Intumescent Seals is a division of Dixon International Group Limited


Building service cables often need to be modified during the life of a building to meet changing requirements and building uses. Where these services pass through fire compartment walls frequent, service changes can be a challenge to the maintainance of adequate integrity of the building’s fire compartments. THERM-A-PILLOW provides a simple and reusable solution to satisfy this requirement.


THERM-A-PILLOW is a silver grey heavy duty silicone coated glass fabric bag containing a mixture of perlite, gypsum and graphite intumescent material. The activation temperature of the intumescent contents is approximately 180°C. THERM-A-PILLOW has a normal in service temperature range of -20°C to +120°C THERM-A-PILLOW has a typical density of 0.31g/cm3 and is available in a range of 4 sizes.


THERM-A-PILLOW is suitable for temporary and permanent cable penetration fire seals in fire compartment walls. The penetrating cables, which may vary in size and type may be supported on cable trays or cable ladders. Before installation of THERM-A-PILLOW, remove any loose debris within the penetration to be sealed. Ensure the penetrating cables are adequately on either side of the penetration i.e. do not rely on the THERM-A-PILLOW to provide cable support.

Install THERM-A-PILLOW starting at the bottom of the penetration with the long dimension through the wall. Select suitable sizes of THERM-A-PILLOW to ensure a close fit around services, using the largest appropriate size for each location. Stagger the joins in each layer of THERM-A-PILLOW. Check for visible gaps, using small pillows to ensure the penetration is adequately sealed.


THERM-A-PILLOW will provide 120mins fire resitance integrity when sealing around PVC sheathed copper cables up to 80mm diamater. Smaller diameter cables may be sealed in bunches up to 140mm diamater. Cable ladders up to 300mm wide and cable trays up to 500mm wide may be used. See details below for further guidance.

Cable Type and Size
Integrity E
Insulation (I)
4x185mm2 Cu, XLPE/PVC, Ø55mm 120 mins 60 mins
4x185mm2 Cu, EPR/CSP, Ø80mm 120 mins 120 mins
1x185mm2 Cu, XLPE/PVC, Ø24mm 120 mins 60 mins
5x1.5mm2 Cu, PVC/PVC, bunch 20,  Ø140mm 120 mins 120 mins
5x1.5mm2 Cu, EPR/CSP, bunch 10,  Ø140mm 120 mins 120 mins
5x1.5mm2 Cu, XLPE/EVA, bunch 10,  Ø140mm 120 mins 120 mins
1x95mm2 Cu, XLPE/PVC, Ø21mm 120 mins 120 mins
4x95mm2 Cu, XLPE/PVC, Ø45mm 120 mins 90 mins
4x95mm2 Cu, CPR/CSP, Ø60mm 120 mins 90 mins
20x2x0.6mm screened comms, PVC/PVC, bunch Ø100mm 120 mins 120 mins
1x95mm2 Cu, PVC/un-sheathed, Ø21mm 120 mins 120 mins
1x185mm2 Cu, PVC/un-sheathed, Ø23mm 120 mins 120 mins
Cable ladders up to 300mm 120 mins 120 mins
Perforated cable tray up to 500mm 120 mins 120 mins
Unperfortated cable tray up to 500mm 120 mins 120 mins



THERM-A-PILLOW is available in the following nominal sizes:

Small 320mm x 50mm x 25mm
Small-Medium 320mm x 100mm x 30mm
Large-Medium 320mm x 150mm x 30mm
Large 320mm x 200mm x 30mm

The approximate  number of THERM-A-PILLOWs to seal a 600mm x 60mm opening is:

Free Area
No. Pillows
79% (21% concentration of cables) 48 lge, 64 lge-med, 95 sml-med, 228 sml
100% 60 lge, 80 lge-med, 120 sml-med, 228 sml


Test Evidence

THERM-A-PILLOW has been tested in accordance with BSEN1266-3:2009 Annex A and classified in accordance with BSEN13501-2:2007 A1:2009

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