Orifice Size for Propane Kiln?

[Polydeuces]

Hey y'all—I've been working with a propane kiln for the past year with mixed results. The orifice size I had drilled was (I thought) too large—it's a homemade burner out of black iron pipe. I had actually closely followed the High Bridge fellow in making it, since it seemed to work out pretty well for him.

Anyway, I recently acquired the means to drill a much smaller hole, like tiny—1/32". The previous orifice was (I think) 1/16".

So, when running it with a squirrel cage fan it *really* seemed to struggle to climb. It looked weird, sounded weird. I was just calcining some dry material as a test run, and wound up breaking the bisqueware that was containing it in the effort to push it up to △020. With the larger orifice, I felt like I could go easier on the pressure and it wouldn't struggle against the air as much.

I had the fan intake completely covered, and *also* tried putting a piece of cardboard partially between the fan's output & the burner's air-intake end.

So for now, I'm planning on drilling the hole a size larger (5/64") and seeing how that goes. But maybe I'm thinking I should just stick with the old orifice. The only issue I had was that in reaching higher temperature (△6) the pressure required would often cause the flame to "splay" against the bottom of the kiln, which made me think I might have been doing it wrong.

I thought that in the world of burner/torch things, you wanted the smallest orifice you could get—but I'm struggling to find the practical reasoning behind this, at least in my experience running it today. It felt like I had to shove the flame up into the kiln in order to get it to climb, and with a larger orifice I felt like it drifted or was "pulled" a little better, perhaps.

I hope I'm just doing it wrong. Would love y'all's input and to hear what you have to say about it. Thanks!

[Rex Johnson]

I have two squirrel cage burners, if I remember right I drilled 3/32" holes in my crosspipes fpr propane.

Post some pics of your burners and your kiln interior, bagwalls, flue, etc.

It might be more than just the orifice.

I know this is not an answer, but here's a good read: http://www.wardburner.com/orificesmessing.html