Summary of Topics

This new Fourth edition of CAN/ULC 646 dated April 29, 2024 is being issued as a binational joint standard and incorporates changes from proposal dated October 27, 2023.

1 Scope

1.1 These requirements cover Type I commercial kitchen exhaust hoods intended for placement over commercial cooking equipment. Exhaust hoods with and without exhaust dampers are covered by these requirements.

1.2 Exhaust hoods with and without exhaust fire actuated fire dampers are covered by these requirements.

1.3 Exhaust hoods are evaluated relative to minimum exhaust air flow required and maximum supply air flow allowed for capture and containment of cooking effluents under laboratory conditions.

1.4 Exhaust hoods may incorporate non-continuous welded joints, seams, and penetrations when evaluated by these requirements.

1.5 Exhaust hoods with fire actuated fire exhaust dampers are intended to have the exhaust fire actuated dampers automatically close to prevent exhaust duct gas temperatures from exceeding 191 °C (375 °F).

1.6 These requirements do not cover fire-extinguishing systems.

NOTE: All exhaust hoods are intended for use with fire extinguishing system units.

1.7 These requirements cover exhaust hoods provided with manually or automatically operated cleaning or washing systems. These requirements do not cover the fire extinguishing aspects of such systems.

1.8 These requirements do not cover evaluation of Ultraviolet (UV) systems for use in commercial kitchen exhaust systems. Annex A covers the requirements of these products.

1.9 These requirements do not cover evaluation of Electrostatic Precipitators (ESP's) for use in commercial kitchen ventilation. Electrostatic Precipitators (ESP's) are covered under the Standard for Electrostatic Air Cleaners, UL 867.