When an escalator pierces more than two floors, there are several methods to prevent a fire from spreading through the escalator opening. One approach calls for a fire shutter, activated by temperature and smoke detectors, to shut off the wellway of a given floor, thus preventing drafts and the spread of fire up through the building.
In a second method, fireproof baffles surround the wellway and hang 51 cm (20 in.) from the ceiling, creating a smoke and flame deflector. An automatic curtain of water from sprinkler heads on the ceiling then further isolates the escalator.
Another way to isolate the fire is with a spray-nozzle curtain of water similar to a smoke guard. The close-spaced, high-velocity water nozzles create a compact water curtain, preventing smoke and flames from rising through the wellways. Automatic thermal or smoke relays open all the nozzles simultaneously.
In a final method, a sprinkler-vent fire control system uses a fresh air intake on the roof. A blower drives air down through the escalator floor openings, and an exhaust fan on the roof creates a strong draft upward through the exhaust duct. This draws air from just under the ceiling of each floor opening. The system includes spray nozzles on the ceiling.
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