Burners 101

[Mikey98118]

 

 

 

 

 

Dual-fuel torch-head to 1/4” burner conversion

(adapted from my book notes)

This canister-mount torch-head to burner conversion is not my hottest design (that would be one of the high-speed tube burners); it is intended to create a very hot equipment burner and hand torch with minimal expense or effort.

    The Bluefire Trigger Start torch is my preferred sot/fuel torch-head choice; it is small, light, and surprisingly well-constructed; other canister-mount torches can be substituted for it, so long as they have a stainless-steel flame tube of about 3/8” diameter, but you might need to vary the building instructions somewhat to accommodate their differences.

    The dual-fuel (propane and propylene) torch-head being repurposed, features a stainless-steel flame tube that allows it to be mounted in heating equipment without melting like a brass tube would, and a needle valve for gas regulation. If you connect it to an adapter hose and refillable D.O.T. propane or propylene cylinder later on, a variable pressure regulator should be added to maintain hose safety.

    But aren’t fuel hoses rated for maximum cylinder pressures? Yes; and your car probably is rated to do over a hundred miles and hour, but how long would it last at that speed? How about a cheap import at that speed? What makes you think your fuel hose was actually made in the USA?

    The only changes in this torch head, will be made to accommodate the addition of a flame retention nozzle on the end of its flame tube; there are two reasons for this. In the first place, upgrading the flame tube from brass to stainless-steel isn’t sufficient to allow it to survive over time, when mounted within heating equipment, because its thin wall would oxidize away in that super heated environment. So, a replaceable outer tube (the spacer ring) is being added to protect the last inch of it (the section that is subject to oxidation from the flame). Secondly, a third tube can be mounted onto the spacer ring, to increase the burner’s flame size and air induction; together they become the flame retention nozzle; this inexpensive replaceable part is gradually oxidized away by the presence of flame, instead of the torch-head’s original flame tube, which isn’t a replaceable part.

Note: this torch-head features a piezoelectric ignition system, which creates a spark to ignite the fuel gas. That spark jumps a gap between a hard stainless-steel wire and a metallic part in the torch-head that serves as a ground. The spark tends to move the positive wire a little bit, each time it jumps the gap. Eventually, the wire will move position enough that the gap becomes too large to jump; then, the torch’s plastic shell must be opened, and the wire bent back into proper position. The wire is made of hard enough alloy to snap apart after being bent back into position a few times. So, eventually, the piezoelectric ignition system will fail. There is no getting around that.

Materials list:

(1) The Bluefire Trigger Start torch is a great value for your money at $17. If you think that’s too cheap, you can buy a similar design in the TurboTorch brand (built in Mexico) for $96.

(2) The flame retention nozzle is a 1-3/4” long piece of 1/2” (nominal measurement) #316 schedule #10 stainless-steel pipe; its O.D. is 0.840”; its I.D. is 0.674”. You can buy this part precut to length from Onlinemetals.com (part #19690). There should only be about two-thousandths of an inch to sand from its inside, for a 1” depth, for the spacer ring to slide into place within it.

(3) The spacer ring is a 1” long piece of 3/8” (nominal measurement) #304 schedule #40 stainless-steel pipe; O.D. is 0.680”; its I.D. is 0.493”. You can buy this part precut to length from Onlinemetals.com (#942).

(4) Three 1/4” long 10-32 socket head stainless-steel set screws from your local hardware store

The flame retention nozzle is designed to overhang the end of the torch-head’s flame tube by a maximum of 1-3/4”; but it should end up at 1-5/8” of overhang for best tuning; giving you about 1/8” variance between soft and hard flames.

 

 

 

 

[Mikey98118]

Please understand that this burner requires some power sanding or grinding to make the spacer ring  press into the flame retention nozzle, and for it to freely slide back and forth on the flame tube. the three set screws require drilling and tapping of threaded holes into the flame retention ring.

[Frosty]

Mike: I was under the impression peizoelectric spark wires in high temp applications were Ni Chrome or tungsten. The lower temp spark wires are SS and are fun to watch jump, the one in our Blackstone griddle is easily visible and it's good to look to make sure it lights. 

Frosty The Lucky.

[Mikey98118]

It also good to make sure the torch-head has no problems that would require returning it, before cutting off that lasst inch of flame tube

 

As you know, I've been playing around with Propane torch-head conversions for a couple of years, since guys started insisting on using them in two-brick forges. This is my latest design. I'm still in the middle of building it; may have jumped the gun a little bit; we'll have to see

[Mikey98118]

Torch-head to 1/4” burner conversion; additional note

    The greater air induction created by the flame retention nozzle makes it necessary to increase the area of the flame tube’s air intakes; two drilled holes in the near the bottom of the flame tube. These openings must now be enlarged, or they will create a choke point for air flow.

    There is a tiny Philips head screw holding the two parts of the torch-head’s plastic body in place. Remove the screw and elongate both holes into slots with a 1/8” diamond coated or solid carbide rotary burr. In the past, I have pushed a drill bit through both holes in a tube, and rocked it back and forth create  slots, but a little added expense and patience is the safer choice.  

[Mikey98118]

Actually, there are three holes, but only two of them will be expanded. You ignore the third hole, which has the piezoelectric wire running through it.

    The gas orifice isn’t very far to the rear of the air holes; don’t allow your drill bit or rotary burr to touch its face, or you will have to unscrew the male gas valve connection on the end of the torch-head, screw the needle valve wide open, and insert a piano wire into gas orifice to remove a burr in its tiny hole; best to just not go there! If you don’t feel confident to create a slot, without touching the gas orifice (best), then carefully drill the two holes large, on at a time (better than nothing). 

[Mikey98118]

Three versus four

It is never good to see  four screws holding burners in a forge's burner portal; or good to see four screws holding the gas tube in the burner itself. Why then, is it so common?

I figure its is the lack of shop class or trade jobs in the computer generation. Anyone who ever ran a lathe knows why they common with three jaw chucks, and you have to mount the four jaw variety for special projects. Three jaw chucks automatically center the part. I think guys just find it easier to divide circles in half, and then half's in two. But anyone who ever took a shop class knows that the secret to good math, is to avoid it whenever possible 

So, speaking of secrets, what is the secret to dividing a circle (or tube) in thirds, and sixths without doing the math? Hex head bolts down at your local hardware store.

[cleatusj]

Here's the first look at my version of a 1/2" Frosty T. I drilled a 1 3/4 x 1 1/4 bar with 1" hole saw, then 3/8" length wise for the 1/8" sch 80 pipe holding a .023 mig tip. I then drilled the other end 7/8" to create the tee so I could weld in a 6" x 1/2" nipple, with the threads cut off the welded end. I drilled and taped for a 1/4" set screw to set depth of mig tip.  The is the first firing if the burner, that I plan to use for a NARB.

[Irondragon Forge ClayWorks]

An interesting variation to the T burner, don't see why it wouldn't work with tuning.

[Mikey98118]

But I do, The "T" fittings on his burners do one thing that this doesn't. Where the pipe fitting's inside surfaces come together at  the central exit, they are rounded; this creates a short funnel section. The funnel works together with the two air entrances, to help form a vortex, exactly like a tornado's funnel cloud is formed by wind shear. The two air entrances can create more wind shear because of vortical flow, It all works together.

If he adds a section of kitchen funnel between the box and the pipe, his burner should work much better.

[cleatusj]

Mikey, I have the inside junction funneled, even the top of pipe is tapered. I cut 5/8" of threads off the 6" nipple, so I may need to remove another 1". In the pic it's only running 3psi.

[cleatusj]

Best pic I could get at this time.

[Frosty]

Looks like a fun build, a little tweaking and it aught to make a fine burner. One tweak is the mixing tube length. The ratio is 8:1 or L=8Dia. Your mixing tube is 1/2" Dia, yes?  8 x .5" isn't 6"is it?

1/2" T burners seem to have more leeway than larger diameters but . . . 

Frosty The Lucky.

[cleatusj]

My pipe ID measures .62 x 8 = 4.96 . I measure to have 5" of pipe from the 1" hole to the end of threads. This seems to tell me to find a smaller mig tip. 

[Mikey98118]

18 hours ago, cleatusj said:

Mikey, I have the inside junction funneled, even the top of pipe is tapered. I cut 5/8" of threads off the 6" nipple, so I may need to remove another 1". In the pic it's only running 3psi

I stand corrected; that should work just fine. Have you looked at the flame with additional gas pressure?

[cleatusj]

At 10 to 15 psi the flames went orange.

[Frosty]

12 hours ago, cleatusj said:

My pipe ID measures .62 x 8 = 4.96 .

I never took a mic anything, there is quite a bit of range to tune. 

Frosty The Lucky.

[Mikey98118]

Why Small High-speed Burners?

Why construct small burners at all? Few people desire a miniature forge or furnace. But there are plenty of people who want to get more concentrated heat from air-fuel torches. More concentrated? Yes; you need look no further than a $5 blue flame pocket lighter to realize that much better flame management is possible than is being offered--commercially.

    With rising fuel prices, people are looking to maximize efficiency. Naturally aspirated burners have large turn-down ranges. So, it might seem that a wide selection of burner sizes isn’t needed. But heat management is about more than how well fuel burns.

    There is another factor to control; that’s equipment atmosphere. It’s easy to see what goes wrong when a forge or furnace receives too much, too little, or too weak flame; it is harder to discern what goes right, with superb control of the flame’s exhaust path.   

    Efficiency requires balancing flame and exhaust speeds. Fast flames burn hot, but a fast exhaust wastes heat. The reason burners, whenever possible, are aimed on a tangent, is to cause their combustion gasses to swirl around equipment interiors; creating a longer distance from burner flame to exhaust opening. A long exhaust path increases the amount of "hang time” for heat to be deposited on equipment interiors. That seems obvious doesn't it?

    What isn't so clear is that most of that increased time isn't gained by hot gases blowing farther at a given velocity; it’s provided through a continuing drop in velocity over that added distance. Small flames decelerate faster than large flames.

    The smaller flames of a pair of 1/2" burners will burn the same amount of fuel as a single 3/4” size, but will drop velocity much faster in a five-gallon propane cylinder forge, greatly increasing efficiency; because they can be made faster/hotter without creating a tongue of fire out the exhaust port. What about people who want to build a two-gallon forge from a nonreturnable helium or Freon cylinder? They will need two 3/8" burners to do the same trick. Someone who wants to forge hand tools in a one-gallon paint-can or three Lb. coffee-can forge is going to need two 1/4" burners to run it proficiently; these same figures hold true in casting furnaces. The law of diminishing returns reducer fuel savings as a money issue in miniature equipment, but heating time and portability remain significant advantages. Portability? Yes; miniature equipment isn’t all that portable, when it must be fed from a five-gallon fuel cylinder!

    But don’t multiple flame burners (ex. Ribbon burners) take deceleration further? Yes they sure do; unfortunately, ribbon burners tend to be on the large side. In time compact ribbon burner designs will be perfected; first there has to be a lot more interest in them.

 

[ThomasPowers]

Next door; this buildings Geology and related sciences...Semester is starting back up.  Doing IT for the department I have a mask with a kid's drawing of dinosaurs on it.

I'm trying to talk my wife into one with an anvil surrounded by flames...

[Mikey98118]

Drill presses for burner construction?

Drilling on pipes and tubes can be done—with care—on benches, tables, or in bench vises. Of course, the work is going to be easier in a drill press, which brings us to an important question: Since a totally adequate table-mount five-speed drill press can be purchased from Harbor Freight Tools for about $50, why would anyone settle for a rotary tool drill press? The main answer is weight. As part of your tool kit, or when moving day comes, you’ll learn to care about weight—over and over. You will also need to add an additional chuck into the one that comes on the machine, to drill really small holes. You can find a nice variety of rotary drill presses on Amazon.com. But what about drilling larger holes? In recent years, stepped drill bits became a better answer to that question than multiple speed drill presses.

[Mikey98118]

Universal bench vises

A handy method for holding burner parts is to employ a universal bench vise.  You give up some control by hand drilling, and gain back more in all the other operations. There are two kinds of vice; double axial, and swivel-ball. Either type allows universal positioning of parts for drilling, cutting, and grinding.

[671jungle]

I suspect the scale build up on the closest nozzle has made the I.D. a good bit smaller causing the flame to lift and improper combustion. Also the angle at which the burners enter is too hard against the liner preventing flow and swirl within the forge. Two 1/4” injectors in a gallon forge

[Mikey98118]

1/4" burners have a much narrower margin of satisfactory behavior than larger burners, to begin with . they don't need  major malfunctions to present major problems

So, your burners may not actually have major problems that need fixing

[Mikey98118]

So, are you looking into the burners before getting back to us?

[Frosty]

That's my bet Mike, he's pretty sharp. 

I need a little clarification Jungle. By 1/4" "Injector" are you using the "UK term for inducers?

Burner is an application for an inducer/injector For example a jet ejector type inducer is primarily used to draw a vacuum. Where the linear inducer/injector is frequently used to drive burners and air circulators. 

We of course tweak them to make small hollow boxes REALLY HOT!

Frosty The Lucky.

(as an aside, I really miss being able to change font size and color)