加拿大国家标准涵盖B型（圆形或椭圆形）和BW型排气口的设计和施工。B型排气口用于排放温度不超过245°C的烟气，这些烟气来自经通风罩或分流器认证的燃气装置。B型排气口也适用于不带通风罩或分流器的燃气器具，符合本标准概述的某些要求。BW型排气口用于从嵌入式燃气壁炉排放烟气。 BW型排气口的最大输入由拟连接BW型排气口的通风壁炉的最大输入确定。

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.