Requirements for fireproof sealing and fireproof boards for cable trays

Fireproof sealing and boards for cable trays require UL-listed firestop materials, proper gap sealing, fire-resistant backing, and coatings to ensure rated fire protection.Fireproof Sealing RequirementsFirestopping for cable trays involves sealing openings where trays pass through walls, slabs, or shafts to prevent the spread of fire, smoke, and toxic gases . Key requirements include:Tight and reliable sealing: All gaps around cables and trays must be sealed without visible cracks or voids .Firestop materials: Use fire-rated boards, firestop packs, firestop mastic, or mineral wool depending on the application .Gap control: The area between firestop packs and cables should not exceed 1 cm², and packing thickness should be at least 24 cm .Backing plates: For large openings, install a fire-resistant backing plate before sealing to support the firestop material .Cover plates: Square, evenly painted plates should close the opening, ensuring complete encapsulation .UL-rated systems: Use UL-listed pillows, moldable putty, or intumescent caulks to meet fire ratings for concrete or gypsum walls, e.g., 3 HR F-rating for concrete and 1–2 HR for gypsum .Fireproof Boards and CoatingsFireproof boards and coatings enhance the fire resistance of cable trays and structural elements :Material selection: Boards and coatings must comply with national safety standards and provide excellent fire resistance and durability .Surface preparation: Clean trays to remove oil, dust, and rust; sandblasting or acid washing may be required .Primer application: Use primers with strong adhesion and anti-corrosion properties, applied uniformly to meet design thickness specifications .Intumescent coatings: Expand under heat to protect cables and structural steel, preventing fire penetration .Encapsulation: Cut edges of mats or boards should be sealed with intumescent caulk to ensure complete fire containment .Installation ConsiderationsTray type and size: Ensure mechanical strength of trays is sufficient to support cable weight and maintain fireproofing integrity .Segregation: Separate power and signal cables to reduce interference and facilitate fireproofing .Maintenance access: Layout and positioning of firestopping materials should allow for inspection and cable maintenance .Reuse and retrofit: Some firestop devices allow for additional cables to be added without compromising fire protection .By following these requirements, cable tray installations can achieve effective fire containment, comply with UL and national standards, and maintain long-term safety in industrial and commercial environments .