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4. System enables damper operation as appropriate for
smoke control mode.
5. Operator verifies operation as appropriate (e.g., action
of differential pressure switch).
6. Operator cancels smoke control mode as long as initiating
panel is not in alarm and FSCS is not in manual override.
CONTROL OF MALLS, ATRIA,
AND LARGE AREAS
The objective of malls, atria, and other large area smoke
control systems is to prevent the area from filling with smoke
as a result of fire in the area or an adjoining area. Purging is
used as the means to dilute and remove smoke.
In large areas (Fig. 10), the smoke produced is buoyant and
rises in a plume until it strikes the ceiling or stratifies because
of temperature inversion. The smoke layer then tends to descend
as the plume continues to supply smoke. Smoke can be
exhausted to delay the rate of descent of the smoke layer. Also,
sprinklers can reduce the heat release rate and the smoke
entering the plume. Adjacent spaces to the mall or atrium can
be protected from the smoke by barriers or opposed airflow.
Additional information can be found in NFPA 92B, Guide
for Smoke Management in Malls, Atria, and Large Areas.
Typical Operation for Smoke Control Systems for Malls,
Atria, and Other Large Areas (Fig. 6):
ACCEPTANCE TESTING
Smoke control systems must be tested carefully and
thoroughly. All measurements should be recorded and saved.
ASHRAE Guideline 5-1994 should be followed.
The system should be activated by an appropriate sensor
within the zone (if applicable) and the results should be
monitored and recorded.
Where standby power is used, testing should be conducted
with both normal power and standby power.
The use of smoke bombs or tracer gas to test smoke control
systems is discouraged because they cannot accurately simulate
LEAKAGE RATED DAMPERS
Refer to the Damper Selection and Sizing section for
information on leakage rated dampers.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
SMOKE MANAGEMENT FUNDAMENTALS
EXHAUST
FAN
SPRINKLER
FIRE
AREA
Fig. 10. Control of Smoke in Malls,
Atria, and Other Large Areas.
1. Any fire alarm initiates smoke control mode.
2. System turns on exhaust fans.
3. System enables damper operation as appropriate for
smoke control mode.
4. Operator verifies operation as appropriate (e.g., action
of airflow-proving sail switch).
5. Operator cancels smoke control mode as long as initiating
panel is not in alarm and FSCS is not in manual override.
fire conditions. Smoke bombs and tracer gas lack the buoyant
forces caused by heat generated in a fire. These items can be
used, however, for identifying leakage paths and leakage areas.
Periodic testing should be conducted in accordance with the
following:
— NFPA 90A, Installation of Air Conditioning and
Ventilating Systems
— NFPA 92A, Recommended Practice for Smoke Control
Systems
— NFPA 92B, Guide for Smoke Management Systems in
Malls, Atria, and Large Areas
181
DAMPER
SMOKE
PLUME
FAN
FIRE
M13027
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