Historically, fatalities from dust explosions have largely been the result of secondary dust explosions. Secondary dust explosions are the result of dust accumulation inside a building being disturbed and ignited by the primary explosion, resulting in a much more dangerous uncontrolled explosion that can affect the entire structure. Primary dust explosions may occur inside process equipment or similar enclosures, and are generally controlled by pressure relief through purpose-built ducting to the external atmosphere. If the spread of flame is at subsonic speed, the phenomenon is sometimes called a ' deflagration', although looser usage calls both phenomena ' explosions'.ĭust explosions may be classified as being either 'primary' or 'secondary' in nature. The sudden release of energy from a ' detonation' can produce a shockwave, either in open air or in a confined space. If rapid combustion occurs in a confined space, enormous overpressures can build up, causing major structural damage and flying debris.
