What specification is required for flexible air ducts in AC systems?

The specification required for flexible air ducts in AC systems is UL 181. This standard applies to the materials and construction of air ducts to ensure safety and performance in heating, ventilating, and air-conditioning systems. UL 181 covers various aspects, including strength, flame resistance, and durability necessary for effective operation in these systems.

By adhering to this standard, manufacturers ensure that their flexible ducts can withstand the conditions typically encountered in HVAC installations, including temperature variations and pressures that might be present during operation. Compliance with UL 181 standards is crucial for both safety and efficiency in air distribution, helping to prevent fires and ensuring that air quality is maintained.

Other options focus on different aspects of safety and performance. For instance, UL 180 deals with general rules for air ducts, while UL 182 and UL 184 pertain to different components and applications, but none are specifically designated for flexible air ducts in AC systems. This distinction makes UL 181 the correct reference for ensuring that flexible air duct systems meet necessary safety and functional requirements.