SCS Series Manual —
P/N 15712:L 7/18/16
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Smoke Control System Types
Concepts of Smoke Control
2.5.2 Elevator Hoistway Systems
Elevator hoistways have been known to adversely contribute to the movement of smoke throughout a building. This is due mainly to the fact
that elevator doors are not tight fitting and elevator hoistways usually have openings or vents at the top. In addition to these factors, the major
contributor to smoke movement in an elevator hoistway is the stack effect of the building.
There are two categories of elevator smoke control - smoke control for evacuation via the elevators and smoke control for prevention of
smoke movement. Smoke control for the prevention of smoke movement is intended to prevent the migration of smoke to other floors by
way of the elevator shaft. Smoke control for elevator evacuation is intended to provide a safe means of egress in the event of a fire. This
would include not only smoke protection, but fire protection and any other features necessary to make the elevator safe for fire evacuation.
There are several ways of accomplishing elevator smoke control:
•
Exhausting smoke from the fire floor
•
Pressurizing elevator lobbies
•
Constructing smoketight elevator lobbies
•
Pressurizing elevator hoistways
Prevention of Smoke Movement Systems
These types of systems are usually designed to supply air to a shaft, produc-
ing pressure differences sufficient to prevent the flow of smoke into the ele-
vator hoistway in the event of a fire, as shown in Figure 2.17. During a fire
condition for this type of system, elevator cars should be taken out of nor-
mal service and automatically returned to the ground floor (or an alternate
floor if the fire is detected on the ground floor).
Elevator Evacuation
Most elevator systems do not provide the proper protection necessary for
evacuation in the event of a fire. The question of using elevators for the pur-
pose of fire evacuation has resulted in many concerns, some of which are
listed below:
•
While waiting for the elevator during a fire condition, occupants may
be exposed to fire, smoke, or developing panic.
•
Elevators could stop at floors involved in fires unnecessarily, exposing
occupants to fire and smoke.
•
Elevators cannot start until the doors are closed. In a fire situation,
large numbers of people trying to crowd into an elevator might make it
impossible to start.
•
Any power failure due to fire or water damage could render elevators
inoperable, possibly trapping occupants between floors.
Therefore, an elevator system used for fire evacuation must have the fol-
lowing requirements:
•
Elevator control must ensure safe efficient evacuation.
•
Reliable electrical power must be supplied.
•
Elevator controls, control wiring, and electrical power must be protected from fire or water damage.
•
Elevator lobbies, hoistways, and machinery rooms must be protected against fire and smoke.
Smoke control systems for elevator evacuation must provide protection for elevator lobbies, elevator hoistways and elevator machinery
rooms. During an evacuation that uses the elevators, building occupants must be protected in the elevator lobby while waiting for the eleva-
tor. Another area that needs to be protected is the elevator machinery room to prevent damage to the elevator controls. Figure 2.17 shows an
elevator hoistway that is being pressurized and as a result it indirectly pressurizes the elevator lobbies and machinery room.
NOTE:
For systems implementing elevator smoke control, the open vent at the top of the hoistway should be eliminated.
Figure 2.17 Elevator Smoke Control Using Shaft
Protection
Machinery Room
Elevator Lobby
Hoistway
Fan