[TheForge] Problems with propane burner
Larry Zoeller
[email protected]
Sun Sep 7 17:40:02 2003
To All,
I sold (6) 3/4" modified side arm burners to a guy out in Arizona that use
them to replace the five burners in a N.C. tunnel forge and he was able to
get it up to forge welding temps with no problems, he replaced the original
five burners because he could not weld with them. This should give you
some idea how many burners you will need in a sword forge.
Thanks
Larry Zoeller
[email protected]
> [Original Message]
> From: gblacksmith <[email protected]>
> To: <[email protected]>
> Date: 9/6/2003 2:21:02 PM
> Subject: Re: [TheForge] Problems with propane burner
>
> Frosty: Good info on burner performance! I use a Forgemaster Blacksmith
> unit with two atmospheric, vs. forced-draft burners. Mine also has a 90
> degree downward bend on the burner tubes, with a 2.5 " dia. intake end
on a
> 1.5" main/flame end. This unit works well for general work and
> heat-treating, but I have not been able to weld with it. I am guessing
that
> this problem is a combination of venturi construction, 2 burners, vs. 3
and
> the fact that it is rectangular in shape, vs. circular. I have heard that
> efficient welding requires a "vortex" for even heating of the interior. I
> have been sticking to coke or charcoal fires for welding, to date.
>
> What are your thoughts on this issue.
>
> I would welcome comments from all hands as well.
>
> I plan on building a sword-length propane forge that will get hot enough
to
> weld in. I am interested in the thoughts of others on these issues.
>
>
> Grant
> ----- Original Message -----
> From: "Jerry Frost" <[email protected]>
> To: <[email protected]>
> Sent: Saturday, September 06, 2003 10:33 AM
> Subject: Re: [TheForge] Problems with propane burner
>
>
> > Morning Marc:
> >
> > There are a number of factors determining what your minimum operating
psi.
> > will be for a naturally aspirated burner. You can't just look at the
> > pressure gage; you have to adjust your expectations to the entire
device's
> > characteristics.
> >
> > Thanks to your reasonably complete description I can hazard a couple
> > opinions with some hope of accuracy. <grin>
> >
> > First, you have a 90* bend in the burner tube, this will cause back
> > pressure, requiring more psi to drive around.
> >
> > Second, you're running a "sidearm" configuration jet ejector with only
a 1
> > 1/4" intake on a 1" tube. This is not a free breathing configuration and
> > requires higher psi to draw sufficient air.
> >
> > Thirdly you're using a 0.035" orifice which requires more psi to deliver
> > sufficient propane. How well aligned is your jet in relation to the
burner
> > tube? This is really critical.
> >
> > You have several options open:
> >
> > First accept higher operating psi as normal for your burner, you're
> getting
> > plenty of heat even though it doesn't idle like you want. Still,
running a
> > "smaller" orifice delivers less gas at a given psi so you may have the
> > economy you're looking for already. In short it could already be singing
> the
> > tune you want, just in a higher key. <grin>
> >
> > Second look at changing the 90* to a longer sweep or even two 45*s .
This
> > will increase the radius of the direction change and reduce the back
> > pressure a bit though probably not enough for a stable idle. You should
> also
> > place any bends as far as practical from the throat (narrowest point
> between
> > the intake and burner tube) of the burner. The longer the jet of propane
> can
> > travel down the exact (as possible) center of the tube, the more
> efficiently
> > it'll draw.
> >
> > Thirdly you could try a "T" configuration jet ejector, I have a pic of
> mine
> > on photoaccess under forges and hoods. Mine is a 1 1/2" x 1 1/2" x 1
1/2"
> > "T" reduced to 1" with a simple bushing. I had to drill through the back
> of
> > the "T" to install the gas supply. (#7 drill, tapped 1/8" pipe) It has
two
> 1
> > 1/2" intake ports and runs with a 0.045" orifice (Miller mig tip). Mine
> > burns stably at any psi my gage registers, 30psi. to below 1 psi. but
the
> > low end is inadequate to keep my forge in range so I just run it around
5
> > psi. My old forge only has 1" of Kaowool insulation around 3/4" rammable
> > refractory so if I idle it very low it cools down and I burn more fuel
> > reheating it than just keeping a steady burn. I do bump the psi up to
7-8
> > psi. to weld but for general forging 5 psi. is just right.
> >
> > Fourth, filing the port in your forge liner to form a taper might be
well
> > worthwhile. On my next forge I plan on building my burner nozzles into
the
> > refractory liner myself, mostly to save on tube burnout but also to
> improve
> > performance.
> >
> > Lastly, how completely are you closing your forge up? If you're not
> allowing
> > enough opening for exhaust gasses to escape you're really building back
> > pressure and inhibiting your burner performance.
> >
> > Frosty
> > ------------------------
> > If it ain't forged
> > it ain't real.
> > Wrought iron is.
> > The FrostWorks
> >
> > Meadow Lakes, AK.
> >
> >
> > ----- Original Message -----
> > From: "Marc Godbout" <[email protected]>
> > To: "TheForge" <[email protected]>
> > Sent: Saturday, September 06, 2003 7:13 AM
> > Subject: [TheForge] Problems with propane burner
> >
> >
> > > 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
> > >
> > >
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