Function
A vent plenum, or connection plenum, is used in an air transport system to connect a vent to an air duct. The pressure build-up within the plenum for the supply air vent also ensures an even air distribution and a correct operation of the vent.

Material quality and thicknesses
For normal comfort ventilation, vent plenums are manufactured from the following materials:

• Casing: Sendzimir galvanised steel, plastic or PIR/PUR sheets;
• Other choice of material, depending on the application, in consultationwith the supplier.

Connections
The vent plenum has a circular top or side connection, fitted with a rubber sealing ring for an air tight connection to the air duct system. To prevent leakage or damage, drilling etc. must be avoided during assembly.

Dimensions
The nominal connection diameters available for the vent plenums are standardised to NEN-EN 1506 (circular connections) and can be selected as shown in the tables for standard dimensions, as referred to in this guide under section 2.1.3.6 (circular connections). They refer to the internal dimensions with a tolerance of +0 to -5 mm. The available connection diameters depend on the manufacture. The dimensions of the vent plenum and the connection to the vent depend on the manufacture and the type and dimensions of the vent.

Inspection possibilities
To allow for easy inspection of the vent plenum, front panels can be chosen to be removable or hinged.

Assembly instructions
The fitting is fitted with a push-fit flange, provided with a rubber sealing ring. The sliding part is pushed into the spirally seamed pipe and fixed with rivets or self-drilling screws.
If no further specification of the ceiling structure is given in the specifications, a grid of 600 x 600 mm is assumed for the installation of the ceiling plenums.
Vents must be delivered per room where they are to be installed and provided with a code that corresponds to a location on the installation drawing. The customer must ensure that the "technical ceiling tiles" are laid in the grid. So-called "technical ceiling tiles" are ceiling tiles (with or without back-planks) with recesses in accordance with the spacing of the relevant vent plenums. The air duct company mounts the tiles to the vents and places the tile with vent in the grid, at the location indicated on the installation drawing. Next, the vent is connected to the duct system with a flexible hose. To prevent contamination of the surrounding ceiling tiles, the described work must be carried out before the remaining ceiling tiles are installed. Where a vent is supplied with a 595 x 595 module board, the vent is laid directly into the 600 x 600 grid. If the specifications state that the vents must be suspended, this is normally done by means of two quick release hangers (with a maximum length of 600 mm) from the ceiling above. If the suspended ceiling does not consist of a grid, but of interlocking boards, laminated board or plaster ceiling, the vents will have to be suspended from the ceiling above using quick hangers with a length of maximum 600 mm during the assembly of the ceilings. In connection with the planning and to avoid waiting times, this must be carried out by third parties.

Sustainability aspects
Vent plenums with circular connections, fitted with rubber sealing rings, can be connected efficiently to air ducts and contribute to the airtightness of the air duct system, if the fittings comply with the airtightness requirements in NEN-EN 15727.