A kitchen hood, exhaust hood, hood fan, 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 air by evacuation of the air and filtration. [1] In commercial kitchens exhaust hoods are often used in combination with fire suppression devices so that fumes from a grease fire are properly vented and the fire is put out quickly. Commercial vent hoods may also be combined with a fresh air fan that draws in exterior air, circulating it with the cooking fumes, which is then drawn out by the hood.
In most exhaust hoods, a filtration system removes grease (the grease trap) and other particles. Although many vent hoods exhaust air to the outside, some recirculate the air to the kitchen. In a recirculating system, filters may be used to remove odors in addition to the grease.
The device is known as an extractor hood in the United Kingdom, as a range hood in the United States, and as a rangehood in Australia. It is also called a stove hood, hood fan, cooker hood, vent hood, or ventilation hood. Other names include cooking canopy, extractor fan, fume extractor, and electric chimney.
An extractor hood consists of three main components: a skirt or capture panel to contain the rising gases (also known as the "effluent plume"), a grease filter, and a fan for ventilation.
Extractor hoods may be ducted (or vented) or ductless (or recirculating). Ducted hoods blow the gases to the outdoors; ductless hoods filter the air, often using activated charcoal, to remove odor and smoke particles from the air and then release the cleaned air back into the kitchen.
A ducted system removes of all forms of airborne contamination, while a ductless one recirculates heat and moisture. In addition, a ducted application eliminates the need for regular replacement of the filters and avoids the airflow restriction (and the resultant loss of power) caused by them. However, the ducted application can be impractical, due to lack of space or ability to install a duct system, make-up air requirements, or the additional cost of heating or cooling the make-up air.
Exhaust hoods almost always include built-in lighting to illuminate the cooking surface. Extractor hood controls are typically electronic, though some low-end models use electromechanical controls. Extractor hoods with electronic controls can offer remote control, motorized height adjustment, thermal sensor, overheat protection, boost mode, delayed shut-off, filter cleaning reminder, active noise cancellation, temperature display, user presets (memory), and so on.
Extractor hoods may be made from a variety of materials, including stainless steel, copper, bronze, nickel silver, zinc, tempered glass, wood, aluminum, brass, heat-resistant plastics, and more.
NFPA 96 Standard for Ventilation Control and Fire Protection of Commercial Cooking says that mesh filters shall not be used. It requires that "Listed" grease filters shall be tested in accordance with UL 1046, Standard for Grease Filters for Exhaust Ducts.
Kitchen hoods are broadly classified into ducted hoods and ductless hoods. This classification of these kitchen hoods [2] [3] is done purely on the basis of how the hoods process the air that is being sucked in.
Ducted kitchen hoods are the most common and a primary type of kitchen hood. As the name suggests, a ducted kitchen hood has a duct that is used to process and expel any smoke that is generated on top of the kitchen hob.
Large sized duct hoods are widely used not just in homes but also in commercial restaurants and communal kitchens too.
Ductless kitchen hoods do not have a duct that is used to process the air. Instead, it makes use of strong air filtration and then pumps out the air back into the room. These types of range hoods are usually used in houses.
Filters remove most odors and particulates, including grease, from the vented air. There are three main types of filter:
Greater hood overhangs are suggested to help contain cooking fires in the hood area protected by the fire suppression system. [4]
Loud kitchen hoods can affect well-being, and may even contribute to hearing loss. [5] Variable speed fans are generally noisier at higher speeds and different models may have different noise levels. Vented hoods are generally noisier but more effective than recirculating hoods. [5]
Noise levels are measured on dB(A) scale [6] or in sones (in the U.S.). [7] Most kitchen hoods produce 60-70 dB(A), while "quiet" models can go as low as 40 dB(A). [5] [8]
Noise levels are generally given for the maximum speed, [6] so it may be useful to compare noise levels at specific flow rates.
The European Union standardizes the measurement of hood noise. [9]
Hood air flow is measured in liters per second (L/s), cubic meters per second (m3/s), or cubic feet per minute (cfm). [10]
Filtration is a physical separation process that separates solid matter and fluid from a mixture using a filter medium that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as oversize and the fluid that passes through is called the filtrate. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as blinding. The size of the largest particles that can successfully pass through a filter is called the effective pore size of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles. Filtration occurs both in nature and in engineered systems; there are biological, geological, and industrial forms. In everyday usage the verb "strain" is more often used; for example, using a colander to drain cooking water from cooked pasta.
A vacuum cleaner, also known simply as a vacuum, is a device that uses suction, and often agitation, in order to remove dirt and other debris from carpets and hard floors.
Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR.
Dry cleaning is any cleaning process for clothing and textiles using a solvent other than water. Clothes are instead soaked in a water-free liquid solvent. Perchloroethylene is the most commonly used solvent, although alternative solvents such as hydrocarbons, and supercritical CO2 are also used.
A fume hood is a type of local exhaust ventilation device that is designed to prevent users from being exposed to hazardous fumes, vapors and dusts. The device is an enclosure with a movable sash window on one side that traps and exhausts gases and particulates either out of the area or back into the room, and is most frequently used in laboratory settings.
A clothes dryer is a powered household appliance that is used to remove moisture from a load of clothing, bedding and other textiles, usually after they are washed in the washing machine.
Ventilation is the intentional introduction of outdoor air into a space. Ventilation is mainly used to control indoor air quality by diluting and displacing indoor pollutants; it can also be used to control indoor temperature, humidity, and air motion to benefit thermal comfort, satisfaction with other aspects of the indoor environment, or other objectives.
A deep fryer is a kitchen appliance used to cook foods by full immersion in hot oil (“deep frying”. The cooking oil are typically between temperatures of 350 to 375 °F.
A particulate air filter is a device composed of fibrous, or porous materials which removes particulates such as smoke, dust, pollen, mold, viruses and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbon) may also remove odors and gaseous pollutants such as volatile organic compounds or ozone. Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.
An air handler, or air handling unit, is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blower, furnace or A/C elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the AHU, sometimes exhausting air to the atmosphere and bringing in fresh air. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served without ductwork
A cooktop, stovetop or hob, is a device commonly used for cooking that is commonly found in kitchens and used to apply heat to the base of pans or pots. Cooktops are often found integrated with an oven into a kitchen stove but may also be standalone devices. Cooktops are commonly powered by gas or electricity, although oil or other fuels are sometimes used.
A dust collector is a system used to enhance the quality of air released from industrial and commercial processes by collecting dust and other impurities from air or gas. Designed to handle high-volume dust loads, a dust collector system consists of a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system. It is distinguished from air purifiers, which use disposable filters to remove dust.
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 ventilation air as part of the supply air. As such, air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort.
Smoke exhaust ductwork, in Europe, is typically protected via passive fire protection means, subject to fire testing and listing and approval use and compliance. It is used to remove smoke from buildings, ships or offshore structures to enable emergency evacuation as well as improved firefighting. In North America, fireproofed ductwork may be used for the purpose of smoke exhaust, but it is more common to use unfireproofed return air ductwork, whereby no fire testing or listings are employed to qualify the ductwork for this use.
A grease duct is a duct that vents grease-laden flammable vapors from commercial cooking equipment such as stoves, deep fryers, and woks to the outside of a building or mobile food preparation trailer. Grease ducts are part of the building's passive fire protection system. The cleaning schedule is typically dictated by fire code or related safety regulations.
Kitchen exhaust cleaning is the process of removing grease that has accumulated inside the ducts, hoods, fans and vents of exhaust systems of commercial kitchens. Left uncleaned, kitchen exhaust systems eventually accumulate enough grease to become a fire hazard. Exhaust systems must be inspected regularly, at intervals consistent with usage, to determine whether cleaning is needed before a dangerous amount of grease has accumulated.
CaptiveAire Systems is a privately held manufacturer of commercial kitchen ventilation systems in the U.S. and a manufacturer of HVAC equipment. The company, founded by Robert L. Luddy in 1976, is headquartered in Raleigh, North Carolina. Since its inception, the company has expanded from fire suppression to a wide array of products including exhaust, pollution control, fire suppression and prevention, HVAC, and utility distribution. In 2018, CaptiveAire brought in over $500 million in revenue.
A biosafety cabinet (BSC)—also called a biological safety cabinet or microbiological safety cabinet—is an enclosed, ventilated laboratory workspace for safely working with materials contaminated with pathogens requiring a defined biosafety level. Several different types of BSC exist, differentiated by the degree of biocontainment they provide. BSCs first became commercially available in 1950.
Kitchen ventilation is the branch of ventilation specialising in the treatment of air from kitchens. It addresses the problems of grease, smoke and odours not found in most other ventilation systems.
In fire classes, a Class B fire is a fire in flammable liquids or flammable gases, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, or alcohols. For example, propane, natural gas, gasoline and kerosene fires are types of Class B fires. The use of lighter fluid on a charcoal grill, for example, creates a Class B fire. Some plastics are also Class B fire materials.