A lighter is a portable device used to create a flame. It consists of a metal or plastic container filled with lighter fluid (usually naphtha or liquid butane under pressure), as well as a means of ignition and some provision for extinguishing the flame, either by depriving it of air or of fuel. A butane lighter flame averages 700 degrees Celsius.
Lighters using naphtha have a wick which is immersed in the fluid and becomes saturated. This type usually has a fiber packing material which absorbs the liquid to keep it from leaking. They also must have an enclosed top to prevent the volatile liquid from evaporating, and to conveniently extinguish the flame. Butane lighters have a valved orifice that meters the butane as it escapes as a gas.
A spark is created by striking metal against a flint, or by pressing a button that compresses a piezoelectric crystal, generating a voltaic arc (see Piezo ignition). In naphtha lighters the liquid is volatile enough that flammable gas is present as soon as the top of the lighter is opened. Butane lighters combine the striking action with the opening of the valve to release gas. The spark ignites the flammable gas causing a flame to come out of the lighter which continues until either the top is closed (naphtha type), or the valve is released (butane type).
A metal enclosure with air holes generally surrounds the flame, and is designed to allow mixing of fuel and air while making the lighter less sensitive to wind. The high energy jet in butane lighters allows mixing to be accomplished by using Bernoulli's principle, so that the air hole(s) in this type tend to be much smaller and farther from the flame.