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Burners 101


Mikey98118

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You can endlessly improve on any forge design (one of my favorite indulgences). But a few hard bricks for a baffle wall allows you time to think before jumping. After you make a more permanent exhaust opening, the bricks remain a handy addition to your shop.

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Looks good Rich. Mike and I only have different approaches to the same results. We might tune a burner via different methods but I never doubt his assessment of performance.

For instance I've completely changed my opinion of how forge "doors" should work. Now I think of them as baffles and have tested the results. My next forge will reflect the difference.

Frosty The Lucky.

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17 hours ago, Frosty said:

Looks good Rich. Mike and I only have different approaches to the same results. We might tune a burner via different methods but I never doubt his assessment of performance.

Nor I yours. We came to tune our forges differently, but getting the forge running its best is al that matters.

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So, Frosty stated "tune our burners.." and I stated "tune our forges"; he tunes his burners in the forge from beginning to end. I tune my burners out in the shop as the final part of the construction process, BUT, thereafter I fine tune the burner in a heated forge, because even though the burner is running perfectly in a cold forge, once the forge heats into the incandescent range it can be tweaked just a little more to get perfect performance in that environment. And once a burner is mounted in a forge I do all further tuning the forge.

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So I know I said I was gonna do stock removal, but I started hammering and It sorta took on a life of its own. This started as half of a lawn mower blade. Tested a part of the blade first and after the test quench in canola oil it was hard, at least with a file test. Hammered out the basic shape then stared refining with my belt grinder. Still a lot to do, but happy so far for a test run. Thanks to all for the help and advice. 

4BDD9051-BB49-4CD1-8EA8-7FC3AD1E9375.jpeg

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6 hours ago, ThomasPowers said:

I'm sure she will come around after you sit and watch "The Iron Mistress" a dozen times with her...

Believe it or not, we’ve actually watched it a couple of times. LOL. It’s what old married people do, watch old movies. 

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What about secondary flames in NA ribbon burners?

I am no great fan of secondary flames in forges; the problems that come with them should be clear by now. On the other hand, they aren't the "knell of doom" ether. Some times how bad boils down to a question of how much. With ribbon burners there is a clear divide between fan-blown and naturally aspirated ribbon burners (NARBs). The only ribbon burners I've seen with one hundred percent primary combustion are all on fan-blown commercial burners. You may achieve this at home, or not. What I have not seen is complete primary combustion in a NARB--YET; I think that will come, eventually.

In the meantime, what about their secondary flames? On the one hand, they have the same advantage that the primary flame does on multi-flame burner heads; they are tiny, and those are more inclined to complete combustion in the limited area of a forge. On the other hand I see lots of photos of big time dragon's breath exiting NARB forges. Does it depend on how far the forge is turned up?

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Hmmm.  I'm not sure how many answers I can provide to those questions, but I can share a little bit of my observations/experience.  With my NARB I'm still getting a significant secondary, or perhaps tertiary, blue flame envelope that encompasses pretty much the entire face of the burner block and is visible several inches above the individual flames when the burner is outside the forge and facing upwards.  I plan to play around with some different combinations to see how much I can reduce that, but as with most things it comes down to time and money.  Right now I'm using a 1/2 inch T burner to feed the NARB, but my plan is to see what happens with a 1", 1", 3/4" T with a schedule 80 3/4" nipple and stick with the .023 mig tip I've been using.

As for the dragon's breath issue it's been a bit of a mixed bag for me.  Once my forge is up to temperature I can turn the pressure down below the point where a single port burner would function and still maintain a good forging temperature.  When running like that I have very little dragon's breath escaping the openings.  However, if I want to increase the temperature significantly I will see a fair amount of dragon's breath.  The increase in temperature does not seem to be proportional to the increase in pressure.  In other words turning the pressure up significantly only seems to give a modest increase in temperature while significantly increasing the amount of dragon's breath.  I know I'm running rich already, and I take these symptoms to mean that I'm not drawing enough air to complete as much combustion in the forge as I'd like to have, so a fair amount of the increased fuel is burning outside the forge openings. Since I don't have a good way to get accurate temperatures in the forge (yet) all I can do is judge by color, and that's my perception of what I'm seeing.  I'm interested to see if others have different experiences though.

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I keep looking for information regarding how to calculate the flow rate of propane knowing the PSI and orifice size.  I have seen several references on the forum, but each one is broken as they are from 2011 that I have found so far.  Can someone point me in the right direction?

 

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1 hour ago, Mikey98118 said:

look for a typical fuel BTU chart online.

I'm confused as to how this will help.  Can you explain this more?  I know the BTU of propane, but I don't know how much propane is being pushed through my orifice at a given PSI.

 

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1 minute ago, ThomasPowers said:

If you are trying to figure out the BTUs; then the easiest way to measure  BTUs is to weigh the propane bottle before and after a measured time and convert weight of propane used to BTUs.

I probably should have stated that I want to make sure I know how much air I need to make sure I have when I add a fan/blower.  I want to make sure that I have more than enough air for a given PSI based on the current burner.

I could be overthinking it, but I am thinking that if I know the volume of propane, I can calculate the minimum air required for combustion and then increase from there.  I don't want to add a blower (my estimate is using a hair dryer at this moment) and find out that I have to little air available to the forge.

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2 hours ago, Lazagna said:

'm confused as to how this will help.  Can you explain this more?  I know the BTU of propane, but I don't know how much propane is being pushed through my orifice at a given PSI.

These charts usually have orifice size and PSI amount listed too;some are even interactive. Work backward from the end figures to come up with what you want.

You can also find the amount of air needed for proper combustion for a given fuel, and add that figure into the mix.

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14 hours ago, Mikey98118 said:

These charts usually have orifice size and PSI amount listed too;some are even interactive. Work backward from the end figures to come up with what you want.

You can also find the amount of air needed for proper combustion for a given fuel, and add that figure into the mix.

Perfect, thanks!

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On 8/27/2018 at 2:36 PM, Lazagna said:

I probably should have stated that I want to make sure I know how much air I need to make sure I have when I add a fan/blower.  I want to make sure that I have more than enough air for a given PSI based on the current burner.

I could be overthinking it, but I am thinking that if I know the volume of propane, I can calculate the minimum air required for combustion and then increase from there.  I don't want to add a blower (my estimate is using a hair dryer at this moment) and find out that I have to little air available to the forge.

If you construct your burner correctly, mix the air and gas well, and have a well insulated forge you will need surprisingly little air. A hair drier my be overkill. I have my small blower choked off about 80 percent and I get forging temperatures quite easily (with half the outlets in my ribbon burner blocked off). A good design is surprisingly efficient. 

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Be a little careful; even when you're being practical

Loads of guys will use a pipe reducer rather than take the time to build a "proper" flame retention nozzle. Where does the balance lay between practical and sloppy? Leaving out the obvious "according to who?" answer,I will point out that how well it can be done may be the new balance point. The major stumbling block with using pipe reducers as flame retention nozzles used to be that they provided too large a diameter distance to work effectively; instead they tended to just be "better than nothing," which is no where near good enough. Their practicality was also reduced by nearly all of them being made of mild steel because stainless steel pipe reducers had to be special ordered and were expensive. If you're going to cough up the money, wait the time, and pay for shipping on such an item, why not buy a tapered stainless steel sliding nozzle from Larry Zoeller Forge and do the job right?

But lately I've been seeing a new stainless steel (slimmer) threaded pipe reducer featured on new burners, which could close the gap enough for me too accept them as practical.

BUT, even with this part change, be sure to clean up any internal burr or narrowing of the threaded end on the pipe used for your mixing tube, if you hope to come up with a decent flame!

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