By Andrew Liszewski
Popular Science has an interesting article on Fire Pistons, which use nothing but compressed air to produce a flame, making them seem like the perfect fire starter to bring along the next time you’re camping. The model pictured above ($49.95), with its heavy aluminum rod inside a clear acrylic tube, is actually designed to be used for science demonstrations so you can see the materials inside igniting under pressure. You just quickly push down on the plunger, and the rapid increase of air pressure inside the tube produces more than enough heat to create a visible flame.
Air gets very hot when compressed under high pressure. If you have ever pumped up a bicycle tire, you have noticed the heat generated. The Unit has a “compression ratio” of approx. 18:1 (the volume of cylinder is 9ml and reduces to .5 ml when the plunger is compressed).
When the air in the Fire Piston Demo Unit is compressed, it is done so fast and efficiently that it results in a temperature increase to well over 210°C (378°F), the “flash ignition temperature” of cotton. In fact it can reach instantaneous temperature of over 260°C (500°F) inside the cylinder!
But if you’re actually thinking of replacing your Zippo with a Fire Piston, there are considerably smaller versions available for roughly the same price made of wood, aluminum, plastic and other materials that use something called Char Cloth to produce a glowing ember that can be used to ignite whatever fire starting material you have on hand.