Wherever a ventilation duct crosses a fire separation, that separation would have a hole in it without measures. The fire damper solves that: in a fire, the damper closes the duct so fire and smoke cannot spread to another compartment via the ventilation system. A damper that does not close - or is not installed correctly - undermines the entire compartmentalization, no matter how well the rest of the separation is executed.
How does a fire damper work?
Most fire dampers work with a fusible link or a thermal sensor that closes the damper blade at a set temperature (usually around 72 °°C), often assisted by a spring. In buildings with a fire detection system, dampers are increasingly electrically controlled, so they already close on an early fire signal, before the local temperature has risen. A damper is tested and classified according to NEN-EN 1366-2, with an EI classification just like penetrations and glass.
The surrounding seal is just as important as the damper
A common assumption is that a certified damper automatically results in a fire-resistant penetration. That is only true if the damper is also installed with the prescribed surrounding seal between the damper housing and the wall or floor - often a specific mineral wool package or mortar, exactly as in the test report. A damper that works technically well but hangs loosely in an oversized opening still lets smoke and flames through around the housing in a fire.
How often should a fire damper be tested?
Fire dampers generally require a periodic function test, in which the closing mechanism is actually activated and checked. In practice, depending on the use of the building and the requirements of the insurer or competent authority, we use an annual test frequency as a starting point. Critical environments - healthcare, data centers, buildings with continuous operations - may need a shorter cycle. Your fire safety consultant or maintenance contract determines the exact frequency for your building.
| Check point during a function test | Why it matters |
|---|---|
| Does the damper close fully and on time | A partially closed damper offers no fire resistance. |
| Does the damper reopen after reset (where applicable) | Prevents unnecessary ventilation downtime after a test or fault. |
| Is the surrounding seal still intact | It sometimes gets damaged after renovations or nearby pipework. |
| Is the damper accessible for inspection | Dampers that have been built over or made inaccessible cannot be tested or maintained. |
Common mistakes
- Missing surrounding seal. The damper itself is fine, but the connection to the wall or floor was not executed according to the test report.
- Skipping function tests. A jammed or corroded mechanism often only becomes apparent during a test - not during normal use.
- Making it inaccessible after renovation. A new suspended ceiling or fixed furniture blocking the inspection hatch makes maintenance impossible without demolition work.
Not sure whether all the fire dampers in your building still demonstrably work? We test, repair, and register them in a digital logbook, as a one-off visit or within a maintenance contract.
Frequently asked questions
An annual function test is a good starting point for most buildings; critical environments such as healthcare or data centers often require a shorter cycle. The exact frequency depends on the building's use and the requirements of the insurer or competent authority.
The installation matters just as much. Without the prescribed surrounding seal between the damper and the wall or floor, even a certified damper does not provide full fire resistance.
The fire separation is no longer intact at that point: fire and smoke can spread to the next compartment via the ventilation duct. A malfunctioning damper must be repaired or replaced as a priority.
Want to know more about fire dampers?
Automatic fire dampers in your ventilation system prevent fire and smoke from spreading through the ducts.
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