Burners 101

[Frosty]

Cory: You don't need a lot of pressure to seat the brass plug. Cut it so it's a couple thousandths larger than the pipe and put it in the freezer. Heat the pipe to black heat, the brass plug will slip right in. When the temps equalize you'll have an interference fit. Meaning the plug is larger than the hole it's in.

That's one HOT burner, nice job.

Frosty The Lucky.

[jwmelvin]

Hi all. I’ve been reading around a bit in preparation of building my first burner. I would like a forge so I figure I will start with the burner. Then I was thinking that I’d like to build a deep fryer in my kitchen, using our existing natural-gas stove. So I am curious if you would guide me regarding my design considerations?

I am thinking of two ribbons burning inside of cylindrical housings. I’m attaching a sketch of some ideas. Oh and I took a picture of the burning gas out straight out of the jets in case it tells you anything regarding scale of the burner I need. I think not, as they can flow a lot more gas; it just blows the flame out without proper air entrainment and mixing. 

 

Thanks,

jason 

 

[Irondragon Forge ClayWorks]

35 minutes ago, jwmelvin said:

reading around a bit

Have you read this yet? READ THIS FIRST  It will help you get the best out of the forum. Reading Burners 101 and Forges 101 will put you on the road to make a successful forge for heating steel to hammer on. Don't know about the deep fryer in the kitchen though, sounds risky to me.

[jwmelvin]

35 minutes ago, Irondragon Forge & Clay said:

Have you read this yet? . . . Don't know about the deep fryer in the kitchen though, sounds risky to me.

Yes I’ve read that. I don’t think there is so much risk, but regardless I am prepared to proceed. I was hoping for some general considerations regarding natural gas vs. propane burners. Maybe I should post in the NARB thread though?

[Mikey98118]

I think you would find that homemade heating equipment would void your home owners insurance. You would end up in trouble with the fire department, and your bank.

[Soopafeen]

Frosty,

Thanks for the comments on my burner it was a good process I am glad it actually works well to be honest.

Mikey had noticed that there was a considerable amount of oxygen being pushed up into the burners airflow by the gap between my burner and the burner portal into the forge, I planned to close it up already but the suggestion he made to resolve it was much better.

I found a stainless washer at the exact 2" diameter of the portal to my forge all I had to do was bore out the center with a file until it slid over my burners mixing tube pretty simple and effectively blocking secondary air by ~95%.

Oxygen molecules when heated want to separate and seek out moisture while cold molecules want to stick together, secondary oxygen has already been combusted so the molecules are thin and inefficient for re-combustion it is like eating a soggy half eaten burrito.

Oh and was she beautiful with a good nights rest with the air filter on, the forge purred beautifully after increasing the cold airflow and there was instantly a noticable amount of increased infrared heat.

Picture #1: Forge with stainless choke plate installed.

Picture #2: Forge at 20# burn after just a few minutes.

Thanks, Corey

[Soopafeen]

Addition to above post.

Frosty, I thought about heating it but I thought it required higher temperature for enough thermal expansion and the freezer trick is smart stuff, great info thank you.

Also high speed burners are more susceptible to secondary oxygen due to higher vacuum current which should be easily felt with your hand.

Mikey has given me a statistic of up to 20% increase in performance for his burner design.

[Irondragon Forge ClayWorks]

9 hours ago, Soopafeen said:

thermal expansion and the freezer trick

My grandfather taught me about that decades ago. I was trying to get a stuck piston out of an engine I was rebuilding. Tapping on it with a wooden mallet wasn't working. He had me put some heat with a hair dryer around the outside of the cylinder then after it was warmed up, put ice cubes inside the piston. I thought ya right he has lost his mind but in about 30 seconds the piston fell out. Gotta pay attention to old guys because they know stuff you would never thought of.

[Another FrankenBurner]

17 hours ago, jwmelvin said:

I don’t think there is so much risk

Deep fryers contain risk.  Gas heated deep fryers contain more risk.  You are heating a large quantity of oil in close proximity to flames.  If heated to high enough temperatures, oil is happy to become a fuel.  

Deep fryers need control systems.  Basic commercial gas deep fryers have a pilot flame safety thermopile, a pilot safety dual gas valve, an easily accessible manual gas shutoff valve, a thermostat with a maximum of 400°F, and a high limit thermostat which triggers at 450°F.  In commercial kitchens around here, they are also required to have fire resistant surroundings, an exhaust hood, and an ansul system which is an automatic fire suppression and gas disconnect system.  Even with all this, I have responded to several fryer fire calls.  Some of which damaged the building.

If you skip the controls for manual monitoring and control, there is even more risk.  

As to type of burners, most basic commercial models have 3 or 4 cast iron NARBs which send the flames into heat exchanger tubes with baffles and up a flue.  Natural gas in commercial kitchens runs very low pressures, the burner manifold pressure is usually 3.5 inch wc (0.126 psi).  To get the btu's needed, burner tubes have to be designed for the low pressure and employ large gas orifices(comparatively).  

The flames impinge on the welds at the front of the heat exchanger tubes which often crack and oil leaks into the flame.  My company will not fix these welds(even though it would be easy) because we don't want to be liable.  Too much risk.

If you need a visual demonstration, do an internet search for "dangers of deep frying."

Small electric deep fryers are fairly inexpensive.  

[u_p_country]

Corey, thank you for the close ups. Pictures really are worth a thousand words. Mike, thanks for the encouragement to experiment and the good advice to keep us on track.

Frosty, the freezer trick is excellent! That one will go on my mental bag of tricks.

[Mikey98118]

 

Making small fuel jets

 

MIG tips only go down to 0.023" call-out size; this is the welding wire size they are meant to feed--not the actual size of the orifice, which is .031". The best orifice size for a 1/2" burner is 0.028" orifice diameter. But you can't get smaller than an .031" diameter orifice using a MIG tip...unless, you add a section of hypodermic needle or heavy wall capillary tube as an internal sleeve to it. It was this frustration (which being a perfectionist) lead me to start experimenting with capillary tube and dispensing needles. I won't pretend to have any idea how available various products are outside the USA, and therefore assume that hypodermic needles would be the easiest source of capillary tube for many to find. Hypodermic needles are all made from stainless steel, which requires boron modified flux for successful silver brazing; fortunately, all these needles can be bent in a curve, and all of them retain a certain amount of spring afterwards. So by combining the right sized orifice with the closest MIG tip orifice diameter, you can slip such a needle into a MIG tip, and it will stay in place (If you can’t find a proper match, carefully drill out the MIG tip with the closest hole diameter to the needle's outside diameter) Afterward you grind off the excess needle length, and sand away the inevitable internal burr with some spit and a circular motion on very fine sandpaper (#400 grit).

 

 

    The best gas jet orifice size for a 3/8" burner is 0.025" but you can reduce that to as little as 0.019" by shortening the needle length down to about 5/8".

The best gas jet orifice size for a 1/4" burner is 0.020" but you can reduce that to as little as .016" by shortening the needle length down to about 1/2".

 

 

    Obviously you're not going to have a lot of success bending a 1/2" to 5/8" long sleeve from a hypodermic needle, so for such a short length, the alternative plan is swaging the copper MIG tip down around the needle, so that it firmly grips it; this is done by drilling a hole in a small block of steel, cutting the block in half, and setting the MIG tip (with needle inserted) in the bottom half, covering the tip with the top half, and tapping the block with a hammer; rotate the tip one quarter turn and tap the block again.

    Or, you can use a drill to enlarge the MIG tip’s hole a little under the diameter of the needle, and then use a set of torch tip cleaners to ream it out further, and make an interference fit.

 

 

Sumary for reference, orifice size to burner:

The best orifice size for a 1/2" burner is 0.028" orifice diameter. 

The best gas jet orifice size for a 3/8" burner is 0.025"

The best gas jet orifice size for a 1/4" burner is 0.020"

MIG tips only go down to 0.023" call-out size;  the actual size of the orifice, which is .031".

[Mikey98118]

Aligning reducers to mixing tubes

 

Most burner designs are considered easier to make with threaded plumbing parts; that can be true, or far from it; depending on the quality of those parts. Cheap imported fittings are becoming the rule as steel water pipe is marginalized by copper and plastic. Cheap pipe fittings are often made from marred castings, which don't thread properly, producing axially misaligned threading in the finish part; such parts make misaligned burners, which cannot be properly tuned, and thus produce poor flames. Here are some answers to this problem:

 

(1) Avoid buying threaded fittings from large generic hardware stores. They don't have a good selection of fittings, and tend to use cheap imported stock. Look for regular plumbing supply stores or HVAC supply stores, instead.

(2) Hand screw fitting and pipes together, and inspect them before purchase; crooked fittings are easily spotted this way. Don’t stop with screwing the reducer to the smaller pipe that will be used as its mixing tube; add a larger pipe on its large opening and revolve the assembly in your hands. Whether the parts are axially true or not becomes instantly apparent.

(3) If you must buy your fittings online, consider using stainless steel instead of cast iron; stainless parts are likely to be much higher quality.

(4) In the end, the surest answer to a problem, is to avoid it. Every threaded pipe fitting has a much higher quality butt-weld equivalent. Pipe can be used in the next smaller size to the fitting's opening, slid into position (after a little power  sanding, or filing), and held in place with socket-head setscrews.

    This is a little more work than screwing together threaded fittings, but gives much better part control, and superior flow. Don’t forget to grind an internal bevel on the end of the pipe that slides into the reducer fitting.

[jwmelvin]

On 3/30/2019 at 12:50 PM, Another FrankenBurner said:

Deep fryers contain risk. . . . .

As to type of burners, . . . .

I appreciate your response, thank you. I definitely would not omit safety systems. This was primarily a mental exercise to consider the design parameters for the appropriate burner. Understood that it is out of scope for this forum/thread, but thank you again for the help. 

I will be building a burner for a forge/furnace, and will certainly be using the information here. I have some machine tools so will try to optimize my approach to the extent possible for a first timer. Do you think a 3/4" is a good size for first burner? I have an empty helium tank and an old propane tank I could use for a forge shell. I haven't given much thought to a furnace and really being able to cast may be a higher priority for me. 

[Mikey98118]

3/8" to 1/2" burner if the helium tank is one to two gallon. Two 1/2" or single 3/4" burner for a five gallon tank.

[Jbradshaw]

On 4/2/2019 at 5:28 PM, Mikey98118 said:

 

Making small fuel jets

Sumary for reference, orifice size to burner:

The best orifice size for a 1/2" burner is 0.028" orifice diameter. 

The best gas jet orifice size for a 3/8" burner is 0.025"

The best gas jet orifice size for a 1/4" burner is 0.020"

MIG tips only go down to 0.023" call-out size;  the actual size of the orifice, which is .031".

Thank you for this. It's perfect timing. I recently put together a 1/2" Frosty T 1/2" NARB and it's burning rich no matter where I position the mig tip (.023"). I was thinking of grinding out the openings on the T with a die grinder. But I'll try the hypodermic  tube instead. 

Amazon has a tube with a 0.02775" ID for $6 for a 12" length.  So unless someone can suggest a better source I will purchase it and see where it gets me. 

[Mikey98118]

Please note that most burner designs fall pretty closely into my parameters; this doesn't include "T" burners, for which you should go up one jet orifice size in every  T burner size. His design have a far different rate of flow then mine or most other burners.

[Jbradshaw]

I also have a 1/2" Mikey burner that I use outside the forge that could benefit from a smaller orifice. So I think I'll order the tubing anyway. If it doesn't improve the T burner (I think it will since going from 0.025" to 0.023" tip was an improvement)  it's no loss since I can use the part anyway. If it does help than I can report back on the NARB thread about using that method to improve the burn since there is not much info on 1/2" burners in that thread.

[Frosty]

I've never made a 1/2" T myself. Teenylittlemetal guy is the 1/2" T burner maker to consult. He didn't do it the way I do but makes them work a treat.

Frosty The Lucky.

[Buzzkill]

FWIW for my NARB I ended up still using a .023 mig tip, but switched to the 1x1x3/4" T and a schedule 80 3/4" pipe nipple (which I reamed out to taper the ends) in order to combat the excessively rich burn. That may not be the best solution, but it seems to work for me.

[Frosty]

Good GRIEF Buzz you must have to choke heck  out of the burner using that small a jet! 

I realize using a too small jet and choking the air makes it easy to tune a burner but an 0.023" jet in a 3/4" burner? HOLY MOLY!

Frosty The Lucky.

[Buzzkill]

I don't choke it at all.  Keep in mind that I did use a schedule 80 pipe nipple, so the ID is less than a "standard" schedule 40 nipple.  The reality is the .023 tip is probably slightly larger than "normal" as well due to repeatedly running torch tip cleaners through it to verify I had no burrs.   I may get a very small amount of scale forming in the forge, but I need to check that with some clean shiny metal to verify it.  On the other hand I can forge weld just fine with flux.  I do want to try some fluxless welding at some point and might have to block intakes a little or do something different with the jet to give that a shot.

[Frosty]

Gotcha, I was confused. I don't keep actual IDs of various schd. pipe and tubing in mind. I can't even tell you the actual ID of plain plumbing pipe. Since we've been discussing burners here a 3/4" x 1" T or as you called it 1" x 1x 3/4" T is used to make a burner with roughly a 3/4" ID mixing tube. Sounds like you made a disguised 1/2" burner.

I'll try to remember to ask clarification next time.

Frosty The Lucky.

[Mikey98118]

Actual inside diameters of schedule 40 (water) pipe run roughly 1/8" larger than their nominal sizes.

[Jbradshaw]

On 4/4/2019 at 2:01 PM, Frosty said:

I've never made a 1/2" T myself. Teenylittlemetal guy is the 1/2" T burner maker to consult. He didn't do it the way I do but makes them work a treat.

Paging Teenylittlemetal:  Any tips? Or maybe if you have a thread on it I couldn't find you could point me in the right direction?

[Buzzkill]

20 hours ago, Frosty said:

Sounds like you made a disguised 1/2" burner.

Yes, that's basically true.  Originally I had a standard 1/2" T burner feeding the NARB, but I couldn't seem to get as close to a neutral flame as I wanted even when trimming the mig tip way back, so I made those modifications to help induce more air.