US Patent 11661735 Fire stop for a passageway

A tubular fire stop assembly for a poured concrete structure defines at least a portion of a passage through the structure during use. The assembly has a base with a tubular sleeve, both encircling and extending along the passage. A fire ring is connected to the base and has a plate with a central opening encircling the passage. An intumescent ring has inner and outer sidewalls and opposing top and bottom walls. The intumescent ring is inside the base, encircles the passage and rests on the fire ring plate. A woven, galvanized wire mesh casing extends along the inner and outer sidewalls and the top wall of the intumescent ring.