In simple terms, an intumescent substance is one that expands in response to exposure to heat. In fire protection terms, an intumescent seal is used to stop flames or smoke passing through a gap. So an intumescent fire door seal expands to fill the gap around the door and prevents a fire from freely spreading through.
In theory, a fire door is supposed to shut out a fire. However, the problem is there is often a very small gap where fire can pass through the door.
An intumescent door strip is added, either to the door edge or inside the door frame, in order to counter this problem. While it does not extinguish the fire, it further delays the progress of the flames, giving people an additional 30 -60 minutes (depending on the size of the strip) to evacuate the building. Every second can potentially count and this is a relatively small investment to keep people safe.
Types of Intumescent Fire Door Seals
There are a number of different types of strip available. What you choose largely depends on your environment. A good example for most environments is a strip with an additional smoke pile. The reason this is important is because it also reduces smoke passing through the gaps. It is easy to forget that smoke inhalation can be just as lethal as the flames themselves so anything you can do to stop them is strongly worth considering.
There are other potential benefits as well. For example, an additional draft seal can also reduce heat escaping from your building, thus reducing energy use and lowering your heating costs.
Finally, some places like hospitals and schools prefer to use hygienic wipe clean seals. This strip still maintains the same protection as the others but it simply changes the nylon pile used in the other strips for a wipe clean material. Furthermore, they can be used as acoustic insulation as well (which is why they are often referred to as “quad seals” due to their multiple uses).
In short, there are a number of intumescent seals available. It is worth looking online to compare the different options available and see which features are best suited for your environment.