A grease duct is a purpose-designed duct that is used to vent grease-laden vapours from commercial cooking equipment such as a stove, "double-decker" pizza oven, deep fryer or wok to the outside of a building or mobile food preparation trailer. Ducts are used in heating ventilation and air conditioning ( HVAC) to deliver and remove air A vapor or vapour (see Spelling differences) is a substance in the Gas phase at a Temperature lower than its Critical temperature A stove is an enclosed heated space The term is commonly taken to mean an enclosed space in which fuel is burned to provide heating either to heat the space in which the stove is situated Pizza (ˈpiːtsə, in Italian:) is a popular dish made with an Oven -baked flat generally round Bread that is covered with tomatoes or a tomato-based An oven is an enclosed compartment for Heating, Baking or Drying. A deep fryer (or frier) is a Kitchen appliance used for Deep-frying. Grease ducts are regulated both in terms of their construction and maintenance, forming part of the building's passive fire protection system. Passive fire protection (PFP is an integral component of the three components of structural Fire protection and fire safety in a Building. System (from Latin systēma, in turn from Greek systēma is a set of interacting or interdependent Entities, real or abstract Even the cleaning schedule is typically dictated by the fire code and evidence of compliance must be kept on file by the owner. Fire safety refers to precautions that are taken to prevent or reduce the likelihood of a Fire that may result in death injury or property damage alert those in a structure
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Special hazard
 Kitchen exhaust hood interior view, before and after cleaning. |
 Rooftop fan on top of grease duct being cleaned in order to remove congealed grease. |
 Top view of kitchen exhaust fan assembly on top of a grease duct - before and after cleaning. |
 Bucket of kitchen exhaust grease after removal from commercial restaurant grease duct. |
The grease laden vapors are hot, to begin with. As the vapours cool down, the grease settles on colder items. It is thus important for occupational safety and health as well as compliance with local fire codes to vent such vapours outside the kitchen and outside the building where the kitchen is located. Occupational safety and health is a cross-disciplinary area concerned with protecting the Safety, Health and welfare of people engaged in
Grease, of course, is not only slippery, but also highly flammable. In fact, it qualifies as a hydrocarbon due to its inherent chemistry. In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties Regardless of what state it is in, vapour, liquid or solid, it ignites easily and burns very rapidly, necessitating special provisions to accomplish a fire-resistance rating based on an internal grease fire as well as an external fire. A state of matter (or physical state, or form of matter) has physical properties which are qualitatively different from other states of matter A fire-resistance rating typically means the duration for which a Passive fire protection System can withstand a standard fire resistance test. Special provisions also include the necessity for proof that any adjacent firestop must be compatible with the grease duct system. A firestop is a Passive fire protection System of various components used to seal openings and joints in fire-resistance rated wall
Requirements
In North America, grease ducts must be in compliance with NFPA 96 as well as the local building codes and fire codes. The National Fire Protection Association (NFPA is a US organization (albeit with some international members charged with creating and maintaining minimum standards and requirements A building code, or building control, is a set of rules that specify the minimum acceptable level of safety for constructed objects such as Buildings and Nonbuilding Cleaning takes place typically every 3 months, 6 months or annually, depending on the nature of the appliances below the hood. For instance, woks require quarterly grease duct cleaning, whereas normal stoves may necessitate the grease duct to be cleaned only every 6 months. Compliance must be proven through certificates issued by the cleaning and maintenance contractors. Purpose-designed fire suppression systems inside the hoods must also be routinely maintained. Proper cleaning must be enabled through the use of approved, fire-resistant access panels. Grease ducts should be kept as short as possible to minimise grease build-up.
Systems
A proprietary duct system that has its own inherent fire-resistance rating can be used, or a metallic duct, typically from 16 gauge sheet metal, all welded, per local codes, which is then externally treated with fireproofing. Sheet metal is simply Metal formed into thin and flat pieces It is one of the fundamental forms used in Metalworking, and can be cut and bent into a variety Welding is a fabrication process that joins materials usually Metals or Thermoplastics by causing coalescence. "Fireproof" redirects here For the album see Fireproof (album. Typical materials used for fireproofing are:
- ceramic fibres
- rockwool
- calcium silicate
- vermiculite boards pressed and bonded with sodium silicate
- intumescents
- endothermic materials, sometimes on their own, sometimes in combination with ceramic fibre
Trade jurisdiction
In North American unionised construction sites, metallic ducts are typically installed by the sheet metal trade, whereas external wraps are usually installed by the insulators. Calcium silicates are a set of four compounds obtained by reacting Calcium oxide and silica in various ratios Vermiculite is a natural Mineral that expands with the application of Heat. E550 redirects here For the Italian locomotive see FS Class E550 Sodium silicate, also known as water glass or liquid glass, available An intumescent is a substance which swells as a result of Heat exposure thus increasing in Volume, and decreasing in Density. In Thermodynamics, the word endothermic "within-heating" describes a process or reaction that absorbs Energy in the form of Heat. A trade union or labour union is an organization of workers who have banded together to achieve common goals in key areas such as wages hours and working conditions forming In the fields of Architecture and Civil engineering, construction is a process that consists of the Building or assembling of Infrastructure Inherently fire-resistant systems are likewise installed by the sheet metal trade.
See also
- Passive fire protection
- Duct (HVAC)
- Pressurisation ductwork
- Smoke exhaust ductwork
- Circuit integrity
- Kitchen exhaust cleaning
External weblinks
- UL treatise on wrapping systems
- NFPA 96: Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations
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