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. Consequently, their use is required by law in many jurisdictions worldwide. Applications Engines Steam 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. The problem of equipment-started fires continued into the 20th century. University of California, Berkeley researchers J.P. Fairbank and Roy Bainer provided the first known academic research on the subject. Their experiments demonstrated that hot particulate matter larger than 0.023 inches (0.584 mm) in diameter was capable of igniting wildland fuels. Internal combustion In the 1950s, the United States Forest Service became interested in reducing the number of fires started by logging equipment in the National Forest System. This interest led to a partnership with the Society of Automotive Engineers and the development of the following test standards for spark arresters: SAE J335 – Multiposition Small Engine Exhaust System Fire Ignition Suppression SAE J342 – Spark Arrester Test Procedure for Large Size Engines SAE J350 – Spark Arrester Test Procedure for Medium Size Engines Modern technologies have largely eliminated the production of large particulate matter from internal combustion engines. However, as engines wear, carbon deposits can build up on the internal walls of the engine. When these deposits break free, they exit through the exhaust system and present a potential fire hazard. Vehicles without properly functioning spark arresters have been suspected of starting numerous wildfires, including the devastating track fire near Raton, New Mexico in June 2011. Today, spark arresters can be found as OEM or aftermarket components on many types of equipment, such as large agricultural machines, off highway vehicles (OHVs), and small engines (chainsaws, string trimmers, leaf blowers, etc.). Buildings Spark arresters are also fitted to the top of a flue (or a chimney pot) to prevent floating embers from a fire (particularly one burning wood) setting light to a flammable