You will have to make a fitting for attaching the hose at the dust-bag outlet and arrange the cleaner so
that air can enter at the suction end.
At the torch, a gate of sheet metal is arranged to regulate the amount of air entering the mixing tube. You
can also reduce the airflow by reducing the speed of the blower. A simple light dimmer found at any
hardware store would do the job very good if you have a DC blower motor.
The fuel is supplied through a rubber tube of a size to fit the supply pipe and the fitting on the torch. You
should have a 1/4 inch needle valve to adjust the gas to air mixture. Using Butane or Propane from a
5-gallon bottle works better as there may not be enough pressure from natural gas. If you use butane,
make sure all your fittings, and hose are for high pressure.
It has rubber ends that will fit on the gas nipples at each end. Any other good rubber tube can be used,
such as a 3/8-inch garden hose. The mixing tube must be long enough so that the gas and air are
thoroughly mixed by the time it gets to the burner end.
Artificial gas will burn at the end of a plain mixing tube, but for natural gas there must be a special tip on
the burner end to maintain the flame, or else the air blast will snuff it out.
This special tip consists of a jacket fitted around the end of the mixing tube with several small holes
drilled into the mixing tube. This gives a low-velocity supply of gas and air to the jacket.
This will maintain a small circular flame around the end of the mixing tube, which will keep the mixture
ignited as it comes out of the end of the main burner tube.
The air blast tends to blow the main flame so far away from the end of the mixing tube that it will mix with
so much outside air that it will no longer be a combustible mixture and will be snuffed out. This annular
ring of low velocity flame surrounding the outlet of the mixing tube will keep the main flame ignited unless
so strong an air blast is used that the entire flame is blown away from the end of the mixing tube.
When you start up the burner, shut off the gas until you have the air adjusted, and then slowly turn on the
gas, while holding a lit Butane torch over the opening of the furnace. It is best to reduce the air blast until
the gas is ignited and then slowly open it until the desired flame is obtained. The flame should burn with
a firm blue center cone, and the hottest spot will be at the tip of the blue cone. A yellow flame is not as
hot and is very sooty. After the bricks of the furnace have become well heated, the air blast may be
opened a little farther, and the blast will thus be increased.
The flame from this torch is very hot and will heat steel to a white heat for forging, but it is not hot enough
for welding, however a supply of oxygen for the air intake will increase the temperature.
Get a large enough cement drill to drill a hole through the firebrick about 2 inches from the top. The heat
sensor will fit in there. I find a short length of iron pipe that is large enough on the ID to allow the sensor
to fit inside. This pipe is then mortared in place. See Drawing.