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| Commercial Kitchen Ventilation Codes, Standards
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The 2000 International Mechanical Code
addresses commercial kitchen hood,
exhaust ducts and exhaust equipment in Sections 506
and 507.
Standard for Ventilation Control and Fire Protection
of Commercial Cooking Operations
(NFPA 96) details the minimum fire safety requirements
(preventative and
operative) related to the design, installation, operation,
inspection, and maintenance of
all public and private cooking operations, excluding
single-family residential usage.
These requirements include, but are not limited to,
all manner of cooking equipment,
exhaust hoods, grease-removal devices, exhaust ductwork,
exhaust fans, dampers, fire
extinguishing equipment, and all other auxiliary or
ancillary components or systems
that are involved in the capture, containment, and control
of grease-laden cooking
effluent.
2003 ASHRAE Handbook: HVAC Applications addresses kitchen
ventilation in
Chapter 31. The chapter covers cooking effluent, exhaust
hoods, exhaust systems, replacement (make-up) air systems,
systems integration and balancing, energy considerations,
fire protection, operation and maintenance and residential
kitchen ventilation.
UL 710 test protocol was established to determine minimum
exhaust rates for 400 F, 600 F, and 700 F (solid fuel)
surface temperature appliances. The air-flow portion
of the test is a visual one made by a U.L. inspector,
who observes the removal of visible cooking vapors.
If, in the judgement of the inspector, the hood captures
and contains this visible effluent, then the tested
exhaust air flow rate passes the test. What UL 710 does
not test for is the amount of heat escaping the hood
at a given air flow. Listed hoods can have a fire damper
to protect ductwork and maintain temperatures below
375 F or can exist without a fire damper. UL 710 does
not cover evaluation of the exhaust hoods with respect
to their grease extraction efficiency. UL 1046 test
protocol was established for grease filters used in
exhaust systems with Type I restaurant type cooking
equipment. Grease filters are investigated to insure
they remove grease from the effluent, drain-off of the
collected grease in such a manner that it does not fall
back on to the cooking surface, and limit the projection
of flames into the exhaust ductwork when fire breaks
out on the upstream face of the filter and after exposure
to grease-laden air.
UL Subject 762, Power Roof Ventilators for Restaurant
Exhaust Appliances covers roof or wall-mounted ventilators
for restaurant exhaust appliances. Power ventilators
for restaurant exhaust appliances covered by these requirements
are intended for installation in accordance with NFPA.
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Common Problems
Some of the most common conditions found in poorly designed,
constructed, and operated grease exhaust systems:
• Over designed exhaust/make-up air rates, leading
to energy cost/waste.
• Make-up air is not
sufficient (too little or too much) to provide proper
capture and containment.
• Hoods are not
located properly to provide capture and containment
of effluent or drafts exist from neighboring supply
diffusers that impede capture.
• A short-circuit
hood is used causing spillage.
• Appliances
are not grouped according to effluent production and
the highest effluent producing appliances are not placed
in the center of the hood system.
• Duct
systems are not liquid tight. The contractor
should perform a pressure test.
• Duct construction
is less than the required 16- gage steel or 18-gage
stainless.
• Improperly installed or sealed
access panels.
• Inaccessible sections in
the ductwork.
• Inadequate clearance to combustibles.
• Improperly sloped ductwork and grease drainage.
• Aluminum mesh filters are used or no filters
at all.
• Under-powered fans or fans that
cannot be
tipped for cleaning.
• Improperly cleaned
or maintained exhaust system.
• A proper
air balance and system commissioning
was never performed. |
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