Contents:

Venturi Style Burner

Burner
Hose Assembly
Performance
Parts List

Mongo Style Burner

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The Venturi Burner

Design Consideration

Since the objective was to melt aluminum in a small furnace, the burner size and design  had to be consistent with that objective. There are successful designs for burners on the internet, so I used one of them (the venturi style) as the basis for my first burner. Venturi style burners don't need a blower to provide air to mix with the propane. The propane gas coming out of the jet pulls air into the burner barrel (venturi effect) and works well for a burner this size.

BURNER:

The first thing that I did was draw a sketch of what I thought I wanted to build. I wasn't sure how big to make the burner since the furnace wasn't going to be very big. Once I decided on one inch black pipe for the burner body, I put together a parts list. The venturi is a 1 1/2" X 1" pipe reducer. A short piece of 1 1/2" pipe has been drilled with a hole to hold  a piece on 1/8" nipple perpendicular to the burner body. The jet is a hole drilled in the pipe nipple with a #60 drill. I bench tested the burner by inserting the body inside a piece of 1" X 1 1/4" pipe to reduce the velocity of  the gas as it came out of the burner. As it turns out, the #60 hole is o.k. for this size burner.  

Connecting the burner to the Propane Tank: The Hose Assembly

The hose assembly serves two purposes: to connect the burner to the propane tank and to control the rate that the propane is delivered to the burner. The hose assembly consist of a regulator (0 to 20 psi.), a pressure gage (0-30 psi), a eight foot gas hose, a gas cutoff valve and miscellaneous brass connectors. The regulator connects to a propane tank and the cutoff valve connects to the burner. All the connections are sealed with #5 Rectorseal soft set pipe dope. 

Performance inside the Furnace:

The burner has proved to be an excellent fit for the freon furnace. The burner will melt a crucible of aluminum in less than 15 minutes with the regulator set at 2 1/2 psi. I should be able to use it in a larger furnace or to melt bronze or brass.

The Mongo Burner

I haven't provided any construction notes or parts list for this burner. The design comes from Ron Riel's website and I used off-the-self components, with no effort to duplicate the dimensions of the plans on his site. The burner shown in the following pictures was constructed early this year (2002). The feature unique to this burner is the flame holder (see below) that I added. This burner will stay lit outside the burner without a flare. No need to worry about getting the proper taper that is required in a flare. The flame holder doesn't need a taper. The pictures show several different configurations, since the parts are interchangable.

This mongo burner is shown with a long barrel and flame holder. The barrel is made from 3/4" black pipe. The parts are, left to right: jet assembly, air intake (red), barrel (blue) and flame holder (black). This configuration did not produce enough heat in the freon-bottle furnace to bring aluminum to pour temperature in a reasonable time.

At the left end of  jet assembly is the quick connector (male) to the propane gas hose. The jet itself is made from a nipple cap, drilled with a #60 drill.

This is another configuration with a short barrel
(1" blackpipe). You can see the air intake assembly (red) and choke. This burner blows and goes, even without a flameholder.

This is a test burn of the burner with a 3/4" barrel and a flame holder. The flame can be adjusted with the choke.

At some point, I will test the mongo burner with a 1" barrel in my furnace. I expect that it will produce enough heat to melt aluminum without any problem.

August 30, 2002