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Air Ducts, Air Connectors & Closure Systems

Duct running along an enclosed bridge

Underwriters Laboratories has helped develop the industry standards for air ducts, air connectors and closure systems. Backed by UL's unmatched breadth and depth of expertise, the UL Mark is one of the most recognized and accepted certification marks in the industry. UL provides a full range of services, including physical examinations such as corrosion resistance, mold growth and humidity, high and low temperature, puncture, impact, erosion, positive and negative pressure, and leakage, as well as flammability examinations, including surface burning characteristics, flame penetration and burning tests.

Look for the UL Mark on Air Ducts, Air Connectors and Closure Systems

Air ducts and air connectors are Listed as Class 0 or Class 1 and installed in accordance with the requirements in the standards of the National Fire Protection Association (NFPA) for the Installation of Air-Conditioning and Ventilating Systems (NFPA 90A), and the Installation of Warm-Air Heating and Air Conditioning Systems (NFPA 90B).

Air ducts and air connectors are also evaluated to UL 181-Standard for Factory-Made Air Ducts and Air Connectors. Closure systems consisting of either tapes or mastics, or polymeric mechanical fasteners are evaluated according to UL 181A and/or UL 181B.

As part of the UL certification process, ongoing unannounced product inspections take place at the manufacturers' facilities. UL's follow-up service is a key element in maintaining the quality and integrity of the UL Mark. That's why products that bear the UL Mark are more readily accepted.

Listed air ducts, air connectors and closure systems are included in the UL Product Directory, which is referenced by more than 2,500 authorities having jurisdiction (AHJs) and code officials each year. When AHJs see air ducts, air connectors and closure systems with the UL Mark, they can be confident that those products have been properly tested, certified and audited to the industry standards.

Test Standards:

  • UL 181 - Factory-Made
  • UL 181A - Closure Systems
  • UL 181B - Closure Systems

To start the submittal process or access more information:

  • Contact UL Customer Service at 1-877-854-3577.
  • Learn how to submit a product for testing.
  • Begin the product submission process.