If a duct penetration is not sealed by a liquidtight continuous external weld, it must be sealed by a __________ device.

• A. a listed device
• B. foam sealant
• C. caulk only
• D. heat-shrink tube

Answer: (A)

When a duct penetration through a fire-rated assembly isn’t sealed by a liquidtight continuous external weld, you must seal it with a listed firestop device approved for duct penetrations. The listing shows the device has been tested to maintain the fire-resistance rating of the surrounding construction and is installed according to the manufacturer’s instructions and the authority having jurisdiction. Non-listed materials like generic foam sealant or caulk aren’t guaranteed to preserve the rating unless they are part of a documented listed system, and heat-shrink tubing does not provide the required fire-resistance performance. Using a listed device ensures the integrity of the fire barrier.