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Forge dosent seem to be getting enough air


T.J.

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My burners act like there not getting enough air to run a nice blue flame even when both ends are open (4"×4" and 6"×6" door) only seams to produce a nice flame when the wind (5 to 10 mph) is blowing threw the forge (with only one burner going at a time). What can I do to improve on this and get it to act right? Do i not have it set right? Any help is greatly apprciated.20180131_161947.thumb.jpg.c823e34cacc1f562b1a04c5848b12b36.jpg20180131_161956.thumb.jpg.022812334c38e754f485336baa9df17a.jpg20180131_162013.thumb.jpg.bd64adfff048e23eefd0e2dd308d2437.jpg

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We need a lot more info and some pictures of the flames to offer much help.  What plans did you use for the burners? Did you follow them exactly or did you substitute parts? Is your regulator adjustable and what range if so?  What's orifice size on your jets?  What is the tube length and diameter?

Even though a fair number of DIY propane burners use off the shelf plumbing parts, those parts have been chosen so that when combined they give the right balance of air and fuel over the practical operating pressure of the burner.  Even small deviations from what has been specified can result in poor or sub-optimal performance.

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I'l try to get pics of flames when it gets dark outside (camera won't adjust enough to get a pic). Plans came off YouTube videos (multiple videos of same size and detention burners). Followed them exactly except I used galvanized plug vs brass. They would be considered 1" burners. Tube lingth is 8" plus fittings on each end. Regulator is adjustable from zero to probably 60 (I have a 0 to 30 and this one will flow 2x as much). Orifice size is 1/16"

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1 hour ago, T.J. said:

They would be considered 1" burners.

So, is that the inside diameter of the smallest pipe or fitting used between the jet and the end of the burner?

 

It looks like you have a lot of things blocking air flow at the top of your burners.  I'd be really surprised if you can pull the air you need with that setup.  I'd expect a significantly larger big end on the reducer for a 1 inch burner.  If it is indeed a 1 inch burner then a 1/16" orifice should be fairly close.  If that pipe is only 3/4" then the orifice is way too big.  Also, the further down the jet is in the top end of the burner, the less air it will pull in.  If you can pull those up some it may help, but again I don't think you'll be able to get enough air pulled in with all that stuff impeding the flow.

Next we need to discuss the forge itself.  What are the dimensions of the forge chamber?  To me it looks like two one inch burners are significant overkill for that size forge.  The bigger the burner, the more space you need between the point where the flame enters the forge and the opposite surface in order to get good combustion of the fuel/air mix.  If those are 1" burners I don't think you have the space.

You probably don't want to start over again on the burners, but I'd suggest you look at Frosty's T burner plans for a low cost, proven, and effective design.  One of the great things about building those is you can ask the designer for help tuning them.

https://www.iforgeiron.com/topic/43976-t-burner-illustrated-directions/

 

 

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I have access to a lathe so tomorrow I'm going to try and cut down the couplings that hold the orific and widen the reducers (someting I thought about doing when putting them together originally) along with pulling them out further. As far as the chamber goes its dementions are 6"T x 6"W x 17"L on the inside. If that dosent work then I'll revert to frostys T burner plans

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One thing that jumps out at me without looking any further is the wimpy reducer fittings your burners have. A naturally aspirated linear burner should have a three to one reduction ratio on its pipe reducer. There is no use looking for other glitches until you change this.

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There is a lot of room for improvement, as said above. However, the easiest single thing to do to improve the burners you have is probably to fit smaller gas jets.

You clearly feel there is not enough air for the gas. Turning that around, there is too much gas for the air supply. Fitting a smaller jet will reduce the gas supply relative to the air supply and will increase the flame temperature. 

I would probably aim for a jet diameter around 80% to 85% of that which you are currently running (64% to 72% of the current area), fit the new jets, see what happens and decide where to go from there.

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Tryed the lathe thing today and it seemed to help but still not working properly. Managed to mess up the threads on the top reducer on one of them so I'm going to try the T burner design mentioned above. But before that I'm going to try a smaller jet on the burner that's still working.

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Greenflames+lots of dragonbreath=not enough oxygen.

 

So theres a number of issues with the burners that i can see.  You can be told all day the design problem but all those problems lead to the one simple fact your burners are not capable of drawing enough oxygen.  The simpliest possable solution i can come up with for this.  Drill some air intake holes.

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  • 4 months later...

...having had a similar issue on a different design... I ground down the tops of my reducer intakes to an angle into the cup...instead of the flat tops. That alone , I went from barely enough air to more than I need, and need to choke it down.  Having it draw air in from the very edge instead of across the flat surface and then down into the obstruction of your gas jets, it should greatly improve the draw past the jets. The smaller tip with a greater velocity of fuel should increase the suction and mix.....

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1 hour ago, KENR2600 said:

...having had a similar issue on a different design... I ground down the tops of my reducer intakes to an angle into the cup...instead of the flat tops. That alone , I went from barely enough air to more than I need, and need to choke it down.  Having it draw air in from the very edge instead of across the flat surface and then down into the obstruction of your gas jets, it should greatly improve the draw past the jets. The smaller tip with a greater velocity of fuel should increase the suction and mix.....

I ended up installing a T instead of the reducer and that helped tremendously but I still feel like it could be better. I might try this on the t and see if that helps

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The smaller the gas jet is the higher its pressure can be turned up before it produces too much fuel for the volume of incoming air.

The larger the ratio between large and small openings in the reducer fitting, or other cone shape the larger the volume of air a gas jet can induce; 3:1 is a good ratio for naturally aspirated burners, and is the safe limit on burners with impeller bladed axial fans.

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