[TheForge] Sidearm burners, Murphy burners & blown burners

[Jerry Frost]

A frit or similar is common for home made oil burners 
where the volume of fuel per BTU is low but mixing is 
critical. The problem you'd run into in a propane 
burner is volume and back pressure. You'd have to have 
a really large cross section to carry sufficient 
air:fuel without backpressure stopping it. Even a gun 
burner would have trouble.

The volume of air fuel mixture necessary requires a 
high enough velocity the flame can't travel back up the 
tube. Even with the gas pressure turned down to the 
point a naturally aspirated burner does backfire it's a 
non-event. It almost immediately chokes itself into a 
yellow relatively cool flame directly on the jet.

If a reducing fire and it's attendant excess of CO is 
unacceptible but you still require an oxy free fire a 
Don Fogg knife forge is for you. Don't forges are 
vertical cylinders with the burner(s) introduced in the 
lower half tangentially. The opening for your work is 
at the top of the cylinder. By time the flame reaches 
your work there is no free oxygen unless your burner(s) 
are grossly out of tune.

Frosty
-------------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

http://www.artmetalradio.com/

From: "Bruce Freeman" <FREEMAB at pt.fdah.com>


Of course, given sufficient TIME, gases will mix 
thoroughly.  Apparently, burner design can be largely 
dependent upon getting gases to mix in the very brief 
time between their coming in contact at all and the 
beginning of combustion.

Traditionally, that has been a very short time for a 
very good reason:  Once propane mixes with air, you've 
got an explosion waiting to happen.   It makes me 
wonder, though, whether one could mix propane and air 
thoroughly under conditions in which they could not 
possibly explode, and then move them into the burn 
area.

Imagine a fairly large metallic frit - little beads of 
metal fused together to form a porous mass.  (This 
stuff exists and is commonly used for filters.)  If 
within such a material you had a combustable mixture of 
air and propane, it wouldn't burn (I think) because it 
could not easily reach ignition temperature - the frit 
would suck the heat away.  (Maybe the outside of this 
frit would have to be finned, or even actively cooled, 
say, by expansion of liquid propane.)  Hence, in 
principal there'd be time to effect complete mixing.

Bruce
NJ