All dry submersible motor pump with a concordant seal system

An all-dry submersible motor pump comprising a motor within a motor room, a vertical rotary shaft driven by the motor and connected to a pump means, an air chamber positioned between the motor room and the pump means, a radial airtight disc provided between the motor room and the air chamber with a central hole for passing through the vertical rotary shaft, and a concordant seal means arranged below the disc and around the central hole, wherein said concordant seal means comprises a shaft fluid-seal means and a pressure equalizing means, said shaft fluid-seal means further comprising a sealing tube and a sealing cup arranged concentrically with the rotary shaft and adapted to rotate relatively, said cup being filled with a certain amount of sealing liquid, and said pressure equalizing means comprising an air envelope, the outer surface of which being exposed to the pressure of the air chamber and having an opening through which the air envelope communicates only with the motor room.