Concept
A fire piston, sometimes called a fire syringe or a slam rod fire starter, is a device of ancient Southeast Asian origin which is used to kindle fire. In Malay it is called "gobek api" . 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. Sizes range in length from 3 to 6 inches (7.5 to 15 cm) with a bore about 0.25 inch (6–7 mm) in diameter, to 10 to 14 inches (25 to 35 cm) with a bore about 0.5 inch (14 mm) in diameter. A piston with an airtight circular seal is fitted into the cylinder. A string packing lubricated with water or rubber gasket lubricated with grease is used to create an air-tight but slippery seal. At the end of the piston a small cavity is made, where tinder can be inserted 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 The piston can be completely withdrawn from the cylinder for installation or removal of the tinder.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 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 The piston is then quickly withdrawn, before the now-burning tinder depletes the available oxygen inside the cylinder.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.
