Fire Code of the Philippines Ebook - SafetySignsPH.com Fire Code of the Philippines eBook - SafetySignsPH | Page 87

c. Every vestibule shall have a minimum dimension of not less than
the required width of the corridor leading to it and a dimension of
not less than one hundred eighty three centimeters (183 cm) in the
direction of travel.
8. Mechanical Ventilation
Smokeproof enclosures using mechanical ventilation shall comply
with the following requirements:
a. Vestibules shall have a dimension of not less than one hundred
twelve centimeters (112 cm) in width and not less than one
hundred eighty three centimeters (183 cm) in direction of travel.
b. The vestibule shall be provided with not less than one air change
per minute, and the exhaust shall be 150 percent of the supply.
Supply air shall enter and exhaust air shall discharge from the
vestibule through separate tightly constructed ducts used only for
such purposes. Supply air shall enter the vestibule within one
hundred fifty millimeters (150 mm) of the floor level. The top of the
exhaust register shall be located not more than one hundred fifty
millimeters (150 mm) below the top of the trap and shall be
entirely within the smoke trap area. Doors, when in the open
position, shall not obstruct duct openings. Controlling dampers
shall be permitted in duct openings if needed to meet the design
requirements.
c. To serve as a smoke and heat trap and to provide an upward-
moving air column, the vestibule ceiling shall be not less than five
hundred ten millimeters (510 mm) higher than the door opening
into the vestibule. The height shall be permitted to be decreased
where justified by engineering design and field testing.
d. The stair shall be provided with a dampered relief opening at the
top and supplied mechanically with sufficient air to discharge at
least 70.8 m3/min through the relief opening while maintaining a
positive pressure of not less than 25 N/m2 in the stair, relative to the
vestibule with all doors closed.
9. Stair Pressurization
a. Smokeproof enclosures using stair pressurization shall use an
approved engineered system with a design pressure difference
across the barrier of not less than 12.5 N/m2 in sprinklered
buildings, or 25 N/m2 in nonsprinklered buildings, and shall be
capable of maintaining these pressure differences under likely
conditions of stack effect or wind. The pressure difference across
doors shall not exceed that which allows the door to begin to be
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