Most people will be familiar with at least some of the apparatus of fire-fighting – extinguishers, sprinklers, water buckets – but effective fire suppression in buildings also requires measures that will minimise the spread of fire, should it occur.
Passive fire protection helps ensure that general fire precautions are backed by built-in elements to restrict the growth of fire and fumes. A thorough fire risk assessment will identify requirements for passive fire protection, and assess existing measures to see if they are sufficient.
Passive and Active Systems
Active fire protection systems include two key elements: fire detectors and fire suppressants. Detectors will detect where there is smoke, heat or flames; suppressors actively attempt to extinguish or control fires, extinguishers and sprinklers being the most well-known examples.
Passive fire protection (PFP) is different because it is about structural fire resistance, where the fabric of a building acts as fire protection. This can include fire resistant walls, doors and floors. These are considered passive elements because they are effectively always switched on, requiring no activation to fulfil their function. Typically, they are built-in to the building, unlike active systems that are added later.
Restricting how smoke and fire can spread involves controlling flammability by dividing the building into fire-resistant compartments. PFP systems do not work to extinguish fire but to contain it, so compartmentation makes every room or section of the building into a sealed unit, restricting the spread of fire.
In many cases, the fire, if contained, will burn itself out without spreading further throughout the building. Should the fire continue to spread, compartmentation still allows greater chance of survival and evacuation for people in the building.
At the same time, this system also helps preserve the building’s structural integrity, so that it is less likely to collapse from fire; and it makes the job of professional fire-fighters easier, as it provides a safer environment for them to work in – clearing remaining people from the building and extinguishing flames.
Testing PFP Effectiveness
Properly maintained fire barrier materials are essential to ensuring the effectiveness of PFP. When testing PFP products and materials, it is vital that they can perform their protective role within a specified period.
Testing involves three criteria: stability, integrity and insulation. This means that within the specified time, the system must be able to fulfil any load-bearing element; it must prevent the spread of fire, smoke and dangerous gases; and it must ensure that, when exposed, the temperature of the area covered does not increase beyond a specified limit within the time set.
There may be other requirements, depending on the PFPs’ location, such as in a multi-level building.
Passive fire protection is not an alternative to active or other fire precautions, but should work alongside them to help preserve buildings and protect the people in them.