direction of forced air burner

Got a question for anyone with experience and knowledge of building a forge with a forced air burner ....... I have a forge built, yet to have it's first firing and someone has raised the question over my burners being directed vertically downwards ....... has anyone got any thoughts or opinions on the legitimacy of these concerns? ... the only thing that comes to mind is that the propane is heavier than air and CO and might get passed the needle valve control for the propane
image can be seen here

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forge
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try here ..... eager fingers on buttons
http://www.britishblades.com/forums/attachment.php?attachmentid �3

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PS ... just in case Ron still visits this group... i am waaaaaayyyyyy over 21 ..... :-) ..... an oil fired forge in the basement? :-O ... I hope no one was injured or worse :-(

My main concern would be that since heat rises, that you might cook some of your valving. And, from what I see, the propane line, which is flexible and maybe rubber covered (or some composite) could lie against the outer surface of the forge and burn off. I'd think I'd turn the whole thing 90 degrees clockwise, to get the heat away from the valving and hose. That way, YOU won't get cooked either when you are adjusting things.
Pete Stanaitis -----------------
Simon wrote:
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thanks pete
the hose is actually stainless braided and wasn't going to rest against the body of the forge in operation ..... the overhead issue of the valves has already been raised and I am working out my options ... one being to put an elbow below the tee to offset the controls ... or a baffle to protect the valves ... the main concern still remains any potential risk of having them set vertically/
thank again for the input
Simon

Simon wrote:
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Well, they're off-center, so that will impart swirl. Where's the exhaust, out the back? What's the area of the exhaust port relative to the inlet ports? Fire gets you a LOT of volume increase in your box, flow rate is important if you don't want to build a slow hand grenade. Think jet engine without turbines.
Charly

Charly the Bastard wrote:
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Sorry about this double, I was interrupted and had to logout.
I run a four-burner gas and forced air rig. It's got an 8" impeller running at 3600 rpm, with an inlet area of about 3.5 sq in., and fed with a half inch city gas line. I usually keep it choked down to about 2 sq in for welding heat with all the burners lit, going into the side of a 26" X 4" X 4" box with a swing away lid. At heat, there's about a one inch gap around the lid, and the fire still pours out about six inches through the gap. I figure I'm getting at least 10 to 1 expansion in volume, and about 1-2 psi increase in the box with the lid in place. Just something to thimk on...
Charly

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Thanks a lot for that Charly ... front and back doors of at least 7" diameter, figured that would be plenty enough exhaust and I can set the doors ajar at any angle .. or just leave the back door ajar and work through the small opening in the front door ... as long as the gas is burning I can't see it being a "grenade" and i have no intention of not being on hand when the forge is running ....... a multi safety device is fitted incase of flame failure, also has a gauge, temperature fuse and flow rate sensor that shuts of in the case of a sudden fluctuation.
My main concern still currently revolves around the fact someone mentioned something about a problem with vertical, down firing burners. Only reference I could find was from Ron Reil's site;
"6. There are two more items I will mention, but only as a cautionary note. The first involves burner position. There have been reports of burner malfunction in atmospheric burners when they are mounted vertically in a furnace or forge. This is not specific to the T-Rex line, but to all atmospheric burners. Apparently a problem can develop when the rising hot gasses interact with the down flowing gasses in the burner tube. I have been unable to duplicate the problem when conducting tests, but that doesn't mean that it can't happen. Be aware that vertical burner positioning can cause a problem that may cause erratic operation or flame-out. The second item regards propane contaminate deposition in the jet of the burner. Apparently some propane has more contaminates than other propane, depending on its source. You may need to periodically clean out the jet of your burner if your propane leaves a tarry deposit over time. You will simply see a degrading performance over time, but cleaning the jet tip will quickly bring your burner back to like new performance."

Simon wrote:
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Well, Ron is pretty good at poopane, I guess the only way to find out is to light it off and see what happens. It's probably only a problem when it's first lit. Once everything starts to come up to temp, seems to me that it should stabilize. Mine is like an early jet engine, finicky to light and you don't want to turn your back on it until the back wall gets to autoignite temp. I've had backfires, compressor stalls, flameouts, hung starts... Fire is a Live Thing, it has a personality and a twisted sense of humor.
Charly

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You never know when the power is going to quit on you either! :/
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What do you mean "compressor stalls"?
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My heat treater used to sound like a jet engine but I calmed it down and the same time I improved it's heat treating qualities.
BTW, those with forges might get a different result. ;)
Alvin in AZ

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Awww it's my chipmunk friend :-D ... how's ya doin and whadya think of da monster Mr 2nd Dumbest :-P ;-)

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I figured that was you. You don't get far out of my mind since there never was a week, while I was in school, someone didn't ask me where the hell you were. ;)
The weather is great and I need to get off here and go grind some knife blades! :)
Alvin in AZ (dumbest guy here on a.c.b) ps- I'm named after my dad's best friend from when he was a kid

snipped-for-privacy@XX.com wrote:
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A compressor stall is a condition where the back pressure from the outlet balances the boost derived from the compressor and the airflow drops to zero. The compressor 'stalls' in the laminar flow aerodynamics sense, and creates a zone of turbulence around the impeller. It's like a cavitating boat prop, it carves a hole in the fluid and no work gets done. This doesn't happen with positive displacement blowers, like a Roots or vane or piston, just turbine impellers, like the comperssor section of a turbocharger. Clear as mud, no?
Charly