1700 feet per minute to maintain particulate matter in
suspension. Provide accesses for cleaning ducts without
Fire Protection. Refer to MIL-HDBK-1008B, Fire
Protection for Facilities Engineering, Design, and Construction.
Ranges, ovens, broilers, deep-fat fryers and other appliances
that present fire hazards shall have exhaust hoods, ducts, and
fans. Install high-limit thermostats in exhaust ducts as near as
possible to the hood to protect the hood exhaust system from
grease fires. For more information, refer to ASHRAE Handbook.
Exhaust fans for hoods with dry chemical extinguishing systems
shall remain on when the extinguishing system is activated.
Similarly, exhaust hood and ductwork dampers shall remain open
when the extinguishing system is activated. For other types of
extinguishing systems, the fan shall be turned off.
An easily accessible, independent and well identified
manual switch shall be provided for the fire extinguishing system
of each hood. Do not install volume control dampers in range and
kitchen hood exhaust ductwork, but provide a fire damper in the
outlet, except in ductwork with extinguishing systems. In
addition, provide an automatic hood cleaning system.
Calculation of Exhaust Hood Air Volume Rate. To
calculate actual exhaust rate required for kitchen equipment
exhaust hoods, apply the following procedure:
a) Determine, for each item of kitchen equipment, the
equipment type, fuel type, and ventilator type; and determine the
equipment width, depth, and surface area, including work tables
from the kitchen equipment plan requirements.
b) Select the appropriate thermal current velocity
from Table 4 for each piece of equipment.
c) Select the appropriate safety factor from Table 5
for each item of equipment.
d) Calculate the duty group cfm per foot of width for
each item of equipment by multiplying the equipment area times
the thermal current velocity times the safety factor, and divide
the result by the equipment width.
e) Classify each item of equipment into its duty group
in accordance with Table 6, and assign the appropriate standard
air volume rate for each item of equipment.