A Commercial Kitchen Hood is required above all cooking
equipment appliances that produce smoke or grease laden vapors such as deep fat
fryers, ranges, griddles, broilers, woks, tilt skillets/ braising pans which
have surfaces that often become ignited by the user-operator and are open to the
plenum/ductwork, etc., per NFPA 96 (2001), Section 4.1.1 [see Figure 5.1.8.1,
and Section 5.1.8.1, for ovens that produce grease laden vapors ~ the use of
environmental air as an exhaust for cooking operations is not
acceptable. If oven has to be periodically cleaned of grease
residue, then it produces grease laden
vapors!]. The NFPA 96 committee has formally interpreted that kettles are
required to be protected based upon coverage limitations provided for deep vat
fryers since they are typically utilized for boiling meats (stewing) or cooking
soups thus producing grease-laden vapors. A suppression system complying with UL
300 is required per Section 10.1.1 to be provided for the hood/duct/grease
removal devices, and per Section 10.1.2 to be provided for cooking equipment
that might be a source of ignition (fryers, ranges, broilers, grills, etc.). A
minimum Class K type Fire Extinguisher shall be located within 30-feet of travel
distance from the cooking appliances per NFPA 10. Hood to be mounted to provide
for thorough cleaning of its surfaces. Clearances per NFPA 96 (2001), Table
A.3.3.34 shall be provided from any limited-combustible (3”) or combustible
(18”) construction. The manual release for the hood suppression system is to be
no closer than 10-feet and no further than 20-feet from hood along path of
egress from the area as required by 2003 IFC, Section 904.11.1. Activation of
suppression system shall automatically shut down fuel supply to equipment with
the reset being manual per NFPA 96 (2001), Section 10.4.4. Any make-up air fans
are also required to be shut-down after the extinguishing system discharges per
the exception to Section 8.3.2. Plans by the installing contractor for the hood
suppression system is required for review. The shop drawings by the suppression
system installing contractor shall include the following information as
applicable so that the construction plans may be properly reviewed (see NFPA 17A
[1994], Chap.4):
a. Fire Suppression Systems and Portable Fire Extinguisher
Contractor’s license holder’s name & license number. Include a completed
Transmittal Form.
b. Plan view of layout drawn to scale indicating location
of equipment (hood, agent cylinder, pull station, extinguisher, etc.). Indicate
piping sizes and lengths, fittings, nozzle type and location, etc. on an
isometric view. Include a graphic scale. All cooking equipment located below the
hood shall be indicated.
c. Kitchen Hood details, sections, etc., including
grease filters or listed grease extraction methods.
d. Technical Data Sheets
on the equipment used (shutoff valves, nozzles, switches, etc.). Provide
Pre-Engineered system information (manufacturer’s distribution piping
requirement data, or manufacturer’s limitation data sheets, with piping
calculations including volumes, lengths, equivalent lengths,
etc.)
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Special
Occupancies permitted by Code Amendments to use a Residential
Hood:
A 120-3-3-.04(70)(a) modifies NFPA 96 (2001),
Section 1.1.4, permitting a residential kitchen range to have a Residential
Style Hood system equipped with a listed Residential Hood Fire Suppression
System provided ALL the listed conditions
are met (e.g. four-burner residential range, not within an assembly occupancy
[other than a place of worship with limited
cooking - that would be kitchen in a place of worship not
attached to a large serving area such as a dining room, fellowship
hall, multipurpose room, etc. that is capable of serving >50], etc.). The installing
contractor for the hood suppression system should comply with all applicable
NFPA 96 provisions that may be feasible. System shall be installed per the
manufacturer’s listing requirements. The extinguishing unit shall disconnect
electrical power to electric stoves, or shut off the gas supply to gas stoves,
with a manual reset. A signed ‘Letter of Intent’ shall be submitted from the
owner indicating the hood will be used for ‘food warming and limited cooking
only’ as one of the requirements for using this option ~ see item (3) in Section
1.1.4 [note: kitchens serving a large seating area (e.g. with 50 or more
occupant load = assembly occupancy), located in a Mercantile Occupancy, or with
frying operations, are no longer ‘limited cooking’]. Hood unit shall be
ventilated to the exterior of the building per item (4) in Section 1.1.4. Hood
to be mounted to provide for thorough cleaning of its surfaces. A minimum Class
K Fire Extinguisher should be located within 30-feet of travel distance from the
cooking range per NFPA
10.
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Recirculating
(Ventless) Hood protection
NFPA 96 (2001), Section
13.1(9) for recirculating hood systems (Auto-Fry, etc.) requires compliance with
all of Chapter 13, and Section 13.5 requires the listing to provide an
appropriate fire protection system (i.e. Ansul, Pyrochem, etc.). Furthermore,
the UL Listing for these devices all
include the required suppression. The Georgia amendment to 120-3-3 for
section 13.2 requiring the room with the unit to be sprinklered was because of
the outcry from local Fire Marshal's over allowing these devices in the first
place, because these things are so portable, they can be easily moved near
combustibles in addition to the high probability that inspectors will overlook
the un-conventional things. Plus that the safety lockouts can be easily
bypassed, maintenance ignored (usually a dirty filter, jury-rigged switch, etc.,
is burned-up in the process so evidence has a high probability of being
obscured, etc.).
Georgia's change to the standard was to allow the use
the “up to 6-sprinklers off of the domestic water” provision of the 2000 LSC to
provide additional reliable protection to the protection from the integrated
suppression system of the unit required by the listing and the standard - which
works as long as the room did not exceeded the area that 6 sprinklers could
cover (otherwise requiring an equivalency say, by allowing the use of an 8-inch
‘lintel’ draft-stop to reduce the area as a ‘compartment’ verses a ‘room’ which
requires full height walls). Typically records of the equipment placement is in
so much flux that by the time the building is occupied, the layout has
significantly changed so placing a sprinkler only over the equipment would be
unreliable. Sprinklering the whole room allows for moving the equipment in the
future as well.