[TheForge] Problems with propane burner

[Marc Godbout]

First of all, my castable project went really well. The forge has been
through its first firing with only a few small stress cracks. Now time
will tell.

But my new burner has some problems and I'm hoping to get some ideas
from you guys. I'm trying some slightly different design to better match
my application. First, the mixing tube is a 90 degree sweep of 1" rigid
conduit. I wanted to lower the profile. 

The other difference is that I cast the nozzle into the refractory wall,
but I didn't flare it. Also, this is a side-arm, using a 1 1/4" cross
fitting with a reducer to the 1" tube. I've got a .035 mig tip for the
orifice.

The problem is that I have a tough time keeping it running at low
pressures. I don't have a gauge on it, but from the sound it's probably
well over 5 psi, maybe even 10, before it starts sputtering (with a
nifty "whoop" sound), and then the flame travels all the way to the mig
tip. I was able to get much lower when I had it out of the forge, using
just a straight pipe for the nozzle.

High end is no problem. Things get bright yellow hot in there in no time
at all. And that's with just one burner in an 18" long half-tube,
half-stacked-brick, with 25 psi (the max that my delivery system will
do).

I'd like to get really low for idling between heats to save propane, so
any thoughts would be welcome. Should I try flaring the nozzle? This
castable is easy enough to carve with a round rasp.

Thanks.

-Marc

-- 
Marc Godbout
http://www.ironringforge.com

New England Blacksmiths Membership Director
http://www.newenglandblacksmiths.org