圆形管道风机系列主要由外壳，叶轮，电机和接线盒组成 The GDF series are consisted of casing, propeller, motor and wiring box. （1）外壳：采用优质冷轧板或镀锌板，具有优良的耐大气腐蚀性能.进风口设计呈符合空气动力学的形状，便于气流进入叶轮。进风口和出风口外形尺寸相同，以便于安装。进风盖和出风盖采用螺钉连接，便于维修与清洁。 （1）Shell: the shell is made of cold-rolled sheet or galvanized sheet, which has good atmospheric corrosion resistance performance. The shape of air inlet is designed in conformity to aerodynamics. Air is easy to go into the impeller. Air inlet’s size is the same air outlet’s. It’s easy for installation. The inlet cover connects with outlet cover by bolt which is easy for repairing and cleaning. （2）叶轮：GDF 100A、GDF125A、GDF150A、GDF160A圆形管道风机采用新型塑料叶轮，直径为190mm；GDF200A、GDF250采用新型塑料叶轮或金属叶轮，直径为250mm;GDF315A圆形管道风机采用金属制成，直径为280mm。均设计成后向式叶轮，在正常运转的情况下，均能与外壳良好配合，风量大、效率高、噪音低。叶轮与外转子电机构成整体，成为叶轮轮毂的驱动电机被气流高效地冷却，可以延长风机寿命。 (2) Impeller: fans in the mode of GDF100A, GDF125A, GDF150A, and GDF160A adopt new plastic impeller with the diameter of 190mm: fans in the mode of GDF200A and GDF250A adopt new plastic impeller and metal impeller with the diameter of 250mm; fans in the mode of GDF315A adopt new metal impeller with the diameter of 280mm.Impeller and exterior rotor motor are integral, helping to cool down drive motor and prolong fan’s life. (3)电机：采用外转子单相异步电动机，该电机的特点是叶轮直接压装在电机外壳上，由电机外壳旋转直接驱动，电机与风轮一体，结构合理，体积小，节省安装空间；重量轻,运行平稳，效率高，寿命长。 (4)接线盒：采用加有阻燃成分的ABS材料制成，防火性能较好。安装在整机外表面接线、拆装非常方便。