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Ribbon Burner Problem?


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I can only see the top video so that's all I can comment on.  

For starters you have way too much fuel going into the burner at the start of the video before you start adding air, so as you add air to balance the burn you end up with a higher velocity of fuel/air mix than the burner head was designed for and that creates excessive flame lift.  Try significantly less fuel at the start and slowly increase the air to see how it behaves.  Or conversely after you add a little air decrease the fuel supply and observe what happens to the flames.

Did you build a baffle/diffuser into the plenum?  Have you tried a wide range of fuel and air combinations yet?

Another thing to keep in mind is that the burner will behave differently inside the forge due to the back pressure it will experience in that environment.  There's nothing I saw that should prevent you from being able to get that burner working well as long as you have a way to make small adjustments to both the fuel and air supplies independently, but in the top video even at the end it appears as though you are still running very fuel rich.

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Thanks Buzzkill!

Dumb me didnt built in a baffle plate. I thought for such a small plenum it would be alright. I dont think i can get one in now without casting a new burner block. So how bad is this for the burner performance?

Problem is my regulator is to rough. It shows 0 bar and i can still turn it down. But i dont know how much gas is going through. I will get a new one. 

I will test some more gas/air combinations tomorrow.

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It might be simpler than that on the regulator issue.  If you restrict the gas flow then pressure will show at the regulator (assuming you have a gauge there).  So, for your gas line input you can use a cap or plug with a drilled hole, a mig tip, or you can even squish a piece of copper tubing and solder it in the fitting - anything the restricts the flow enough to build up some pressure, but not enough to prevent the volume needed to run the burner.   You could also install a needle valve between your regulator and input to the mixing tube.  When you have a wide open line there is no opportunity to build up any pressure so it can register on your regulator.  What really matters in a blown burner is the total volume of gas and not the pressure.  However, we can use pressure through a given orifice to approximate the volume passing through.  A reading on a gauge is just a good way to easily return to a setting that worked well for you.   You can tune your burner by sight and sound without a regulator or gauge (although I do not recommend eliminating the regulator).  A needle valve gives fine control on the gas side, and I prefer gate valves for the air, but there are quite a few options.

I don't know how well your burner will perform without the baffle plate since the holes in the burner are lined up with the incoming fuel air mixture.  You would almost certainly get a better burn with a plate in place as that promotes extra mixing and helps even out the pressure before the fuel/air gets to the burner ports.  However, it may be ok for now.  You'll have to experiment a bit and see what happens.  You could potentially still install a baffle without recasting, but the cutting and welding required on the plenum could very well end up damaging or destroying the burner head.  If it were me I probably wouldn't risk it unless I was convinced the burner was a failure as it is.

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Welcome aboard Tim, glad to have you.

I'm not really a gun burner guy but they aren't really hard to get tuned. First, put a needle valve in your fuel line. Too much gas is better than to little, it's easy to restrict the supply with a needle valve. Do NOT try to adjust gas flow with the shut off valve they are NOT intended for the job and don't do it well while being damaged. 

For now forget a gauge, one won't really be much use until you learn how to tune and adjust your burner. Being home built it will be one of a kind and not operate like ANYBODY else's burner. Nobody CAN tell you how much pressure to use, no matter what THEY say. Sure we can say try more or less but nobody can put a specific number on what' good or not.

Sure buy a better regulator but without knowing the range of you reg I can't say yes or no. There's no harm having a spare regulator on hand if it turns out you don't really need a different one.

And PLEASE no videos! They take up a huge bandwidth and IFI has members in places where they have to pay for time on dial up connections. Still pics work just fine, I saw all I needed in the first and last second of the first video so 2 still pictures would've been enough for me to evaluate your burner. After more than 10 minutes and the second video was still blank and downloading so I killed it unseen.

Before you cast a new burner block let's get this one burning a neutral flame and then decide if the flames are uneven enough across the outlets to need a diffuser of some sort. Relax on that for a while, okay? So far, as out of tune as it is now the flames looked reasonably even, you may not have to worry about it at all.

How are you controlling the air supply? You MUST be able to control the air as well as the fuel gas or you won't be able to adjust the heat. 

Why all the plumbing? You only need to put ONE elbow between the gas jet and the plenum to assure good fuel air mixing. You can simplify that if you like, something like: Straight pipe (Nipple) from blower to (T and gas jet), short straight nipple to 90* elbow, straight nipple to the burner plenum. When you make your next ribbon burner try experimenting with holes drilled in a block of wood before casting it. It'll only last for 10-15 seconds before the wood starts burning and you can't see the burner flame for wood flames but that's long enough to evaluate the flame and it's so much less frustrating to throw a failed piece of wood burner block in the wood stove than have to scrap a cast refractory burner. Yes? 

For now and this burner. Close the air valve until you feel a modest breeze coming out of the outlets. Now with a lit flame, burning paper, soldering torch, etc. to act as the pilot light SLOWLY open the NEEDLE valve controlling the gas flow. Slowly increase the gas until you have a stable flame. IF it burns back into the plenum, kill the gas and open the air a LITTLE and try again.

Change ONE thing at a time a LITTLE BIT! If you're using a plumbing "Gate" valve for the air, 1/8 turn on the valve handle is probably WAY TOO MUCH! 

With some minor changes and experimenting you can have that burner working just fine. Remember though, it WILL behave differently in the forge than it does clamped in a vise. Get it close then put it in the forge and fine tune it. 

Also you'll need to tune it for a neutral flame every time you turn the heat up or down.

Frosty The Lucky.

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Thanks Frosty and Buzzkill for the input,

I experimented with the burner todSee the picture below on my setup and my regulator. I think theres still a needle valve on the regulator.

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The blower is regulated by a power supply unit.

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I turned on the blower and tuned the burner to a bright and rich flame. Then I slowly reduced the gasflow. I just adjusted the gas, not the air. I tried this procedure with several air/gas configurations. But it seems that the flames wont stay near to the burner head, if I turn the blower up more to some point.

See below the pictures of the blower configuration which will just hold the flames near the burner head. From there I turned down the gas to a point, where I cant turn it down anymore without the flames dieing. The flames are burning stable and quiet but are fairly small. I really dont think they can bring a forge to welding temps.

So what are you thinking about this?

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Tim

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Don't worry too much about the flames lifting off the burner head when it's outside the forge.  It will behave a bit differently inside.  As long as you can get a good neutral to slightly fuel rich flame without backfiring or the flame blowing out inside the forge you are good.   Once your forge begins to glow inside you'll be able to turn the gas and air up enough to forge weld.  After the forge passes the ignition temperature of the fuel/air mix it will burn no matter how high you turn up the fuel and air (within anything approaching normal operation anyway). Then it's just a matter of adjusting the two inputs so that scale is not forming on the steel while it's in the forge and avoiding excessive dragon's breath which translates to wasted fuel.  

I think you will find that if you install it in your forge now you will be able to play around with the air and fuel a little bit to get used to the tuning and then you will have little to no trouble getting the heat you want.

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I installed the burner in my forge today. The forge is probably too small for the burner but it worked out very nice. I started slow on the air and gas mix and cranked it up further as the forge heats up.

A bright yellowish, nearly white heat was no problem! I just need to get used to the tuning to reduce scaling a bit more.

Thanks for all of the replies. You helped me very much.

 

Tim

 

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Congrats!   We love success stories.  After spending a little more time with the air and gas controls you should be able to quickly tune it how you want.    This is where a pressure gauge reading can come in handy (but it's still not crucial).  Once you find a setting that works well for you, take note of the pressure reading so you can easily return to that spot and then you only adjust the air as needed.   If you can't get a pressure reading don't worry about it,  tuning a blown burner by sight and sound will become easy once you know what you are looking for.

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  • 4 months later...

Good day all.

I am not sure if I am allowed to jump in here on this thread but I have some issues with a forge that I built. This is my first forge and ontop of that I decided I wanted to do a ribbon burner, although I am kind of regretting it now

So just to get jou updated on what I have done so far.  The forge was lined with ceramic blanket 3 layers of 1 inch each and then covered with  approx 1/4" refractory. The mesurement for inside of forge is now 16" long and 7.5" diameter (cylindrical shape with flat bottom). Volume calculates to approx. 650cu.

The burner body is 4" x 8" and I have 23 holes of 5/16 spaced accordingly in a 3 then 2 pattern. There is a baffle plate in the plenum of burner.

The piping for the burner is 1 1/2 " and you can check my configuration in the photo.

Gas is supplied with a high pressure regulator and is controlled by a needle valve. Gas is injected into system via a diy injector made up from a piece of pipe blanked off in front and then 3 holes drilled around it. Diameter of holes are 5/64.

The blower is a squirrel cage type. It is probably a bit small but I did hook up a variable speed leaf blower with same problem although a lot better heat.

So the problem is that I do not get the flames to burn on all of the holes in the burner block. I checked and all holes are open.  I played with the gas air mix quite a bit. I can get both rich and carburising flames. There is no popping or Bach burning. Everything looks good. I would have thought that forge would heat up sooner and that it would get hotter. I ran the forge as hot as I could for about 15min and although the forge got nice and hot and I am sure that I would be able to heat treat and forge with it, I was hoping that I would be able to forge weld at a later stage as well.

I am poking around in the dark here so any pointers and advice would be appreciated. Heck maybe I just nedd to run it a bit longer or something I don't know.

One thing that I am concerned about is that I might have drilled the holes in the mixing plate in the plenum a bit big. So instead of some of the gas going around the plate it can now gow streight through. And also do I have to many holes in the burner block?

Regards

From lock down in South Africa

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4 hours ago, GateKeeper said:

South Africa

Welcome aboard... We won't remember that once leaving this post, hence the suggestion to edit your profile to show location. Have you read this yet? READ THIS FIRST   It will help with getting the best out of the forum. Sorry I can't help with the ribbon burner, but I'm sure the folks who know all about them will be along shortly.

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Welcome aboard Gatekeeper, glad to have you. If you put your general location in the header we'll know where you are later on. 

You've already jumped in. It's a LITTLE LATE to ask if you're allowed don't you think? :rolleyes: 

I can't see anything but the forge and flame. A pic of the outside of the burner might help.

The flame I see is a little rich. rich and carborizing is the same thing. Lean and oxidizing are the same thing. Not nit picking it just really helps if we use the same words and meanings. Yes?

It's not looking bad from what I see,  little tuning won't hurt and the more you mess with it the sooner you'll learn how to tune your burner.

Is a couple few outlets not burning your main concern? It just indicates more fuel air flow is hitting some outlets harder than the ones that aren't burning. Without knowing more about your burner that's about the best I can say. 

Frosty The Lucky.

 

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I apologize for barging in not reading everything as I probably should have. (I read it now...) 

Also I would like to apologize for using the wrong terminology. For some reason I got it mixed up. 

I have done many hours of research not only on YouTube but also reading forums and info on other sites. Part of my poor forum etiquette is due to the reason that I tend to not want to ask questions alot. I read, search, read, search. If I run into something I don't understand I will search some more and read some more. 

One thing that I have learnt is that there is a huge difference in knowing something and actually doing something. You might have all the info stuffed in your brain but as soon as you actually try to apply it.... That's when you realize how little you actually know. 

Therefore when I started my forge build I went in knowing that I would probably make some mistakes and that was OK I just need to ensure I Don, t kill myself in the process. 

Thanks for reading and commenting anyhow. I know that I will probably ask alot of questions and get hit over the head with a comment or to in the process. 

 

As for my current problem.... 

I am curious as to why not all the flames on the ribbon burner are not burning. That is my only concern at this stage. 

I am starting to question alot of the things I did while building the forge and just need someone to objectively look at what I did and spot potential issues. I Don't want to change things that is not actually a problem. 

Here are pics of the forge outside. I know the blower might be a bit small so I will get a better one. Although I do question the huge blowers that I see some have. I might be wrong there as I have no experience to back it up. 

Thank you for all your help. I really do not have any means of getting to a blacksmith at this stage. Lock down and my remoteness comes into play. I stay almost 500 miles from the closest blacksmiths. 

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Good grief MAN don't apologize! I was only joking with you to put you at ease! Seriously how could anybody ask permission to post without posting? Heck I thought you were joking so I played along. You weren't using the wrong terms, I only pointed out a commonly used synonym so you'd know what other folk were talking about. I like to try to get folks using the same terms for things, it saves a lot of explanations? Yes? 

You have nothing to apologize for, you've built a heck of a burner from often dubious information. You deserve KUDOS for a job well done.  You have it down to tweaking for higher performance. Brother you should be SMILING! :D

I'm not a fan of the huge blowers with the giant flames shooting out of the forge openings you see in most ribbon burner forge videos.  Looking at the most commonly used plans shows the reason they need such strong blowers to make them work. They place the diffuser right on top of the air fuel supply so it takes a lot of pressure to get any flow past it and what does get past is moving so fast it just blows right through the forge. Sure the forge gets hot but the amount of fuel burning OUTSIDE the forge is nothing but a dangerous waste of money. 

I'm a proponent of low velocity flames so they stay IN the forge longer and transfer more heat to the forge liner so it can work for me. I paid for that propane, I want all it has. It's the Scot in me. ;)

You might need a LITTLE larger blower but you might be able to rearrange your air plumbing and increase the flow enough. Right now the flow is entering the T with the gas jet and impacting the far wall. This is a hard impact and very turbulent. Turbulence is good for mixing the propane and air but it is inhibiting  the free flow of air more than I THINK it should. 

With me so far?

Good. I can't see what you're using for an elbow on the blower itself but if you rotate the blower so it's in line with the air line it will flow more easily not having to go around the corner. Yes? I would put the T IN LINE right after the gate valve you're using to control the air flow so it can blow straight through the T . Got the picture?

Good. Your propane jet now mounts in the T's CHASE. If you look at a Capitol T a plumbing T has the "Run" the cross on top and a "Chase", the single part at 90* to the run. In plumbing the main flow RUNS straight through a T and if you need to some for a faucet or another  room or whatever, it CHASES off the run. Make sense? This is just more jargon so we don't have to explain everything. Yes?

Anyway,  now your propane jet is mounted in the Chase so you'll need to adjust it's length so it's more or less centered in the Run. (the air flow)

Where the T used to be needs an elbow to turn the corner. 

I think that little change MIGHT improve the air flow without increasing it's velocity as much as a larger blower. Introducing the propane earlier in the air flow will improve mixing and there's plenty of turbulence turning the corner at the top. It will help, if not enough you're only out a little time and a new blower can just be mounted and hooked up. Yes? 

The only fix for uneven flames would involve cutting your plenum open adding a diffuser and welding it back together. I'd live with uneven flames were it me.  What's happening now is the air:fuel flow is entering the plenum aimed straight at the holes in the center of the block, they are getting the most pressure and the flow isn't changing direction so those flames are longer. The farther fro the center the smaller the flames until you get to the outside ends and there isn't enough flow to feed them.  Make sense?

The way a lot of guys try to even the flow is with a diffuser with a lot of holes right on the inlet but as I said it takes a lot of static pressure from the blower to overcome the restriction. What I did instead was to weld a solid piece across the plenum half way to the burner block. My plenums are 2" x 2" tubing set almost 1/2" into the block leaving 1 1/2" space between the inlet and the block. My diffuser is 2" of the side I cut off the tubing I made the plenum from, a 2" x 2" square welded about 3/4" from the inlet.  I should've made it 3" long but it worked well enough at 2". All my diffuser does is deflect the stream from going straight in the center outlet holes. The flames aren't perfectly even in my burner but good enough. I don't need perfection.

What really evened up flames was mounting  my fuel air inlet on the side of the plenum rather than the top. The main flow isn't aimed at any of the outlets it's aimed at the far wall of the plenum and disperses sideways to the far ends almost as much as to the closest outlets. The flames in the center of my burners are still longer than the ends, it's a pretty smooth curve but they're close enough. My forge is evenly HOT across the length and doesn't make excessive dragon's breath. 

Frosty The Lucky.

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Hi thanks for the reply Frosty

I have been out for the last two days, hurt my back moving a piano.... Funny I barely touched the darn thing... Looked at it planned the move bent over and boom... Anyway.

I will be following your advice and applying the changes that you recommended. It does make sense that that the additional turn I have might be slowing down the flow of air fuel mix.

Thinking on what you said regarding the entry point of the air fuel mix on the burner block itself (Top vs. side) producing a better distribution of flame I definitely made a mistake by the type of baffle I placed in the plenum because I understood the baffle to be more of a mixing device than a spreading device. I suppose it needs to do both, but if you ensure a good mix before getting to the burner block the only function for the baffle would then be to spread the mixture evenly to the whole burner. When thinking of it like this a baffle is not just a plate full of holes...

The idea of building another burner assembly actually is kind of exiting. I know I still have a lot to learn but the only way to learn is to make mistakes... 

I am not offended at all by the previous post. It's all good... I have a bit of a thick skin.... I tend to apologize easily and avoid arguments that way we can carry on with business...

Will apply corrections to forge and post back with results .

Regards

 

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OW! The worst I ever hurt my back was picking up an empty box and turning, I was a total gimp for a month.  

About baffles or diffusers in the plenum, I related my opinion and experiences not everybody agrees. Below is a pic of the NARB (Naturally Aspirated Ribbon Burner) in this configuration with the baffle I described. Before you cast a refractory block if you experiment with drilled wood blocks you can find what works best for you without a bunch of work and expense. That's how I came to my current intake/plenum configuration.

The first pic is one of the wood test blocks they didn't have to survive more than 30 seconds to tell me all I needed. All the yellow in the flame is burning wood, not mal-adjusted burner. The T inducer is mounted the way your intake is. The blame size is like yours, typical.

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The second pic shows how I mount the T inducers to the plenum.

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This last pic shows the flame distribution. The burner on the right still had crud in it and evened out nicely once I got it clean.

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Frosty The Lucky.

 

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  • 2 weeks later...

This thread is super educational, as I have a similar issue to the OP, and one more as well...

I've learned from this forum and elsewhere that one of the great benefits of a forced air ribbon burner - in addition to the great heat output - is the fact(?) that you save so much propane. Mine does not. My first and only new forge of this kind requires NO LESS than 10psi on the gage, or the flames will cease entirely. What would lead to such high pressure requirement on the fuel?

The burner I made is really small at about 2x6 inches and has 26 holes to try to match the open area of 1-1/4 inch pipe. Like the OP, I do not get a healthy flame from the ends, PLUS the flame goes out at less than 10psi. This IS an open air test of the unit. The furnace itself (yet to have the burner) is quite small, with an open area of approximately 8 inches length by 4-1/2 inch diameter. From comments, I see things will behave differently in there.

Note also that, even though the flames look neutral to me, there is a good hint of yellow flame a few inches away from the blue. I'm sure that is a clue to something. Sorry, no photos of flames yet.

I do have a normally aspirated two-burner forge I have used for years, but this ribbon forge is totally new to me. Thank goodness for this forum!

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The assertion that a forced air ribbon burner uses significantly less fuel than other options is mostly myth.  Regardless of how you deliver the fuel, it takes a certain amount of fuel with the correct amount of air to produce a given amount of heat in a certain amount of time.  There's no getting around this; it's just chemistry and physics.  There is a slight caveat to that. Multiport burners, such as ribbon burners tend to not have quite as "fast" flames.  What that amounts to in simple terms is that a little more of the heat can stay inside the forge longer before it's pushed out.

Where a fair amount of the confusion seems to lie has nothing to do with the volume of the fuel being delivered, but the pressure at which it's being delivered.  Naturally aspirated burners rely on high pressure small fuel streams to induce the air needed for combustion.   We accomplish this by using a small fuel delivery orifice.   With forced air burners there is no particular advantage to using a small high pressure stream, so the fuel delivery line typically has a much larger orifice.  The result is that even though the volume of fuel delivered may be identical, the pressure is much lower. For this reason, your reported fuel pressure really doesn't tell us anything valuable at all.  We don't know how large your fuel delivery orifice happens to be.

For some people the lower pressure equates to less fuel used in their minds.  From my personal experience my impression is that switching from a single port burner to a ribbon burner (both naturally aspirated using the same mixing hardware) resulted in a slight decrease in the fuel used to achieve and maintain the same temperatures in the same forge. I only ran a forced air burner for a short time and it was not a ribbon burner, so I can't compare anything there from personal experience.  What I can tell you is that for a forced air burner with independent fuel and air supply controls you should be able to get whatever atmosphere you want from very rich to very lean (and everything in between) very easily by adjusting the fuel and air as needed.

For what it's worth I have not been able to mathematically determine how much total cross-section area the combination of the burner outlets should be compared to the delivery tube for a multiport burner.  There are too many variables to take into account for me.  For instance, a single port burner only has friction on the inside of one delivery tube, whereas a multiport burner has friction to take into account in every outlet, and that is also affected by the material used and the surface area of the outlets.  That's just one thing.  My observation for the naturally aspirated ribbon burners (NARBs) I've made to date is that the sum of the area of the outlet holes of the ribbon burner were usually at least 3 times the cross-section area of the mixing tube that delivered the fuel to the plenum, but I always end up fine tuning by starting with more holes than needed and plugging holes until I find the number that allows for good operation.  A forced air ribbon burner should allow for more latitude in the number and size of the holes compared to a naturally aspirated burner, but there are certainly limits to everything.

When your flame "goes out" is there a somewhat loud pop, does it blow the flames off the end of the burner, or does it seem to you that it just disappears?

 

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THANK you Buzzkill for the great response. You really brought up some really important points, a couple of which I should have known -- especially the idea about fuel and air consumption = the heat output desired. Duh - I feel pretty dumb on that one.

For what it's worth, my orifice is 1/16 inch and the gas comes in closer to the air supply (the familiar 3Amp cast aluminum kind with "BLOWER" embossed on the side) than to the the burner manifold so it gets plenty mixed. The setup seems best with the blower air inlet closed as much as possible and the gas "reading" 10 psi (thanks so much for your explanation of that). I've added a photo of the open-air test setup. Yes, I know three elbows on the 1-1/4 supply pipes is a lot, but that should not hurt. I am using a cutoff valve because that is what I have at the moment - glad to replace with needle valve if I must.

To answer the flame-out question, yes it appears the flames just blow off -- no pop to speak of. Just sudden silence and no flame IF I dial the tank regulator under 10 with lowest possible airflow. I do not think it is a the regulator actually shutting off or quitting, since a smell test verifies fuel is still present, just not lit.

 

THANKS!

Burner-Orig 2.jpg

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My first impression is that's a lot of blower for a small ribbon burner.  I have a few questions for you though.

1. If you completely close the blower input gate do you still get significant air out of the burner holes?  If the answer is yes then you need a better way to control the air, such as a gate valve.

2. Does your regulator have a minimum pressure or will it let you turn the gas completely off?  If you can shut the gas completely off then the regulator should suffice for your gas control.  Just leave the ball valve wide open and control the gas with the regulator.

3. Did you build a diffuser/baffle plate into your burner construction?

If you are blowing the flames off the burner that's a good indication that you have too much air pressure.  When installed in the forge there will be some back pressure to compensate for this, but you really should be able to get it burning in the open air.  The size of your gas delivery orifice is on par with a 1"to 1.25" naturally aspirated burner, so 10 psi is a LOT of fuel compared to the size your ribbon burner appears to be.  Without knowing the number and diameter of the holes I can't be sure, but I believe you just have way too much air and fuel (currently) for that burner.  If you can decrease the inputs with more precision you will probably be able to make it work though.

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I concur, the cross section area of my crayon dia. outlets is approx 3x the cross section area of a 3/4" T burner. 

The reason Phillip's burner doesn't pop when he shuts it off is because he turns the propane off while the blower is running so there is never a flammable mixture in the plenum that isn't moving. This is an advantage of GMOBs (Gun Multiple Outlet Burner) or the venerable GRB (Gun Ribbon Burner) You can let the blower cool the burner block and forge after you're done with it for the session. 

Phillip: I heartily concur on your placement of the gas jet, the farther and more turns the mix has to pass the more thoroughly they mix. Propane is an unfriendly gas where air is concerned it doesn't mix easily, left on it's own it will separate.

Nice burner by the way, I agree it could use better control of the air and I disagree about using the regulator as the fuel control. It requires more pressure i the propane supply than the static pressure in the mixing tubes or it can't deliver. A needle valve right after the 1/4 turn valve will give you precise fuel control.

Were it my set up I'd mount the 1/4 turn valve between the regulator and gas hose and the needle valve between hose and gas jet. Let the hose drain when you shut it down, no good reason to leave it pressurized to bleed over the next hour or two. It's not much propane but it doesn't take much hiding in a floor drain or something to provide an energetic welcome to the next spark.

Frosty The Lucky.

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He didn't state that he shut the gas off, just that the flames went out. Additionally he said he could still smell propane (the indicator anyway) after the flame went out.  So, if he was running both gas and air and the flame went out it should either have the pop/backfire or the flames were blown off the end of the burner due to the speed of the FA mix being greater than the speed of the flame front.   He's indicated that the latter is the case.

I think I understand what you are saying about the static pressure, but in my mind at least if he's running several psi of static air pressure in the whole system - enough to prevent the propane from flowing - while its flowing through the burner ports (as opposed to a closed system) it would be way more air than needed with that diameter of piping. So, he'd either need more/bigger outlets on the burner to decrease the pressure and keep from blowing the flames off the end or less air. Either way, even if a needle valve isn't necessary it certainly won't hurt anything and can provide maybe even a little more fine adjustment.   I was just trying to help him get up and running with the least amount of hassle.

 

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Thanks Guys - I'm really learning thanks to you and this forum.

1. If you completely close the blower input gate do you still get significant air out of the burner holes? 

Yes, it is closed in these experiments. Not visible in the photo, but there is an arc-shape slot -- maybe a square inch in area -- just below the movable vanes (no doubt to prevent burnout of the motor), so there IS still enough air blowing to fill a typical 13 gallon kitchen trash bag in about 3-5 seconds...if I recall correctly but unscientifically.

2. Does your regulator have a minimum pressure or will it let you turn the gas completely off?  

The 30psi regulator can visibly go below the 10 I noted above, all the way down to zero, so fuel still flows until the adjusting knob is turned counter clockwise to less than "0" on the dial. At that point, the knob becomes very lose, just like the gages do on oxy/acet tanks. In fact, this is just like the regulator on my old 2-burner (not forced air) forge.

3. Did you build a diffuser/baffle plate into your burner construction?

Yes, I've attached photos showing that part.

AND, Frosty , I just ordered the needle valve. It surely might help! Thanks again, fellas.

BurnerPlenum1.jpg

BurnerMold.jpg

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With all of that in mind I still think the main issue for you is too much air for that burner.  If you get a needle valve you can test for the static pressure issue by turning the pressure up at the regulator past 10 psi (the point where you indicated the flameout issue) and then regulate the flow with the needle valve.

I think you will find that if you can tame that air supply with a way that you can make small adjustments (like the aforementioned gate valve) you will be able to keep the flame lift minimal to none in the open air.  In my mind you should be able to run that burner at a significantly lower gas pressure than 10 psi if you can get the air flow decreased to match the fuel delivery better.

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