If a fire should break out in a building, there are two things that pose an immediate risk to life – fire and smoke, with smoke posing the greater threat. Buildings are designed in such a way that fire can be contained and smoke controlled.
In effect, a building is a series of compartments. If fire breaks out in one area, the system works to restrict it to that area. This is achieved first, by making sure that the walls, floor and ceiling are fire resistant, and second, by ensuring that where those boundaries need to be breached – by ductwork for the heating, ventilation and air-conditioning (HVAC) system, for example – there are barriers in place that will close and seal the breach. Those barriers are fire and smoke dampers. They might be designed to prevent either fire or smoke from passing, or to direct smoke outside of a building, or else a combined fire/smoke damper can be fitted.
How dampers work
Fire dampers remain open to allow for airflow during the normal day-to-day operation of a building. When fire or smoke are detected, however, fire dampers are designed to close, to seal the boundary wall of the compartment. Smoke dampers can be used in two ways, closed to control smoke circulation through the duct, or open to direct smoke and hot gases to an exit point, expelling smoke from the building.
Fire dampers generally operate via a fusible link – when the temperature reaches a certain point, the link melts and the damper automatically slams shut.
Smoke dampers can be triggered by smoke detectors, meaning heat doesn’t need to be a factor.
As well as preventing smoke from entering a particular area, a smoke control system can be designed to safely channel it from the building via a smoke extract path. Having the choice of which dampers to close and which to leave open facilitates this.
Fire/smoke dampers may be fitted with resettable electric heat release devices, which allow for controlled closure of the damper; this can help avoid pressure problems within the HVAC system.
The job of dampers
Dampers are designed to prevent ducting becoming a weak point in a building’s fire safety system. They don’t only prevent the spread of fire and smoke in order to protect buildings and the property they hold, they allow time for people to safely evacuate the building and can help minimise the risk to firefighters.
A compartmentalised fire containment and smoke control system will only work as it should if all the elements can be relied upon to operate as expected, when needed. The system relies on the capacity to close down and safely isolate compartments while having the option to leave open channels for smoke, gases and heat to evacuate. If just one damper fails in its function, the entire system is compromised – and so is the safety of the people within the building.
If you want to know more about how to maintain the integrity of fire and smoke dampers, we can help. Here at Indepth we have a highly experienced team able to test dampers, carry out remedial works, and also provide a comprehensive report to prove compliance with regulatory requirements. Call us today if you require any advice, we’ll be happy to help.
