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HVAC systems are an integral component of a building; providing suitable air circulation, heating and cooling so buildings can be safely and comfortably occupied. An important safety consideration for designers is that the various ducts and plenums used to ventilate buildings may pass through barriers that are designed to limit the spread of fires.
Fire dampers prevent the spread of fire through ventilation systems by closing when smoke or heat is detected, shutting off airflow to block the passage of smoke and flames. In this article, we’ll take a closer look at how fire dampers work, and how different types of fire dampers function in the context of a passive fire protection system.
Dampers close off ducts so that smoke and fire can’t pass through them which can prevent the ignition of combustible materials outside of the compartment of origin and reduce the spread of the products of combustion throughout the building. This provides both necessary life safety and to a lesser degree property protection outcomes.
Heat exposure can cause ductwork to deform or collapse during fires, breaching fire-resistant barriers by creating physical openings. These barriers form “compartments” that are designed to prevent the spread of fire and smoke. Fire dampers are strategically located to stop this from happening. Even if ductwork were to collapse, the damper which is integrated into the compartment wall will remain and prevent the creation of a physical breach of the compartment which contains fire and smoke to the compartment of origin.
Dampers can be broadly classified based on the routes of air transfer they are designed to safeguard. They can also be classed according to the closure mechanisms used. Fire safety regulations and the fire engineering strategy will govern how and where specific types of fire dampers should be installed.
It’s worth noting that not all fire dampers are smoke dampers and vice versa. However, some dampers protect against both the spread of fire and the spread of smoke at once. Combination smoke and fire dampers are frequently used to preserve the integrity of compartmentation systems.
Several sets of regulations and guidance support the installation of fire dampers in the UK. Provisions regarding dampers can be found in the following regulations:
These regulations stipulate a range of fire damper requirements, including where they should be installed, how firestopping around dampers should be approached, and how often these assemblies should be inspected and tested.
In general, fire dampers must be installed at any place where ducts pass through the fire-resistant walls, floors, and ceilings that define a compartment. All non-ducted air transfer openings must be protected by dampers, and penetrations in floors or shaft enclosures may also require dampers.
As previously mentioned, all ductwork that passes through fire-resistant barriers requires dampers. In general, this would mean that fire dampers are required in exhaust ducts. However, if they’re used for venting toxic gases, dampers may not be required. Consult a passive fire protection specialist to verify whether your exhaust ducts require fire dampers if you’re uncertain.
There are many different types of fire dampers, and correctly installing them will require careful observance of manufacturers’ instructions. There are pitfalls for the inexperienced, with fire safety inspections uncovering simple errors like installing dampers upside-down or at 90 degrees to their proper position. Incorrectly oriented dampers cannot function when they rely on gravity to close, so they will offer no protection at all.
The way in which fire dampers have been secured will also contribute to determining their efficacy. Dampers must seal air spaces between compartments in a building, so if there are gaps around the outside of the damper, it can no longer work effectively. Finally, dampers must be accessible for inspection and testing, and they must be tested immediately after installation.
Fire stopping around fire dampers can be just as important as the dampers themselves. Dampers that have been fitted so that gaps are left around them are all too common, and they represent a breach in compartmentation. Since the aim is to maintain the fireproof rating of the compartment, fire stopping around fire dampers must comply with the fire strategy outlined in the compartmentation plan. Certified fire stopping materials must be used to retain the integrity of compartments. For example, fire batts made from mineral wool and coated with an intumescent material are frequently used in this context. Designers should ensure that they consider the wall type and whether appropriate fire testing has been conducted to enable a complaint installation.
UK regulations specify that fire dampers must be tested annually by a competent person. Before testing, a visual inspection is conducted. This will include checking that the fire dampers are correctly installed and that there are no signs of wear or corrosion.
Apart from looking for signs of physical damage and wear, inspectors check for obstructions, debris, and any accessibility issues. To test fire dampers properly, technicians must check that they close properly. For example, fire dampers that are activated by a fusible link are tested to ensure that they will shut off airflow when the release mechanism is activated and are then reset by replacing the fusible link.
Following the testing of fire dampers, a full report must be issued, and building managers must retain their fire damper inspection reports as part of their regular record-keeping in adherence to the golden thread approach.
Simple as they may seem on the surface, it takes skill, knowledge, and experience to correctly fit and inspect fire dampers. With regulatory compliance and the safety of building occupants at stake, certified professionals should be chosen for their installation and the regular inspections that are to follow.
CLM Fireproofing is the UK’s leading passive fire protection company with decades of experience in the installation and maintenance of fire stopping and compartmentation systems. Contact our experts today to discuss our fire remediation services, passive fire safety audits or compartmentation surveys.
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