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RobertMunford

propane buner not acting proper

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So here I am again hope y'all don't get tired of my questions.  Searched high and low and probably in places that I shouldn't have and did not see the answer to my question anywhere.  Sometimes my eyes cross and I don't see info in plain sight so don't yell to loud if I missed it lol

I put together a simple propane forge out of fire bricks and a homemade burner.  it is sitting under a lean to and has whatever breeze there is at the time blowing on it.  it has a nice healthy roar to it for most of the time and seems to heat rather well.  but every now and again it will stop roaring, flutter and pop softly while still burning and then start roaring again.  anyone have any ideas.  to much breeze blowing across it or ??? if it is a simple fix I am thinking about adding a second burner so can head longer objects more evenly.  thank you all in advance.  

Robert aka bob

 

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Posted (edited)

I just have a wild hair theory that just maybe a venturi burner coming in at top dead center of the chamber may be subject to a choking effect as the heat in the chamber creeps up the burner tube and meets the air coming in the tube.. hot air trying to escape meeting cold air coming in basically. Natural airflow and pressure changes in the work area might accentuate the problem. 

That is just a "first blush SWAG" soo.....

 

 

Edited by Vern Wimmer

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28 minutes ago, Vern Wimmer said:

I just have a wild hair theory that just maybe a venturi burner coming in at top dead center of the chamber may be subject to a choking effect as the heat in the chamber creeps up the burner tube and meets the air coming in the tube.. hot air trying to escape meeting cold air coming in basically. Natural airflow and pressure changes in the work area might accentuate the problem. 

That is just a "first blush SWAG" soo.....

 

 

OK what do you think 6 or 8 inches longer tube on burner, heat shield about 6 inches above top brick, or both.  it would be ugly but if ugly works I don't care.  lol

btw haven't heard SWAG used in a long time.  :)

 

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If my wild chimney effect theory is correct I'm not sure how you would increase the down flow. One of the reasons I shudder a bit everytime I see a burner in the 12 o'clock position. It just seems to add a layer of complication.

Of course I wouldn't jump to anything yet. I will bet someone else will come along who has beaten the same problem. That's one of the great things about this forum. There's always someone who's been there, done that. 

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29 minutes ago, Vern Wimmer said:

If my wild chimney effect theory is correct I'm not sure how you would increase the down flow. One of the reasons I shudder a bit everytime I see a burner in the 12 o'clock position. It just seems to add a layer of complication.

Of course I wouldn't jump to anything yet. I will bet someone else will come along who has beaten the same problem. That's one of the great things about this forum. There's always someone who's been there, done that. 

Almost like the flame would go right back up into the tube it gives me the willies too Vern.  That’s why I love coal.  He could easily re position his burner to a side mount. That would probably work well maybe.

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If it happens when it's windy, it's probably disrupting the venturi effect.  First, blow some air across the mouth of the inlet and see if you can replicate the effect.  If you can, then some sort of a wind screen should help.  You should also try increasing the gas flow, it sounds like you are running right on the low edge of the burner, a bit more gas will probably give you a more stable burn.

Geoff

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OK I run across what I think is a solution to my problem.  Quite by accident I have to add.  I was heating a blade and when I kept it up off of the floor about an inch the burner began to behave.  So today I bought a half brick and put it in the forge.  I did two heats of two different blades for normalization and it behaved.  I don't know the reason that it began to work properly but it did.  My uniformed opinion is it needed a little bit of back pressure.  Other than that maybe it was the old FM working.  I thank all for their opinions and suggestions but as the man said I would rather be lucky than good.  LOL  If someone knows reason why that narrowing of the forge height worked I would love to know.

BTW I plan to use the propane forge only for heat treating and normalization as I can control the heat a little better.  Maybe after I learn how to control my heat better with coal I will dismantle this  gas hog.

Thanks again everyone 

Robert aka bob

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Never question the way the gods of the forge enlighten you. If the answer comes to you as mysteriously as the problem did then chalk it up to the gods whimsical nature. Remember that when you see someone forging with a pair of Fruit-of-the-Looms on his head and a peacock feather in his hip pocket--- he found something that worked for him!

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13 minutes ago, Vern Wimmer said:

Never question the way the gods of the forge enlighten you. If the answer comes to you as mysteriously as the problem did then chalk it up to the gods whimsical nature. Remember that when you see someone forging with a pair of Fruit-of-the-Looms on his head and a peacock feather in his hip pocket--- he found something that worked for him!

I go with what ever works best at the time.  letting the smoke out or FM   LOL

Thanks Vern

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got some gas today.  did a normalization on my blade.  I took a short video of it roaring like it is supposed to.  guess it was FM  (frigging magic).  LOL

thanks to everyone who responded to my query.

 

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Ok one more question.  Willies with burner at 12 o clock position.  Why? Dangerous? 

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11 minutes ago, RobertMunford said:

Ok one more question.  Willies with burner at 12 o clock position.  Why? Dangerous? 

I think burner position is more of a preference. I have 2 burners at 12.00.....my only regret is not putting them closer so it would make one larger hot spot instead of 2.

When it comes time to reline my forge I am gonna bring the back burner forward about 6 inches.

If I read your post right....you are saying having them at 12;00 is dangerous?!?

 

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No sir Vern and Geoff above shudder and get the willies when they see it and I was wondering why.  Thought maybe it was dangerous.  Just asking as I am new and don't want to blow myself sky high.  LOL   I only use my propane forge for heat treating and normalization so I have never had much to do with one.

Plan on staying with my coal for the heat and  beat portion. :)

 

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Dangerous is not the right word.  It's a personal preference thing; some people don't like the oxidizing hot spot coming straight down on the blade.  With a square forge, there will be that hot spot somewhere, and you get to choose.  The only safety issue is when you turn it off.  The burner tubes will act like chimneys and pull the heat back up.  If you have rubber gas lines too close they can melt.  

I need to post a review of my new forge soon, I think you'll like it.

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8 minutes ago, Alan Longmire said:

Dangerous is not the right word.  It's a personal preference thing; some people don't like the oxidizing hot spot coming straight down on the blade.  With a square forge, there will be that hot spot somewhere, and you get to choose.  The only safety issue is when you turn it off.  The burner tubes will act like chimneys and pull the heat back up.  If you have rubber gas lines too close they can melt.  

I need to post a review of my new forge soon, I think you'll like it.

Thanks Alan you have answered my question well.  I had an issue with it popping and sputtering at first but by raising the floor with a half brick it now seems to work well.  I have done two normalizations on the blade that I asked about and today did a third.  It seems to stay nice and smooth with very little scale.  I have to keep it moving so there are no real hot spots developed.  Going to finish sanding and cleaning it up and then the truth will be known.  Did I do it correctly.  LOL 

Thanks again Alan. 

Robert aka bob

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I like the hot spots.....I am getting Much better watching for the phase change. I usually heat the handle first.

I am not sure how you guys can even heat a blade with out one(hot spot)......tip is gonna get to critical way before the thicker part of the blade.

Like you said.....personal preference. As far as the chimney dealio....my lines have quick disconnect couplers so thats a non issue unless I am to dumb to unhook em.

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2 hours ago, Kreg Whitehead said:

I am not sure how you guys can even heat a blade with out one(hot spot)......tip is gonna get to critical way before the thicker part of the blade.

My newest forge is much more evenly heated than my last, and I noticed this exact thing the first time I used it for heat treating.  I had to do a lot more in and out to keep the heat even than I did when I had a big hot spot.

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Update  since the last time on here I have found a 15 psi regulator to replace the 10 psi regulator on my propane forge.  Geoff you were spot on when you said not enough gas flow.  took the half brick out and run it for 15 minutes.  not one single spit or sputter.  

thanks to everyone who responded to my questions.

Robert  aka bob 

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