AAVCs是化学废物系统中用于防止存水弯密封虹吸的装置。这些装置不会释放背压；它们只允许空气进入系统。它们被设计用于单个固定装置或服务于多个固定装置的水平支管。当装置安装在建筑物内时，应至少有一个开放式通风终端，以释放延伸至建筑物外大气的正压力，该正压力为安装这些装置的同一建筑物排水管提供服务。这些装置不得安装在恒压差大于+/-0.3英寸（7.6毫米）WC的区域。

AAVCs are devices used in chemical waste systems to prevent the siphonage of trap seals. These devices do not relieve back pressure; they only allow air to enter the system. They are designed to be used for individual fixtures or for a horizontal branch serving multiple fixtures. When the devices are installed in a building, there shall be at least 1 open vent terminal to relieve positive pressure which extends to the atmosphere outside of the building serving the same building drain on which these devices are installed. These devices shall not be installed in an area with a constant air pressure differential greater than +/-0.3 inches (7.6 mm) WC.