advantage：
(1) compact structure and small area. This pump can be directly installed in the sewage tank because it works under the submersible human fluid, so there is no need to build a special pump house to install pumps and motors, saving a lot of land and infrastructure costs. (2) convenient installation and maintenance. Small submersible sewage pumps can be installed freely, large sewage pumps are generally equipped with automatic coupling devices for automatic installation, installation and maintenance is quite convenient. (3) long running time. Because the pump and the motor are coaxial, the shaft is short and the rotating part is light, so the load (radial) on the bearing is relatively small and the service life is much longer than that of the general pump. (4) low vibration noise, low temperature rise of motor, no pollution to the environment.