The Hyman Fire Piston is an informative piece of kit that demonstrates the rise in temperature that is produced when a fixed mass of gas is compressed. In this apparatus the contained air is compressed by a hand-operated piston. The heat generated is sufficient to ignite a small quantity of tinder supported inside the transparent cylinder. Suitable tinder is included, but almost any organic material will work if dry enough, i.e. cotton, charcoal, tissue paper, etc.The Hyman Fire Piston can also be used to demonstrate the need for oxygen to support combustion, by attempting to re-ignite a piece of part-burned tinder. Combustion will only occur if the piston is completely removed from the cylinder allowing a supply of fresh air to be introduced.Additionally, a cloud can be formed in the cylinder by having compressed moist air inside it, allowing a sudden decompression. The reduction in pressure lowers the temperature and immediately condenses the water vapour inside the cylinder. |
