Qdx small submersible electrical pump( all casing, Referred to as electrical pump hereunder)consists of three components, water pump, sealing and electrical motor. The motor is mounted on top of pump and divided into single phase and three phase asynchronous types. The pump is below the motor and divided into centrifugal impeller and worm casing structures. Double-face mechanic sealing is mounted between pump and motor. O shaped oil-proof rubber sealing ring is used at each stationary port as static sealing. Cartons