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The possible failures of multistage pump and its solutions

24-12-2018
The multistage pump does not absorb water, the pressure gauge and the vacuum gauge pointer vibrate vigorously, or the vacuum gauge shows a high vacuum Reasons
1. Insufficient water is injected into the pump before starting (when the vacuum pump is used, the vacuum is not enough)
2. Steering is wrong
3. The bottom valve is not open or blocked
4. The pump's water absorption height is too high
5. Air leakage at the inlet pipe or instrument connection
6. The sealing part is leaking
7. Impeller flow path is blocked
8. Pump speed is not enough
 
Solutions
1. The water injection at least floods the impeller, preferably filling the pump chamber (vacuum time).
2. Replace the motor wiring.
3. Check the bottom valve for cleaning, repair or renewal.
4. Reduce the installation height of the pump.
5. Tighten or block the leak.
6. Check the bushing and bushing nut. When leaking, it should be padded in time.
7. Clean the impeller.
8 Check the motor, overhaul or update.
 
Insufficient capacity or no water of the multistage pump
Reasons
1. The water channel is blocked
2. The gap between the impeller and the seal ring leaks too much
3. The speed does not reach the specified value
 
Solutions
1. Check whether the inlet and outlet channels are unblocked and remove the blockages.
2. Repair or replace the impeller and seal ring
3. Check if the voltage is too low, the motor is damaged, check the motor and adjust the voltage
 
The multistage pump consumes too much power and the motor current is over rated
Reasons
1. The total lift of the system is much lower than the design head of the pump
2. The pipeline bursts running water
3. The outlet gate valve is not closed at startup
4. The pump shaft is different from the motor shaft
5. The rotating parts and the fixed parts friction
6. Bearing wear
7. The rotor is unbalanced, producing vibration
8. The voltage is too low
 
Solutions
1. Close the gate valve for adjustment, or reduce the number of pump stages
2. Stop pump processing pipeline
3. Close the valve and restart
4. Re-align, avoid system forces on the pump
5. Remove the pump to re-adjust
6. Replace the bearing
7. Remove the rotor for static balance, dynamic balance detection
8. Increase the voltage
 
Leakage, heating up and smokes in the packing seal
Reasons
1. The pump shaft is not the same as the motor shaft
2. The shaft is bent
3. The shaft sleeve of the packing is damaged, or the packing is improperly installed, or the packing type is incorrect.
4. Impurities between the packing and the bushing
 
Solutions
1. Re-align
2. Disassembly, correction axis
3. Grind or replace the shaft sleeve, or reinstall the packing, evenly press or replace the packing
4. Replace the packing
 
Multistage pump vibration or noise
Reasons
1. The pump cavitation
2. The flow channel is blocked or the bottom valve is partially blocked.
3. The pipeline bursts running water
4. The outlet valve opens and starts
5. The pump is not concentric with the motor shaft, or the shaft is bent
6. The basic rigidity is insufficient
7. The rotating parts and the fixed parts friction
8. Impeller defect
9. Too much or too little grease in the bearing
10. The bearing is worn or there is dirt inside
 
Solutions
1. Reduce the geometric installation height of the pump and reduce the suction pipe resistance
2. Clean the flow path or clean the bottom valve
3. Stop pump processing pipeline
4. Close the gate valve, restart
5. Re-align, or overhaul, change oil
6. The basis of reinforcement
7. Disassembly, new adjustment pump
8. Replace the impeller
9. Add grease to be appropriate
10. Replace or clean the bearing, and pay attention to the sealed bearing
 
Bearing of multistage pump heating
Reasons
1. The pump shaft and the motor shaft are not concentric, or the shaft is curved
2. The rotating part rubs against the fixing piece
3. Damaged bearings, or dirt or water in the bearings
4. Too much or too little grease in the bearing
 
Solutions
1. Re-align, or overhaul, change shaft
2. Disassemble and re-adjust the pump
3. Add grease to the right
4. Replace or clean the bearing and pay attention to the sealed bearing
 
Leakage of middle section or other joints in the multistage pump
Reasons
1. Insufficient tightening force or uneven force on the pull rod bolts
2. The manufacturing accuracy (roughness, runout or verticality) of the part does not meet the design requirements, or the residual applied force deforms the part.
3. Uneven or damaged joint surface
 
Solutions
1. Retighten the pull rod bolts
2. Disassemble the pump and check
3. Repair the joint surface