The Air Movement and Control Association (AMCA) has developed Standard 99, which offers guidelines for the construction of spark-resistant fans. This standard categorizes fans into three levels of spark resistance, allowing manufacturers and users to select the appropriate design based on the specific hazard level of the environment.

• Type A: The highest level of spark resistance. All parts of the fan that are in contact with the airstream are made from non-ferrous materials, and great care is taken to ensure that no stationary and rotating parts can touch.
• Type B: Provides a medium level of spark resistance, where the impeller must be made of non-ferrous material. However, some other components may not need to meet the same standard.
• Type C: This is the “entry-level” of spark-resistant construction. The focus is on ensuring that rotating and stationary parts are designed and assembled in such a way as to minimize contact, even though ferrous materials may be used.

Additional Safety Considerations

Beyond material selection and design, there are additional strategies to ensure safety in hazardous environments:

• Regular Maintenance: Ensuring that fans are regularly inspected and maintained is key to preventing accidental sparks. Loose or worn components increase the risk of friction and should be promptly addressed.
• Vibration Control: Excessive vibration can cause unexpected contact between fan components, leading to sparks. Installing vibration dampers or using balanced fan impellers can help reduce this risk.
• Temperature Monitoring: In environments where high temperatures are a concern, fans should be equipped with temperature monitoring systems. This helps detect and prevent overheating, which could also lead to ignition.