2.4.2.1 Sheet quality

Durable and reliable air ducts are indispensable. Plastics score well with respect to these 2 criteria and are therefore extremely suitable for ventilation applications. The following plastics are eligible for the realisation of air ducts: PVC, PVC-C, HDPE, PP and PP-S.
These plastics are chemical and corrosion resistant. This makes them also suitable for the extraction of aggressive vapours and steam.

PVC: PVC is extremely suitable for corrosive and aggressive conditions. The PVC pipes have a grey colour according to RAL 7011. Processing is done by gluing or welding.

PVC-C: PVC-C has a high chemical resistance and better temperature resistance than PVC. Processing is usually done by means of adhesives.

HDPE: HDPE is an inert material with good resistance to abrasive and corrosive substances. HDPE has a very smooth surface and is fairly impact resistant. Processing is done by welding.

PP and PP-S: The industrially used PP pipe is supplied in a light grey-beige colour RAL 7032. Thin-walled PP pipes are used for low pressure ventilation applications. PP-S is a difficult inflammable polypropylene with self-extinguishing properties. These pipes have a grey colour according to RAL 7037. Processing is done by welding.

2.4.2.2 Wall thickness

The pipes and fittings are made with a wall thickness, which depends on the diameter, with a minimum thickness of 1.8 mm.

2.4.2.3 Connections

The various plastics can be joined in the following ways;

• PVC: glued, welded or mechanically bonded;
• PVC-C: glued or mechanically connected;
• HDPE: welded or mechanically connected;
• PP: welded or mechanically connected;
• PP-S: welded or mechanically connected.

The fittings are equipped with socket connections as standard.

2.4.2.4 Length of pipes

Due to transport-technical aspects and manageability, standard pipes are delivered up to a length of 5000 mm with a tolerance of ± 0.005 x L.

2.4.2.5 Diameter/tolerances

2.4.2.6 Bends

As regards form, bends are carried out as standard with a radius measured over the centre of the bend, equal to the diameter, except for diameters 63 and 80 where the radius is 100 mm. Bends are standardly made in angles of 15°, 30°, 45°, 60° and 90° in a pressed or seamed version with a tolerance of ± 2°. Segment bends ≥ 45° consist of a minimum of 3 segments.

2.4.2.7 Adapters

Adapters can be both symmetrical and asymmetrical and have a top angle of minimum 15° and maximum 60°. Symmetrical adapters are used as standard.

2.4.2.8 Branches and splits

A branch (split off from a continuous main duct) can be made by means of a T-piece, as a complete fitting and can be done as standard at angles of 90° and 45°.

A junction is a division of a main duct into two ongoing ducts. Some examples of branches and splits are:

2.4.2.9 Adjustment valves

Adjustment valves are manually adjustable and serve to regulate an installation. They are provided with a sound locking device which also indicates the valve position. The damper blade, of the same material as the air duct, is made of single sheet with a thickness of at least 3 mm up to a maximum diameter of 400 mm. The valves are provided with a good and tight bearing.

2.4.2.10 Smoke development, fire spread and flammability

PVC: hardly inflammable, self-extinguishing according to DIN 4102/class B1
PVC-C: hardly inflammable, self-extinguishing according to DIN 4102/class B1
HDPE: normally inflammable, not self-extinguishing according to DIN 4102/Class
B2 PP: normally inflammable, not self-extinguishing according to DIN 4102/Class B2
PP-S: hardly inflammable, self-extinguishing according to DIN 4102/Class B1

2.4.2.11 Operating temperature

The maximum operating temperature for PVC ducts is 60°C.
The maximum operating temperature for PVC-C ducts is 90°C.
The maximum operating temperature for HDPE ducts is 70°C.
The maximum operating temperature for PP ducts is 100°C.
The maximum operating temperature for PP-S ducts is 100°C.