Grease Laden Vapors

Type I Grease Extraction Hood
A Type I hood is designed to be liquid-tight and of a specific construction thickness. The hood should be sized for the appliances that will be located under the hood. Along with the size of the hood, the size of the exhaust fan must also be considered.

Grease filters are required; mesh filters are not code compliant.

Grease Duct
Exhaust duct work provides the means to transfer contaminated air, cooking heat, and grease vapors from the hood to the fan.Ducts accumulate combustible grease and should be constructed from 16- steel or 18-gage stainless steel as per code requirements.

The ducts must be securely supported by non-combustible duct bracing and supports designed to carry the gravity and seismic loads as per code requirements, no fasteners shall penetrate the duct.

The duct is often run inside a shaft enclosure and that enclosure must be an approved continuous fire-rated enclosure. The duct enclosure shall serve a single grease exhaust duct system and shall not contain any other ducts piping wiring or systems.

Installation Considerations
A few design and installation considerations. Please refer to the Indiana Fire Code and Indiana Mechanical Code for specific requirements.
  • Clearance to Combustibles - 18" clearance or enclosure * Grease duct protection system may be used.
  • Grease Duct Protection System - Duct wrap systems used to achieve zero clearance to combustibles must meet the ASTM E 2336 test standaRoad
  • Access for Cleaning - Grease ducts need to have access for inspections and cleaning.
  • Prevent Grease Accumulation - Required horizontal duct slope