question about temperature build-up on an atmospheric burner

[nogrodoth]

Hi, im new here and in the process of making my first gas forge, using the instructions for a ammo box forge i was directed to at forgemonkeys.com. I've seen the design mentioned a couple times here, and i guess this question really applies to gas forges in general, but how hot does the top end of the burner get under use? The picture at http://www.forgemonkeys.com/projects/ammo-can-forge shows the burner hooked up right to a propane regulator hose i think, apparently without heat damage, yet the pipe flange 8" below (according to the site it was origanlly galvanized steel) is looking like the coating was burnt off. Is heat build-up at the top of the burner something i should plan for, or is it not significant?

[jcornell]

The mixer end of an atmospheric burner is actually quite cool during operations.  The flare end is another question.  After you turn the burner off, it tends to act as a chimney and a lot of heat creeps out and up (especially when the burner is vertical as with the ammo-can forge).

 

Galvanized propane forge pieces should be pickled - put some water in a plastic pail, pour in muratic acid (always add acid to water, not the other way around), drop in your galvanized piece.  It will bubble for a while - when it stops bubbling, the galvanized coating will be gone, the water will be sludgy black, and wherever you parked the pail will stink.  The bubbles coming off the solution should be  hydrogen if my high school chemistry is remembered correctly, so this is something good to do where there's no danger of sparks or other flames.   Neutralize your waste acid solution before you dispose of it - I add a bunch of baking soda.

[swedefiddle]

The top of the burner is drawing in cold air, it will be cold. There shouldn't be any heat in the burner until close to the forge. If there is heat in the burner body, that means than the flame front is moving back up the pipe. NOT GOOD. The flame should be at the opening of the forge wall, not inside the pipe.

 

You can build a forge with stacked fire-brick, floor, walls, ceiling and using brick to control the open ends. It is not magic.

 

That kind of burner needs the propane jet at the center of the pipe and pointed directly down the pipe. You can loosen the thumb screw and adjust it to get the best burn, you will hear it when it is right.

 

Neil

[nogrodoth]

Thank you:) that's really helpful
hopefully ill be able to get this going soon

[ThomasPowers]

Note too that having the burner located above allows a better chance to recycle exhaust fumes and so increase carbon monoxide production.