Mikey98118

Providing that your burner's mixing tube is a 3/4" pipe, its length is plenty long enough. You asked "Is it 8" with nozzle?" NO; it is at 8" to the end of the mixing tube, just as you have it. The flame retention nozzle extends beyond the end of the mixing tube. You have loads of time to determine the right size plug fitting for the male pipe thread in the first photo because the ceramic blanket, etc., that you will line your forge with will effectively prevent the hole from creating any problems; you may decide you want to use that opening for something later on, so there is no point to being in a hurry. You're doing fine, so far. But you need to add a second circle of bolts in your burner port's tube so that you can aim the burner somewhat within the tube. Why? You will want to be able to point the flame a little offside from your heating parts.

Based on length to diameter, you will need at least two 1/2" burners or three 3/8" burners for an even internal heat.

Great! Or you could start a new thread about sheet metal in burner and forge construction, making it easy for people to look at and contribute to; I think the topic is important; in any case, I don't want what you are doing to eventually get shuffled off to obscurity. Frosty and others have repeatedly advised people how easily forges can be constructed of sheet metal. Two or three guys have posted photos of their sheet metal fabrications on IFI, and this important technique keeps being ignored; I think people assume that anything new to them must be hard to deal with. Sheet metal work as something new and frightening; what a side state of affairs that is!

Everything Frosty wrote was right on. On top of that, you must remember that ceramic fiber, being insulative, gets very hot and stays that way as long as the equipment is running. The higher the sustained temperature the faster the fiber shrinks. It is the process of shrinking that breaks the fiber down. BUT colloidal silica rigidizer (when applied and fired to the fiber) acts like millions of little welds where the fibers cross oneanother, trapping the boken fibers in position far longer, instead of accummulating as toxic dust particles.

Without being subject to chimney effects, a linear burner has no need for an air choke. By using a short bit of tubing, with an inside diameter just larger than the gas tube, to hold the inner edges of the three vanes, you will be able to move the gas assembly back and forth between both burners. I am assuming you have already read the Burners 101 thread, and need no help figuring out the details of gas assemblies; including the whys and wherefores of maintaining the gas jet centered and parallel the mixing tube axis and at the proper distance from its entrance? BTW it just kills me that you didn't post this juicy little item in that thread And those same tools help electronic techs and computer geeks build perfect cases for their gear.

First off, there presently isn't a more economical or easily built burner than one of Frosty's "T" burners. To bring this burner design up to snuff, just use two sets (circles) of THREE screws each. To help offset the rickety nature of longer screws, hand-sand the end of each screw to be smooth and flat. These two changes should make the burner safe enough.

To begin with, nice work so far. Forget ten diameters; you want nine diameters for the length of your mixing tube. Why; because longer mixing tube lengths smooth out the flame by slowing the incoming gas/mixture through friction. Nothing's for nothing, and the price you'll pay is a weaker flame. You already have a slightly weakened flame, do to the MIG tip being a couple of thousandths over ideal diameter, for a half-inch burner size, so don't add to that with a longer mixing tube than needed. How do you plan to mount your gas tube and gas jet to the funnel? And are you building a standard linear burner or a Vortex burner? If a standard burner, I would suggest mounting the gas tube in a steel or half-hard brass tube, which is mounted within your burner's cone via three 1/2" to 3/4" wide sheet metal curved vanes, set at a 30-degree angle, just like the impeller blades used on axial computer fans. Instead of curving the vanes, you could cut them out from a tin can. So, why go to the trouble? While not anywhere near as strong a swirl as provided by the right fan, three such curved vanes will double the effectiness of your funnel. If you have a rotary tool, you could cut the end and a short section of wall from cans just larger that your cones to serve as caps, cut out three sides of the areas for vanes between the the the wall and a central area used for a central lamp nut (to be silver brazed over a central hole), and bend the cut outlines down to become rib-vanes; this will allow you to cut metal discs mounted on lamp nuts for air chokes, which will be needed to seal the burner against the chimney effect. Yes, it will. It may also be very encouraging to sheet metal enthusiasts. I think a lot more people will be working with sheet metal as time goes by; it is a natural skill to be coming on strong in a high tech age

After.

That forge basically needs to be turned on its side; at present it doesn't have enough room to for the flame to combust before impinging on the floor.

No steel wire, fiber, screen. chicken wire, etc., which helps to break down your hot-face refractory. Steel is fine and dandy as an outer shell where it can only become a little lose around the forge ceramics, as it enlarges more than the ceramics can; it is BAD inside of refractory where that same enlargement will only crack the refractory

I have made lots of casting furnaces with two-inch thick refractory linings and never managed to drive all the chemically locked water from them until I turned the refractory yellow all the way through to the steel shell. Furthermore, the outer layer of refractory will regain moisture from Seattle town's air until that is accomplished Just a little friendly advice from the REAL rust belt

S0 then, you won't mind my suggesting that you continue cutting out your shell, so that to can rotate it to bring your burner up to two inches down from top dead center. Then, use wood or angle iron to trap it there. Mount the burner in position, and check to be sure the flame will impinge near tor the near end of the shelve, but clear of the wall. Now employ a level to mark both ends of the shell for floor hight. Check to be sure the projected flame path will intersect the floor where you want it, Rotate the shell until it does You next have the choice of kiln shelve or refractory for a floor. If you go with a high alumina kiln shelve, buy it one inch wider than the opening's width where your planned floor would intersect the hole. Obtain the shelf first, and then cut out recesses on both sides of both openings, for the shelve to slide into. Be sure that the four recesses are 1/8" higher and wider than the shelve. Wrap your two 1" layers of ceramic blanket around the forge, and then rigidize and fire them. Next, fold a large enough pillow of ceramic blanket between the rigidized layers and the shelve recesses so that it needs to be compressed in order for you to slip the shelve into the forge (don't rigidize this pillow). The shelve should now spring up against the top of the recesses. The pillow will lose its springiness after a few heats, but will still help secure the shelve in place.

Grind off the nails, and replace them with...NOTHING!!!

how new is your refractory? Any moisture in the refractory or insulation will leak steam until it is eliminated; that would be consistent with what you are describing; just a thought...

If you change over from a drilled hole to a .023" MIG tip, then you need to change out the 1-1/2" x 3/4" reducer fitting for a larger 2" x 3/4" reducer. Otherwise, the increased ability to induce incoming air will be hampered by an undersized reducer.

However smart you are the more improvements your brain will come up with, right after they are too late to act on; that's what happens to all us other smart guys

Unlike most new burners, this design was never in need of any help to attained a perfect flame, but eighteen years ago it was a radical development, and safety wise I wanted to cover my bets. So, I deliberately avoided three air openings; sacrificing some of their power to keep them running smooth and safe. In those days I expected them to be run as often out in the open air as they would be mounted on heating equipment. That never happened, and no slavering mob of lawyers descended on my doorstep with court summonses. I took a long time to conclude that it would be safe to out the "power of three" I am still as conservative with new burner designs as I was back then, and just as liberal in giving safety advice; when the nasty brown liquid hits the fan is way too late for doing anything but wishing we had a second chance!

If you carefully rigidize the bottom, fire the area with your burner, and then rotate the forge to move another side area to the bottom, and repeat, repeat, repeat, for each layer, you should end up satisfied with the result.

congratulations on the forge design...about the burner; it's running well, but its construction is behind the times. The spindly ribs between the air openings don't have to be tolerated anymore. Just use three air openings, and keep the three ribs between them wide enough to be strong. No reduction of incoming air needs to result. You will no doubt have learned that opening the choke all the way isn't needed to reach a maximum of incoming air. As an engineer, you have probably already computed how much the air openings could be reduced in width and still induce the same amount of air, if it simply means that your burner ends up using the dead area. You not only lose no air induction on the deal but will gain more swirl in the fuel/ air mixture, for a still stronger flame; a win-win solution on this burner design. There have been several refinements since the book was published. You can read all about them in the Burners 101 thread. Frosty is right about your opening; keep playing with the brick; lower is better.

Possibly; more flame of lower temperature will save your refractory but at the price of a higher fuel bill. This is one of those situations, where the only truthful answer is...how does it look to you? Naturally, I would prefer to insist that you get Warmerbrothers hat before watching their cartoons, but wiser heads would give me the raspberry.

The devil was always in the details; whenever we got them wrong, it resulted in another session in front of the infamous stinky fan...

The why behind air entrance design It is all but impossible for your burner to establish a stable flame without swirling the air and fuel gas into a somewhat homogeneous mixture, as they travel through the burner’s mixing tube. Any burner providing a stream of gaseous fuel before the entrance to a cylindrical opening (the mixing tube) will induce air entertainment (via Bernoulli’s principle), a funnel shape behind the gas stream will also provide swirl to the air entering the mixing tube. All linear burners need some type of constricting form mounted at the air entrance, to create air swirl for sufficient mingling of air and fuel gas. Jet-ejector burners create air swirl with the geometry of their side air entrance or entrances. A single entrance will weakly swirl incoming air. Dual entrances strengthen swirl, and triple entrances maximize it.

You can detune that burner enough to save your refractory where the flame impinges on it by simply increasing the amount of overhang the flame retention nozzle extends past the end of the mixing tube; fortunately, that burner's flame will soften as easily as it hardens. Then you can tune it harder a bit at a time, until it threatens your refractory, and back off a touch at that point. It is also fortunate that your forge design provides the maximum distance for the flame to transfer its energy into the refractory face. A secondary flame will need secondary air to be inducted (by the primary flame) through the burner port. something like a flat washer, sliding back and forth on the burner's mixing permits you to control the amount of secondary air into your forge, so you can completely combust a given amount of propane, without an overabundance of air needlessly cooling your forge. Good luck.

Burner technology is a mixed blessing. I think it is driving us to play in the mud

Yes; you desperately need a heat-reflective coating, and Wayne can supply it. Also, choose a burner design with a fairly large secondary flame, because a really hot burner will badly overheat that refractory.