Exhaust fans shall be installed in accordance with Section
511.1.1 through Section 511.1.6. Exhaust fans shall comply
with UL 762 and be installed in accordance with the manufacturer's
installation instructions.
Upblast fans with motors
surrounded by the airstream shall be hinged and
supplied with flexible weatherproof electrical cable, and
service hold-open retainers. Installation shall comply
with the requirements of Section 510.9. Upblast fans
shall have a drain directed to a readily accessible and
visible grease receptacle not to exceed 1 gallon (4 L).
[NFPA 96:8.1.2]
In-line fans shall be of
the type with the motor located outside the airstream and
with belts and pulleys protected from the airstream by a
greasetight housing. In-Iine fans shall be connected to
the exhaust duct by flanges securely bolted as shown in
Figure 511.1.2(1) through Figure 511.1.2(4), or by a
system specifically listed for such use. Flexible connectors
shall not be used. [NFPA 96:8.1.3.1 - 8.1.3.3]
For SI units: 1 inch = 25.4 mm, °C = (°F-32)/1.8
FIGURE 511.1.2(1)
TYPICAL SECTION OF DUCT-TO-FAN
CONNECTION-BUTT JOINT METHOD
[NFPA 96: FIGURE 8.1.3.2(a)]
For SI units: 1 inch = 25.4 mm, °C = (°F-32)/1.8
FIGURE 511.1.2(2)
TYPICAL SECTION OF DUCT-TO-FAN
CONNECTION-OVERLAPPING METHOD
[NFPA 96: FIGURE 8.1.3.2(b)]
For SI units: 1 inch = 25.4 mm, °C = (°F-32)/1.8
FIGURE 511.1.2(3)
TYPICAL SECTION OF DUCT-TO-FAN
CONNECTION-SEALANT METHOD
[NFPA 96: FIGURE 8.1.3.2(c)]
For SI units: 1 inch = 25.4 mm, °C = (°F-32)/1.8
FIGURE 511.1.2(4)
TYPICAL SECTION OF DUCT-TO-FAN CONNECTION-DIRECT
TO
FAN INLET CONE METHOD
[NFPA 96: FIGURE 8.1.3.2(d)]
Where the design or positioning
of the fan allows grease to be trapped, a drain
directed to a readily accessible and visible grease
receptacle, not exceeding 1 gallon (4 L), shall be
provided. In-line exhaust fans shall be located in an
easily accessible area or approved size to allow for
service or removal. Where the duct system
connected to the fan is in an enclosure, the space or
room in which the exhaust fan is located shall have
the same fire resistance rating as the enclosure.
[NFPA 96:8.1.3.4 - 8.1.3.6]
Duct systems connected to
fans in an enclosure shall be in accordance with the
following:
The space or room in which the exhaust fan is
located shall have the same fire resistance rating
as the enclosure.
The fan shall be connected to the exhaust duct
by flanges securely bolted as shown in Figure
511.1.2(1) through Figure 511.1.2(4) or by a
system specifically listed for such use. [NFPA
96:8.1.4.3, 8.1.4.4]
Exhaust fan housings shall be
constructed of carbon steel not less than 0.060 of an inch
(1.524 mm) (No. 16 MSG) in thickness, of stainless steel
not less than 0.048 of an inch (1.219 mm) (No. 18 MSG)
in thickness, or, where listed, in accordance with the
terms of the listing. [NFPA 96:8.1.5]
Openings for cleaning, servicing. and
inspection shall be in accordance with the requirements
of Section 510.3.2. Clearances shall be in accordance
with the requirements of Section 507.3, or Section
510.7.3 and Section 510.7.4 where installed within an
enclosure. [NFPA 96:8.1.6.1, 8.1.6.2]
Transition duct sections that do not
exceed 3 feet (914 mm) in length and do not contain
grease traps shall be permitted to be connected to hoods
and exhaust fans that do not meet this velocity. [NFPA
96:8.2.1.2]
Exhaust air volumes for
hoods shall be of sufficient level to provide for capture
and removal of grease-laden cooking vapors. Test data,
performance tests approved by the Authority Having
Jurisdiction, or both shall be displayed, provided on request, or both. [NFPA 96:8.2.2.1, 8.2.2.2] Lower
exhaust air volumes shall be permitted during no-load and
partial load cooking conditions, provided they are sufficient to capture and remove flue gases and cooking
effluent from cooking equipment.
A performance test
shall be conducted upon completion and before final
approval of the installation of a ventilation system
serving commercial cooking appliances. The test
shall verify the rate of exhaust airflow in accordance
with Section 508.10.1.2 through Section 508.10.1.5.
The permit holder shall furnish the necessary test
equipment and devices required to perform the tests.
[ASHRAE 154:4.8.1]
The
permit holder shall verify capture and containment
performance of the hoods. A field test shall be
conducted with the appliance under the hood at operating temperatures, with the source of outdoor air
providing makeup air for the hood operating and with
the source of recirculated air providing conditioning
for the space in which the hood operating is located.
Capture and containment shall be verified visually
by observing smoke or steam produced by actual or
simulated cooking using devices such as smoke
candles or smoke puffers. Smoke bombs shall not be
used. [ASHRAE 154:4.8.2]
A hood exhaust fan(s) shall continue
to operate after the extinguishing system has been activated,
unless fan shutdown is required by a listed component
of the ventilation system, or by the design of the
extinguishing system. The hood exhaust fan shall not be
required to start upon activation of the extinguishing
system where the exhaust fan and cooking equipment served by the fan have been shut down. The exhaust fan
shall be provided with a means so that the fan is activated
when an appliance under the hood is turned on. [NFPA
96:8.2.3]
The makeup air quantity shall prevent negative pressures in the commercial cooking area(s) from exceeding 0.02 inch water column (0.005 kPa). Where the fire-extinguishing system activates, makeup air supplied internally to a hood shall be shut off.
For compensating hoods, where a Type I or Type II hood
has an internal discharge of makeup air, the makeup air flow
shall not exceed 10 percent of the exhaust airflow, the exhaust
airflow shall be the net exhaust from the hood in accordance
with Section 508.10.1.2 through Section 50S.10.1.5. The total
hood exhaust shall be determined in accordance with Equation
511.3.
Design plans for a facility with a
commercial kitchen ventilation system shall include a
schedule or diagram indicating the design outdoor air
balance. The design outdoor air balance shall indicate the
exhaust and replacement air for the facility and the net
exfiltration where applicable. The total replacement
airflow rate shall equal the total exhaust airflow rate and
the net exfiltration.
Master kitchen
exhaust ducts that serve multiple tenants shall include provision
to bleed air from outdoors or from adjacent spaces into
the master exhaust duct where required to maintain the necessary
minimum air velocity in the master exhaust duct. [NFPA
96:8.4.1]
The bleed-air
duct shall have the same construction and clearance
requirements as the main exhaust duct from the connection
to the exhaust duct to not less than 12 inches (305
mm) on both sides of the fire damper. [NFPA 96:8.4.4]
Unused tenant exhaust connections
to the master exhaust duct that are not used as bleed air
connections shall be disconnected and sealed at the main
duct. [NFPA 96:8.4.8]
Incidental airmovement from pressurized rooms within health care facilities, provided that the corridor is not the primary source of supply or return ...
