Flexible Fire-Stopping Sealant for Linear Joints and Penetration Seals (Up to 4 Hours Fire Protection)
The FIREFLY® FR Intumescent Acrylic Sealant is a water-based, halogen-free intumescent mastic designed to seal joints, gaps, and service penetrations while providing up to 4 hours fire resistance. Its flexible formulation allows for movement accommodation of ±12.5%, making it ideal for both rigid and semi-flexible construction elements.
Tested to BS EN 1366-3, BS EN 1366-4, and classified to EN 13501-2, this high-performance sealant delivers proven fire and acoustic protection (55dB sound reduction). It forms part of the FIREFLY® FB180 Ablative Batt system, ensuring full compliance for fire-stopping installations in walls and floors.
✅ Key Features:
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Provides up to 4 hours fire protection in certified applications
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Seals joints up to 35mm wide without slumping
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±12.5% movement tolerance to ISO 11600:2002
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Suitable for metal pipe penetrations, joints in concrete, steel, gypsum, and timber
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Reduces sound transmission by 55dB, tested to BS EN 10140-2
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Compatible with FB180 Batt systems for a tested, integrated firestop
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VOC rated M1, Indoor Air Comfort GOLD® – safe for interior use
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Paintable once cured
🧪 Technical Specifications:
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Colour: White
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Skin Time: 15–60 minutes (depending on conditions)
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Cure Time: 5–15 days for a 15 × 20mm bead
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Application Temp.: +5°C to +40°C
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Specific Gravity: 1.60 – 1.68 g/cm³
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Coverage: Approx. 1m per 310ml @ 20 × 15mm bead
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Shelf Life: 24 months (unopened)
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Packaging: 310ml cartridge or 600ml foil sausage
⚠️ Limitations & Safety:
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Not suitable for cPVC pipework
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Do not use where movement exceeds ±15%
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Classified as non-hazardous under CLP, but may cause skin/eye irritation – contains 1,2-benzisothiazol-3(2H)-one (may trigger allergic reaction)
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Store between 5°C and 25°C, away from frost and direct heat