A grease duct is a
duct that vents
grease-laden flammable
vapor
In physics, a vapor (American English) or vapour (British English and Canadian English; see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature,R. H. Petrucci, W. S. Harwood, and F. G. Her ...
s from commercial cooking equipment such as
stove
A stove or range is a device that burns fuel or uses electricity to generate heat inside or on top of the apparatus, to be used for general warming or cooking. It has evolved highly over time, with cast-iron and induction versions being develope ...
s,
deep fryer
A deep fryer (also referred to as a deep fat fryer), is a kitchen appliance used for deep frying. Deep frying is a method of cooking by submerging food into oil at high heat, typically between temperatures of .
While commonly used in commercia ...
s, and
wok
A wok (; Pinyin: ; Cantonese ) is a deep round-bottomed cooking pan from China. It is believed to be derived from the South Asian karahi. It is common in China and similar pans are found in parts of East, South and Southeast Asia, as well as ...
s to the outside of a building or mobile food preparation trailer. Grease ducts are part of the building's
passive fire protection
Passive fire protection (PFP) is components or systems of a building or structure that slows or impedes the spread of the effects of fire or smoke without system activation, and usually without movement. Examples of passive systems include floo ...
system. The cleaning schedule is typically dictated by
fire code
Fire safety is the set of practices intended to reduce the destruction caused by fire. Fire safety measures include those that are intended to prevent the ignition of an uncontrolled fire and those that are used to limit the development and eff ...
or related safety regulations.
Fire hazard
Vapors are created when grease is heated to and beyond its vaporization point. As the vapors cool, the grease condenses and settles on colder surfaces. Grease is a flammable
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...
. A
fire-resistance rating
A fire-resistance rating typically means the duration for which a passive fire protection system can withstand a standard fire resistance test. This can be quantified simply as a measure of time, or it may entail other criteria, involving eviden ...
is required for the construction around the duct.
Design
In North America, grease ducts must be in compliance with
NFPA 96 as well as the local
building code
A building code (also building control or building regulations) is a set of rules that specify the standards for constructed objects such as buildings and non-building structures. Buildings must conform to the code to obtain planning permiss ...
s and fire codes.
A proprietary duct system that has its own inherent fire-resistance rating can be used, such as a metallic duct, either field fabricated or UL certified factory-built designs. Factory-built fire rated designs are tested to UL 1978 and UL 2221
Maintenance and cleaning
Periodic cleaning is required. Compliance is proven through certificates issued by the cleaning and maintenance contractors. Purpose-designed fire suppression systems inside the hoods must also be routinely maintained.
Hazards associated with improperly maintained hoods include, but are not limited to, poor ventilation, excess heat and smoke, and the potential risk of fires.
See also
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Passive fire protection
Passive fire protection (PFP) is components or systems of a building or structure that slows or impedes the spread of the effects of fire or smoke without system activation, and usually without movement. Examples of passive systems include floo ...
*
Duct (flow)
Ducts are conduits or passages used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. The needed airflows include, for example, ''supply air'', ''return air'', and ''exhaust air''. Ducts commonly also deliver '' v ...
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Pressurisation ductwork
Pressurisation duct work is a passive fire protection system. It is used to supply fresh air to any area of refuge, designated emergency evacuation or egress route.
Purpose
The purpose of pressurisation ductwork is to maintain positive pressur ...
*
Smoke exhaust ductwork
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Circuit integrity
Circuit integrity is how little can a fire affect an electrical circuit's operation. It is a form of fire-resistance rating. Circuit integrity is achieved via passive fire protection means, which are subject to listing and approval use and co ...
*
Kitchen exhaust cleaning
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Kitchen hood
A kitchen hood, exhaust hood, extractor hood, or range hood is a device containing a mechanical fan that hangs above the stove or cooktop in the kitchen. It removes airborne grease, combustion products, fumes, smoke, heat, and steam from the ai ...
References
External links
UL treatise on wrapping systemsNFPA 96: Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations
* ttp://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=50385 ISO 6944-1:2008 Fire containment -- Elements of building construction -- Part 1: Ventilation ducts{{HVAC
Passive fire protection