Let me start by saying working as a carpenter for years I built many concrete forms and my question is this: Should there be any reinforcement wire (such as lath screen) in or on the outside edge of my castable to help bind it together. I was worried that as I vibrate it without the screen the weight may crush the wool to significantly less than 2” towards the bottom. The screen would bind it to a set size. Here’s a picture of the screen. Maybe it’s better off without it. I’m sure someone has tried it. Let me know how it worked out and if I should stay away from it or not. Thx
No. But most people use cardboard concrete casting tubes as a mold to cast both the inner and outer walls. Lot's of examples here on the forum. The concrete tubes are only water proofed on the ID so one will need to be waterproofed on the OD with this approach. Best, Kelly
The main concern would be the mesh expanding differently than the refractory and causing it to crack... Maybe on the outside edge of the hotface you would be safe, but I would not risk it. I used aluminum flashing for the outer form and removed it before adding the insulation, but I guess you could just leave a sono tube in place to burn up eventually. Tip: Measure your sono tunes before you buy them; the nominally sized tubes are shipped nested together like russian dolls, so they are all different diameters regradless of what is marked in them. Borrow a tape measure from another aisle if you forget to bring yours. Make sure you mold the tuyere hole into your hot face too, as drilling one out later won't be any fun! Good luck. Jeff
.......and, if the tubes available aren't the exact size you want, they can be reduced in diameter by up to 10-15% and still stay round by just using a razor knife to cut out a section. Then use filament tape on the joint. The diameter will be reduced by the width of the segment removed divided by 3.14. Best, Kelly
Good to know. Went and shopped all the materials today. With this info in mind looks like I’ll have a few returns. I do plan to cast the tuyere larger than I need. Do you think 2” is big enough? I’m starting out with propane because I sell it at work and I get it at cost but the diesel burners intrigue me more and more so I may land there at some point.
2inch is fine for the tuyere. 3 would be better, but I welded a 2inch pipe on the side of my tank. I used PVC to cast the shape in the refractory. When it comes time to remove it, hit it with a torch and melt it out.
I picked up a section it 2” black pipe today to attach to the outside as well. It’s as big as could get locally.
That should work. Here is some photos of mine that might help you out. I used exhaust pipe from the auto store. This way the burner just slips in. Seems I remember I welded the outside exhaust section first on the tank. Been awhile. Mine is kaowool with Mizzou refractory.
You can order 3 inch pipe from ebay cheap, but I suppose if it's installed already its a 2 incher for the win
