Understanding Intumescent Strips: Types, Uses, and Installation

Fire safety is a critical aspect of building design and maintenance, often determining the difference between life and death in emergency situations. One essential component in enhancing fire resistance within structures is the use of intumescent strips. These innovative materials play a pivotal role in containing fires, thereby providing crucial time for evacuation and minimizing property damage.

Understanding the various types, uses, and installation methods of intumescent strips can significantly improve their effectiveness.

Purpose of Intumescent Strips

Intumescent strips serve a fundamental role in enhancing the fire resistance of buildings by expanding when exposed to high temperatures. This expansion effectively seals gaps and joints, preventing the spread of flames, smoke, and toxic gases. By doing so, they help to compartmentalize a fire, limiting its progression and providing a safer environment for occupants to evacuate.

These strips are particularly valuable in areas where fire doors, glazing systems, and service penetrations are present. Fire doors, for instance, are designed to withstand fire for a specified period, but without intumescent strips, the gaps around the door frame could allow fire and smoke to pass through. The strips expand to fill these gaps, maintaining the door’s integrity and effectiveness.

In glazing systems, intumescent strips are used to protect glass panels. When exposed to heat, the strips expand and form a barrier that helps to hold the glass in place, preventing it from shattering and allowing flames to spread. This is especially important in buildings with large glass facades or internal glass partitions, where the risk of fire spreading through broken glass is significant.

Service penetrations, such as pipes and cables that pass through walls and floors, also benefit from the use of intumescent strips. These penetrations can create pathways for fire to travel between compartments. By installing intumescent strips around these penetrations, the spread of fire can be effectively contained, ensuring that the fire-resistance rating of the wall or floor is maintained.

Types of Intumescent Strips

Intumescent strips come in various forms, each tailored to specific applications within a building. Understanding the different types can help in selecting the right product for a particular need.

Fire Door Strips

Fire door strips are designed to be installed around the edges of fire doors. These strips are crucial in ensuring that the door can effectively block the passage of fire and smoke. When exposed to high temperatures, the strips expand to fill the gaps between the door and its frame, creating a tight seal. This expansion helps to maintain the door’s fire-resistance rating, which is typically measured in minutes, such as 30, 60, or 90 minutes. The effectiveness of fire door strips is often tested and certified according to standards like BS 476: Part 22 or EN 1634-1. Proper installation is key, as any gaps or misalignments can compromise the door’s ability to contain a fire.

Glazing Strips

Glazing strips are used in conjunction with fire-resistant glass to enhance the overall fire protection of glazed areas. These strips are installed around the perimeter of the glass panels. Upon exposure to heat, they expand to form a barrier that helps to hold the glass in place, preventing it from shattering and allowing flames to spread. This is particularly important in buildings with large glass facades or internal glass partitions, where the risk of fire spreading through broken glass is significant. The performance of glazing strips is often evaluated according to standards such as BS EN 1364-1, which assesses the fire resistance of non-loadbearing elements. Proper selection and installation of glazing strips can significantly enhance the fire safety of glazed areas.

Pipe Collar Strips

Pipe collar strips are designed to be used around pipes that penetrate walls and floors. These strips are particularly important in maintaining the fire-resistance rating of walls and floors that have been breached by service penetrations. When exposed to high temperatures, the strips expand to fill the gap around the pipe, effectively sealing it off and preventing the spread of fire and smoke. This is crucial in buildings with extensive plumbing and electrical systems, where numerous pipes and cables pass through fire-rated walls and floors. The performance of pipe collar strips is often tested according to standards like BS EN 1366-3, which evaluates the fire resistance of service installations. Proper installation ensures that the fire-resistance rating of the wall or floor is maintained, even in the presence of service penetrations.

Materials Used in Intumescent Strips

The effectiveness of intumescent strips hinges on the materials used in their construction. These materials are specifically chosen for their ability to react to high temperatures by expanding and forming a protective barrier. One of the most commonly used materials is graphite. Graphite-based intumescent strips are highly effective due to their rapid expansion rate when exposed to heat. This rapid expansion helps to quickly seal gaps and prevent the spread of fire and smoke. Graphite strips are often used in applications where a fast response is necessary, such as around fire doors and service penetrations.

Another material frequently used in intumescent strips is sodium silicate. Sodium silicate-based strips are known for their ability to form a hard, insulating char when exposed to high temperatures. This char acts as a barrier, preventing the passage of flames and heat. Sodium silicate strips are often used in applications where a durable, long-lasting barrier is required, such as in glazing systems. The insulating properties of the char formed by sodium silicate can also help to protect underlying materials from heat damage, further enhancing the fire resistance of the structure.

Organic materials, such as expandable graphite and ammonium polyphosphate, are also used in some intumescent strips. These materials are chosen for their ability to expand and form a protective barrier when exposed to heat. Expandable graphite, for example, can expand up to 300 times its original volume, creating a highly effective seal. Ammonium polyphosphate, on the other hand, is often used in combination with other materials to enhance the fire resistance of the intumescent strip. These organic materials are particularly useful in applications where a flexible, adaptable barrier is needed, such as around irregularly shaped service penetrations.

Installation Techniques

Proper installation of intumescent strips is paramount to ensuring their effectiveness in fire safety applications. The first step in the installation process involves thorough surface preparation. Surfaces must be clean, dry, and free from any contaminants such as dust, grease, or old adhesive residues. This ensures that the intumescent strips can adhere properly and function as intended. Using a suitable cleaning agent, such as isopropyl alcohol, can help achieve the necessary level of cleanliness.

Once the surface is prepared, the next step is to measure and cut the intumescent strips to the required length. Precision is crucial here, as any gaps or overlaps can compromise the strip’s ability to form a continuous barrier. A sharp utility knife or specialized cutting tool can be used to achieve clean, straight cuts. It’s also important to ensure that the strips are cut slightly longer than the gap they are intended to fill, as this allows for a snug fit and optimal expansion during a fire.

Adhesion is another critical aspect of the installation process. Many intumescent strips come with a self-adhesive backing, which simplifies the installation. However, for applications requiring additional security, a high-temperature adhesive or sealant can be used to reinforce the bond. Applying even pressure along the length of the strip ensures that it adheres uniformly to the surface. In some cases, mechanical fasteners such as screws or clips may be used in conjunction with adhesive to provide extra stability.