Figure 23.
Gasoline blowtorch.
b. Filling the fuel tank. To fill the fuel tank, the torch is turned upside
down and the filler cap unscrewed from the bottom. The tank is filled three-
fourths full, thus allowing sufficient space to build up the proper air pressure
above the fuel level. (White or unleaded gasoline should be used as fuel in
blowtorches.) The cap is then replaced tightly and the torch set upright. A tank
pressure of only a few pounds should be pumped in by operating the pump handle
approximately 30 strokes for starting purposes -another 10 strokes are added after
lighting.
c. Igniting. Before lighting the torch it is necessary to preheat the
burner. A little gasoline should be run into the drip cup directly under the
burner by opening the flame adjuster valve and holding a flat object against the
mouth of the burner for a few seconds to prevent gasoline from escaping by
directing it into the drip cup. The flame adjuster valve is then closed (all
excess gasoline should be wiped off the torch with a rag) and the gasoline in the
drip cup ignited. It is important for the torch not to be in draft so that the
preheating flame will be concentrated on the burner. Just before the flame in the
drip cup burns out, the needle valve must be opened slightly (by turning the flame
adjuster valve wheel) to allow gasoline to enter the heated burner; this causes the
liquid gasoline to vaporize as it enters the burner and produce a hot flame. A
steady blue flame is desired (insufficient preheating of the burner is indicated by
an irregular yellow flame). While the blowtorch is in operation, the air pressure
in the tank must be maintained to insure a forceful operating flame.
139
Previous Page
