Chapter 3

3.1.4 Assembly instructions for fittings (general)

In this part, general assembly instructions for both rectangular and circular fittings are explained in more detail. For specific product related mounting instructions the supplier should be contacted.

Fittings are available with circular and rectangular connections. The circular connections are provided with a rubber sealing ring for an airtight connection to the air duct system. The rectangular connections are provided with a flange edge according to NEN-EN 1505 or ISO 13351, so that the fitting can be securely connected to the air duct system. To prevent leakage or damage, drilling, etc., other than in the flange should be avoided during assembly. Assembly instructions for rectangular fittings

Rectangular fittings must be assembled in accordance with the manufacturer's instructions. These assembly instructions meet the requirements of NEN-EN 1505 to 1507. The components must be fixed or suspended so that they form a tight and stable unit with the air ducts. This is done with suspension structures that must have a strength such that the total weight is transferred to the structural suspension points by threaded rods.
The suspension is composed of a lower bracket of Sendzimir galvanised material (or other material if this is specified in the specifications), provided with felt or P.E. tape, with minimum dimensions of 18 x 4 mm, with threaded rods at least M6 directly along the fitting. The distance between the threaded rods is maximum 100 and minimum 30 mm larger than the duct width, depending on the presence of external insulation. The bracket must be mounted at a minimum distance of 100 mm and a maximum distance of 400 mm in front and behind the fitting and must be executed in a profile form (see table below) or in a standard commercial profile of sufficient strength, giving sufficient stiffness.

Because the flanges of the air ducts do not always match the flanges of the fittings, there are various ways of connecting them.

  • When the flanges are made with the same profiles, the corners are fitted with a bolt and nut connection (at least M6 x 20) and/or with a profile inlength and width. A sealing band with closed cell structure must be fittedbetween the flanges, with minimum dimension of 18 x 4 mm, with the strap tensioned or overlapping at the corners (see;
  • If the flanges are not made from the same profiles, the angles will be provided with a bolt + nut connection (at least M6 x 20) and withscrew clamps at a maximum distance of 500 mm.
    A closed cell sealing tape with minimum dimensions of 18 x 4 mm must beapplied between the flanges, with the tape passing through the cornerswithout tension or overlapping at the corners. Assembly instructions for circular fittings

There are 2 different ways to attach the circular fittings to the circular air ducts:

  • The fitting is provided with a plug flange (with or without a rubber inlay or "safe" connection). The sliding part is pushed into thespirally seamed pipe and fixed with rivets or self-drilling screws. When nosafe connection is used, the connection will have to be wrapped with asuitable tape (see Connections);
  • The fitting is fitted with a right angle flange. The flange that is attached tothe air duct is fitted with a contrasting flange. A closed cell sealing tapewith a minimum dimension of 18 x 4 mm or an elastic permanent sealantwill be applied between both flanges. The flanges are then connected toeach other using a minimum of M6 bolts.

Fittings with circular connections with safe connections are preferable, as they enable airtightness requirements to be met more efficiently.

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