吸气过滤器：
    制冷剂按过滤器箭头所指示的方向流动时，旁通溢流阀起作用。如果流过元件时产生过大的压力降，则旁通溢流阀稍微开启，以保持足够的气流并使全封闭压缩机的马达得到适当的冷却。当吸气过滤器安装方向与箭头所指示的方向相反时，旁通溢流阀不起作用，不管压力降多高它都不会开启，这是需接一只检修阀，以便测量经过滤芯到压缩机吸气辅助阀之间的压力降。如果吸气过滤器的旁通溢流阀不起作用，就可用此检修阀作压力测量。

Inspiratory filter：
The Bi-flow drier was designed to prevent refrigerant not to get polluted in refrigeration and heat circulatory system. It can prevent the contaminant which is concentrated in one direction to return when it flows in an opposite direction. This device can save two external check valves and normal filter driers. It reduces complex lines and the cost.