Seals for Fire Doors and Windows with Expandable Graphite

Standards in Focus: What Fire Doors Must Achieve

Fire doors are high-performance safety elements and their quality is strictly regulated. In Europe, a unified standard has been in force for several years to ensure these components offer reliable protection in an emergency. For manufacturers, planners and installers, a sound knowledge of these standards is essential.

The Most Important Regulations at a Glance

• DIN EN 16034: The central European product standard for fire and smoke protection closures. It makes CE marking mandatory and refers to the testing procedures of EN 13501-2. Only components that have been tested and appropriately marked may be placed on the market throughout Europe.
• DIN 4102: The former German standard for classifying construction materials and components according to their fire behaviour. It is gradually being superseded by EN 16034, but remains relevant for existing buildings.
• EN 1634-1 / EN 13501-2: These standards regulate the testing procedures for the fire resistance of doors, gates and windows, and form the basis for classification into fire resistance categories such as T30, T60 or T90. The higher the number, the longer the construction withstands fire.
• DIN 18650: Specifies the requirements for the safe operation and maintenance of automatic doors, including fire doors. Regular maintenance by qualified personnel is mandatory.
• DIN 18273: Defines requirements for door hardware, especially lever sets, that may be used in fire and smoke protection doors.

Key Classifications Planners Should Know

• T classes (e.g. T30, T60, T90): Indicate fire resistance in minutes, i.e. how long the door prevents the passage of fire.
• S classes (e.g. S200): Indicate smoke tightness and are tested in accordance with EN 1634-3. Critical for safety in escape routes.
• EI classification: Describes not only fire resistance (E) but also thermal insulation (I) on the side facing away from the fire. Standardised in accordance with EN 13501-2.

Seals: Essential Helpers for Standard-Compliant Fire Protection

The best door is of little use if fire or smoke can penetrate even the smallest gaps. This is precisely where seals come into play. They close construction gaps, ensure pressure balance and are crucial for fire doors to provide their tested protective function. Many of the standards mentioned above, such as EN 16034, EN 1634-1 or S200, do not just require the door leaf itself to be fire resistant, but that the door frame, joint widths and sealing elements also function reliably in an emergency. A weak or missing seal can become the Achilles' heel of an entire fire protection design.

Typical Areas of Application

This is especially critical in highly frequented areas such as:

• Escape and rescue routes
• Public institutions (e.g. schools, hospitals, authorities)
• Industrial facilities and warehouses
• Multi-storey residential buildings and high-rises
• Underground car parks and parking decks
• Hotels and hospitality venues
• Shopping centres and event venues
• Transport infrastructure (e.g. stations, airports, tunnels)

Key Requirements for Seals

The requirements for these seals are demanding. They must:

• react reliably when exposed to heat (from approx. 150–200 °C),
• completely seal cavities in door frames,
• remain mechanically stable and not dissipate,
• pass standardised tests such as those in accordance with EN 1634-1.

It's not just about sealing performance—longevity, environmental compatibility and ease of handling are also important. Expandable graphite fulfils these requirements ideally. We’ll show you why in the next section.

Why Expandable Graphite is the Perfect Solution

Expandable graphite, also known as expandable graphite, is a halogen-free flame retardant with a unique property: in the event of fire, it expands many times its original volume to form a solid, foam-like protective layer. This so-called intumescence reliably seals joints, gaps and cavities—all without mechanical assistance. For door seals in particular, expandable graphite offers key benefits:

• Efficient fire protection: Expandable graphite reacts to heat and begins to expand before a fire can spread. The resulting protective layer acts like an integrated fire extinguisher.
• Effective sealing: The foamed protective layer reliably seals joints, even with irregular gaps or movement caused by thermal expansion of materials.
• Pressure effect—more than just a snug fit: The expansion generates active counterpressure, effectively closing even larger openings.
• Durable and ageing resistant: As a mineral additive, expandable graphite remains stable over the life of the product and only reacts in the event of fire.
• Halogen-free & REACH compliant: Expandable graphite contains no substances harmful to health or the environment and meets the latest construction and safety standard requirements.

Whether in sealing tapes, firestop barriers or profile seals, expandable graphite ensures fire safety components function reliably in an emergency. Next, we’ll show you how these materials are constructed and which standards they must meet.

Other Areas of Application for Expandable Graphite Seals

Seals containing expandable graphite are used wherever the highest fire protection requirements must be met, and where functionality, longevity and environmental compatibility are equally important. The combination of rapid expansion, reliable sealing and a halogen-free formula makes them ideal for a wide range of applications.

Fire doors

Whether in public buildings, industrial plants or residential complexes, fire doors must create barriers against fire and smoke in an emergency. Expandable graphite profile seals reliably close door gaps and make a significant contribution to the fire resistance duration of the overall construction.

Window systems

Window units in escape routes or façades are also subject to strict fire protection requirements. Intumescent seals with expandable graphite ensure that flames or smoke cannot pass through window frames.

Piping and cable penetrations

Openings created for technical installations often provide routes for fire and smoke to spread unchecked. Expandable graphite-sealed barriers and seals ensure fast and effective sealing in the event of fire—helping to contain toxic emissions.

Joints and connections

Joints between components—for example, between door and wall—are potential weak points in fire protection. Sealants with expanding graphite fill these transitions and help to maintain fire protection zones.

Vehicle construction & transport

Fire protection sealing solutions using expandable graphite are also used in rail vehicles, buses and specialist vehicles, especially where high standards such as EN 45545 apply. Here, every centimetre that protects against heat and smoke in an emergency counts.

Technical Implementation: How Expandable Graphite is Integrated into Seals

For expandable graphite to fully develop its protective properties, it must be optimally integrated into the sealing solution. This is achieved using a targeted combination of material technology and application expertise.

• Incorporation in carrier materials: Expandable graphite is integrated during production into flexible carrier materials such as TPE (thermoplastic elastomers), PVC or PU. Depending on the application, graphite content and particle size vary to achieve the desired rate of expansion and sealing pressure.
• Extrusion or profiling: The finished seal mixtures are shaped, usually into profiles, tapes or inserts, ready to be installed in doors, windows or firestop systems. The seals remain flexible and unobtrusive in normal operation.
• Activation in the event of fire: When exposed to high heat, the expandable graphite begins to react. In seconds, the graphite particles foam up to many times their volume, sealing cavities and joints. This intumescent reaction creates a pressure-resistant, carbon-rich protective layer that prevents the ingress of flames, smoke and heat.
• Adaptation to specific requirements: In our laboratory, we tailor the material properties precisely for each application. Starting temperature, expansion pressure, particle structure and pH value are selected to ensure the seal functions reliably even in challenging environments.