A fire piston, sometimes called a fire syringe or a slam rod
fire starter, is a device of ancient origin which is used to kindle fire. It
uses the principle of the heating of a gas (in this case air) by rapid and
adiabatic compression to ignite a piece of tinder, which is then used to set
light to kindling.
A fire piston consists of a hollow cylinder sealed at one
end and open at the other. A piston with an airtight circular seal is fitted
into the cylinder. Rubber gaskets, or grease are used to create an air-tight but
slippery seal. At the end of the piston is a small cavity, where tinder can be
attached without it being crushed during subsequent operations. The piston can
be completely withdrawn from the cylinder for installation or removal of the
tinder.
The piston (or cylinder) has a handle on the end to allow a
firm grip to be applied to it, or a large enough surface area to strike it
sharply without causing pain, while the cylinder (or piston) is braced or
slammed against a hard surface.
The compression of the air when the piston is quickly forced
into the cylinder causes the interior temperature to rise sharply to over 400 °F
(260 °C), the autoignition temperature of tinder. This is hot enough for the
tinder on or in the piston face to ignite with a visible flash that can be seen,
if the cylinder is made of translucent or transparent material. The piston is
then quickly withdrawn, before the now-burning tinder depletes the available
oxygen inside the cylinder. The smouldering tinder can then be removed from the
face of the piston and transferred to a larger nest of tinder material. The
ember is then fanned or blown upon vigorously to create a flame, at which time
various stages of larger kindling can be added until built into a full-scale
fire.
Ancient and modern versions of fire pistons have been made
from wood, animal horns, antlers, bamboo, or lead. Today, fire pistons are
commonly constructed from wood, metal, or plastic.
Principle of operation
Rapid compression of a gas increases its pressure and its
temperature at the same time. If this compression is done too slowly the heat
will dissipate to the surroundings as the gas returns to equilibrium with them.
The same principle is used in the diesel engine to ignite
the fuel in the cylinder, eliminating the need for a spark plug as used in the
gasoline engine. The principle of operation is closer to the hot bulb engine, an
early antecedent to the diesel, since the fuel (tinder) is compressed with the
gas, while in a diesel it is injected when the gas is already compressed and at
the high temperature.
The tinders that ignite at a very low temperature work best.
Easily combustible materials such as char cloth or amadou work well as tinder,
and can hold an ember. In contrast, cotton fibers ignite at 455 °F (235 °C) and
will flash brightly but do not hold an ember. The bright flash of light is
sufficient for demonstration purposes, but will not start a persistent
fire.
History
Fire pistons have been used in South East Asia and the
Pacific Islands as a means of kindling fire for many years. They are found in
cultures where the blow pipe is used as a weapon and this suggests they may have
developed out of blow pipe construction. Their use has been reported from Burma,
the Malay Peninsula, Indo-China, Borneo, Sumatra, Java, Kalimantan, Sulawesi,
the Philippines, Madagascar, and South India.
An 1876 New York Times article reported the discovery of the
earliest date of its use in the west. It reported on a talk by a Professor Govi
that described a book written by Father Boscovich, of Rome in 1755, De
Litteraria Expeditione per Pontifican Ditionem, (The Clever Mechanism) which
made the claim that the fire piston was invented in 1745 by Abbe Augustin Ruffo.
The report also claimed that the modern fire piston was reinvented independently
in the west through experiments with the air gun, and not modeled after Asian
designs.
It is recorded that the first fire piston made its wider
debut in front of scientists in 1802, and was patented in 1807 simultaneously in
both England and France. Fire pistons, or "fire syringes" as they were called
then, were popular household tools throughout Europe during the early nineteenth
century, until the safety match was invented in 1844. The fire piston may have
inspired Rudolf Diesel in his creation of the diesel engine around
1892.
- From wikipedia
