Fire damper classification – limits resulting from the test standard
Autor
Hubert Boćko
Konstruktor klap p.poż. SMAY Sp. z o.o
A concern for safety, health and lives of people using public buildings has led to the development and standardization of fire ventilation systems. As ventilation systems providing comfort and safety must be characterized by high quality and durability, fire dampers must meet various legal requirements in the form of standards. Due to the development of fire ventilation systems and their individual components, every stage of works – i.e. design, selection and proper installation – has become a major challenge.
Fire dampers – installed in both comfort ventilation and smoke control systems – protect against fire, temperature and smoke propagation. Major differences of various fire damper types are: the presence of an actuator with a return spring (or, alternatively, a spring mechanism) and a thermal release device in fire dampers used in comfort ventilation systems or a two-way actuator in fire ventilation dampers.
The main purpose of fire dampers used in comfort ventilation is to isolate an area engulfed in fire from the rest of a building. For that to happen, energy supply to the damper driven by an actuator must be cut off or the set thermal release device temperature must be reached. Those dampers always function in the same manner whenever a fire ensues: the damper closes, isolating an area engulfed in fire, and remains closed, without the possibility of returning to an open position.
If the project requires that the fire damper opens during a fire or transporting hot gases, a damper for smoke control systems should be used. A two-way actuator installed in such dampers makes it possible to set it as either open or closed, as well as decide how the damper should act in case of a fire: whether it should open, close or remain in its normal position.
Fire Damper Classification
When selecting fire dampers, we must first establish fire resistance requirements of the product. Thanks to the damper classification, we can make an initial selection, which consists in verifying how long the product maintains its fire resistance (E), fire insulation (I) and smoke resistance (S) ratings, as well as check in what barriers or ducts a damper can be installed.
Next, we should consider several aspects and limitations that stem from classification and certification. Damper manufacturers test their products in specific conditions in a given wall type (rigid, flexible, ceiling, etc.) with a specific thickness and enclosure. These conditions are set out in classification documents and study reports issued for every damper available on the market. Before using a certain damper within a project we must ensure that a given wall barrier meets the minimum requirements specified in the operation and maintenance manual. A similar limitation applies to duct classification. It determines the operation of a damper in a duct in a specific location. This means that non-standard wall systems, walls with irregular cross-sections or smoke exhaust duct systems cannot replace those specified in the product certificate, even if they offer an appropriate fire resistance rating.
What to do when there is insufficient space for a ventilation system?
Designers working on fire protection systems often encounter the issue of insufficient space for ventilation system components. One common oversight in buildings is the lack of minimum spacing. The EN 1366-2:2015-08 standard specifies minimum required spacing (in Section 13.6). The spacing between fire dampers installed in separate ventilation ducts (does not apply to batteries) should be at least 200 mm. The spacing between dampers and structural elements should be at least 75 mm. The spacing is meant to protect dampers against thermal interaction during fire and against heat accumulation right above or next to a damper in tight spaces.
PN-EN 1366-2 is the basic test standard used in the classification process for all fire dampers available on the Polish market. This means that the minimum space limits apply to all products subject to this basic test. In order to meet customer needs, fire damper manufacturers work together with notified bodies to develop and test products in a manner that would enable their installation in a closer vicinity. SMAY has some great success in this field. The distance between its round fire dampers (KTM) as well as between those dampers and wall barriers is at least 10 mm (while it can, naturally, be larger). A common trick that makes it possible to circumvent this limitation is to remove a damper from a barrier and install it in a duct, away from a wall. However, such a solution has its flaws: it entails additional duct (and possibly its insulation) costs and is not always possible.
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