Page 40 - Moving the Earth_ The Workbook of Excavation

LAND CLEARING AND CONTROLS

1.40 THE WORK

A danger in transition from the hand-tended fire to the roughly piled one is that the untrimmed
brush may include so much airspace that the heat cannot cross it effectively. The fire may burn a
dome-shaped hole over itself, then die down. In such a case, sticks should be poked into the fire
itself to build it up, and the brush over it should be compacted by rearrangement or piling on of
heavy sticks. This is tiresome work and may fail. It is better to tend the fire longer before piling
on loose material, to be sure it will not have to be worked over afterward.
Artificial Helps. Old tires provide excellent material for starting a fire. Trimmed brush can be
piled on them as soon as they are burning.
A dying fire may be pepped up by use of kerosene, fuel oil, gasoline, or similar fluids. To be
effective, these must be applied at the base of the pile. Because of its explosive qualities, gasoline
should be applied only as a stream from a blowtorch or similar pressurized device with a fine nozzle,
and only when it burns as it is ejected. If it does not burn, it may accumulate in sufficient quantity
to cause an explosion.
Putting flammable fluids on the heap itself may produce a fine flame, but it will have little kin-
dling effect, as the evaporating fuel will absorb the heat that radiates downward.
Flame guns produce a hot flame up to 20 inches long. They are effective kindlers when directed
into the base of a pile.
A brush burner is a portable unit that combines a heavy fan to direct a strong wind into a pile
being burned, with a mist of fuel oil for kindling. Few piles can resist one for long. See Fig. 1.32.
If the fire dies down in spite of nursing, it may be best to build a new fire nearby, with greater
care to avoid airspaces and coarse, green wood early in its life.
Transferring Embers. Once a good fire is burning on the job, its embers may be shoveled out
and used for starting other fires. This should be done rather frequently, as a long brush carry adds
greatly to labor costs.

FIGURE 1.32 Brush burner.