Gloryhole build

[Guzzep]

After a 5 year hiatus from glass blowing ... starting again with building my gloryhole... next project... wire melter

 

[charles excee]

Welcome back to the craft! Your build shows a clean and methodical approach. The thick refractory wall in the main chamber should provide excellent thermal mass and stable operating temps. Your forced-air burner assembly looks robust and should provide all the BTUs you need for efficient heating. What are your target operating temp and the specs on your blower motor, like its CFM rating?

I look forward to seeing the design for your wire melter project next.

 

[Guzzep]

Target temp would be about1100c, and I've got a 255cfm blower, haveing a problem with my burner head, and need to do som more experimenting, burns well outside but suffocates in the hole, I think i need to increase the holes nearly double

 

[Guzzep]

Burner

 

[charles excee]

Thanks for the specs. A 255 CFM blower should be adequate for a standard gloryhole. The flame suffocating inside the chamber often points toward a back pressure issue rather than a problem with the burner head itself. What are the dimensions of your interior chamber, and more importantly, what's the diameter of your exhaust flue? If the exhaust port is too small, it'll choke the flame regardless of your burner's output.

 

[Guzzep]

The furnace is 60 cm deep and 30 cm in diameter with a 23 cm mouth. While you make a fair point about the 40 mm exhaust, it shouldn't matter yet because the doors aren't installed. I suspect backpressure in the burner head: I currently have 18 × 7 mm ports, and even with the blower vent closed I still had to close the gate valve to about three-quarters. After some research and calculations, I think I need 30–35 ports. I'm also concerned about the propane orifice—it's only 1.2 mm, and I had to raise the pressure to 2 bar; it should work at 0.5 bar. The last glory hole I built about ten years ago was square and used a Pine Ridge burner; I didn't even have an exhaust then, though I did have a very powerful blower of about 3,500 CFM.

 

[charles excee]

I appreciate the detailed specifications. You're correct, with the doors off, the main exhaust flue would not be a factor in choking the flame. The need for 2 bar of pressure on a 1.2mm orifice suggests your gas velocity is extremely high which can destabilize the flame front. Have you considered enlarging your propane orifice first to achieve a stable burn at a lower, more conventional pressure?