perimeter shall be derived from the environmental air supplied to the
kitchen and/or dining room air-handling units.
(d) Coordinate manual and automatic operation of the exhaust fan with the
hood control panel (furnished with the hood) for washroom cycle and fire
protection.
(e) The design of the grease hood exhaust system shall incorporate the
following fire and safety features:
(1) The exhaust ducts shall lead as directly as possible to the exterior
of the building, and discharge the air above the highest level of the
building. The exhaust ducts shall not pass through the fire walls (3 hours
rating) or 2-hour fire partitions.
(2) The exhaust system serving the grease hoods shall not be connected to
any other exhaust ducts or building exhaust systems. As far as possible,
each grease hood shall have a dedicated exhaust fan and ductwork.
(3) The air velocity through the exhaust duct shall not be less than 7.6
m/s (1500 feet per minute).
(4) For the purpose of cleaning and inspection, openings (clean-outs)
shall be provided in exhaust duct at each change in duct direction and in
horizontal duct rooms at 3 m (10 ft) intervals.
(5) The material, fabrication, and installation of the exhaust ducts
carrying grease-laden air shall comply with the provisions outlined in
NFPA 96. See VA master specification Section 15250 for specifying UL
listed fire rated insulation for grease carrying exhaust air ducts.
(6) Volume dampers and fire/smoke dampers shall not be installed in
exhaust ducts.
(7) The termination of ducts shall be such that:
(aa) The discharge of exhaust air shall be kept away from the roof
surface.
(bb) A minimum distance of 1000 mm (40 inches) shall be maintained between
the roof surface and the outlet.
(cc) A minimum distance of 3 m (10 ft) shall be maintained between the
discharge air outlet and adjacent buildings, air inlets, property lines,
and adjoining grade levels.
(8) The environmental air ducts shall not be located in the same chase
carrying the grease exhaust air duct. See Paragraph 2.11.2.2.
3.12.7.2 HOT VAPOR PRODUCING EQUIPMENT: The hoods (high velocity type) for
hot vapor producing equipment, such as, steam kettles, vegetable steamers,
and high pressure cookers, etc., are either fabricated by the kitchen
equipment manufacturers or of canopy type fabricated by the mechanical
contractor. Make-up and exhaust air requirements for hoods furnished by
manufacturer shall be the same as those outlined under (paragraph 3.12.7.1
items (a) through (d). The remaining provision, subparagraph (e) under
Paragraph 3.12.1 is not applicable to the exhaust systems for hot vapor
HVAC DESIGN MANUAL
3-9
HVAC REQUIREMENTS FOR OCCUPIED AREAS
Previous Page
