Smoke Control And Fire Control System Differences - Simplex 4100U Application Manual

Smoke Control and Fire Control System Differences

Separate System
for Separate Goals
The smoke control system is usually separate from the fire control system, since they have
different goals. The goal of the fire control system is to contain and extinguish the fire as fast as
possible. These systems, which halt the fire but not the smoke, are often triggered automatically,
relying on the heat of the fire to activate the system. Although smoke control systems are also
automatic, you must have manual overrides for the automatic controls.
A smoke control system may also be required to work with gas-based fire extinguishers, such as
gaseous agent systems installed in many computer rooms. If the smoke control system tries to vent
a room with such a system, it may vent the fire suppressing gas as well. Removing the gas lets the
fire continue burning. Also, pressurizing the areas surrounding an extinguisher equipped room
reduces the effectiveness of the system. Air forced into the room from the outside by pressure can
provide the fire with the oxygen it needs to continue burning. Therefore, gas-based fire
extinguishers and smoke control systems should not be active at the same time in the same
area.
The smoke control system receives the location of the fire from the fire panel. The fire panel uses
a combination of smoke and heat sensors to determine where the fire is located. As defined in
NFPA 92A: In the event that signals are received from more than one smoke zone, the smoke
control system will operate in the mode determined by the first signal received.
Specific, zoned smoke control strategies should never be triggered by manual pull boxes. The
risk of someone pulling a box someplace other than the fire zone is too high for you to trust your
smoke control system to this form of activation.
All smoke control systems installed in buildings must be in accordance with the standards
adopted by local codes. You can find additional information regarding fire alarm control units in
Underwriters Laboratories Standard UL 864 and the National Fire Protection Association (NFPA
1-9
®
).