Working in the electrical world, it’s sometimes necessary to create a penetration or hole in a fire wall, in order to install cabling for services. Something we often see is that these holes aren’t sealed correctly after installation, in order to ensure the fire wall retains its fire integrity.
Fire rated foam, often simply referred to as pink foam, is a common tool in a fire safety specialist or electrician’s toolbox, but this isn’t always the product to reach, for when sealing a hole in a fire wall or floor.
Fire rated foam
Fire rated foam is non-combustible, meaning it won’t catch fire and therefore, it won’t contribute to the spread of fire through a building. It’s usually pink in color, to differentiate it from other types of expanding foam that don’t have the non-combustible qualities.
The foam expands after being released from the tube, which then fills the gap or penetration in question, leaving no gaps for fire and smoke to pass through. It sets hard and can be cut back to create a smooth, flush finish.
Pink foam best to fill small holes in fire walls
Fire rated foam or pink foam should only be used to fill small linear gaps, gaps between a door frame and wall
Fire rated foam or pink foam should only be used to fill small linear gaps, gaps between a door frame and wall, and small holes in fire walls, up to 35 mm wide. It cannot be used to fill large voids or openings. While fire rated foam expands on application, it sets hard and will not expand further, and seal up a hole, when a fire breaks out.
Fire rated foam is not suitable for use around pipes and cables, as it doesn’t intumesce or expand in extreme heat. So in the event of a fire, the services would burn away, leaving a void and thereby, breaching the fire compartment. In this scenario, an intumescent product would be better suited.
How to seal a fire wall with cabling installed
Unlike fire rated foam, intumescent sealant does not expand, when applied and only swells up, when a fire has broken out, and it reaches a certain temperature. In this circumstance, when the pipe or cables have burnt away, the sealant will expand and seal the hole, in order to reinstate the wall or door’s fire containment properties.
When installing cabling through a firewall, an intumescent sealant can be used around the cables, so as to ensure any gaps are filled. Make sure to read the associated technical datasheets for the intumescent sealants, as some products have a wide range of test applications and others are more limited.
Some key areas to consider are:
- The number of cables and pipes,
- The material of the cables,
- The material of the wall/floor construction, and
- The fire rating of the compartment.
If a large part of the wall needs to be removed to install several cables, use a fire batt, followed by intumescent sealant around the cables, in the same way as outlined previously.
Fire Pillows
If the cables may need to be removed or additional cables need to be installed in the future, the use of fire pillows can be effective. These products will reinstate the fire compartment, but can be removed easily at a later date, allowing additional cables to be added, without damaging the fire protection products.
Ensure they are replaced once the work is finished, to reinstate the compartment again. Ensuring fire walls and floors are updated and maintained correctly can save lives and buy precious time for people to escape burning buildings.