Burners 101

[Mikey98118]

The end of the matter

The book Gas Burners for Forges, Furnaces, and Kilns originally sold for: $19.95, and was a total bargain at that price. For the first few months after it stopped being published, used copies in good condition hit $350.  $75 for a tattered copy, or $100 for a copy in good condition  is a bargain price, because you can resell it on Amazon.com, once your done with it, for the same amount you paid; try getting back what you paid on a worthwhile book still in print.

For those who feel that is still too inconvenient, there are pirated downloads that can be found on the Net, simply by adding "PDF" after the title; that  has inconvenience too.

I did the extra work needed to make that book acceptable to libraries; does anyone ever look to see if they can burrow a copy that way? Hardly ever.

[Mikey98118]

The idea behind the Burners 101 thread isn't to provide step by step instructions on how to make any particular burner, but to provide general information on the how and why of burner construction, so that people who want to design their own burner has some background information to begin from. If someone asks a question, us old timers always try to give the best advice that experience presents. BUT, for anyone who wishes to experiment; we hope they will disregards that advice, if it gets in the way, and try something new.

[G-son]

3 hours ago, Mikey98118 said:

...BUT, for anyone who wishes to experiment; we hope they will disregards that advice, if it gets in the way, and try something new.

The craziest ideas often leads to the most interesting results. Occasionally the results are good too, not just interesting. 

[Mikey98118]

Orifice tips for 3/8" burners

Small gas jets don't follow our expectations very well at all. A scratch or burr that make little difference in an orifice of .031" I.D. can totally discombobulate gas flow in a .020"  orifice, making torch tip cleaners and 400grit sandpaper a practical necessity, whether using capillary tube, or drilling gas jets in half-hard brass round stock.

Becuas friction losses are so high at .020"  orifice diameters, 1/32" in tube length can completely change jet performance, and therefore, burner performance.

[GrumpyBiker]

I have a couple questions on a burner that came as package deal with a forge I just bought.

First, is this what’s referred to as a Side Arm burner or is it called something else?

Second, what can be the expected results of moving the jet tip closer to the “burner tube, burner leg” (or whatever it’s called) Or moving it more to the center of the opening?

Is there a general effect on the flame & burner performance in adjusting the jet position?

Also, is the burner tube too long ?

Ive seen a few like this in use on other forges and they also look longer than a T-Burner set up.

[Another FrankenBurner]

Ron Reil called that burner a modified side arm burner on his page.

You can find them on Larry Zoellers page and High Temp Tools.  I believe Zoeller was credited back when with using the ward reducer with the larger side opening.

Moving the jet causes more or less air induction.  There is a sweet spot which will pull in the best volume of air to match the fuel volume.  Generally, close to the mix tube pulls in more air.  The one I have likes the jet 3/8" behind the mix tube.

I have High Temp Tools 3/4" which was supplied with an 035 mig tip jet but found that dropping to an 030 tip did a better job with actual forge temperatures and fuel consumption.  It was a little air starved with the larger tip.  This is in my undersized forge.  Maybe you would see similar.

As to tube length, we would need to know the length.  It looks like it might could be a little long.  

Have you pulled the burner from the forge?  I am curious what they are using as a nozzle on the flame end of the burner.

[Frosty]

6 hours ago, Another FrankenBurner said:

Generally, close to the mix tube pulls in more air.

I have to differ with you on this one. The closer the jet to the throat (beginning of the mixing tube) the LESS air it induces and richer the flame. The farther back the MORE air it induces and leaner the flame.

This is how I tune my burners, been doing it this way for 35+ years.

The burner's a Modified Side Arm. A 3/4" ID mixing tube should be around 6" long. They're good burners, they work very well.

Frosty The Lucky.

[GrumpyBiker]

This tube is 12” .

When you are tuning your burner do you adjust the tip position while it’s running so you can see the different results ?

[Frosty]

I'd shorten the tube first and see what happens. ONE change at a time then test, observe, compare. 

No, my jets don't move. I start with a new contact tip then I remove them and trim them with a file and clean the orifice with a torch tip file if they need tweaking. Starting with full length assures me they're too long so I don't have to guess about things.

They can be made adjustable but it's added trouble I don't need, I'm good at tuning this way. It ain't broke you know. 

Frosty The Lucky.

[Another FrankenBurner]

2 hours ago, Frosty said:

I have to differ with you on this one.

We don't differ.  What I said is wrong/backwards of what I have observed as well.  My mind is slipping today.  Thank you for pointing it out so I am not adding to anyone else's confusion.  

[Mikey98118]

Yup; what they said

[Frosty]

Happens to us all. I know I'm getting used to it. 

Frosty The Lucky.

[GrumpyBiker]

On ‎8‎/‎14‎/‎2019 at 1:14 PM, Another FrankenBurner said:

 

Have you pulled the burner from the forge?  I am curious what they are using as a nozzle on the flame end of the burner.

 

Here’s the flare as it is.

Has two set screws holding it in place.

Here it is next to a T-Burner I bought but have yet to run up.

[Mikey98118]

I can't be completely certain, just from looking at the photo, but the nozzle on the modified side-arm burner (bottom) does not appear to have any taper, nor a spacer in it; without one or the other, it wouldn't do much for burner performance.

The "T" burner (top) is using a threaded reducer between the pipe fitting and the threaded pipe used as a mixing tube; does the reducer's thread that inters the pipe fitting have an internal bevel? Does the pipe's end that is screwed into the threaded reducer also have an internal bevel? Internal bevels in those locations should improve performance.

[671jungle]

The longer the mix tube the more friction in play. If this burner’s nozzle has no taper the the difference in area is negligible to affect the flame in a longer tube. Maybe a spacer will improve but the tube looks long. Frosty’s T produces a high velocity swirl with the 2 opposing intakes. The side arm needs a little more finesse to achieve the same being only one intake port, possibly reducing the mix tube length for proper performance. I may be wrong, I probably am. Curious anyhow 

[Mikey98118]

2 hours ago, 671jungle said:

If this burner’s nozzle has no taper the the difference in area is negligible to affect the flame in a longer tube.

If I were concerned with how friction effects this part (the flame retention nozzle), the seemingly minor increase in nozzle diameter from tapering, or from the addition of a spacer ring, would be minor. Since what the nozzle is affecting is a reduction in pressure within the nozzle area it becomes major.

[Mikey98118]

I knows what I knows about flame retention nozzles...and that isn't anywhere near enough. It only takes one look at the needle flame coming out of a butane lighter, with an apparently enormous flame retention nozzle diameter to show me to be more lucky than wise. The next big breakthroughs in in forge burners will all be concerned with their nozzles.

[GrumpyBiker]

You guys keep saying taper (ie, a reduction) but I’ve never seen a nozzle that’s smaller at the flame end.

Everything I’ve seen has been flared at the flame end. Does anyone have photos of these tapered nozzles?

[GrumpyBiker]

Do you mean something like this ?

[Mikey98118]

Yes; that is a tapered flame retention nozzle, with a shorter wider taper than what we have been using for the last couple of decades; this design seems to be very effective on most burners.

Whether the taper is used to  reduce or expand the opening at the end of a burner's mixing tube; is up to the designer; you can see examples of each kind.  All of the homemade forge burners I've seen so far use expanded flame retention nozzles. Air/propane cylinder hand torches use expansion on the end of their brass flame tubes, and use reduction into a partial bullet shape on most of their stainless steel flame tubes; a few of the stainless steel variety use an expanded flame retention nozzle quite similar to a step nozzle, except that it is all one part that is pressed formed.

[GrumpyBiker]

Well here it is with a 6” tube.

I was wrong the original one was 10”.

Here are a couple comparison pics .

Both the 10” & 6” were run with the nozzle it came with in my original post.

There is substantially more “dragons breath” with the shorter tube but I don’t know if it’s a good or bad thing. Or what exactly it’s an indicator of.

Any insight is appreciated.

I ordered the nozzle in the post above (Ebay screen shot) this afternoon so I’ll have that to play with once it arrives.

 

 

 

 

 

 

[Mikey98118]

You're right that there is a lot of dragon's breath; what's worse is that, the third photo shows blue exhaust, and a lot of it. The conclusion is that your burner is, at present, heavily reducing. You need to fix that. On the positive side, once you get your burner flame right, your forge will enter the orange incontinent range. In other words, practical for forge work.

[GrumpyBiker]

What does “heavily reducing “ mean?

Most of the terms used are meaningless to us beginners.

Is it running too rich,  to lean - do I need more air or more LP ?

Did it look better with the 10” tube ?

The bottom photo collage was after running for 10mins & the middle collage pic was at 3 minutes (with the overhead lights off in my shop so I could get a better photo) , if that matters.

 

What would your first / next step be?

I have an 8” tube on the T-Burner I could swap out the 6” I bought yesterday and try  it.

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

[Mikey98118]

It means that your burner is putting out a very rich flame; that makes lots of carbon monoxide, and lowers flame temperature. Your burner doesn't need less fuel; it needs more air.

The most common problem that beginners miss on "T" burners is that the MIG tip was never filed shorter, giving a fuel rich flame. The next most common problem is misalignment of pipe parts, or the MIG tip being off center, but that is easy to notice.

[Mikey98118]

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.