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.
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: