Torch Pointers by Clayton & Lambert
This page was originally available at:
http://www.John-Wasser.com/NEMES/BlowTorch.html

To keep your blowtorch in top operating condition, knowledge of the principles of operation and how to clean and adjust the burner is most essential.

A BLOWTORCH is a versatile little heater and, if correctly maintained, it will give years of efficient service for hundreds of small heating jobs both around your home and in your shop. The mechanism of a torch, Fig. 1, is relatively simple, but it must be kept clean and correctly adjusted.

In operation, gasoline in the tank is forced up to the burner through the feed pipe and generating vein or fuel passage by air pressure inside the tank, which is maintained by occasional use of a small hand pump installed as a part of the tank unit. As the gasoline passes through the generating vein, it is vaporized by heat conducted from the combustion chamber when the torch is burning.

When a cold torch is to be ignited, the burner casting must first be heated by burning liquid gasoline in the priming cup. The gas vapours generated in the vein emerge from the gas orifice and mix with incoming primary air. This mixture passes into the combustion chamber where it ignites and burns, causing a long, blue flame at the mouth of the burner. Secondary air passes into the flame through the heater holes in the combustion chamber to complete burning of the gas vapours.

Two types of burners are used on blowtorches.

The type shown in Fig. 2 has a renewable orifice block and liner and cable in the vaporizing vein. It provides a smooth flame and long-burning life before carbonising.

The type of burner shown in Fig. 3 is of the simplest construction and, therefore, the less expensive of the two. It will give a hot, blue flame and the veins are easily cleaned. Temperature of the flame, Fig. 1, is fairly constant at any given tank pressure for various torch models. However, the volume or size of the torch flame varies.

If the flame is too small and weak in force, open and close the gas-control valve several times to clear the burner orifice. If this does not return the flame to normal, the torch needs cleaning.

Allow the torch to cool before dismantling it for cleaning.

Then unscrew the pump and remove and clean the check valve.

Draw oil into the pump cylinder, as in Fig. 4, to lubricate the leather washer on the pump piston.

Before replacing the pump, rinse out the tank, Fig. 5, with gasoline to clean out any sediment.

To inspect the gas-control valve, loosen the packing nut, as shown in Fig. 6, and unscrew the control valve. Then hold the nozzle to a light and look through the fuel passage. If the orifice is enlarged, the orifice block should be replaced with a new one, if it is of the type shown in Fig. 2. Burners of the type shown in Fig. 3 should be sent to the manufacturer for repairing.

Poor operation often results from carbonization of the veins. To clean the veins, remove the clean-out plugs, Fig. 7, and unscrew the burner assembly from the tank.

A short length of pipe may be inserted in the nozzle, as in Fig. 8, for leverage.

After removing the burner, unscrew the feed pipe containing the wick, Fig. 9.

If the upper end of the wick is charred, it should be scraped clean with a pocketknife, Fig. 10.

The fuel passages, or veins, can be cleaned with a drill turned by hand, as in Fig. 11.

Before assembling the torch, carefully apply brown laundry soap, as shown in Fig. 12, to the threads of each part to prevent leaks.

There's a trick to getting the wick back into the tank. First twist it tightly, and then push it through the feed-pipe inlet with a screwdriver as in Fig. 13.

When the torch is assembled, fill the tank three quarters full with clean, uncolored and unleaded gasoline. Most torches must be turned upside down, as in Fig. 14 to fill.

After checking to make sure the gasoline control valve is closed, pump about 20 strokes of air into the tank for starting pressure, Fig. 15.

The torch can be tested without lighting it by pointing the nozzle toward a container and opening the control valve. If a small stream of gasoline sprays out as in Fig. 16, the torch will burn when properly generated.

To start a cold torch, open the control valve slightly to allow gasoline to flow slowly into the priming cup until about three quarters full. Some torches, Fig. 17, are equipped with a priming valve for this purpose.

Then ignite the gasoline in the cup. The burning gasoline, Fig. 18, will heat the burner casting to the generating temperature.

When the gasoline in the cup has nearly burned, open the control valve. Often the torch will light itself from the priming flame. If not, hold a lighted match close to the heater holes or just below the nozzle as in Fig. 19.

An intense blue flame should result. A yellow flame indicates the burner has not been properly generated. When this happens, shut off the torch and allow it to cool, then fill and relight the priming cup. To increase the flame volume, regulate the control valve and increase the air pressure in the tank. After shutting off the torch, back out the control valve one-eighth turn to prevent jamming when it cools.