Ductwork that is in service should have butterfly dampers with neoprene seals.

• A. False
• B. Not required
• C. Only for outdoor ducts
• D. True

Answer: (D)

Containing smoke and fire through ducts that stay in service requires a reliable way to isolate those ducts quickly and effectively. When a duct is actively serving the building, you need a closure that can seal tightly to prevent smoke or flames from traveling between zones and to maintain proper pressure relationships in the protected spaces. A butterfly damper is well-suited for this because it operates smoothly, fits compactly in the duct, and can close the passage with a tight seal. Pairing it with neoprene seals gives a durable gasket that resists heat, humidity, and cycling, ensuring a reliable closure when the damper is shut. This combination minimizes leakage of smoke or extinguishing agents and helps preserve the integrity of fire barriers as conditions change in the system. So, this setup is appropriate for in-service ductwork. The other options would either skip needed containment, limit protection to outdoor ducts, or imply no requirement, which doesn’t provide the necessary protection for ducts crossing fire barriers and serving occupied spaces.