Burners 101

[John in Oly, WA]

Find one that has a range from 0-30 psi. You don't want to start at 20 psi.

[ThomasPowers]

I don't ever think I've run any of my propane forges at above 20 psi.

[Mike Hall]

Would a 10-30 psi regulator work?

[Mikey98118]

It's this way; lots of things go wrong with regulators, and are usually do to physical damage from bumping or dropping.

Still, just because I've never heard of a 0-45 regulator, doesn't mean they don't exist.

I take burners to very high pressures only to test them. If you need to push them pass 20 PSI, either your burner or forge was designed badly; 0-20 regulators are dirt cheap.

So, how much does the guy want for the regulator, and what do you think of him, because damaged LPG regulators usually cost more to have fixed than a new regulator costs...

[Mike Hall]

I've never met the guy. He did say he has a 10-30psi regulator. It is through a local propan company here in Charlotte.  

[Mikey98118]

Do yourself a favor, and buy a brand new 0-20 regulator for about $20. Leave the chump offer for others with more money than since BTW, cute kid!

[Mike Hall]

17 minutes ago, Mikey98118 said:

Do yourself a favor, and buy a brand new 0-20 regulator for about $20. Leave the chump offer for others with more money than since BTW, cute kid!

Thanks Mikey! She's a great kid! I just ordered a new one from Amazon and it will be delivered tomorrow. Thanks for all your input. 

[Mikey98118]

Horrors! Amazon is killing kids now?

[Mike Hall]

3 minutes ago, Mikey98118 said:

Horrors! Amazon is killing kids now?

HAHA That is funny.  I'm keeping the kid, but I'm getting a new regulator. 

[Mikey98118]

Gas Burners for Forges, Furnaces, & Kilns have pirated copies for download from the Net; it has all the nuts and bolts information you need

Combined that information to Reil's instructions on building a mini-forge.

Finally, forget about using an angle grinder with a cut off wheel to do the cutting on burners and forges, and substitute a hand held rotary tool with cutoff wheels to do the job easier and SAFER.

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[Mikey98118]

If a MIG tip’s orifice is only a little too small for the capillary tube, You can use torch tip cleaners to enlarge it a few thousandths of an inch. You will find one round file in the set to be  small enough to push back and forth within the MIG tip, while turning the tip slowly. Every few moments, you need to check the enlarging hole against the capillary tube, as it gradually increases.

    Tapered reamers are another tool for enlarging deep micro holes in copper, and brass; tapered micro reamers: http://www.micromark.com/Micro-Size-Precision-Reamers-Set-of-6?gclid= Note CjwKEAjwpJ_JBRC3tYai4Ky09zQSJAC5r7ruLUVklPZWW-kb-eNTyowHGilJt855GrvXq7Jodb9CZRoCv57w_wcB

     Pivot cutting broaches allow rapid micro hole enlargement by hand:  http://www.esslinger.com/five-sided-cutting-broaches-available-in-0-013-to-0-227-diameter-stub-15-to-80/

Wire gauge drill bits will get your MIG tips within a couple thousandths of your capillary tube, with or not tips original orifice size couldn't be find that close, but you still need to deal with that lart couple thousandths of and inch for press fits.

[Mikey98118]

That should read " Wire gauge drill bits will get your MIG tip orifices within a couple thousandths of your capillary tube diameter, whether or not a tip's original orifice size couldn't be find that close, but you still need to deal with that last couple thousandths of an inch for press fits."

[Mikey98118]

Where is all the pictures, huh? They wuz promised, so where they is?! Juss cuzz I do you-all  tha way, don mean I wan some back

[Mikey98118]

[blacksmith-450]

Cool !  see it works ?

[Mikey98118]

What is it? It's the steel section for a 1/2" "V" (for Vortex) burner, with the extra large flame  nozzle attached. Looks like a cannon, doesn't it? Before you ask, yes it will blow a 3/4" Mikey burner right off the road with its supercharger engaged. At the top of the photo (rear of the burner) is a cut down Sausage Stuffing Tube; it looks like it is thick wall stock, because it contains a spacer ring between the SST and the stainless steel mixing tube for a 1/2" pipe equivalent burner size. There are six set screws in the SST, and six in the flame nozzle. That was just habit, you can get by with as little as one screw for each part, when you use tube. The spacer ring between the mixing tube and flame nozzle is 1/4" thick over twice as thick as the spacer ring on the burner's standard flame nozzle. With two flame nozzles and variable speed control on the supercharger this series of burners all have very long turn-down ranges. This type of burner can also be run with the supercharge stoped, and still give enhanced performance, because of the blade geometry.

26 minutes ago, blacksmith-450 said:

Cool !  see it works ?

Coming soon to a posting near you. We all want to see action photos. But this was posted with Doug in mind; he is interested in construction details; not flame photos.

[John in Oly, WA]

Nice! And how does the gas jet attach to it?

[Mikey98118]

Right to the point, John.

There is need to attach a particular kind of fan to the SST; this requires a mounting plate, so as to match up inevitable size variances between fan and and funnel entrance diameters.

Danger Will Robinson! The one big booboo you can commit with there burners, is to allow back-pressure to accrue between the fan and funnel interface; so streamlining is not to be taken litely here  

Making a beveled hole through 1/2" thick aluminum plate, facilitates that goal. Such a thick plate is also an invitation to mount copper refrigeration tubing, as a gas conduit (for a gas jet in its end) to threaded, through a side hole, and bent into perfect position within the the funnel, yes?

[Mikey98118]

Mounting the gas line and gas jet.

You will be ordering about one foot of 1/4" fully annealed refrigeration tube, which has an inside diameter of 0.190”. You may only use four or five inches of it, but hardware stores simply aren’t interested in cutting it off the roll in less than one foot lengths. The section of 1/4" refrigeration tube is going to hold a MIG tip (part for a gas jet at one end and a gas-tight fitting on the other end.

Note: 1/4” refrigeration tube has an I.D. of 0.190”. MK brand MIG contact tips have 12-24 thread, which has a nominal minor diameter of 0.1722” and a nominal major diameter of   0.2160”(I have measured them at as low as 0.2110”); MK series #621 tips come in short (1”)  and long length (1-1/2” beyond the thread); Praxair carries them, and they can also be ordered online: http://www.mkproducts.com/pw-contact-tips2.htm You would probably want to silver solder an inch long section of 3/16” refrigeration tube inside to help to help form thread.

Or, you can use a Tweco 14T series MIG contact tip for the gas jet; they are available online and at most welding supply stores. Spin tips in a hand drill, under a file, to turn down the threaded end, and braze the tip into the refrigeration tube. Or, you would want to silver braze an inch long section of 5/16” refrigeration tube outside to help to thicken the tube to thicken the tube wall for forming the thread, if you choose to tap the refrigeration tube for 1/4-27 thread.

The refrigeration tube should be inserted through a side hole drilled in the mounting plate's center hole, forcing the tube from within center hole to beyond the plate edge. This side hole should be drilled out to run parallel to one of the fan's supporting ribs; the rib that the fan wiring runs under. So, you can't drill the side hole without having the fan for comparison.

Support ribs on most fans bridge the gap between rim section and center section at an acute angle rather than at ninety degrees, and it will become obvious to you that the gas tube will have to be bent in two places for the tube to end up in the center area immediately below the fan motor in the center section. You can’t easily adjust the gas tube’s centering after those bends are made.   

Keep two things in mind before allowing yourself to become discouraged by this task: In the first place, you can use another fan rib to lay out the gas tube on for visual comparison, before insertion; secondly, annealed copper tube is easily bent and re-bent so as to adjust the tube’s position perfectly; use of the centering rod (needed for silver soldering the tube in position within the aluminum plate) to help provide assurance that you can eventually stumble over the victory line, no matter how clumsy your efforts might seem at this point. LA-CO aluminum flux enables copper tube to be soldered with tin/silver solder to aluminum alloys.

The first bend is made after mounting the MIG tip. Ideally, you want the tip to end up about 1/4” short of the mixing tube entrance at the funnel’s small end. However, linear burners are more forgiving than jet-ejectors, about whether or not your tip’s end is placed in the “sweet spot” for distance from the mixing tube entrance.

After the gas jet (MIG tip) is installed in the 1/4" refrigeration tube and the first bend is made, it gets pushed and pulled through the side hole in the mounting plate. Then, it is kept centered and aligned while the tube is being hard soldered into permanent position within the mounting plate by use of a wood centering rod; which you need to find or sand to the right diameter for a slip fit within the funnel’s mounting collar. Drill a 1/4" + hole in the end of the wood. plastic, or metal rod used to trap the gas jet's refrigeration tube centered and aligned to parallel with the tube axis.

Note: The centering rod only needs to be a few inches in length (3” to 4” is fine). Afterward, you pull it out of the collar. Be sure to keep the centering rod for checking alignment during maintenance work, later on.

La-Co aluminum flux and one of the tin/silver solders (ex. 95/5) is suggested for permanently affixing the refrigeration tube into place within the mounting plate. All other connections should be silver brazed. You must prep, bend, and fit the refrigeration tube, and then solder it into position as soon after drilling the side hole through the aluminum plate as possible; this means that you'll want the MIG tip mounted and the refrigeration tube’s first bend made before you even begin drilling the side hole. The reason for all this haste is that aluminum immediately begins forming a new oxide layer after drilling; the longer between drilling and soldering the more work your flux has to do to overcome that layer.

Once the gas tube is fitted into position within the mounting plate, but before soldering it, the other end of the refrigeration tube gets a threaded fuel hose fitting, or a 1/4" hose barb silver brazed on (compression fittings aren’t recommended; they don’t need brazing, but have their own complications).

 

[John in Oly, WA]

Do I assume correctly that the spacer ring between the SST and the mixing tube has a bevel to match the taper of the SST for a smooth transition into the mixer tube? What particular type of fan is needed for this burner?

[Mikey98118]

Yes. John.

 Both mixing tube and the spacer ring are beveled to promote proper air flow. They are also sealed against gas leaking where into where it doesn't belong with thread locker. These joints are not brazed, because it is convenient to take off the mixing tube when positioning the gas jet durning construction, and checking it occasionally afterward. 

the particular type of fan is  an axial computer fan with impeller blades.

Introduction to Vortex Burners

(from my book notes)

Hobbyists have constructed forced-air gas burners for decades; typically employing squirrel cage blowers. During R&D for a general reference work on powered burners, I discovered the performance that can be gained from powering air swirl, instead of air push at a burner’s air intake, and had previously gained the experience needed to see what the difference changed to output performance.

I promptly discarded prevailing views that the best purpose of a fan was to push more air through a burner; starting from such a premise, you’re not going to get very far. Why? Because the more forceful the output of a burner is the more its output must somehow be braked in the flame nozzle, to keep the flame from being blown clear off the burners end; pretty counterproductive, wouldn’t you say? While flame nozzles can be used to ease the problem, stopping the problem at its source is even matter. 1Unfortunately, the idea of pushing burner air is so entrenched that the other popular terms for powered burners are “forced-air, and fan-blown” Standard forced-air burners still have a place, but it isn’t on compact high efficiency heating equipment.

To begin with, let’s clarify just what is meant by the term vortex burner; technically it’s any burner that swirls the fuel/air mixture at some point; so technically, every stable fuel/air burner would qualify—even some Bunsen burners. Often, the term vortex burner is granted to those that swirl the flames they make. But, causing a flame to swirl happens way too late in the process to provide more than minimal benefits; applied this way the title is total hype.  

Forcing an air current directly at the funnel wall of a linear burner will create a weak vortical flow, but at the cost of also increasing air pressure at the passage source. The special fans on “”V” burners, are used to power up an otherwise passive vortex by creating lateral spin—not straight push, at a funnel entrance; thus, all the energy is spent strengthening vortical flow down the funnel transit, which then reduces incoming air pressure, while speeding up mixture feed and spin rate, all the way through the burner to the flame nozzle, where pressure is reduced still further. Positive pressure in the gas/air mixture severely limits how much a flame can be strengthened, so deliberately powering up the vortex instead of creating air push results in much larger and faster flames than are attainable with a standard forced air burner. Every part of a Vortex burner is designed either to enhance, or benefit from, the principles of vortical flow; so the name Vortex burner is utterly relevant—not just something that sounds impressive. 

Once you construct a burner that can produce a compact (with near to total combustion in the primary wave front) flame from LPG fuels, it would seem that it’s the most you're ever going to get. So, if the safety cautions to follow make you nervous, why would you go on to build this kind of burner? 

The truth is that performance involves more than complete and compact combustion. Further improvements can still be made, like: Much greater flame variance (turn-down range); more powerful flames from smaller burners; and the ability to simply change out flame nozzle diameters on a single burner, rather than switching between two or three separate burner sizes; all of these advantages are very much missing in all other fuel/air burners, including my own previous designs.

Vortex burners are quieter than other turbulent flame burners for the same reason that their flames are incredibly stable; because of more thorough air/fuel mixing. I believe they come as close to the silence of linear flames as turbulent flames can get. Vortex burner designs can be used for the same stable performance on the smallest burner you can construct.

In miniature burner sizes (3/8” and under), the available turn-down range from a perfect flame can be increased by more than an order of magnitude! When it comes to jumbo size burners (1-1/2” and larger) that extra flame stability happens to be very comforting; if you’ve ever run one of those monsters, than you know just how desirable a smoother flame is.

Note: flame noise is generated by flame variance from millisecond to millisecond during combustion; such variance is mainly the product of imperfect fuel/air mixing; improved mixing results in increased flame stability, and therefore in reduced flame noise.

It should be noted that, since this is the first text on Vortex burners, it can’t possibly be “the last word” on this subject; that will take several years and thousands of burner builds to establish, if ever. For instance, I’ve concluded that a 3:1 impeller blade to mixing tube diameter is the highest ratio that can be safely employed, but what is the best ratio; or, the best ratio for each burner size and fan power? What are the absolute best proportions on a cone shape? What motor and control refinements are optimums for each funnel size and shape? Such particulars can only be established with feedback from many people over several years.

 

Four aspects of vortical flow, which make it a dynamic “motor” for burners:

(1)  Fluid movement through a restriction (ex. a funnel) will create a vortex.

(2)  The forward motion (linear velocity) of a vortex tends to reach about one-half its rotational speed (angular velocity).

(3)  When a fluid (liquid, gas, or plasma) is forced to spiral down a circular reducing passage ( such as a funnel), rotational speed increases more the smaller the restriction gets, because, in a vortex, angular velocity (spin rate) increases the closer a spinning fluid is forced to its center of axis; the opposite result of spinning a solid. Thus forward motion is quite rapid at the funnel’s small opening.

(4)  BUT, fluid pressure drops at the same time; an ideal situation for fuel/air mixing, high feed rate and especially for maintaining a very low pressure feed into a burner’s mixing tube and flame nozzle.

So, if air pressure from an ordinary axial fan, or squirrel cage fan, will contribute to vortical flow, why insist on impeller blades? Direct air flow from an ordinary fan has to be turned almost ninety degrees before it makes a positive contribution to air flow in a restricted shape like a funnel, losing a lot of its kinetic energy in that motion; impeller blades fling most of their air against the funnel wall almost parallel with it, contributing much more energy to vortical flow, without raising air pressure at all. In fact, since the air is first slung toward the tips of the blades a low pressure central area is created at the fan, forming a vortex right at the funnel opening, which only increases in power as it travels down the funnel, instead of forming part way into the funnel.

Placing a pressurized gas stream just before the mixing tube entrance (near the funnel’s small end) adds air induction, while minimally increasing flow pressure; this synergistic “double motor” effect constitutes a peerless way to feed an air/fuel gas mixture into a gas burner’s mixing tube. A vortex burner employs a modified cone or bell shape, on which an axial fan is mounted; because they are also gas-jet powered (air induced), they will run in both powered and naturally aspirated modes, although not with as much output,

[Mikey98118]

Safety

It is a given that any type of properly constructed, fan-blown burner will always have a slightly greater risk of backfire than an equally properly constructed naturally aspirated burner does. If you want the increased overall heat output of a powered burner, some increased risk goes along with it. By understanding and applying the operating principles given here, you can greatly minimize that risk, in these burners only.

Vortex burners have important differences in proper safety practice from forced-air burners; this is due to their ultra-low mixing tube pressures, and must not be ignored, lest a fire ball from burn-back should exit through your fan motor; because of this difference, be sure to keep the area behind the fan clear; stand beside—not back of it.

Any powered burner design can suffer a back-fire through the fan, if you block its flame path at the source (ex. allowing the burner to fall over on its nozzle during operation); these burners will do so; instantly and every last time! Secure the burner in position before running it. Place your burner opening sufficiently high above a casting furnace’s floor to keep it clear of any spilled metal in case of crucible failure. Place burner openings out of the direct path of heating materials in forges.

It is necessary to initiate fuel gas flow first, and then ignite the fuel/air mixture from the burner’s forward end (in front of the flame nozzle), BEFORE STARTING THE FAN MOTOR on Vortex burners; these are a combination of natural induction and power burner, and initiating the flame nozzle dynamics first will strengthen the establishment of flow direction; greatly reducing the chance of reversing fuel gas flow from backpressure in the funnel after the fan is turned on. Fans installed on this burner series create some back pressure in the funnel opening, which can pick up fuel gas, if the normal direction of mixture flow is allowed to reverse.

Note: Fuel ignition follows starting the fan on standard forced-air burner designs, because fuel in such systems can collect in the combustion area of heating equipment, leading to minor explosions when it’s ignited; so the fan is started first with them, to prevent this possibility. But, on Vortex burners, the fuel air mixture has no chance to collect in the combustion chamber with the burner lit, nor will starting a weak impeller fan blow out the burner’s flame.

Close the gas feed, but keep the fan running, during Vortex burner shutdown; then it is best to remove the burner from your forge or furnace. Furthermore, the fan should be left running, until your burner is completely cooled down and ready to be stored.

Caution: The larger the burner the greater the danger from backpressure against the fan, because of the increased air pressure needed to power the vortex. Therefore, blade to mixing tube diameters, funnel shapes, and fan strengths that are safe enough on small burners are not necessarily acceptable on large burners. You need to keep this in mind when tempted to depart from construction recommendations, or in substituting parts. 

Running a larger fan than recommended for a given mixing tube diameter (greater than a three to one ratio) increases back pressure beyond acceptable levels, thus escalating the danger from ignoring the safety procedures given above. The smaller the burner the less sensitive it will be to funnel shape in creating back pressure through the fan. Therefore, the larger the burner the longer its funnel should be.

Backfire photo here

Any burner can be snuffed out if it is placed in a vertical-down position, facing at a steep enough angle; what causes this is spent exhaust gases (which rise through buoyancy/displacement), and enter the burner’s air intake.

To safely install Vortex burners in horizontal tube forges, they should, preferably, be aimed with the flame nozzle angling somewhat upward. If installed facing down, a Vortex burner’s plastic fan can easily be overheated by the chimney effect, when the fan isn’t running.

Vortex burners used in any position other than the horizontal need ball-bearing axial fans. Motors with sleeve bearings are only meant to run in a horizontally placed burner, so that its bearings are positioned vertically; otherwise their lubricating oil will seep out, letting the bearings run dry and seize up.

[Mikey98118]

Dead silence. See, this is why I've been reluctant to open up about "V" burners; they aren't complicated, but the subject is. Shall we just go back to discussing saddles for old style linear burners now?

[Square Nail]

3 minutes ago, Mikey98118 said:

Dead silence. See, this is why I've been reluctant to open up about "V" burners; they aren't complicated, but the subject is. Shall we just go back to discussing saddles for old style linear burners now?

I can only hope that someday I will gain enough Knowledge to even begin to understand all that you are saying! I am trying to follow but get lost very easily! 

Keep it up and I may gain some from just plain osmosis! 

[Mikey98118]

I have downloaded book sections; they are meant to build knowledge, chapter by chapter, with the help of photos and drawings that don't exist yet. Of course they seem exhaustive, when taken out of context. On the other hand, nothing presents you from asking questions, to learn what you need to make these burners.