Final answer:
An intumescent fire-stopping material expands in the presence of heat, containing water that vaporizes to cool and form a protective barrier during a fire.
Step-by-step explanation:
An intumescent fire-stopping material contains small amounts of water that cool the penetration as it is burned. This material expands when exposed to heat, effectively sealing any gaps or penetrations in fire-rated walls or floors to prevent the spread of fire and smoke. Intumescent materials can be of various forms, including sealants, putties, and sheets, and are used in passive fire protection systems.
These fire-stopping products may often be combined with other components, such as a fluorinated solution, which can spread across a burning surface to extinguish a fire. Such solutions or foams are universally used to combat large-scale fires, particularly those involving organic liquids. The water contained in the intumescent product vaporizes when heated, aiding in cooling and forming a char barrier that insulates and protects the substrate.