Did you know that technically there is no such thing as an explosion proof fan? While there are enclosures and motors that are rated explosion proof, it is not possible to rate a fan as explosion proof. The reason: explosion proof design requires isolation from the potentially explosive air. By nature of the way a fan operates, a potentially explosive air stream will always be in contact with the interior of the fan housing and the fan impeller.
So what options do you have when your application involves a potentially explosive environment? The Air Movement and Conditioning Association (AMCA) Standard 99-0401 Classification of Spark Resistant Construction was developed to meet the need for fans in potentially explosive environments. These guidelines give fan end users and manufacturers a number of options to choose from in the construction of such fans.
The AMCA has 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.
When selecting a spark resistant fan to meet your explosion proof fan requirements, you will need to consider which type of construction will best suit the ambient location and application conditions to which your fan will be subjected. It is extremely important to select the right type of spark resistant construction for your application, as well as a motor that 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.