An exhaust system consists of a hood or canopy, a fan and duct system, and grease-removal equipment.
Hoods should be made of stainless or carbon steel or other approved fire-resistant material. They should extend completely over all equipment that produces grease-laden vapors.
A duct system is a passageway that transmits grease-laden vapors to the outside. Ducts should consist of fire-resistant materials, be isolated from other exhaust or ventilation systems, and lead directly to the exterior. Qualified personnel should also maintain and clean ducts regularly.
Fans move air and grease-laden vapors to the duct system. Fans and motors should be UL listed for use in grease-laden atmospheres and have blades of nonferrous metal, such as aluminum.
Grease filters and extractors
Those systems help rid hoods of grease. Commercial cooking operations require metal filters. They should be UL-listed.
Exhaust systems should meet the following clearance criteria:
- minimum of 18 inches from hoods and ducts to combustible material
- minimum of 6 inches to noncombustible material if duct is enclosed
- minimum of 10 inches from outlet to adjacent buildings
- minimum of 10 inches from outlet to air intakes, space permitting