it apply as a hazardous material.
Good luck,
Randy H.
Don't forget the firebricks! Heavy bar will take a few minutes to heat up, even with a hot forge.
Tim
-- Deep Friar: a very philosophical monk. Website:
It would help if you would define "heavy bar" in terms of size.
Meanwhile, visit
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