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A non-plenum airspace can become a plenum airspace by accident if the ductwork is disconnected and not properly repaired and resealed. Ductwork disconnection can occur due to building damage such as earthquakes, aging, or adverse environment causing the metal to corrode and fall apart, or simply negligence on the part of building contractors ...
Distinct from ductwork as a plenum is part of the structure itself. Cable and piping within a plenum must be properly rated for its fire and smoke indices. See also: plenum chamber
A plenum chamber is a pressurised housing containing a fluid (typically air) at positive pressure. One of its functions is to equalise pressure for more even distribution, compensating for irregular supply or demand.
The most common application for an air-mixing plenum is the mixing of return air (or extract air) with fresh air to provide a supply air mixture for onward distribution to the building or area which the ventilation system is serving. [1] The air transferred from the return air stream to the supply air stream is termed recirculated air.
Example of a typical commercial building with the space above the drop-ceiling acting as an air-return plenum. If a fire were to start above the drop ceiling, toxic fumes would be drawn into the open-air system and potentially poison building occupants before they are aware of the fire. Date: 10 April 2024: Source
The Type A2 cabinet, formerly designated A/B3, has a minimum inflow velocity of 100 ft/min. A negative air pressure plenum surrounds all contaminated positive pressure plenums. In other respects, the specifications are identical to those of a Type A1 cabinet. [3]: 9–11 [5]
The building envelope or enclosure is all of the elements of the outer shell that maintain a dry, heated, or cooled indoor environment and facilitate its climate control.
A platen (or platten) is a platform with a variety of roles in printing or manufacturing. It can be a flat metal (or earlier, wooden) plate pressed against a medium (such as paper) to cause an impression in letterpress printing. [1] Platen may also refer to a typewriter roller which friction-feeds paper into position below the typebars or print ...