What defines a plenum in a fire protection system?

A plenum is specifically defined as a chamber or space that is connected to ducts and is used in heating, ventilation, and air conditioning (HVAC) systems. In the context of fire protection, the plenum plays a crucial role because it serves as a location where air can be distributed or collected, including the movement of smoke in the case of a fire. This function is integral in smoke control strategies during a fire event, as the design of the plenum can impact airflow patterns and smoke spread.

The connection to ducts means that a plenum often acts as a pathway for air to travel through a building, which is vital for both heating and cooling as well as for maintaining safe conditions during emergencies. Understanding the role of plenums is critical for Fire Safety Directors, who must ensure that fire protection systems are effectively managed in these areas to minimize smoke migration and maximize occupant safety during a fire incident.