What classification of duct material must nonmetallic ducts comply with?

Nonmetallic ducts must comply with the classifications outlined in the National Fire Protection Association (NFPA) standards, specifically focusing on their flame spread ratings. Class 0 or Class 1 materials are designated as those that have limited combustibility and a satisfactory resistance to fire spread. This requirement is crucial in ensuring that, in the event of a fire, the duct materials do not contribute significantly to the spread of flames or smoke, thereby enhancing occupant safety and facilitating effective fire control.

The emphasis on Class 0 or Class 1 aligns with safety standards intended to reduce the risks associated with fire within HVAC systems. These classifications help ensure that, even if a fire occurs, the nonmetallic ducts will not easily ignite or support combustion, making them suitable for use in various applications according to the code. Such adherence to standards is essential for maintaining a safe environment in buildings and for compliance with mechanical codes.