A grease duct is the ductwork component of a kitchen exhaust system that transports grease-laden air from the hood to the exterior or to a grease collection system. Grease ducts must be constructed from rigid, corrosion-resistant materials and installed at specific angles to facilitate grease flow and drainage. These ducts are subject to special cleaning requirements under NFPA 96 standards due to the accumulation of flammable grease residue.
Technical Details
Grease ducts are typically constructed from 16-gauge stainless steel or galvanized steel and must maintain a minimum slope of 0.25 inches per linear foot toward a grease collection point. Ductwork diameter is calculated based on air velocity, typically maintained between 1,500 and 2,500 feet per minute to prevent grease settling. Ducts require professional cleaning every 6 to 12 months depending on cooking volume, per NFPA 96 standards, which mandate cleaning frequency documentation.
Applications
Grease ducts are installed in all commercial kitchen exhaust systems handling grease-laden vapors. They extend from kitchen hoods through building structures to rooftop or wall terminations.
Practical Significance
Proper grease duct installation and maintenance prevent fire hazards, reduce building damage from grease accumulation, and ensure regulatory compliance. Professional cleaning services are essential for safety and code adherence in commercial food service facilities.