A spark arrester (sometimes spark arrestor) is any device which prevents the emission of flammable debris from combustion sources, such as internal combustion engines, fireplaces, and wood burning stoves. Spark arresters play a critical role in the prevention of wildland fire and ignition of explosive atmospheres.
Spark arresters for steam locomotives may be internal (in the form of wire mesh inside the smokebox) or external. The earliest platforms for spark arresters in the United States were steam locomotives. Wood- and coal-burning locomotives produce embers which are readily transported by the wind. One popular design was the Radley-Hunter spark arrester, which used a spiral-shaped cone to separate embers from the exhaust flow by centrifugal force.