This National Standard of Canada covers the design and construction of Type B (round or oval) and Type BW Gas Vents.

Type B Gas Vents are intended for the venting of flue gases having temperatures not exceeding 245 °C, from gas fired appliances certified with draft hoods or diverters. Type B Gas Vents are also intended for use with gas fired appliances, without draft hoods or diverters, which meet certain requirements outlined by this Standard.

Type BW Gas Vents are intended for the venting of flue gases from recessed gas fired wall furnaces. The maximum input to a Type BW Gas Vent is determined by the maximum input of the vented wall furnace to which the Type BW Vent is intended to be connected.