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A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, ...
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.
The term "plenum" was coined in the 1670s, derived from Latin adjective plenus ("filled, full"). The usage originates from classical theories of physics and the notion that "nature abhors a vacuum". These gave rise to the notion of 17th century 'plenum' as the opposite of vacuum, and all things "being either Plenum or Vacuum". [2]
While overhead systems typically use ducts to distribute the air, UFAD systems use the underfloor plenum formed by installation of a raised floor. The plenum generally sits 0.3 and 0.46 metres (12 and 18 in) above the structural concrete slab, although lower heights are possible.
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
The air handler is normally constructed around a framing system with metal infill panels as required to suit the configuration of the components. In its simplest form the frame may be made from metal channels or sections, with single skin metal infill panels. The metalwork is normally galvanized for long term protection. For outdoor units some ...
Without proper ventilation, carbon monoxide can be lethal at concentrations of 1000 ppm (0.1%). However, at several hundred ppm, carbon monoxide exposure induces headaches, fatigue, nausea, and vomiting. Carbon monoxide binds with hemoglobin in the blood, forming carboxyhemoglobin, reducing the blood's ability to transport oxygen.
Plenum cable is jacketed with a fire-retardant plastic jacket of either a low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene polymer . Polyolefin formulations, specifically based on polyethylene compounding had been developed by at least two companies in the early to mid-1990s; however, these were never commercialized, and development ...