Frosty T Burner help needed

[Hunted1]

As a first step putting together a forge, I decided to build a Frosty T Burner. Actually, I decided to build three of them. I had a few issues during the build phase mostly because my drill press is small and I had a hard time getting bits in and out while keeping everything aligned.

In test firing the burners, one of the three runs well. The other two have the same problem where they will not stay lit. I am running at 5 psi and testing one at a time. I have a 0-30 psi regulator hooked up to a 20 lb tank. I am using .035 mig tips that I have cut down. Everything seems pretty straight, but my eyes (and camera skills) aren't so great.

I could get the two bad burners to hold a flame if I choked the air intake by 50%, but then the flame was blue and whispy. Also removing the flare and cutting the propane flow back gave just a small flame. Increasing the propane just blew it out. I tried long and short mig tips, but the results were always the same.

I appreciate any feedback!  Thanks!

Here is the one that runs:

Here are the ones that don't run properly:

 

Here is my general testing setup:

 

[Anthony.Matson]

What size pipe are you using? What are the lengths of the nipples? What is the gap between the mig tip and the nipple(not to the T)?

Threaded pipe uses NPT threads, which are tapered. They have a tendency to not screw together all the way because of said taper.

[Hunted1]

Anthony,

I am using 1/4 NPT fittings for almost all the connections (ball valves, four-way) and 3/8 flares for the hoses. I have a 1/4 NPT to 1/8 NPT hex nipple threaded into the top of each T. Inside the 1/8 side, I drilled and tapped 1/4 28 and screwed in the mig tip. I used LP rated pipe dope on all of the connections and tested them for leaks (I had missed one). The nipple just barely pokes through the T. Let me know if I missed something.

Thank you for questions!

I forgot a few dimensions. The burners are 1" x 3/4" Ts with 6" nipples and the flares are 3/4" couplers

[Anthony.Matson]

I am not too familiar with propane forges, but I have some experience with pipe.. I could be wrong, (and please someone let me know if I am) but it sounds like you are pulling too much air.

Do you have a machinist scale(rule)? If so, measure the distance between the mig tip and the pipe nipple from the inside. The distance between the two is important, as is the length of the pipe nipple(threaded end to threaded end).. but all of this is dependent on the Inside Diameter of the pipe.

[Hunted1]

All of the nipples measured 6" overall with an ID of 3/4". On the burner that works, the distance from the mig tip to the start of the nipple in the T was 2 1/16". The other two measured 2 1/4" and 2 1/2". I did try an uncut mig tip, which obviously was way too long.

[Buzzkill]

Without a good flare on the end of the mixing tube, a properly assembled and tuned T burner will not stay lit outside the forge at normal operating pressures.  The flame will blow off the end of the mixing tube.  If you want to use an easily obtainable pipe fitting for a flare then try a 3/4" to 1" or 1 1/4" reducer on the end of the mixing tube.  These are not really ideal flares, but they may allow you to do some testing outside the forge.  A forge provides some needed back pressure for these burners to function without flares.  Even inside the forge sometimes the flames will blow off the end of the burner until the forge starts getting hot.

[Anthony.Matson]

I didn't think about back pressure.. that is a good point, Buzzkill.

Food for thought: based on the T burner plans, the correct depth of the mig tip when using 3/4 ID pipe should be 2.25 inches.. and in such a small volume system 1/16" is a lot. You could try setting the distance between the mig tip and the nipple to the same measurement for all 3 of the burners. If nothing else it will give you consistency in your flame.