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Naturally Aspirated Ribbon Burner. Photo heavy.


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Just a couple of questions on performance - How are people finding the performance of their NARBs compares to a regular T burner? I ask as I'm looking at building a forge that will be approx 7" x 18" cylindrical after the insulation and refractory, giving it a volume pushing 700 cubic inches (it's long I know, and I may cut is down a few inches, I've just been doing long twists lately in a little beginner forge and it's been a long and inefficient experience. I also have long-term pretensions towards blade making).  From what I have read I'd need two 3/4" T burners, but is a NARB efficient enough to enable me to cut it down to just one burner for this sort of volume? I think I read somewhere else that Frosty reckoned a well-tuned 3/4 fed NARB could just about manage it but I'm looking for further opinions/confirmation of this as it sounds like it would be a bit of a stretch and I may be better off with two NARBs. I was wondering if the NARB could be scaled up to use a 1" T burner and drive a larger outlet, but I'm guessing that without a blower this would run into problems with a lack of pressure that I'm not clever enough to work out the maths for or fully understand.

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It depends on what you mean by performance. If stability is your measure they're many times as good. That's just an example. I believe they hold pretty close to the basic rule of thumb  ratio for furnace volume to tube diameter. one each, well tuned, 3/4" NA, jet ejector type burner should bring 300 - 350 cu/in to welding temperature.  By that rule of thumb you'll need 2 of them.

However if you don't need welding heat you could probably get away with a longer furnace chamber say for heat treating. Twisting wants near welding heat though, I think you need two of them. 

The diameter of the tube means a lot, output is directly related to the area of the tube cross section.  1" is 2 x the area and output of a 3/4" burner. The numbers say you should be able to pull it off with a single 1" T driven NARB. Just off the top of my head that'd be around 40 crayon dia. outlets from a long plenum.

I'd make the plenum from larger tubing. The 3/4" T driven NARB worked well with 2" sq. tubing but spread out that far a larger volume to length might be necessary. I'm just speculating though, I haven't tried going larger. I'm set up to make 3/4" Ts so its easier to just make two NARBs. That's my set up though, if I were starting out I might tinker a different size to perform for me.

Please keep us in the loop if you give it a try.

Frosty The Lucky.

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Thanks for the info Frosty, I feel a bit of experimenting is on the cards. I assume a slightly larger MIG tip would be necessary in a 1" tube? I'll order up some different sized parts so I can see what works. The tank I intend using is currently full of propane so i should really hook it up and actually hit some hot metal instead of reading this forum. I'll let you know how it goes when I get round to building the forge.

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I ran a 0.045 mig tip in the 1" T I built early on. It was the first successful one I made and looks a lot different. The T was a 1" T so the intake ports weren't larger like the 3/4" x 1" that works so well on the 3/4" burner or the 1/2" x 3/4" on the 1/2" burners. I didn't need nearly that much burner in the forges I was using so I never tinkered with 1" burners again. I'd assume it would work well with larger intake ports. 

The gross changes in these things seem to follow a pretty direct ratio. Make the mixing tube DIA. 50% larger, doubles the output the optimum jet Dia.  (for how I build burners that is) is also 50% larger.

Were I messing with 1" T burners again I think I'd compare 1" x 1.25" and 1" x 1.5" Ts as departure points for developing my version of optimum performance. What works best could be different, maybe at that size the intake ports don't need to be larger. I don't know I haven't played with the things.

Frosty The Lucky.

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  • 2 weeks later...

Okay, I am a good way i to my forge and ribbon burner and wanted some feed back.  

So far I built the burner and, when outside of the forge it has the blue jets, a large blue secondary flame but with orange red flames kicking about here and there.  I’ve read that this is commonly caused by the kastolite.  I also determined that some crayon particles were still wedged in the jets and, after cleaning them, I got a cleaner flame.

I completely failed to take a picture of the burner outsid of the forge....no idea why.  But the forge has since been built and I took it outside to finish the rigidizing process.  The flame seems good but it certainly turns into an orange read swirl in the forge.  

I would appreciate any input on the forge, the flame and particularly on the process of lining it with kastolite.  I intend to use metal flashing to make forms for the inside of the forge so I can apply the kastolite in one session.  Is this madness?

EC327B2F-D8B2-4009-B83F-8B3834034742.thumb.jpeg.95ae5fbdace64d4ed48e1120fbb71fde.jpeg

This is at 10 PSI....the next is at 6 PSI.

47720BB7-4CA4-4383-B00C-723C817AB9B6.thumb.jpeg.061ea87bd96bd89d566aa43cb44c856c.jpeg

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Looking GOOD Lou! Yeah, Kastolite has a calcite binder and it makes a bright orange flame that isn't really dragon's breath. When you're curing off the rigidizer the yellow orange you see is sodium flare (I THINK) from the fumed silica. Uncoated Kaowool doesn't make the yellow orange flames, I had to give it a try to see so I tossed a small scrap in. 

I don't think I ran a ribbon outside a forge long enough to even warm it up so I can't say much there. I wouldn't worry about different outlets having flames a little different than others, these are home built. A little yellow or maybe interesting color flickers is no big thing. All the crayon and such won't be cleaned out till you get it good and hot anyway and a little paraffin in the fire will make it really rich. Yellow flame rich, till it's gone. 

Linoleum makes a good mold for refractories. Roll and tape it to shape, when the refractory's set untape it and peal it out. 

The only thing mad about you is trying some of this whacky stuff we dream up. :ph34r:

Frosty The Lucky.

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  • 3 weeks later...

Hello! ^_^  How is this NA ribbon on the noise spectrum?  Is it as quiet as a blown ribbon or only slight louder?  I live in the city and want to avoid the noise of a regular single tube venturi which I gather as being quite loud.  Have yet to be in the presence of one so I can only go by videos which is a horrible way to compare anything.

I assume they are not as efficient as a blown burner.  I do have electric in the garage so a blower is not a problem.. just a matter of finding one that fits the bill.

I have been looking at blown ribbon setups.  Seen the PineRidge burners which look nice (I don't mind paying for quality engineering and not having to mess around with casting and guesswork) but from the sound of it won't work well in a small forge or would require a lot more blower pressure for that.  Is one of these NA ribbon or like  a Giberson going to be my best bet?  This will be a hobby forge.. not a full time venture.  I just don't want to bug the neighbors with burner noise if I can avoid it.

Planning on making a basic IFB forge with some  angle iron to hold it together if needed or at least a frame for the roof to help hold the burner.  I have a box of 2300 brick 3" thick  that I plan to use as the first setup.  I will be keeping it small volume for starters.  If I need bigger I can rearrange or add more brick..   under 300cu in. to start.. likely 9x6x4.5 or smaller.  Might shrink it to 5" wide and add some length.. we will see.

 

Side note:  It's been over 10 years since my last post on here.. My forging started using OA torch for heat and chunk of steel for an anvil.  Made a few roses and leaves chasing the steel around the floor using what I could for fullers.  That was quite some time and have moved a few times since.  I own my first house now so I want to get back into it as a hobby but looking for an easier method for the heat.  I do have an anvil now so I don't have to chase the block of steel around the floor.

 

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I haven't used a blown ribbon burner, so I can't compare to that.  However, I can tell you that my NA ribbon burner is significantly quieter than the single port burner it replaced.  There is still a small amount of roar, but it's quiet enough to carry on a conversation at normal speaking volume or listen to the radio at a reasonable volume within a couple feet of the forge. At normal forging temperatures it wouldn't stand out against normal background noise if you were more than a few feet away.  When I crank it up to forge weld it would be noticeable, but not overwhelming or horribly annoying.

I think I use slightly less propane with the ribbon burner, but it does require a certain amount of fuel and air to heat a given space no matter how it's delivered.  For me the real benefits are noise reduction, fantastic operating range, great flame stability, and more even temperatures inside the forge.  I see no reason to go back to a single port burner at this time.

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3 hours ago, Paragon said:

How is this NA ribbon on the noise spectrum?

Welcome back, Paragon.  I built one of these burners to Frosty's specs (1 X 1 X 3/4 Tee air /feul mix generator with a 2 X 2 X 7 Chamber behind the ribbon.  I settled on 20 holes, or ports in the ribbbon.  The ribbon itself is 3 X 9) and my nephew and I had it burning at10 PSi the other night.  We were standing close enough to feel the heat from the Dragon's Breath and were able to talk in normal tones of voice.

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Thanks guys.  Good to hear.   I guess casting isn't really all that much work.  The most work seems to be making the steel housing (plenum?).  Are you all running without an internal baffle?  Seems that is the only difference on a blown burner or is it the inlet/outlet hole size matchup that is specific for NARBs?  Just wondering if I build a NARB with baffle, would the baffle slow down the jet stream too much.. and if not, would it go as a NARB and a blown setup easily?

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Good to see you back on active duty here. 

When I put the fuel/air port in the side of the plenum and left the diffuser out the individual flames were acceptably uniform, say from 3/4" on the ends to 1" in the center of the burner outlet array. 

I went back and tried the vertical/fuel air port on a wood test block without diffuser and the flames were only a little more long over the port. 

You can buy commercially made naturally aspirated multiple outlet burners in a whole bunch of shapes. 

Oh yeah, the ribbon is a lot more quiet than the single flame burner. You can easily hear the 3/4" single flame burner from the house about 130' away through closed shop doors. You can carry on a normal conversation within 3-4' with two 3/4" driven NARBS. 

Using less fuel is to be expected with a NARB as the flame velocity is much lower so the flame stays in the forge transferring heat to the liner and work longer. 

My single flame and NARBS are driven with 3/4" T burners. A single 3/4" T will start to frost a 20 lb. propane tank in an hour or two depending on ambient temp & humidity. I can run two 3/4" T driven NARBS up to 8 hrs. on a 20 lb. tank and only develop condensation.

At home I use a 100 lb. tank and normally use a 40 lb. tank at demos but I had to do a test.

Oh your first "question"(?) Why do you assume a gun burner produces a hotter fire than a naturally aspirated one? I've been using both for years and there isn't really a difference except maybe it's easier to make a gun burn hotter. You have to tune a naturally aspirated burner properly which takes more time, care and a better eye. It's not a big deal, just a little more hassle.

Frosty The Lucky.

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5 hours ago, Paragon said:

or is it the inlet/outlet hole size matchup that is specific for NARBs? 

A NARB does require the right number/size of holes.  Too few and the flame will lift off the block and possibly blow out.  Too many and you'll get backfires or the flame will burn inside the plenum even at medium to high pressures.  If you get it right you can run down as low as 1 or 2 psi without backfires and up to 20 psi without blowing the flame off the block even before the forge is hot.

If you introduce your fuel/air perpendicular to the outlet holes I don't think there's any benefit to a baffle and it may possibly degrade performance.   I'm not sure a blown burner would really need a diffuser or baffle either if the fuel/air mixture was introduced that way.  I haven't tried it so I don't really know though.

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8 hours ago, Buzzkill said:

I'm not sure a blown burner would really need a diffuser or baffle either if the fuel/air mixture was introduced that way.  I haven't tried it so I don't really know though. 

I don't think PineRidge burners have a air baffle to spread the mix in the plenum box..  What they call a baffle is just what the metering tubes stick into so basically the back of the casting in these home brewed burners. 

14 hours ago, Frosty said:

Why do you assume a gun burner produces a hotter fire than a naturally aspirated one? I've been using both for years and there isn't really a difference except maybe it's easier to make a gun burn hotter. You have to tune a naturally aspirated burner properly which takes more time, care and a better eye. It's not a big deal, just a little more hassle.

I guess it should be the same if the same flame type (neutral/ox/carb) and flow rate of fuel.  It would be easier to adjust a blown to whatever mix you require.

 

.. I so like the easy quote adding on this forum

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I think the need for baffle in the current gun version of the ribbon burner as seen in The Hammer's Blow or Anvil's Ring is a  matter of too much blower. The inlet to the plenum as drawn aims directly at the outlets so unless it's deflected a little the center flames in the ribbon are WAY over pressured.

It was easy to soften up, NA is sensitive to back pressure so you have to have enough outlets or it won't work and if you have too many there isn't enough velocity to keep it from burning back into the plenum.

I didn't express myself very well regarding burner types and effectiveness, I'll try again. It doesn't matter how you get fuel and air in the furnace, equal quantity per second is equal output.

A gun burner is easy to make, you see a lot of fancy stuff but most aren't important to function. The farther from the furnace you introduce the gas the better it mixes, turn a corner or two and you're golden. However to adjust output you must make two adjustments, fuel AND air.

A NA burner requires some precision, the gas jet must be centered down the mixing tube and the correct diameter and position from the tube's beginning. Air intakes: position, type and size tube length are all factors that make significant differences in outputs. However, once you have a NA burner tuned changing output is just a matter of changing fuel psi. 

 What's the purpose of changing the atmosphere in the forge? I can melt steel running a SLIGHTLY reducing flame, the NARB forge is close but that's the forge not the burners. 

Frosty The Lucky.

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A question about alignment of the burner tube relative to the forge: most of the pictures shown here have the tube running horizontally or a bit below, with the burner blowing either straight down or a little off TDC. I'm planning to set the block of my NARB so that the flames enter the forge horizontally and roughly tangential to the interior of the shell. This would mean that the burner tube will be vertical, as in this photo of my setup awaiting refractory:

27CE955F-EEAF-42C3-952C-6DCC3D114401.jpeg

My question is this: should I leave the burner in this alignment, with the tube rising UP from the plenum, or can I have it pointing DOWN? If the latter is okay, the air inlet will be below the opening of the forge (possibly even below the level of the top of the stand), thus reducing the chimney effect and distancing the air intake from the heated forge exhaust. Additionally, the gas supply line would be both farther from the heat and not sticking out in the middle of my (rather small) shop.

Any thoughts?

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For burner placement and orientation I like Daguy's setup.  It has great distance between the burner block and the opposite wall, it induces significant swirl, and it doesn't take away much, if any, of your floor space.

https://www.iforgeiron.com/topic/60067-it’s-finally-burning-a-first-build-story-photo-heavy/

As far as the tube orientation, IMO extending down is better for the reasons you gave.  I've only used horizontal, or nearly so, tube orientations, but I can think of no reason your idea wouldn't work as well or better than other options.

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16 minutes ago, Buzzkill said:

For burner placement and orientation I like Daguy's setup. 

That's the basic idea, but rotated clockwise about 30°.

17 minutes ago, Buzzkill said:

I can think of no reason your idea wouldn't work as well or better than other options.

Good; I shall plan on that, then.

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The only difference I can see in rotating it 30 degrees is secondary combustion may not be complete before impinging on your stock.  If you look at the video of his swirl the visible flame diminishes to almost nothing about the spot where your stock would rest on the floor.  I don't see this as a major concern, and it may even be a moot point once the forge is up to temperature, but it is a slight difference.

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That should work fine John though I haven't experimented with that orientation in a forge. 

Even with the tube vertical up I haven't noticed much chimney effect. I don't think it can draw well through all the outlets as opposed to one large diameter one.

Frosty The Lucky.

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22 hours ago, Buzzkill said:

It has great distance between the burner block and the opposite wall, it induces significant swirl, and it doesn't take away much, if any, of your floor space.

JHCC, just FYI , in the videos I posted in the thread that Buzzkill linked, complete combustion was at like 1 or 2 PSI.  At higher propane pressures, the  combustion continues into the second rotation of gasses at the least.  The reason I oriented the burner the way I did was to distance the intake of the burner from the exhaust but mostly to induce the swirl.  I actually thought about mounting it with the tube projecting downward  rather than upward to more fully protect from the chimney effect on cooling and double burning (Carbon Monoxide) The reason I went with a (Frosty T-burner based)  NARB was that I didn't want to be dependant on electricity.  with my setup, I can take it anywhere my vehicle can go with only a propane tank.  That being said, I like and prefer your idea of orienting it downward IF it is permanently mounted to its base.  That makes it safer as far as Carbon Monoxide production goes.  You just need to consider wether you'll be moving it or not after the build. Either way, if it accomplishes the mission, it's all good!  :D

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The plan is to mount it on top of this old gas grill base, which is currently the support for my forge’s removable flue and previously was my hammer rack. Still figuring out how to make that happen. 

B7074059-5FC2-487E-AAF1-BD991A3240BB.jpeg

Nice that it already has a spot for the propane tank, though. 

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17 hours ago, JHCC said:

The plan is to mount it on top of this old gas grill base, which is currently the support for my forge’s removable flue and previously was my hammer rack. Still figuring out how to make that happen. 

I LIKE!

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