plenum space is part of a building that can facilitate air circulation for heating and air conditioning systems, by providing a path for heated/conditioned air flow or return, usually at a pressure greater than the atmosphere. The space between the structural ceiling and the descending ceiling or below the elevated floor is usually considered plenum; However, some drop-ceiling designs make tight seals that do not allow airflow and therefore may not be considered a plenum air handling space.
Video Plenum space
Destination
Space cavity/plenary is usually used to place communication cable for computer and building telephone network; However, it has been proposed that increasingly abandoned cables in the plenary hall can pose a serious danger in the event of a fire, because once a fire reaches the courtroom, the airflow in space supplies fresh oxygen to the flame and makes it grow much stronger than it should.
Recent testing by ASHRAE has shown that, while flame deployment is limited by accumulated bundles of cables, other structural problems may still be present due to increased load on deferred components. Since the plenum is restricted from use as a storage area, the principle behind the abandonment of abandoned cables is the deletion set that prevents the use of plenum space as storage areas for abandoned cables. In addition, no high-voltage powered equipment is allowed in the courtroom because the presence of fresh air can greatly increase the danger of spreading rapid fire if the equipment is on fire.
Persistence is needed to ensure that non-pleno airspace remains that way. A plenary-free space may become accidental airspace if the air duct is disconnected and not repaired and sealed properly. Termination of employment may occur due to damage to buildings such as earthquakes, aging, or a bad environment that causes the metal to rust and fall apart, or only the negligence of the building contractor leaving the unfinished work. In all such cases, the discovery and repair of such problems to remove unwanted plenaries is difficult because of the concealed nature, limited space, and the difficult access of most of the falling ceilings installed. For the highest fire safety, it is best to assume that all the ceiling spaces falling are plenary spaces, whether they are formally designated as one or not.
Maps Plenum space
References
Source of the article : Wikipedia