[TheForge] Traveling Gas

[Jerry Frost]

Typically the screen is a flame holder and in the case 
of a Fisher burner a diffuser as well.

Properly tuned they're totally unnecessary. By the time 
your air:fuel reaches the flame holder it's going into 
the forge and it's WAY too late for proper mixing. The 
burner tube end flares do the job a lot better than ANY 
restrictive flame holder. The flare causes a 
pressure/velocity drop as the mix expands in the cone. 
This increases induction throughout the burner and the 
sharp pressure/velocity differential acts as a flame 
stop. A flare improves a naturally aspirated burner's 
performance all other flame holders reduces performance 
and must be countered.

Having as smooth a laminar flow from the jet, as 
perfectly aligned down the burner tube as possible will 
eliminate virtually all the expressed concerns. If you 
still get backfires use a smaller jet for higher 
induction rates and velocity in the burner tube. Moving 
the jet closer to or farther from the throat will also 
vary the induction rate to produce the desired air: 
fuel ratio. I like mine a little rich so my jet is 
closer to the throat.

On a practical note: If you find yourself needing an 
inbetween size, say 0.037" jet, don't try chasing a mig 
tip with a dril bit. Copper work hardens quickly and 
galls (gets really grabby) so you'll break lots of 
little drill bits. Use tip cleaning files instead.

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

Meadow Lakes, AK.

http://www.artmetalradio.com/

From: "Grover Richardson" 
<grover.richardson at gtri.gatech.edu>



> The screen performs two purposes.  One is to mix the 
> gas, the other is a
> fire block.  A third thing that is generally 
> unnoticed is that the screen
> also keeps infra red from getting back to the 
> orifice.  I have a plumbing
> pipe version of a burner and I ran it a few times 
> without a twist of shim
> stock inside it for a mixer.  There was enough infra 
> red in the forge to
> ignite the flame at the orifice.  A fun time was had 
> by all until the burner
> was turned off<G>.
>