What failures are easy to happen in centrifugal oxygen pump and how to deal with them?

The most common failure of the liquid oxygen pump is the leakage of the seal. For the structure of mechanical seal, the key is the bad contact of the sealing surface of the dynamic and static ring of the friction pair. It is related to the grinding quality of sealing surface, the assembling quality of pump shaft and bellows, and the material of friction pair.
For the labyrinth type seal structure, it is related to the adjustment of the seal clearance and the pressure of the seal gas. Other faults and handling methods are as follows:
1) the pump cannot start:
The current is blocked. Recheck the circuit and switch on the current;
The rotor gets stuck or the gap is too small. The pump should be removed for inspection and the clearance should be adjusted.
2) no drainage after starting:
The steering of the pump is opposite. Check motor steering and change power wiring;
The pump is not fully precooled, and gas is generated. Stop the pump and conduct full precooling again;
The inlet pipe of the pump is blocked or the inlet valve is not open. Need to stop the pump, open the pipeline to check.
3) the outlet pressure of the pump decreases or the flow is insufficient:
Low voltage leads to decline of motor speed. The power supply voltage should be checked;
The import pressure is too low. Check the liquid oxygen level and pump inlet pressure, check whether the inlet valve is frozen and whether the Inlet Pipeline is blocked;
Pump outlet pipeline rupture, interface flange leakage, or outlet valve frozen;
Impellers are blocked or damaged. The impeller should be removed for cleaning or replacement;
The seal is damaged. Damaged parts should be replaced.
4) pump vibration and noise:
The installation of motor shaft is different from that of liquid oxygen pump shaft. Should be adjusted to the scope of technical requirements;
If the sliding bearing wears too much, the radial positioning function disappears. New sliding bearings need to be replaced;
Friction or bite occurs between rotating parts and fixed parts. The clearance should be adjusted according to the requirements, and the parts with serious bites should be repaired or replaced, and the concentricity of installation should be checked;
Fastening parts or loose parts on the rotor. It should be tightened evenly;
The pump generates severe cavitation.
5) exposed middle seat Frost:
The sealing part is worn or the close surface is not well closed;
The discharge line of the pump is broken or the interface flange leaks;
Insulation and cooling are not good.
6) the motor current exceeds the rated value:
The gap between impeller and pump shell and pump cover is too small, or impurities particles may fall into the gap. The pump should be stopped for adjustment or cleaning;
If the body is different from the rotor or the pump shaft is bent, the assembly quality should be checked;
The voltage is too low.