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Chapter 1 Smoke control overview
16 BAS-APG001-EN
Design considerations for smoke
control
Two occurrences will hinder smoke control:
• Plugholing
• Smoke feedback
Smoke control systems should be designed to address the problems that
are caused by plugholing and smoke feedback.
Plugholing
Plugholing occurs when an exhaust fan pulls fresh air into the smoke
exhaust (
Figure 10). Plugholing decreases the smoke exhaust and
increases the smoke layer depth. It has the potential of exposing
occupants to smoke.
The maximum flow of smoke (Q
max
) exhausted without plugholing
depends on the depth of the smoke layer and the temperature of the
smoke. If the required total smoke exhaust is greater than Q
max
,
additional exhaust vents will eliminate plugholing. The distance between
vents must be great enough that the air and smoke flow near one vent
does not affect the air and smoke flow near another vent.
Figure 10: Sample plugholing