[TheForge] hybrid burners, reducing atmospheres, andSAFETY

Tue May 8 17:42:45 EDT 2007

Hey Bruce,
Good theory, but I get basically the same colored flame when I first light 
off the forge, before it heats up. As soon as I give it an excess of air the 
color disappears
If you light it off with no air , you get a deeper yellow orange color.
I've observed this in new forges that haven't been contaminated with borax 
flux.
Ben ,
I believe that if you try my idea you will still be able to determine the 
different flames.
by observing that the reducing flame is much brighter than the oxidizing 
flame when viewed from the side.
Chuck

----- Original Message ----- 
From: "Bruce Freeman" <FREEMAB at pt.fdah.com>
To: <theforge at mailman.qth.net>
Sent: Tuesday, May 08, 2007 7:34 AM
Subject: Re: [TheForge] hybrid burners, reducing atmospheres, andSAFETY

Try this trick.  Do it first with an ordinary propane torch:

Take a piece of thin copper flashing (sheet metal) and place it in the flame 
(with tongs, of course).  Try different orientations - parallel to the flame 
or crosswise to it.  In the outer, oxidizing cone of the propane torch, the 
copper will oxidize - i.e.,  "tarnish".  In the inner, reducing cone, the 
copper will deoxidize - i.e., turn bright copper metal color.  This happens 
quickly, almost immediately, so the change in apperance can be used as an 
indicator whether the flame is oxidizing or reducing.

I have not tried this in the exit flame from a gas forge, but I expect it 
would work the same way.  I judge a gas forge essentially the same way Chuck 
describes.  If you want to get technical, however, the yellow flame is not 
due to it being oxidizing, but due to the presence of sodium hot enough to 
emit light.  I suspect the cooler reducing flame simply isn't hot enough to 
cause the sodium to emit light.  I have NOT researched that, however, so 
don't quote me.  In any event, the effect is the same as Chuck describes.

Bruce
NJ

>>> stircrazyben at gmail.com 5/7/2007 9:00 PM >>>
Thanks Chuck -- I'll try that.  I just fired up my new Art Anderson
burner (with a *real* regulator, as well), and wow does it pump out
the heat!!  Wretchedly powerful, I was laughing wholeheartedly.  Looks
like I'm very oxidizing right now, as I still get a ton of scale, so
I'm experimenting with turning down and tuning, of course.

Is there any interactive test though, since my colorblindness makes
differentiating flames difficult?
(yes, this is also an issue for me with oxy/acet!  but I'm getting
used to shape and size of flames there)   I think I could burn
something at the forge entrance, which would burn more readily while
it is oxidizing.... maybe a charcoal briquette there, and time how
long it take to burn to dust?  :)

ben

On 5/7/07, Chuck Robinson <robi5515 at bellsouth.net> wrote:
> Light your forge up at night. Let it come to temperature, then stand to 
> the
> side of the opening and look at the color of the exhaust.
> The richer the flame, the more yellow (reducing) it will be .
> Reduce gas flow till you don't see any color that's oxidizing.
> Finally increase flow slowly till you just start to see color again. That
> should give you the optimum heat output without excessive scaling.
> If you mount a 0 to 30 PSI gauge down stream of your gas adjusting valve,
> you can mark the gauge face with a felt tip marker, when you reach optimum
> setting. The pressure reading should be pretty much the same each time you
> light up.
> Chuck
> ----- Original Message -----
> From: "Ben Barrett" <stircrazyben at gmail.com>
> To: "Sponsored by ABANA" <theforge at mailman.qth.net>
> Sent: Monday, May 07, 2007 2:24 PM
> Subject: Re: [TheForge] hybrid burners, reducing atmospheres, and SAFETY
>
>
> > So I've been following these burner threads, and now try to call my
> > venturi "atmospheric", and to call my buddy's forced-air + propane
> > setup a "gun burner"... so what qualifies as a "hybrid"? :)
> >
> > More importantly, what tips can you offer in finding the sweet spot?
> > I have trouble finding it on my 3/4" mini-rex... I just got one of
> > Art's fine Montanan burners at the Spring NWBA conference, and haven't
> > hooked it up yet, but am anxious to try out my 2nd burner and learn by
> > comparison.
> > So far, I've been limited by a BBQ regulator, also, so I'm not
> > surprised that I'm having trouble tuning the rex.  I know it
> > deserves/needs better.
> >
> > Anywhoo, is there something I can do by observing the little wads of
> > paper I toss in there?  I'm pretty sure my current/old setup is too
> > oxidizing, so it makes sense to slowly (say, session by session) turn
> > it back until the evidence of oxidization disappears.... surely there
> > are some good tricks out there from all y'all old-timers ;)
> >
> > regards,
> >
> > ben
> >
> > PS - some said this conf in Enumclaw, WA was smaller than usual,
> > prolly due to being only a week after the one in California.  I had a
> > great time though, very treasured time in my smithing memory.  Thanks
> > to all who help make these conferences happen, and especially to the
> > extra attention to welcome new-bees like me :)
> >
> >
> > On 5/4/07, Kathy <keporter at comcast.net> wrote:
> >> 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
> >>
> >>
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