Employing Dedicated Smoke Control Systems; Stairtowers; The Effects Of Too Much And Too Little Pressure - Andover Controls Infinity Manual

TOC
The Fundementals of Smoke Control
Employing Dedicated Smoke
Control Systems
Most of the systems discussed so far have been nondedicated systems.
Even in a building whose primary smoke control system is
nondedicated, you may have special zones or functions where you need
to use a dedicated system. The most common dedicated system is a
dedicated smoke control system for a stairtower.

StairTowers

Stairtowers are stairwells with a ventilation system and are isolated
from the main building. The only connection between the building and
the stairtower is fire-rated doors on each floor. Since the building's
occupants should use the stairtower to leave during an evacuation,
keeping the stairtower smoke free is vital.
A stairtower has its own dedicated system that pressurizes the stairwell
to keep smoke out. This dedicated system can take several forms, from
a fan mounted in the roof of the stairtower, to a duct system that delivers
air to each level.
You must pressurize a stairtower enough to keep smoke out. However,
if the pressure in the stairtower is too great, then opening the doors
leading into the stairtower can be difficult. You must strike a balance.
The stairtower smoke control system must pressurize the stairway
enough to keep the smoke out, but it must not pressurize it so much that
the doors cannot be opened.
Figure 1-4. The Effects of Too Much and Too Little Pressure
Too Little Pressure
Too Much Pressure
Stairtower Building Stairtower Building
Andover Controls Corporation 1-15
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