Firestop pillows are passive fire protection items, used for firestopping holes in wall or floor assemblies required to have a fire-resistance rating. Firestop pillows are used in openings that require frequent access (e.g., cable changes), requiring the removal of the firestopping and resealing after the changes are completed. The intumescent resins in batt-based firestop pillows contains hydrates, or chemically bound water. On the fire side, the plastic bag burns off exposing the intumescent to the fire, which releases the water in the form of vapour or steam. The steam rises and hits the plastic bag interior on the unexposed side, where it condenses back to water, and runs back down to cool the installation below. Batt-based pillows are held in place by compressing them, allowing friction to restrain them. If replaced enough times, the pillows will retain a permanent compression, requiring their replacement with new components.
