Combustible dust issues have become an important area of focus in the prevention of industrial fires and explosions. The Imperial Sugar refinery disaster in 2008 brought to light the dangers of older facilities using outdated equipment without understanding of the nature of combustible dusts. While today’s plants are designed to address combustible dust hazards, plants in older facilities using less advanced equipment must update their operations to address new regulations. In operations involving the handling of any kind of powder, precautions must be taken to control combustible dusts.
Fans and blowers are a key element in the design of a wide range of industrial operations, and therefore an important consideration when assessing combustible dust hazards. While explosion proof design is technically not achievable with fans and blowers, there is an acceptable alternative that provides safety and regulatory compliance.
In order to be considered explosion proof, a design requires isolation from the potentially explosive air. Since the basic operation of a fan or blower requires a constant flow of air, it is impossible to avoid a potentially explosive air stream coming into contact with the interior of the fan housing and the fan impeller.
In order to meet the need for fans in potentially explosive environments, the Air Movement and Conditioning Association (AMCA) developed the Standard 99-0401 Classification of Spark Resistant Construction. These guidelines provide fan end users and manufacturers with fan construction options within three main classifications for spark resistant fans and blowers:
Type A fan construction requirements specify that all materials that are in contact with the air stream be constructed of spark resistant nonferrous material such as aluminum or brass. These fans offer the highest degree of spark resistance. In addition to requiring that the fan components be comprised of non-ferrous material, they must also be assembled in a manner such as to reduce the possibility of contact between any stationary and rotating component.
Type B fans require a non-ferrous wheel and a rubbing ring around the hole where the fan or motor shaft enters the fan housing. These fans provide a medium level of spark resistance, requiring that the fan components be assembled in a way that reduces possible contact between any stationary and rotating component.
Type C fans offer entry level spark resistant construction, and require that the fan components be designed to reduce the possibility of contact between any stationary and rotating component. Construction requires a nonferrous plate on both sides of the inside of the fan or blower housing.
Proper spark resistant fan selection should involve consideration of the application’s ambient location and conditions, since the fan will need to operate reliably in that environment. It is critical that the right type of spark resistant construction is selected, and that the motor is properly classified for your area.
Air Solutions is your source for the most dependable air movement solutions, including fans designed to reduce the risk of explosion in volatile environments. Contact our team to discuss your application needs.