What are the causes of mechanical seal failure of centrifugal pump

Centrifugal pump is the use of impeller rotation to make the water centrifugal movement to work. Before the pump is started, the pump shell and the suction tube must be filled with water, and then the motor is started, so that the pump shaft drives the impeller and water to do high-speed rotating movement, and the water has centrifugal movement, is thrown to the outer edge of the impeller, and flows into the pressure water pipe of the pump through the flow channel of the spiral pump shell.

The pump body is also called the pump shell, which is the main body of the pump. It plays the role of supporting and fixing, and is connected with the bracket for mounting bearings. The function of the pump shaft is to connect the coupling and the motor to pass the torque of the motor to the impeller, so it is the main component of transferring mechanical energy.

Centrifugal pump downtime is mainly caused by the failure of the mechanical seal. The performance of failure is mostly leakage, and the reasons for leakage are as follows:

① The leakage of the sealing surface of the dynamic and static ring of the centrifugal pump is mainly caused by: the flatness of the end face, the roughness does not meet the requirements, or the surface is scratched; There is particulate matter between the end faces, resulting in the two end faces can not run equally; Installation is not in place, the way is not correct.

② Centrifugal pump compensation ring sealing ring leakage, the main reasons are: gland deformation, preload uneven; Incorrect installation; Seal ring quality does not meet the standard; Wrong type of seal ring.

The actual use effect shows that the most failed parts of the centrifugal pump seal element are the end faces of the moving and static rings, and the cracking of the end faces of the sealing and static rings of the centrifugal pump is a failure phenomenon, the main reasons are:

① The clearance of the sealing surface is too large during installation, and the washing liquid cannot take away the heat generated by the friction pair; The flushing liquid leaks from the clearance of the sealing surface of the centrifugal pump, causing the end face to be overheated and damaged.

② The liquid medium vaporizes and expands, so that the two ends are separated by the vaporizing expansion force. When the two sealing surfaces of the centrifugal pump are forcibly fitted, the lubricating film is destroyed, resulting in overheating of the end surface.

③ The lubricity of the liquid medium is poor, coupled with the overload of operating pressure, the tracking rotation of the two sealing surfaces of the centrifugal pump is not synchronous. When there is a sealing surface lag can not track rotation, high temperature will cause damage to the sealing surface.

④ Centrifugal pump seal washing liquid hole plate or filter screen is blocked, resulting in insufficient water, so that the machine seal failure.