The purpose of self-priming centrifugal pump: used to transport gasoline, kerosene, diesel, aviation kerosene and other petroleum products; medium temperature is -20 ° C ~ 80 ° C, is an excellent marine loading and unloading oil pump, can also be used as a sweeping pump. It is also suitable for oil transportation of oil storage devices such as land oil depots and tank trucks. It can also be used to transport seawater and fresh water. 1. Evacuation, cavitation or rolling for a long time, resulting in seal damage; 2. The actual output of the pump is too small, a large number of media pumps circulate, heat accumulates, causing gasification of the medium, resulting in seal failure; 3. The return flow is too large, causing the bottom of the suction side container (tower, kettle, tank, pool) to rise and damage the seal; 4. For a longer period of time, there is no manual turning when restarting, and the friction pair tears the sealing surface due to adhesion; 5. Increased corrosive, polymerizable, and gelatinous substances in the medium; 6. The ambient temperature changes drastically; 7. Frequent changes or adjustments in working conditions; 8. Sudden power outage or downtime. The centrifugal pump suddenly leaks during normal operation. If it cannot be found in time, it will often cause a big accident or loss. It must be taken seriously and effective measures taken.