What is smoke damperin construction?

A fire damper is a passive device, listed to UL 555, that slams shut when a fusible link melts at its rated temperature to keep fire from passing through a rated wall or floor. A smoke damper, listed to UL 555S, closes on an electrical signal from a duct detector or the fire alarm system, which means it needs an actuator and wiring. Combination fire/smoke dampers do both jobs in one housing and cost accordingly.

Generally where ducts penetrate smoke barriers and smoke partitions, with the exact requirements and exceptions set by the building code and the project's life-safety design. The mechanical engineer places the symbols, but the smoke barrier locations live on the architectural life-safety plan, so a careful estimator counts from both. Hospitals, laboratories, and high rise buildings carry far more of them than ordinary office floors.

It splits three ways on most commercial jobs: the mechanical contractor furnishes and installs the damper with its factory mounted actuator, the electrical contractor brings power, and the fire alarm contractor supplies and connects the duct detector and monitoring. Every bid should state which contractor carries each piece, because this is one of the most common scope gaps in MEP buyout, and an unpriced detector circuit resurfaces later as a change order.