|A very standard disposable lighter|
Butane lighters like this one work by releasing compressed liquid butane as a narrow stream of gas. When this stream of gas meets a spark, it ignites and produces a flame. Holding open the valve continues to draw fuel out of the reservoir to support the flame and the outrush of gas prevents the flame from traveling inside the canister irrespective of orientation.
Lighters are dirt cheap, yet have a seemingly long working lifetime (it runs out of fuel long before it breaks) They do well on the cost/performance curve because they have very few moving parts - just the thumb-lever fork and the rotating spark wheel. They are also fairly idiot-proof - one swipe of the thumb rotates the sparkwheel with enough force to strike the flint and produce sparks, and that same motion lands the thumb on the fork lever to open the gas valve.
|Parts of a lighter|