Propane tank/fueled furnace build

Interesting, seeing as it's same manufacturer as Satanite.

 

I think most people bought it from Hightemptools. Never heard Budget mentioned unless I missed a post on it.

 

Attached

 

I picked up two bags of the Kastite yesterday. It is obvious that there are many ways to build a working furnace and I think most work with what they have access to. So as much as I found a supplier of a material like Satanite, I still need the insulation. But I also found a nice big bag of Perlite yesterday locally. So I think I would like to try my first furnace with the castable and perlite...I have it all already, and an 8" sonotube. Ratios I have read are 4:1 perlite to castable, but also, as Billy did, some just use all of the refractory so I would guess any ratio in between should be good....?

I would think, the more perlite, better insulation but harder to work with and weaker. Less insulation, easier to work with or even pour? Does that sound reasonable or have I misconstrued all of the reading I have been doing.

I do think the insulation and Satanite is the "better" way to go, but I would also guess there are more furnaces in my future cause I like building things. And a friend will want one....

Thoughts? Input?
Thanks everyone
Shawno

 

I would just use castable and try it out. Think you will find you dont need anything else, but if you feel like you do you can always go back and do a hot face coating. I over heated my brass and was probably close to cast iron temps with mine at less than two inches thick and the outside of the furnace didnt have any hot spots or glowing red spots. I doubt you will even get the outside of the tank hot at aluminum temps with 2" of castable.

 

Not sure but that sounds kind of condescending.

 

Well alrighty then... I understand what you are saying but I think you missed the point I was making. I was double his temp with less than two inches of refractory and had no hot spots or issues...with nearly the same setup he is building.....meaning at aluminum temps he will be fine with two inches of refractory. He is having issues getting the materials that are so easy for us to get here is the only reason it was mentioned. He doesnt need to waste time waiting on hard to get items when what he has will work fine for what he is doing. Just trying to make his life easier and probably save him time and money.

 

Solid castable refractory is definitely less effecient than wool and a coating....unless you are doing multiple melts in succession in which the solid refractory will hold higher temp much longer reducing the time of the following melt considerably. That comes in pretty handy if you only have a few flask or jackets to pour with and are making multiple castings. I think most people usually just do one melt at a time. I did four the other day and each time the melts came quicker and quicker...hence the reason I over heated the brass and probably reached cast iron temps while making new molds to pour..apparently I mold much too slowly.LOL

 

Yes Kelly, that is the direction I was leaning for sure cause I think that is the best way, given materials availability. but, as I am finding some stuff locally, and learning a little more, I am starting to compromise a bit (or getting a bit impatient to start building. .. ), I am changing my plans a bit. Sorry for confusing those trying to follow my zig zag thought processes...welcome to my Wife's world....

I read somewhere that the perlite melts, leaving air pockets, which work as insulation so I thought this process would be a second choice compared to the satanite/ceramic insulation method. Hard to keep all this information straight.

In one of your other posts, you suggest an outer wall of the perlite/refractory mix with an inner hot face. I am really liking this! I think I would pour the outer insulating about 1 1/2", then line it with about a 1/2" solid refractory casing. Does that sound reasonable? Would I have any separating concerns/dramatic cracking with the two different compositions abutting each other? I read that it all cracks a bit so those are ok. Falling into the middle might not be so good. I would be fine with Billy's style too, but I think the perlite improves it a bit by adding an insulation factor. No offense Billy.

I checked steel stock and plans so can start building the cart/furnace stand at least. Won't be mixing refractory for a while yet. Need to build version 2 of the burner too.

Thanks all

Shawno

 

Well, I figure I can't do anything with what ever refractory/insulation recipe I go with until I have a place to put it so I might as well work on the furnace housing/cart. Made pretty good progress the last couple of days, I think. I am trying to use up stock I have rather than go buy more stuff....need to make room. So far, all good.

Tomorrow, I will make the hole for the vent (currently just the old valve fitting ). From the Metal Casting book, it suggests 2.5". And the drain hole about 3/4" so I will need to make the vent hole bigger and the drain hole that I have, smaller. Then I will get back to the burner experiments so I can decide the size of the tuyere and lay it out.

 

Back to experimenting with burners today.... I made up a spread sheet to consolidate (Organize? Simplify?) the data I have been reading. Or, actually, chart the ratios data below, quoted from the book referenced. The #57 drill bit suggested by Zapins is a .043 bit and according to the data in the Metal Casting pdf common on line (and the sticky of this forum), it should work with the 3/4" pipe. Off to test the theory. And make burner version 2


Nominal pipe Actual id Venturi min Venturi max Orifice min Orifice max Burner length Flare length
Half inch 0.642 0.899 1.091 0.021 0.032 6.420 0.963
3 quarter inch 0.85 1.190 1.445 0.028 0.043 8.500 1.275
One inch * 1 1.400 1.700 0.033 0.050 10.000 1.500
1&1 half inch * 1.5 2.100 2.550 0.050 0.075 15.000 2.250
* not yet measured precisely

Apparently, the nice columns I had do not work in a paste ...sorry. It looks kind of jumbled...I can attach the spreadsheet if anyone is interested.

"The burner detailed here has a bore of 1/2” (nominal), and a practical output between
approximately 7,000 and 74,000 BTU/hr. This design can be scaled up or down as needed,
as long as the proportions between the various parts are kept roughly the same. Here are
some rough ratios in the sizes of the components:
The venturi inside diameter (ID) should be from 1.4 to 1.7 times the burner ID.
The burner ID should be 20 to 30 times the orifice diameter.
The burner tube should be roughly 10 times as long as its ID.
The flare length should be about 1.5 times as long as the ID." (Reference “The Hobbyists Guide to Casting Metal” )


From experience, do burners, generally, fall within these parameters?