Propane Burner Query

[///]

Hi guys,

Years and years ago(10 maybe), I built myself a small furnace.
The only fuel I had available to me at that time was BBQ heat beads with a blower. This worked well but as many of you know it is messy when the ash vitrifies into a hard glass like substance. This was very difficult to remove from the furnace floor/walls and would damage the refractory.
I used it a couple of times for some simple aluminium castings, but due to the mess I tired of the heat beads and then it went into storage while I made a propane burner, which never got finished.

I am starting to build a Kerzel Hit&Miss engine and would like to cast the flywheels in brass/bronze.

I purchased a propane torch kit the other day(Primus/Sievert Tradeflame) for silver soldering needs for another project and noticed there was a large-ish burner available for the torch.

The burner has a diameter of 25mm(1") has gas consumption of 550g/Hr (~ 1.2lb/Hr) and a claimed power of 7 kilowatts, which according to an online calculator is equivalent to approx. 24,000 BTU's.

My question... how well will this burner work with my furnace, which is(from memory.. it is currently burried under crap in the shed) about 8" Internal diameter, approx, 12" high with an approx 2" exhaust hole in the lid. The floor,walls and lid are about 2.5" thick castable refractory (which was very expensive!)

While I'm reasonably confident I could do ali .... what are my chances with brass/bronze?
I would test it, but I'm still waiting for delivery of a couple of crucibles.

Cheers,
Simon

 

[///]

Here is a screengrab from the Seivert catalogue:

 

[///]

Sorry, three posts before a reply.
Have just dug the furnace out from the shed, it is:
180mm (7") internal diameter,
250mm (10") internal height,
60mm (2.3") thick walls.

The refractory was purchased from an industrial furnace manufacturer, I bought two 20kg bags and used one and a half of them, so about 30kg(65 lbs) went into the furnace. I struggle to move it around.

Cheers, again.

 

[hi speed scrap]

from 1 strayan 2 anuva,
perhaps all the melters are melting, just
to keep warm this weekend, fingers too cold to type!

Cheers, from broneya.
Dave
PS. someone will be along soon!

 

[old-and-broken]

Since no one has spoken up yet...

Your propane burner can reach somewhere close to 2000º C. Most all brass and bronze alloys melt around 1000º C. Even cast iron and steel alloys melt way below 2000º C
The real question is one of insulation. How well does your furnace retain the heat. This will determine your ultimate success or failure, and also how big a charge of metal you can melt.

Add pure oxygen to the torch flame and you can reach nearly 3000º C and proceed to fuse your insulation.

 

[chipenter]

I have a set of old Sielvert burners the 1 inch one has a flame of about 5 inches long , with the regulator at max and the torch on full , and it melts silver solder without a hearth on my 3 inch by 16 swg boiler yesterday.

 

[kiwi2]

I'm not sure if this is useful information for your project or not but I used one of the seivert burners for melting out the crap from the back of a big glass furnace. I think it was about a 2" burner. The area I wanted to heat was way too hot for the burner to be exposed to so I attached about a meter of 2" stainless tube to the outlet of the burner turned on the gas and gingerly applied a match to the end of the tube. It worked a treat with a normal flame coming out of the end of the tube with no backfires.This may be useful for getting the flame into your furnace.

 

[abby]

Simon you need forced air , a self blowing torch will not work in an enclosed space such as a furnace or kiln.
In practice all you need is a piece of steel tube,
The air from your blower , shopvac or whatever , goes in one end , the propane feed comes in around 2 or 3 inches from the air inlet.
The mixed gas/air goes into the lower furnace area at a tangent to the walls.
Nothing special required just some way of controlling the gas/air mix.
1200°C can be reached easily with propane , a little more advanced burner and kerosene/diesel can be used to melt iron.

 

[///]

from 1 strayan 2 anuva,

G'Day Dave!

Your propane burner can reach somewhere close to 2000º C. Most all brass and bronze alloys melt around 1000º C. Even cast iron and steel alloys melt way below 2000º C
The real question is one of insulation. How well does your furnace retain the heat.

Cheers! I had read recently read that propane burns at a temperature of 1980 degC in air, but didn't really put much thought into it.
With the refractory (insulation) I have, the furnace used to get pretty hot on the outside. Too hot to touch, yes, but nothing too crazy. The furnace was cast inside an old 25 litre drum and there are old paper stickers on the outside which haven't discoloured from heat.
I have seen electric kilns (for ceramics) about twice the volume of my furnace with a similar wall thickness and they get up to 1300-1400 with around 4.8kW (20A @ 240V) input.
If this burner is indeed equivalent to 7kW, I should be good to go.
Thanks for getting the grey-matter working

I have a set of old Sielvert burners the 1 inch one has a flame of about 5 inches long , with the regulator at max and the torch on full , and it melts silver solder without a hearth on my 3 inch by 16 swg boiler yesterday.

Excellent. I wondered about a regulator... but I think this kit is supposed to work without one. Sievert/Primus also sell a POL to 3/8 LH adaptor which connects the torch hose directly to a 9kg Propane bottle. I grabbed one as the 9kg bottles work out far cheaper than any other option.

I'm not sure if this is useful information for your project or not but I used one of the seivert burners for melting out the crap from the back of a big glass furnace. I think it was about a 2" burner.

Actually, that reminds me... I have a 2" burner somewhere that someone gave me. I didn't know what to do with it at the time but I think it might just screw onto this torch... will have to try and find it now.
Tho it is sounding as though the little 1" one may do the job.
I will find out tomorrow

 

[aonemarine]

I use a 3/4" reil burner in my small furnace. Without the blower it melts bronze without issue, but to reach cast iron tempatures the blower is required.
[ame]http://www.youtube.com/watch?v=X-dEjZiPJL8&feature=share&list=UUSrlSdQ3dLlHlahmmmYbb2A[/ame]

 

[///]

I use a 1" reil burner in my small furnace. Without the blower it melts bronze without issue, but to reach cast iron tempatures the blower is required.

That is awesome news, Cheers!
Cast iron is not on the radar... yet.
But I have a blower for when that day comes Thm:

 

[chipenter]

Did some more work on my boiler today , I am running low on gas so turned my foundry on it's side, clamped the 1 inch torch to the drain hole in the bottom and used my 16mm cyclone burner at the other end , worked fine as I only put the burner in up to the air holes , so I would say it will melt bronze .

 

[///]

Hey now there is a good idea! Dual purpose furnace/hearth.. brilliant.
I was about to weld up a trolley today to allow me to wheel the furnace around, with a foot pedal to lift and rotate the lid.
Now I'm thinking ways to build in a lockable 'tilt' mechanism to lay it flat for use as a hearth. Hmmmm.

Overnight I had also been thinking about using two torches like you have just mentioned. One to keep the work warm (maybe the 1" on low flame) and another torch with a pencil flame for the actual soldering.
Will have to search for a manifold with 3/8 LH fittings.