Fireproof sealing methods for prefabricated cable trays

Effective fireproof sealing of prefabricated cable trays involves using intumescent pillows, firestop packs, fire-resistant coatings, and caulks to maintain fire integrity and prevent flame and smoke propagation.

Intumescent Fireproof Pillows

Intumescent pillows, such as AF BAGS, are widely used for sealing cable tray penetrations through walls and floors. These pillows expand under heat to fill gaps, providing fire resistance up to EI 240 according to EN 1366-3 standards. They are encased in non-combustible fiberglass and contain intumescent compounds, thermal insulators, and water-releasing agents, allowing a compact sealing depth of 120 mm for cables up to 21 mm in diameter. They are repositionable, facilitating maintenance or modifications without compromising fire protection .

Firestop Packs and Mineral Wool

For larger openings or complex penetrations, firestop packs and fire-resistant mineral wool can be used. These materials are installed in layers around the cable tray, ensuring tight sealing without visible cracks or voids. The gap between packs and cables should not exceed 1 cm², and the packing thickness should meet the required fire rating, typically 24 cm or more for high-resistance applications. Fire-resistant backing plates may be added for structural support .

Fire-Resistant Coatings and Tapes

Fireproof coatings like FLAMMOTECT-A and fire protection tapes such as DG-CR 0.7 provide an additional protective layer around cables and trays. These coatings prevent flame propagation, resist environmental factors like UV, moisture, and chemicals, and maintain cable functionality during a fire. They are suitable for both indoor and outdoor installations and can be applied directly to prefabricated trays .

Firestop Caulks and Moldable Putty

For sealing edges, joints, or irregular openings, intumescent caulks and moldable putty (e.g., 3M FSP-SLP-M) are effective. These materials expand under heat, forming a barrier that blocks smoke, fire, and toxic gases. They are easy to apply, conform to various surfaces, and can be used in combination with pillows or packs to achieve a complete fireproof seal .

Installation Considerations

• Measure tray dimensions and select the appropriate size and number of fireproof pillows or packs.
• Ensure tight packing around cables to avoid gaps that could compromise fire resistance.
• Use backing plates for large openings or non-standard wall/floor structures.
• Maintain accessibility for future maintenance while preserving fire integrity.
• Regular inspection is essential to verify coating integrity, sealing effectiveness, and absence of corrosion or mechanical damage .

Summary

Combining intumescent pillows, firestop packs, fire-resistant coatings, and caulks provides a robust fireproof sealing solution for prefabricated cable trays. Proper selection, installation, and maintenance ensure compliance with fire ratings, prevent flame and smoke propagation, and maintain cable functionality during emergencies.