Burners 101

[Frosty]

I've sifted the aggregate from castable hard refractory to make thin smooth surfaces and before I learned to rigidize kaowool with fumed silica I used it as a rigidizer. It actually worked quite well rigidizing kaowool though it reduced it's insulative qualities some.

If you remove all the aggregate the castable refractory will be more brittle AND it will spall more easily. If it gets wet moisture will not escape through the voids between aggregate particles. 

Shen I sieved it I only removed aggregate to a -20 screen and I have screens down to -200. That's 200 spaces per inch. 

So, Yes just don't get carried away.

Frosty The Lucky.

[Another FrankenBurner]

The sizes are nominal pipe sizes for the mix tubes, yep.  The 1/4" is an ID 0.364" (9.246 mm) and the 1/8" ID 0.269" (6.833 mm).  The 1/8" nominal build was so critical, an 1/8" actual would be something.  Now I am trying to picture the forge it would fit.

The nozzles are Kast-o-lite 30.  Mine have held up well but they are thicker walled and mounted in forges.  The burner that I have set up as a hand torch has a stainless nozzle.

[Hefty]

OK, cool. The pipe I've got is reasonably thick walled with an ID somewhere between 8 and 9mm so roughly a 1/4".

I'm keen to make one of your style and a Mikey (or possibly Trevor's variant) to get more of a practical/physical understanding of all of the things I think I understand from all this reading.

I made a roughly half inch version of your burner and it was quite a stable flame but my system for mounting the MIG tip was copper tubing which had a bad fit with the printed part leading to misalignment issues.

I need to find some smaller brass nipples somewhere local.

[Another FrankenBurner]

Is there a reason you aren’t reprinting the inspirator to fit the orifice tubing you already have?

I look forward to seeing your progress.

I like a pistol grip and a quick disconnect on my hand burner.  I bent a piece of angle and pipe clamped it to the mix tube. This allows me to grab it in the vise, attach a magnet and stick it to stuff, and hold it with dial gauge mag base depending on what I am doing with it.

[Hefty]

I will be re-printing, just haven't had time. Another one of my "fits-and-starts". Do you just print for a press-fit, or do you have other methods to secure it? I've got to check what the printer's tolerances are so I can allow for them in the printed hole. Part of the issue with the copper tubing was I had 3 set screws at 120 degree intervals around the inspirator but to maintain a strong alignment, they started deforming the copper and threading the plastic.

I've recently bought a TIG welder and I'm getting used to the handpiece on that so I might make up a handle that is reminiscent of it. I like the magnet idea! I think I might have a quick disconnect somewhere in my box of fittings, so I'll see if I can include it.

[Another FrankenBurner]

Some models I print for a finger press fit.  Snug but not stuck. I’ve also printed just a bit tight then used a drill and a hand chuck to open the port.

I have found the printer very capable of hitting dimensions so long as you know your smoosh factor. For a little while I was printing functional tapered pipe threads.  I’ve also added certain percentages to allow for casting shrinkage to hit a dimension.

They are simple machines and I know exactly how they work but it is still magic.  Draw a picture on the computer and there it shows up.

TIG welding, nice.  There is just something about that process that is fun to do.  If you want a permanent handle, weld a piece of pipe perpendicular ish to your mix tube and drill a hole in the upper side of the handle. You can then send your copper supply line up the handle, out the side, and into the burner.  Mount the QD at the base of the handle.  Then it connects to the fuel hose like a pneumatic tool.  Much easier to use then when the supply line is sticking out of the back of the burner.

[Mikey98118]

Gluing gas assemblies together

Note: If done carefully, gas assemblies can be safely glued together, although soldered parts might be a little sturdier, after several years. Either method requires the careful preparation, to assure success, including the cleaning and roughening of metal surfaces; the best gluing choices are:

(1) Loctite 272 Threadlocker for permanent joints; works on all metals. Sets in one hour; completely cures in twenty-four hours. Parts can only be loosened after setting by heating to 400 F. But you can take your time completing the assembly. Oxide buildup does not interfere with the bond.

(2) Cyanoacrylate (super glue) needs close fitting parts (0.006” maximum gaps); it sets in 15 to 20 seconds. You must act swiftly, and there are no second chances. Oxide buildup does not interfere with the bond. Do not get any of this stuff on your hands; it will immediately glue your fingers together.

(3) Epoxies for repairing metal and ceramics, like J-B Weld can be also be used to build up surfaces and bridge gaps. Oxide buildup does not interfere with the bond.

Gluing metal parts to one another, will give about the same strengths as soldering would, if you apply careful preparation to the process. One tube pushed into another tube (or into a socket in a metal part), and affixed with glue will provide a very strong bond, if you clean and wire brush both parts, with a power tool, first.

    A fender washer affixed to a nut with glue, will adhere in accordance with the amount of mating surfaces that are provided, so use a flanged hex nut. Wire brush, both nut and washer with a power tool, before gluing. Use a second nut to trap the nut tightly against the washer on a bolt, or on the threaded gas pipe. This ensures perfect placement.

 

[Hefty]

AFB, is this what you mean: 

[Another FrankenBurner]

Yep, that’s what I meant.  Handy to have around.

If you mount the handle to the mix tube at the balance point, it’s easier to wield.

I have always thought a swiveling QD would be the bees knees but I have not looked for a propane capable version.

[Frosty]

A pistol grip shaped handle would be sweet.

Frosty The Lucky.

[Mikey98118]

AFB and Frosty,

Would you advise using a hose for the gas line section between the air entrance and end of the burner handle, or a small copper tube, ending in a hose fitting, since either way, a hose fitting at that place would be prudent?

[Hefty]

Mikey, I've seen you describe flames as hard or soft. Exactly what do you mean here, and what does it look like when evaluating a flame based on its appearance?

Same question for fast and slow flames. I understand the benefit of a slow flame in terms of maximising heat transfer while still in a forge, but what do they look like? Is it the length of the flame envelope compared to the diameter of the nozzle it's coming out of?

[Mikey98118]

It means related things that aren't always the same exact thing, depending on context. If nothing is wrong with the flame; that is to say that adequate combustion is proceeding (not necessarily perfect but in the ball park), then I will describe  a flame as hard or soft, depending basically on flame speed. Mikey burners create hard flames, and Frosty "T" burners create softer flame. I think, but am not sure, that AFB's 3D printed vortex burners are in between the two. Nevertheless "T" burners are quite hot (remember this, when wrapping your head around the next paragraph).

So, what about flames with poor combustion (nowhere near the ball park, let alone in it); they fall into two unacceptable categories: The first is "lean"; that is to say, oxidizing (too little fuel for the air); or "reducing" (too little air for the fuel). I have been known to call lean flames hard, and reducing flame soft (because they also end up being so). I see now that it is a very bad habit.

Hard flames, good or bad, sound just like my description; they have hard outlines, and regardless of flame shape (from pencil to bushy), their outlines are hard...as compared to softer flames, which only appear soft as compared to hard flames. Clear as mud? Perhaps I need to retool my terms. As for "fast and slow flames," they are exactly what the words imply. However, it may help to know that fast flames are always hard, and slower flames always appear softer. Except, or course, that AFB's flames are in between (I think).

3 hours ago, Hefty said:

I understand the benefit of a slow flame in terms of maximizing heat transfer while still in a forge, but what do they look like? Is it the length of the flame envelope compared to the diameter of the nozzle it's coming out of?

No. Softer flames look that way because they are slower. But your question about flame length and speed is useful; not that flame length is only about speed, but flame length can be important in reducing the speed of exhaust gases. A fast hard flame's length is limited by its diameter. Multiple flame ceramic burner heads, and ribbon burner's exhuast gases slow down faster than a softer flame from a "T" burner; much faster, because they are much smaller

Was this explanation satisfactory, or do you still have questions? If you do, so will everyone else...so we should try again.

 

[Hefty]

So are all fast flames hard and all hard flames fast? Or is it: all fast flames are hard but not all hard flames are fast?

I should probably ask, instead, what is flame speed dependant on? In an NA burner initially it is gas pressure and throughput of the orifice, I suppose, but am I right in saying that the speed this lends the FAM is then affected by the type of motion in the mix tube and at the nozzle (turbulent, vortex, laminar, etc), hence the difference between a T burner and a Mikey burner, or any other burner type that needs comparing?

[Another FrankenBurner]

Now you are asking fun questions.  Careful, it's easy to get addicted.  

Flame speed is dependent on a lot of things.  The ratio of fuel velocity to heat energy coming out of the orifice, meaning how fast is the fuel stream vs the btu's it's putting out.  The air induction to fuel velocity ratio, how much air is being drawn in vs the velocity of the fuel (which is related to the total heat energy).  The ratio of fuel to air.  The temperature of the FAM.  The amount of forward push vs spin down the mix tube.  The length of the mix tube.  The ejection area and pressure (nozzle shape).  

Mikey burners run a smaller orifice at a higher pressure than the Frosty T with a larger orifice at lower pressure.

The flame propagation velocity is based largely on the FAM ratio and mixing.  At a given FPV, the flame speed has some wiggle room before it becomes so slow that it sucks back or so fast that it lifts off.  Slow it down and its edges begin blur (it softens), speed it up and its edges become more defined.  

At least that's my current understanding of things.  

[Mikey98118]

53 minutes ago, Hefty said:

So are all fast flames hard and all hard flames fast?

That is what I believe, at present.

 

55 minutes ago, Hefty said:

I should probably ask, instead, what is flame speed dependant on? In an NA burner initially it is gas pressure and throughput of the orifice, I suppose, but am I right in saying that the speed this lends the FAM is then affected by the type of motion in the mix tube and at the nozzle (turbulent, vortex, laminar, etc), hence the difference between a T burner and a Mikey burner, or any other burner type that needs comparing?

You are correct, as far as you go. Flame speed is also dependent on fuel choice. Acetylene and Hydrogen both have high flame speeds, needing little mechanical manipulation in the burner or torch. LPG fuels; propane, methane, and propylene, have much slower flame speeds, and require a whole lot of mechanical manipulation to raise it, and thereby raise flame temperatures.

Frosty has a different point of view about what makes for a hot flame; considering how well he succeeded, I have no argument with the path he choose. Whatever way works for all of you, is fine by me.

4 minutes ago, Another FrankenBurner said:

At least that's my current understanding of things.

Mine too.

[Frosty]

Sorry for the slow response, got sidetracked. About the torch set up. I'd prefer a copper or other hard line between the supply hose connection in the handle and the burner itself. It's going to be moved around a lot and a copper line can be formed for a tight fit along the handle and burner making it less likely to snag objects and being copper won't be effected by heat from the burner or work.

MAN you're asking good questions Hefty, I'm having to eat a cookie before responding to keep my blood sugar up for all the thinking it takes.

Hard, soft, fast, slow. Yes, a fast flame is harder than a slow flame. The reason is simple physics, as the flame moves through ambient air it entrains that air either into the flame itself or around it. The faster the flame the more momentum it carries and less disturbed it is in it's path. Slower flames are more vulnerable to outside forces so they tend to spread faster on "impact" and mixing with air in front of them, the entrained air can actually penetrate the flame and breezes will deflect them more easily.

The term "soft flame" had a slightly different use when I was in school. The above definition is as a description of it's appearance and behavior. The use I dealt with in school was more performance related. A soft flame was slower and spread more easily and so was better suited to area heating, visibly it looks like a soft brush on the surface. A hard flame was more defined in shape and could be applied to small spots. For example when setting a rivet I use a small tip and fast hard flame so it only heats the rivet and doesn't over heat the piece I'm riveting. 

I can soften the flame in the brazing tip by reducing oxygen or increasing fuel flow to lengthen and soften the combustion final zone. Of course an oxy fuel torch, propane in my case, always has a soft zone in the final combustion zone (sheath). Back the tip away from the work to heat more slowly and evenly over an area. I often move the torch till the flame isn't touching at all to just warm an area, say in preparation for normalizing. I start the flame off the piece and slowly move it closer keeping it in constant motion.

What makes the forge hot is a proper mix of fuel and air. The more per second the more energy released and hotter the forge. That's about as basic as it gets. To do this a NA burner has to induct (Induce?) the right ratio of air. A small jet requires higher velocity to deliver a given quantity of fluid, propane in this case. A larger jet will deliver the same quantity at a proportionally lower velocity. The delivery rate is dependent on the square of diameter, its area. Double the diameter means 4x the delivery at the same pressure. To have it deliver the same quantity you have to change the pressure by the same ratio.

And that's the direction I went when Ron Reil and I were hashing these things out back when. I was gifted with a bunch of info from a friend who was always looking for application patent potentials and bounced things off me. That's where I discovered the difference between a "linear induction device and a "jet ejector" type. commercially linears and ejectors aren't used for the same thing at all, Jet ejectors are used to generate vacuum on large scale and linears are used for delivery systems like our burners, or bug foggers, etc.

After making a couple linear burners then reading Cruz's donation of info I decided that a jet ejector's 29:1 induction rate was WAY better than a linear inducer's 17:1. It allowed easy compensation for the inherent slop of a home build burner. As lots of people note and ask about, the burrs, weld seams, inconsistent diameters, etc. of off the shelf plumbing parts, not to mention the wrong shape of a reduction bell for proper air intake trumpet bell. All these little things effect performance but 29:1 leaves a whole bunch of slack to make producing a neutral flame easy. 

It also allows delivering max FAM at lower speed so I tinkered with jets that would deliver the most fuel at the lowest tuned velocity as possible. If I increase the jet diameter any on one of my burners they burn too rich. Period. It also means there is less deviation in induction with psi (heat output) changes in operation so I've never needed a choke on a T burner. If you see a T burner with a choke it means the person built it incorrectly. It's easier to build a faster T and choke it too neutral but overall performance isn't as good.

The idea is to put as much flammable mix in the chamber per second as possible and to exchange energy with the liner it needs to stay there as long as possible.

A hand torch is a different kettle of KennelRation, it's not heating a chamber's liner it's heating a specific item or area by direct flame impingement. It makes a fast hard flame the better tool.

Is a Frankenburner fast or slow? F A S T! It just isn't a linear flame it's moving at high velocity around the inside of the mixing tube and disperses out of the nozzle in a cone shaped fan so the forward velocity is lower than a T's. Meaning I have to go along with Mike and say it's both fast and slow but it'll never be a hard flame. Unless of course the outlet is fitted with a device to redirect the output into a linear flow.

I don't recall have you made such a nozzle?

Frosty The Lucky.

[Mikey98118]

Since he is already working with refractory flame retention nozzles, it would seem a short step to make wax cores, and experiment along those lines.

Good stuff, Frosty. About all you didn't cover was laminar flames, and Bunsen burners, although that would have been pretty far afield  

[Hefty]

Ok, surprisingly, most of this makes sense to me. I've been building my 1/4"Mikey/Trevor variant but my 3d printer nozzles haven't arrived yet for the jet so I put in a 0.023 MIG tip. Way to big, I know, but it allowed me to test out the sliding step nozzle I made for it. Of course, the flame was rich through the whole adjustment range, but as I neared the too long end of the range, the edges became "fluttery" where in the middle of the range they were smooth and defined. So, that would be the greater length of larger nozzle diameter slowing the FAM due to the lower pressure it causes, thus softening the flame?

[Mikey98118]

23 minutes ago, Hefty said:

So, that would be the greater length of larger nozzle diameter slowing the FAM due to the lower pressure it causes, thus softening the flame?

Exactly right

These burners are designed with three different points of adjustment: Primarily, the amount of overhang of the flame retention nozzle past the end of the mixing tube; secondarily, by the amount of space between the end of the gas orifice and the forward edges of the three air openings; and finally, by how much the air choke is engaged.

And that is the same order by which they get tuned.

[Frosty]

No nozzles, and you let that stop you? What is the ID of the printer needles you're waiting for? Call around hobby shops that specialize in RC models and find out how close to that diameter they have in SS control or construction wire. IIRC the one in Anchorage I was shopping for casting resin a couple years ago carried wire as small as 0.005" IIRC. I'd have to call to be confident that's right.

If a suitable wire is available subtract the wire dia. from the smallest mig tip dia. you have and 1/2 that is how much you need to swage the mig tip down. Select as close to that diameter drill bit as you have or can buy at a good tool store. Clamp a piece of business card stock between two pieces of square stock and drill a hole through them in the gap.

Chamfer the ends of the hole, maybe polish up the inside but that's not necessary. Hoping you have a leg vice, clamp a mig tip in the hole HARD With a length of the wire through it and give the moveable jaw a whack with a hammer. Loosen the vise and rotate the mig tip 1/4 turn. Repeat clamp, whack and rotate until the wire won't move. Remove the mig tip, warm it  until the wire slides out.

Viola! Itsy tiny jet.

It MIGHT work well enough might not but swaging it down in this general way WILL work. This is the kind of solution a Blacksmith thinks of. 

Good luck. 

Do you REALLY want me to start talking about Bunsen and Fisher burners Mike?

Frosty The Lucky.

[Mikey98118]

Nope!

[Hefty]

So, my daughter brought me an envelope today and said "oh, by the way Dad,I got this out of the mailbox for you the other day..." I could have had my tiny flame two days ago!! 

0.4mm jet. Ignore the colour, it's not as rich looking in real life. My camera seems to struggle with blues:

How does the shape look?

[Mikey98118]

The flame shape is okay, and fine for brazing with. If you're planning to put it in a little forge, you may want to improve it a little; or maybe not

If you do want a little more heat, just widen the forward section of the air openings. You probably do not want to even square them. The 1/4" burners are actually more versatile, with some minor de-tuning. The convenient part is that you can reshape the air openings a little bit at a time, and watch as the flame responds to every change; then stop whenever you are satisfied with the result.

[Mikey98118]

This might need some explanation. Starting with 1/2" burner size, and increasingly in 3/8" size, and becoming problematic with 1/4" size Mikey burners; their turn down ranges decrease. With my 1/4" size tube burners, the turn down range of a perfectly tuned burner is shorter than I would wish. Linear burners don't have this defect, and my burners can be de-tuned enough to get around this limitation.