NICET Special Hazards Systems Practice Test

The main idea is preserving fire compartment integrity by closing off unused ductwork inside a protected area. Unused or out-of-service ducts, if left open, can act as a pathway for heat, smoke, and flames to travel from one area to another during a fire, which undermines the fire-resistance rating of the enclosure. Sealing these ducts with metal plates that are caulked and screwed in place creates a solid, fire-rated closure that resists heat and remains intact under fire conditions, helping to contain the fire and maintain the integrity of the protected area. This practice applies regardless of duct material, and it’s not optional—leaving unused ducts open or assuming it’s only required for certain materials would compromise safety and the fire barrier. So the correct approach is to seal unused and out-of-service ductwork in protected areas with metal plates caulked and screwed in place.