1. The pump at the entrance of the pump is generated.

2. The pump entrance is blocked.

3. Insufficient pressure at the entrance of the pump.

4. The medium temperature at the pump is too high, and the saturated vapor is too large.

5. The entrance valve is not opened or the valve core falls off.

6. The export valve is too large or too small.

7. Axial sealing water.

8. The liquid level in the tower or container is too low or no liquid level.

9. The impeller or inner grinding ring wear is very serious.

10. The motor reverses.