These are located in ductwork at the intersection of fire-rated barriers in building zones, like walls or partitions. The damper secures the integrity of the barrier – preventing fire penetration before temperatures reach the fire rating level of the barrier itself. Naturally such dampers are manufactured to high standards of integrity and designed to resist extreme temperatures for as long as possible.
These work in a similar manner to preserve the integrity of smoke barriers (e.g. floors, walls or smoke-resistant ceilings) without the same stringent temperature restrictions. They are often located in sensitive areas where smoke penetration would present particular challenges and must be installed with proper seals to prevent smoke leakage.
While methods of operation can be interchangeable, it’s more common for smoke dampers to be motorised and connected to a control panel. This means smoke detectors and controls are responsible for activating the damper, which makes testing for maintenance purposes easier.
Fire dampers would more usually be fitted with mechanical or fusible linkages, which operate under high temperatures and cause the louvres or shutters to shut firm. This method may be considered more ‘failsafe’ as it’s the action of the fire itself that activates the damper, but it means that by the time the damper activates there may already have been significant passage of smoke (which travels so much faster than flames).
Also note that there are hybrid dampers available, which fulfil the roles of both smoke and fire dampers.
Regardless of operating system or purpose, the message is clear – ducting has the potential to be a building’s Achilles heel in a fire so dampers that are well-maintained and ready to function at a moment’s notice are vital to the success of that building’s fire strategy.
Service and maintenance criteria
Manufacturers’ recommendations can vary but most will suggest annual ‘hands on’ inspection, testing, cleaning and lubrication. The latest HSE bulletins and guidance documents include more of a focus upon the information recorded about dampers’ condition, with traceability and photography a primary concern.
FIRAS accreditation is the only standard that openly seeks to provide accreditation on the methods and standards of work provided during maintenance and also includes details on ‘fire stopping’ and other considerations in the ‘passive’ prevention of fire passing through barriers, e.g. correct installation, inspection, maintenance and refurb etc.