Mikey98118

Burners 101

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Sweet spots

Its "sweet spot" is the position where an adjustable part in or on a burner gives maximum performance. A slide-over flame retention nozzle has an adjustable amount of overhang past the end of the burner's mixing tube; too short and the flame gets unstable and is snuffed out; too long and the flame becomes weak. In between the extremes is a balance point; your nozzle's sweet spot.

Every gas assembly ends in a side hole, MIG contact tip, or capillary tube; the amount of air inducted into the burner depends on how close the gas jet coming out of the gas assembly is to the entrance of the burner's mixing tube; too far away and air induction is weak; too close and the air/gas mixing is poor. The right distance is this part's sweet spot.

Every factor in a burner needs to be balanced, but we only use the term "sweet spot" about the these examples, because, like a tennis racket, their sweet spots are easily seen, and involve exact positioning.

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8 hours ago, GrumpyBiker said:

If it was yours how would you go about getting the most out of this setup?

I would try pulling the MIG tip further away from the mixing tube entrance on the modified side-arm burner.

Re-read Frosty's "T" burner directions, which are posted on this forum; they include the proper steps to tune his burners.

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Thank you for putting it in layman’s terms for me.

Went back and re-read the section you suggested.

Played with the nozzle “overhang(?)” and backed off the mig tip and ditched the 6” tube for an 8”. (When the new nozzle arrives I’ll add that as well)

Its running quite well now.

I have one more question that I’ve racked my brain over, I’ll go post it in the forge section if you feel it’s an issue with the forge.

Why would the temperature & flame be reduced when I block off the back of my forge? The dragons breath has blue tips when blocked off (nothing like in the previous pics) and yet it goes back to running hot & orange if I open it up.

I don’t get that. Is it because of a lack of oxygen?

 

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3 hours ago, GrumpyBiker said:

Why would the temperature & flame be reduced when I block off the back of my forge? The dragons breath has blue tips when blocked off (nothing like in the previous pics) and yet it goes back to running hot & orange if I open it up.

I don’t get that. Is it because of a lack of oxygen?

No; lack of pressure, or to put it another way: too much back pressure for a naturally aspirated burner. However, the solution isn't to leave the exhaust opening wide open. Instead look into using a baffle wall in front of the opening, but a little way forward of it. Your forge has a convenient ledge to stack bricks on, so that you can leave a small opening to move stock in and out of, while exhaust can freely vent upward between the brick and forge shell, and for radiant energy to bounce back into the forge from; a win, win, win situation.

As to which thread these answer belong in...alas, life is not perfect :)

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Well I know this is burner related...

Has anyone done a “Port & Polish” type job to a home built burner?

I bought an extra one of these reducing T’s and thought I’d see if removing the threads & opening it up a bit and polishing the inside would make a difference.

Also beveling the top of the tube & polishing it. It was 95° and I didn’t feel like running the forge. We used to do this to the intake manifolds on my hot rods to improve flow and performance and I got to thinking that while it’s s short run , would it make any positive difference?

I’ve yet to run it but was wondering if anyone had tried it?

 

Also what’s you opinion on altering a coupling into a nozzle? I looked over Frosty’s PDF and thought that while I was making a mess of my shop I’d give this a go as well.

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Any opinions & feelings are welcomed, I’m just playing around at this point since I’ve been helped into a working & usable forge. I now have a little time to mess around.

 

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The last two photos show the MIG tip moved back; that's good. None of the photos show us whether or not it is aimed to center at the mixing tube; why?

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There’s only one set screw holding the mig tip nipple in place .

Theres no lateral adjustment in its current iteration.

 

I’ll disassemble it in a bit and take a pic from the burner tube hole with the tube removed.

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2 hours ago, GrumpyBiker said:

I’ve yet to run it but was wondering if anyone had tried it?

You already did it.  Start at a lower pressure and fire it up.  You can educate us as to whether it's worth doing or not.

42 minutes ago, GrumpyBiker said:

I'll disassemble it in a bit and take a pic from the burner tube hole with the tube removed.

If you sight down the burner from the flame end with the mix tube still on, you can gauge the jet alignment.

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Well that was not easy given a smart phones offset camera .

15 pics later and all with the flash were garbage. This is sadly as good as I got today.

 

I did take a slow-mo video of the swirling flame from the burner.

Not experienced enough with this burner as it’s new to me , to be able to say if it’s better or by how much.

I may start a forge log and keep track of the temp , humidity & barometric pressure each time I run it and document observations for the first couple months until this Forge & I get to know each other better.

 

 

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It looks a little out of center. If the flame comes out of the flame retention nozzle looking even and centered, it is good enough. If the flame is unever and/or lopsided, then you need to get another plug, and try again. Also, the MIG tip's orifice look way too large.

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I've tried cleaning out the threads and machining tapers on my lathe but wasn't impressed. That was years ago and I didn't persist so my impression doesn't mean much now.

When I see swirling orange flames like that in a forge I think it's running richer than I like and I like my forge running a LITTLE rich. 

However it may be the refractory you used in your forge. What refractory is your flame face? 

It's hard to get a good line on the mig tip just looking at the fitting. What looks like an out of line jet in the pic may be the camera angle. If you screw a pipe nipple on it so you have a longer sight line and stand back it'll become obvious. You won't have to ask us if it's aligned. ;)

You're coming along, this isn't as intuitive as it sounds but a little practice and it'll come to you. It's like tuning an engine by ear, you have to know what slightly: too lean, out of time,  corroded points, etc. sounds like. Once you do you can tell as a car drive past. Yes? 

Frosty The Lucky.

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The engine tuning analogy is right on. As you build and tune burners, your knowledge grows. I think a lot of people look of this stuff like it was a single event, and become needlessly  discouraged.  Building the equipment is a learning process, just like learning the work is.

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Miniature "T" burners

Figuring miniature burner sizes as starting at 3/8" and working downward, how do we fit "T" burners into that category? Cast iron pipe fittings are becoming scarcer, and cruder; doesn't this bode poorly for constructing a miniature "T"? Only if you don't look further than cast iron fittings. Brass pipe fittings are still easily available, and are much better quality. The price difference in these small pipe fitting sizes are negligible. Also, brass castings are easier to work with, because their castings are better quality, and thread easier than cast iron in the factory, so they thread true. Misaligned threading on today's cast iron pipe fittings are likely; but not on brass pipe fittings. 

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Zoro has 3/4" to 1/2" brass reducing T fittings for $9.35; this part can allow make a properly constructed 1/2"  "T" burner,with a lot less than the usual hassle.

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Hey, I'm new to this thread but would like to ask a question about a ron reil style burner that I am making. In many of the designs that I have seen they use a 1/8" brass nipple with a hole to blow gas down the burner tube. Is there anything wrong with using copper tubing instead? 

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Yes. It's not just a hole it's a "nozzle." To work properly the stream of propane entering the burner needs to be uniform and not just a random spray. A brass fitting provides enough thickness the hole can act as a jet. As the propane flows into the jet it smooths out into a uniform stream before it exits. 

A piece of copper pipe on the other hand is thin and drill bit it tends to tear out as it breaks through to the inside. If you've drilled holes in thin sheet metal you've seen how the bit will tear out on penetration. This rough interior and short run makes the propane spray like a sprinkler and isn't flowing straight down the mixing tube. It can't induce combustion air properly. CAN NOT.

Originally Ron drilled iron pipe nipples to make the gas jets in his burners and they performed alright. Steel pipe is thicker and steel doesn't tear out like copper does when the bit breaks through so a steel pipe nipple CAN be drilled for the propane jet. There are much better though.

Make sense?

Frosty The Lucky.

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"Nothing's for nothing" in burner design

Most (nearly all) naturally aspirated burners employ a vortex to help gas/air mixing. Nearly all linear burners use a reducer fitting or funnel for their air openings, as do Larry Zoeller's modified side-arm burner, and the Frosty "T" burner (when made per his instructions). The Mikey burner, and Larry's "Z" burner both use other means to instill twist to the incoming air stream. What all these burners have in common is twirling incoming air to promote mixing. However twisting action is only one factor in vortex motion. All the indications of the last two decades are that the full benefit of a vortex inducing air entrance can far surpass simple twisting motions.

BUT:

My burner design promotes twisting with special air openings (that require a lot of extra work".

Larry himself has stated that his "Z" burners run hotter than his modified side-arm burner, and its pipe fitting isn't reducing.

 

And how can a "T" fitting promote the formation of a vortex?

It does so in the classic fashion, by starting with two air openings opposite of each other, which dump into  a center exit in the middle; this starts the incoming air swirling. Frosty instructs us to use a reducer "T" fitting, which serves as a short funnel shape where the swirling air stream enters its exit.; a tornado is formed the same way.

Which leads me to "than something's always for something." the bigger the amount of reduction the stronger the swirl. Any encouragement, such as as fins at the reducer's opening, will multiply the spin at the reducer's exit.

But at least one of those "buts" goes counter to my argument? Yup! This is real life; not a college debate.

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Tapered nozzles; a second look

Burner design is all about balance. You are balancing one force against another, to achieve a stable result. It follows that every time you change one factor, others must be adjusted to maintain balance. Sliding parts, such as gas jets on the end of sliding gas tubes, and slid-over flame retention nozzles, along with adjustable air chokes will go a long way to maintain balance in a burner.

But at some point construction changes become necessary, when reaching for new goals in heat generation and/or efficiency; this requires commitment to persistent hunches; at least enough to chance hours of effort building new parts, which may turn out to be junk. Some ideas can be pursued with a minimum of effort, such as stepped flame retention nozzles, which only needed one stainless steel tube trapped within another one, to create hot new flames. Other ideas may call for designing and then casting unique parts.

Other ideas are likely to look much harder to try then they actually are. The latest twist in flame retention nozzles are back to the taper design; instead of a minimal taper, they use something close to a trumpet shaped end. This design has done a fair amount to increase the heat of some older burners, but I suspect that real progress will be found between minimal and maximum tapers. Still, making useful (and repeatable) tapers in stainless steel tubes isn't a simple task. But a heated tube could be dropped over a drift pin, and tapped into shape...

Just a thought for my fellow wild eyed inventor types :)

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2 hours ago, Mikey98118 said:

Still, making useful (and repeatable) tapers in stainless steel tubes isn't a simple task.

Unless you spin them. ;)

True words Mike balance is the key, drastic changes require drastic measures to balance and it's an investment in time and energy to make them work. 

I'm in stark envy of some of the tools available to today's tinkerers. I had the T burner . . . functioning before the internet went public and when CAD got affordable I was in heaven. Now rapid prototyping is making CAD drawing come to life without having to chuck up something in a lathe or go to the plumbing supply or. . . 

Man I'd love to be able to play with some of this new stuff. 

Frosty The Lucky.

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I think every time has its pluses and minuses; it isn't what cards we're dealt, but how we play them. If I could only be young again, with what I know now...I'd make all new mistakes :D

On the other hand, they do have nice toys.

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So, if it seems odd that someone who goes to such lengths to ensure maximum control of the burner should promote "wild and crazy ideas," well not really. This thread is just here to hand you guys the help to get what you're looking for from a burner, whether that is a sure fire path to a successful build, or help in trying something new.

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Can someone answer me this, all other things being the same ; same burner, psi, Forge etc... 

What effect is to be expected by a longer burner tube? 

By that I mean using Frostys t-burner plans  of a 6” long tube on a 3/4” T-burner, if you went shorter what effect will it have?

If you went longer what would you see / experience? 

It was answered for me how that moving the mig tip closer & farther away from the top of the tube will effect the fuel to air ratio so I’ve got to expect that the gurus here know this one.

In the fine tuning of a burner this seems interesting to me.

From a hot rodders perspective I mean , if this can be viewed as a type of fuel injection system then the tube is the runner that delivers the mix into the combustion chamber....

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2 hours ago, GrumpyBiker said:

What effect is to be expected by a longer burner tube? 

Every burner design has a maximum amount of mixing tube length for achieving its hottest flame; don't I state "hottest": best flame depends on intended use. A shorter than usual burner tube may be desired in order to deliberately shorten a burner's flame, in order to lengthen the distance between flame tip and impingement on work. A larger than "optimum" mixing tube length can be used to tame the flame (make it closer to a laminar type) for braze work, in a burner that is used by jewelers.

There are the factors to play with, and now its time to use them to answer your own question :)

"...don't I state "hottest"  should read "...note that I state "hottest";

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Mike's answer reflects uses for the effects of different tube lengths and I can't really add anything.

However I think you were asking a broader question. The longer the tube the more intake air it will induce until skin friction in the tube begins to inhibit induction. A longer tube mixes propane and air more thoroughly as well. 

A shorter tube induces less and does a poorer job mixing the FA.

As Mike has said many times it's a balancing act. I've found there is a LITTLE leeway in tube length before you have to start changing other components to balance things. Hence my old rule of thumb regarding the diameter to length ratio. 8-9 to 1. Meaning a 3/4" tube can be 6" - 6 3/4" without needing to make physical changes to balance the ratio. 

I've found to run a longer than that range tube you need to make the physical change of using a smaller diameter jet and higher psi. This also increases the flame velocity and tends to increase dragon's breath seeing as it isn't staying in the forge as long. 

The upside is the flame is cleaner, my term for less unmixed fuel and combustion air. It drove Ron Reil nuts trying to figure out how his calcs. and gas meter could indicate the flame should be neutral but steel was still forming scale IN the fire. It's simple really the FA wasn't adequately mixed so there were packets of unmixed propane and packets of unmixed air being injected into the forge with the flame.

I've had poor luck using tubes less than 8:1 for reasons implied above. I only go slightly longer than 8:1 as my thing is putting the most propane in the forge per second as I can and a longer tube requires I step the jet diameter down. Sure I can deliver the same amount of propane and induce enough air by increasing the psi. This sort of bites my bug as it makes a faster flame that doesn't stay in my forge as long and I'm too much the Scot to spend coin to make flames air outside the forge. 

Frosty The Lucky.

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