A circular fire damper is used in an air duct to close off a circular air duct, thus preventing fire from spreading through the air duct. The fire damper contributes to the objective to prevent the propagation of fire to adjacent compartments for a certain period of time.
Material quality and thicknesses
For normal comfort ventilation, fire dampers are manufactured from the following materials:
- Casing: Sendzimir galvanised steel;
- Damper: fire retardant and thermally insulating material.
All fire dampers must have a CE marking and be classified according to EN 13501-3.
Other choice of material, depending on the application, in consultation with the supplier.
The circular fire damper has circular connections, equipped with a rubber sealing ring for an airtight connection to the air duct system. To prevent leakage or damage, drilling, etc. should be avoided during installation.
The nominal sizes available for intermediate circular fire dampers are standardised to NEN-EN 1506 (circular connections) and can be selected as indicated in the tables of standard sizes given in this guide in section 22.214.171.124 (circular connections). They refer to internal dimensions with a tolerance of +0 to -5 mm. The dimensions depend on the manufacture.
It must always be possible to inspect intermediate fire dampers for function and damper position (this can usually be checked from the outside).
Circular fire dampers must be installed and sealed in accordance with the manufacturer's instructions. The type of wall/floor, the sealing and the type of fire damper determine the classification of the fire damper, including the number of minutes fire resistance. Sometimes it is not possible in construction to mount the fire damper partially in the fire separation. When the fire damper cannot be installed in the fire separating wall, the duct section between the fire separating wall and the fire damper has to be insulated in such a way that the quality of the fire separation is maintained. This is carried out under responsibility of the building contractor.
The insulation must be installed in accordance with the manufacturer's instructions.
Fire dampers with circular connections, fitted with rubber sealing rings, can be connected to air ducts efficiently and make a contribution to the airtightness of the air duct system, if the fittings have sufficient airtightness in accordance with NEN-EN 1751.
Fire dampers which are equipped with a fire resistant surface-mounted clam do not require any additional sealing during installation. Thus, the installation time can be shortened and simplified.