1. What are the main causes of centrifugal pump vibration?
(1) The coupling is not concentric;
(2) The bending degree of shaft exceeds the standard;
(3) Excessive or damaged bearing clearance;
(4) Rotor unbalance;
(5) Friction between rotor and stator;
(6) The medium carries gas with cavitation;
(7) Pump out;
(8) There are foreign matters in the impeller passage;
(9) The unreasonable installation of the process pipeline makes the pump subject to external force.
(10) Low load operation for a long time;
(11) The influence of the vibration of the accessory pipeline;
(12) Foundation bolts are loose.
2. What are the causes of Bearing Overheating of centrifugal pump?
(1) Poor quality of rolling bearing or wear during operation;
(2) The clearance of sliding bearing is too small;
(3) Poor cooling of bearing box;
(4) Insufficient or excessive amount of lubricating oil and grease or impurities.
3. How many reasons can cause the motor current of centrifugal pump to be too large?
(1) The medium weight or viscosity is too large, which is inconsistent with the design;
(2) Serious friction between rotor and shell;
(3) The coupling is not concentric or the bearing is worn.
4. Which types of centrifugal pump rotors are generally installed only need to find static balance?
(1) Single stage pump;
(2) Small diameter multistage pump rotor;
(3) Lower speed rotor.
5. What types of centrifugal pump rotors must be installed for dynamic balancing?
(1) More impellers;
(2) Larger diameter;
(3) High speed rotor.
6. What are the methods of coupling alignment?
(1) Single table alignment;
(2) Double table alignment;
(3) Three table alignment.
7. What are the reasons for the unstable or large fluctuation of the pointer of the pressure gauge at the outlet of the centrifugal pump?
(1) The indicator of pressure gauge damage is not working;
(2) Pump evacuation or flow fluctuation;
(3) Impurities or blockage in the pipeline;
(4) Pump vibration;
(5) Gas in pipeline or pump casing;
8. What is the effect of centrifugal pump evacuation on mechanical seal?
(1) It will cause a lot of leakage of mechanical seal;
(2) Destroy the sealing surface of mechanical seal and even cause damage.
9. What are the consequences of too large or too small clearance between the inlet rings of centrifugal pumps?
(1) If the clearance between the ring and the port is too large, the efficiency of the pump will be reduced;
(2) If the gap between the ring and the mouth is too small, it will produce friction and even lead to shaft holding.
10. What must be done before commissioning after maintenance of centrifugal pump?
(1) Check the maintenance work steps;
(3) Open the inlet valve, and slightly open the outlet valve of the high-pressure pump;
(4) Open the vent valve;
(5) Start the pump and pay attention to the direction of rotation;
(6) It can be put into use after checking that the operation meets the requirements.