How does an endothermic fire stop device work?

• A. It reflects heat
• B. It vents heat to the room
• C. It melts to seal the gap
• D. It absorbs the heat

Answer: (D)

Endothermic fire stop devices work by absorbing heat when exposed to high temperatures. The materials involved undergo endothermic reactions or dehydration that pull energy from the surrounding environment, cooling the joint and slowing or stopping the flame’s progression through the opening. This cooling helps maintain the barrier’s fire-resistance rating long enough for occupants to evacuate and for suppression to intervene. Some endothermic materials may also release water during the reaction, which adds to the heat absorption, but the key idea is this: heat is absorbed rather than reflected, vented, or left to melt away.