drewmyrtle

Need help getting a burner running (NOT for a forge)

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Hi everyone,

I'm new to the site and have seen that you guys know a TON about burners; I haven't come across a site specifically for my needs but you guys look like the most knowledgeable folks around when it comes to propane burners. I'm following this Instructable: https://www.instructables.com/id/Build-a-Propane-Jet-Burner-Brewing-Seafood-Wok-Bur/ 

But the flame keeps blowing itself out when I open up the valve, as you can see in the video I attached. I thought the problem was my 1/16" orifice so I switched to a 0.035" MIG tip, but the results are the same. I'd really appreciate it if you guys could give me some pointers, I tried to contact the inventor of this burner but I've gotten no response. I live at 6,000 feet above sea level in Mexico, if that helps as far as air/fuel ratio.

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10 hours ago, Irondragon Forge & Clay said:

Thank you, was looking for something like this. I'll look it over well.

To add to my original post, I found this on another website: "Eventually, if the fuel flow is increased beyond the capacity of the burner, the flame will start standing clear of end and it becomes unstable. In open air, the flame will literally blow off the burner." 

Sounds like it describes my problem pretty well, which is why I switched to the 0.035" MIG tip, but I got the same results. From what I read, this might mean too much pressure? The regulator is 20 PSI non-adjustable, could that be my issue? I thought the valve would make up for the regulator not being adjustable.

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What's the inside diameter of the "shroud" pipe?   He was using about 2.5 inches ID, and the orifice for the gas supply does need to be matched well to the mixing tube (shroud). 

For naturally aspirated burners (where the fuel stream pulls in the air needed for combustion), there is a somewhat delicate balance between the diameter of the fuel delivery orifice, the inside diameter and length of the tube (mixing tube) around the fuel stream, and the pressure.  The shape and surface texture of air inlet and mixing tube can also affect how well a burner performs, as can the shape and size of obstructions at the air inlet. Unless you have a good handle on how those things interact, it's best to follow known working plans *exactly* if you also want a working burner.   In the video you linked to I believe he mentioned something about using tape to decrease how much air is being entrained by the fuel as well.  To me that would indicate that even the author of that video does not have a really well matched setup, but it's close enough that he can compensate a little by choking some of the air off.

At your elevation you may have to use slightly different dimensions than someone at sea level, but those should be relatively minor differences.  For instance if you are using a 4 inch inside diameter pipe that is the same length or shorter than what is shown in the video, you can expect far different results from those shown in the video.  That's far more than just a little change.

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17 hours ago, drewmyrtle said:

In open air, the flame will literally blow off the burner

With the size of your mixing tube (shroud), your orifice is essentially in open air. Try smaller diameter mixing tubes, even down to 1" to 1-1/2" diameter, and see what happens to your flame. And avoid galvanized anything near the heated parts of the burner assembly. You can get nasty (toxic) zinc fumes if the galvanized coating starts to vaporize.

And don't expect your flame to necessarily stay attached to the burner's orifice, but it does need to stay attached to something. Might be the end of the mixing tube, or if you put a constrictor inside your mixing tube, it might be that.

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Save that burner for cooking, it'd take more effort and time to make it work in a forge than it's worth. There are proven home build burner plans posted in the "Burners 101" thread in addition to previous decade or better of propane burner posts in the "Propane burner" section.

Much of what you see on Youtube and other such sites are videos by people with no more qualification for . . . whatever, than something they GOT to . . . "work"(?) a video camera and connection. There are online video reviews in the appropriate section of Iforge, pick the ones with good reviews to even bother to watch. A LOT of the online videos are downright DANGEROUS! Unfortunately a person need some knowledge and experience to weed out the BAD videos.

Keep with us, we'll steer you straight.

Frosty The Lucky. 

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My assumption based on the "how to" video and the location of his burner in his video was that he does intend to use this for cooking rather than for forging.

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Hi all, thanks for the replies. In the video that I took showing my problem, I had a test shroud on that is 4" ID. I have a welded prototype that has a 3.25" ID shroud made of black pipe, they are both 6" tall as per the plans. It's very hard to find the exact pipe that the original builder used down here, but I will keep looking for something smaller and as Buzzkill and John recommended.

John, what do you mean by putting a constrictor inside the mixing tube? Is that something I should consider doing too?

And Frosty, thank you very much, I actually do intend to use this burner for wok cooking. 

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Haha well the first order of business is stir fry in a wok, then maybe some pork carnitas (pork fried in its own fat!). I wish we could get good seafood down here for a nice crab/crawfish boil!

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Well, in the burners we use in forges, there's generally some kind of flared nozzle at the end. The flare slows the flame down and helps keep it attached to the end of the mixing tube. In your burner (or the person who's video you're working from) it looks like you don't exactly want the flame at the end of the mixing tube, so if you were to put a constriction (a ring that constricted the diameter and then did a gradual flaring) inside the mixing tube that would act somewhat like a nozzle flare, you could get the flame to attach there.

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Ok I understand, I have looked at forge burner builds to try to get a better understanding of how these designs work so I know what you're referring to. Would this be in addition to getting a smaller diameter mixing tube or could I try this with the mixing tube I have now? 

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The constrictor, I was thinking kinda like a rocket engine, but that gets a little complicated.

I would think you'd need to reduce the diameter of your mixing tube whatever else you did.

But you're making a cooking burner. And most cooking burners, BBQ's etc. have a lot of little flames. What if you cut a circle of flat metal slightly bigger than the diameter of the inside of your mixing tube (maybe your 3.25" ID one) and drill a pattern of small holes in it. Wedge it down into your mixing tube about an inch or so, and light the gas above it, so you'd have a lot of little flames?

Rocket.jpg

burner.jpg

Or you get a piece of pipe like the guy has in the video and remember to tape off the bottom to reduce the amount of air coming in. It's all a balance of the air to gas ratio and the speed/pressure the gas comes out of the orifice.

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Drew: This is for outdoor cooking I hope. Yes? I'd just buy one of the large burners with the big pot, Crab boiler type things. Making  your own propane burner isn't a trivial thing and entails inherent hazards it takes knowledge and experience to even recognize. Some are obvious of course but some aren't and it's the hidden stuff that usually gets you. 

What kind of fire do you want? A blowtorch against the wok? A large soft flame like a gas range produces? How much turn down do you need? 

There are plenty of commercially produced appliances for not unreasonable and you let THEIR liability insurance handle the risk if you're careful. Web search "Propane Crab Boil Pot" for a bunch of hits including pictures. 

Frosty The Lucky. 

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Yes, this is for outdoor use. I'm looking for a blowtorch type flame and basically I only need "high" and "off". I know you're right, it's just that I'd have to buy a burner the next time I go to the US to visit my family and bring it back in my checked luggage, and those things are heavy! Thanks for your advice.

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How big around do you need the flame? If you were to use a 3/4" forge burner it would impact the bottom of a wok say 6" away in probably a 3"-4" circle of turn the wok high orange low yellow temps say, 1,800 f.

A modified weed burner might do it for you. It's much less intense and more spread but is hot enough to turn your wok red at about 10" - 12". Don't quote me on the distances it's been a couple decades since I used a weed burner for high temp work. We used to thaw drill pipe and casing to get the thread protectors off for inspection and yelled at the ham handed guys who over heated the pipe. 

A weed burner resembles the pics you posted. search "Propane weed burner" the type I'm referring to look like a tin can on a stick. The burner can be unscrewed from the long pipe handle and different fittings applied to make it more convenient. They run about $60 - $120 depending on season.

Frosty The Lucky. 

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So, you can't find 3" OD, sched. 40 pipe in your neck of the woods to copy the build in the video? What about taking some thinner sheet metal, like your piece of stove pipe/duct (preferably not galvanized), roll it up and wrap a couple of large hose clamps around it. Tighten them down to get it to the right diameter?

Frosty's weed burner idea is a good one too.

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Just measured my wok and it looks like an 8-10" diameter flame would be ideal. Is there way I could get the forge burner to provide a wider flame? Maybe a different sized flare on the end? I'll check out the weed burner tip, too. 

I had the same idea John, I'm actually working on that piece of duct right now to try to reduce it (just for testing purposes).

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Sounds like a weed burner from a little distance to me. Just adjust the distance till it's how you like it. You might be able to find weed burners in Mexico but they break down small enough to go in checked baggage but the residual propane might trip all sorts of dangerous substance alarms. 

Frosty The Lucky. 

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Hey guys,

I was sitting at the dinner table finishing the can of Guinness that I drank with my stir fry (that I made on my indoor gas range), and I started thinking that the tall can was almost the right height and diameter for my purposes... so I took a pair of scissors to it, cut off the top and the bottom, and cut open the top to use as a flange as John recommended. Would you believe that it worked?! So know I have a good idea of what size pipe I need and I see that my problem was definitely having the wrong size mixing tube. I'll keep you posted on any further developments, thanks for the tips!

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What if I got a 2.5" exhaust pipe welded onto the burner body for the mixing tube? That should be ok, right? It would be a lot easier to find.

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Guinness induced ingenuity! Love it!

The exhaust pipe might work. Set it on to see before mounting it permanently. And don't forget the tape the guy in the video added to the bottom of his mixing tube. You may or may not need it, but it just shows that the air to gas ratio does need to be dialed in, so you might play around with different amounts of baffling on the bottom of the mixing tube. Another thing to keep in mind - those yellow flames are a sign of carbon monoxide production. The cleaner you can get your flame (nice blue jet), the better the air around you will be to breathe.

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From what I read, yellow means it's running rich, right? So keeping the mixer tube the same size, I'd have to use a slightly smaller MIG tip to adjust the amount of propane. Is that right?

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