Three Elements are Needed to Cause a Fire or an Explosion
For combustion to take place, the oxygen content needs to be above 11%. Our normal atmosphere consists of 21% oxygen. This means that the oxygen element is always present.
Most material that has been transformed into fine particles can burn or explode. Every year, many serious fires and explosions occur in industrial plants as a result of an ignition of combustible dust.
When handling combustible material it is very common that ignition sources, often caused by friction heat, are generated from equipment within the process. Worn parts as well as foreign objects (stones, nails, nuts, etc.) can also increase the risk of generating ignition sources. Not only visible sparks but also hot particles, at temperatures down to around 250°C/480°F, can start a fire or an explosion.