[TheForge] hybrid burners, reducing atmospheres, and SAFETY

[Kathy]

The hybrid style burner has a facet I've not seen discussed; it tends to run
with a slightly oxidizing flame. Each burner has a "sweet spot" in its turndown
range, which is neutral burning with the choke wide open. However, throughout
the rest of its range the choke must be used to keep from ending up with an
oxidizing flame. This is no big deal as long as you're aware of the potential
problem. However, all the comments about oxidizing problems in forges with
hybrid burners has convinced me that it's time someone pointed out the obvious.
Don't just open up the burner and adjust the gas pressure for flame size,
thinking that this is all the adjustment needed. You must also choke the burner
a little if you're outside the sweet spot. 

What Jerry said about the problem of free oxygen in a forge run on propane is
also quite correct. It is truer of propane and methane than other fuels, but
applies even to oxyacetylene. When you burn any fuel, there will be some fuel
molecules, and also some superheated metal devouring scale causing oxygen
molecules blasted out ahead of the wave front of accelerated flames. Whether you
choke your burner to make a reducing (fuel rich) internal environment, or add a
lump of charcoal to make sure the oxygen is eliminated before it can touch your
work, is up to you.

Whichever path you take, make darn sure that your working environment is
protected from the carbon monoxide rich exhaust you will then be creating
(powered exhaust hood and CO monitor).
Mikey