A standard commercial kitchen hoods device consists of an exhaust hood, ductwork, fan device, and means of providing good enough make-up air. Exhaust hoods capture warmness and impure air from the airflow by the use of filters, extraction baffles (cartridges), and/or water wash systems. Exhaust ductwork, supplies the way of transfer of contaminated air from the hood toward the fan. Exhaust fans provide the way to transport the heat and air out of the building. All parts should be accessible, or have detachable access panels for cleaning and inspection. The complete device in commercial kitchen hoods must constitute a safe assembly inside the building.
Make-up air is needed to replace air equivalent to the volume removed. This air flow permits the exhaust device to work correctly. Make-up air can be supplied via an independent system or together with building HVAC systems.
Exhaust air for Commercial Kitchen Hoods
Exhaust air is the starting point in restaurant kitchen hoods. Exhaust air is the air, which is contaminated by smoke, and grease-laden vapor (aerosols) made from the cooking source. This air should be removed from the building.
The standard procedure is to provide outside air through a designed make-up air system. Filtration and separate controls must temper the air. The air velocity during the make-up air system should be low sufficient to eliminate the opportunity of drafts. It’s important that the positioning of the air inlets is carefully considered to get rid of any short-circuiting. For efficient air flow, it is necessary to maintain a moderate negative pressure in the kitchen area. Air currents will naturally transfer from a higher (positive) force area to reduce (negative) pressure area, in this way the air will passively transfer from the dining area in the direction of the kitchen. Thus the kitchen will preserve odors and pollutants produced inside the cooking operations.
In summary, the commercial kitchen hoods appliance discharges air out of the building, which will have to be replaced by an equivalent quantity of air from additional sources (transfer air, make-up air).