What Are Smoke Dampers?

Smoke dampers are a type of building material used to prevent smoke from spreading throughout the structure during a fire. Contractors install these dampers in HVAC ducts to block the flow of smoke in heating, ventilation, or air conditioning systems. Smoke dampers represent a critical part of the life safety system within a building. Many building codes require these dampers to help save lives and reduce injury during a fire. Some building owners or homeowners may also use smoke dampers on a voluntary basis to improve safety for occupants and residents.

A smoke damper fits tightly within an HVAC duct and is designed to allow air to flow freely under normal conditions. When smoke is present, smoke detectors send a signal to an actuator in the damper, causing it to shut off air flow through the duct. Some systems may also include manual dampers, which can be opened or closed using a switch on the outside of each duct. Others allow operators to push a single central button to shut all dampers at once during an emergency.

Different types of smoke dampers utilize a variety of operating mechanisms to stop the flow of smoke and air. Gate-style smoke dampers feature a metal gate or door that drops down to seal off the duct. Baffle units feature vents, or baffles, that close off the duct as needed. Rotational units include a central plate that runs perpendicular to the duct under standard conditions, but rotates to completely close off the duct during a fire.

One of the primary advantages associated with smoke dampers is their ability to save lives during a fire. By slowing or stopping the spread of smoke, they give occupants more time to exit the building while reducing smoke exposure. By limiting smoke exposure, dampers help to minimize smoke-related injuries and keep people conscious and alert.

Contractors and building owners should choose smoke dampers with care to ensure they will operate as intended. All dampers should be selected based on local building code requirements in the area. Each damper is rated to withstand a specified maximum temperature, which is based on the material and construction of the damper. Smoke dampers are also rated to a specific air leakage rate, which measures how much smoke is likely to pass by the damper after it has been activated. For maximum protection, buyers should select a damper with the lowest possible air leakage rates.