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Common Problem of Pump

1.Common fault and elimination methods of single stage pump

Fault Performance The Possible Reasons Elimination Methods
1.Capacity insufficient or not flow. a.The inlet and outlet valves are not open and the inlet and outlet pipelines are blocked. The impeller flow channel is blocked. a.Open the valve to eliminate block.
 
 b.When motor running direction is wrong, motor lack of phase operation, slow speed. b.Adjust motor direction and tighten motor wiring.
 
 c.Suction pipe air leakage. c.Screw tight the nut on the sealing surface to vent the air.
 
 d.The pump is not filled with liquid, there is air in the pump cavity, and the air is stored at the local high point of the suction pipe. d.Open the air release valve to drain the air. Place an air vent at a local high point.
  e.Inlet water supply is insufficient, suction is too high, bottom valve leakage. e.Stop the pump to check and adjust (Grid-connected inlet pipe and suction pipe are easy to be used).
  f.Excessive pipe resistance, pump model is not correct. f.Reduce pipe elbow, increase pipe diameter, and reselect pump model.
     
2.Capacity of pump insufficient a.First, press no. 1, check the reason. a.First, press no. 1, eliminate.
  b.Pipe, pump impeller runner partial block, incrustation deposition, insufficient valve opening. b.Remove blocks and readjust valve opening.
 
 c.Voltage is too low. c.Stable the voltage.
  d.Impeller wear, flow, head, efficiency decline. d.Replace the impeller.
     
3.Noise vibration a.Pipeline support is unstable. Foundation loose. a.Stabilize the line. Reinforce the foundation.
  b.The liquid is mixed with gas. b.Vent the air.
  c.Cavitation is produced. Excessive capacity. c.Increase the inlet pressure, reduce capacity.
 
 
 d.Bearing damaged. d.Replace bearing.
 
 e.Motor overload heating operation. e.To adjust, press no.4.
     
4.Motor heating a.Excessive capacity, pressure gauge indicates that the head is too low, and overload operating. a.Turn down the outlet valve or cut the outer diameter of impeller.
  b.Friction. b.Check to eliminate.
 
 c.Motor bearing damaged. c.Replace the bearing.
  d.Voltage is insufficient. d.Stable the voltage.
     
5.Pump leakage a.Mechanical seal abrasion, rubber parts are damaged by aging. a.Repair and replace.
 
 
 b.Whether the sealing surface, O-ring and gasket are misplaced, damaged, or the fastening bolt is loose. b.Repair the sealing pieces and tighten the bolts.

 

2.Common Faults and Elimination Methods of Submersible Sewage Pump

Fault Performance The Possible Reasons Elimination Methods
1.Capacity insufficient or not flow 1、 The motor reverses. 1、 Correct motor direction.
 
 2、 Flow channel blocks. 2、 To remove sundries, it is better to set a filter grating around the pump (but do not install filter at the pump inlet)
 
 3、 The concentration of pumped medium is too high. 3、 Reduce concentration of the medium with water.
 
 4、 System head is too high, or the selected pump head is much lower than the actual requirement. 4、 Try to reduce the head of the device (e.g., change to a large diameter pipe or smooth pipe, reduce the number of elbows, or increase the arc radius of elbows) or change another pump with a higher head.
  5、 Impeller seriously wear. 5、 Replace the impeller.
  6、 Liquid level is so low that the pump draws in air. 6、 Adjust the float switch position so that the lowest liquid level meets the requirements of the installation dimension drawing.
    7、 Correct the direction of check valve.
     
2.Can not start up. 1、Phase loss 1、check circuit lines to eliminate the problem of phase loss.
  2、Impeller jammed 2、To remove sundries, it is better to set a filter grating around the pump (but do not install filter at the pump inlet).
  3、Winding joint or cable break. 3、Repair after checking with ohmmeter.
  4、The stator windings are burnt out. 4、Repair and replace the winding or stator.
  5、Control the failure of the electric appliance. 5、Check the control cabinet, repair or replace the electrical appliance after repairing the motor.
     
3.The stators are burnout. 1、Phase loss 1、Equipped with protective control appliances: to check the circuit, clear the fault of phase failure. To remove the dirt, tighten the impeller fastening screw and stainless steel spring washer. To dilute the medium with water. Flush and dredge the cooling system.
  2、Impeller jammed 2、Replace mechanical seal or “O”ring.
  3、Winding joint or cable break. 3、Tighten all fasteners.
  4、The stator windings are burnt out.  
  5、Control the failure of the electric appliance.  
     
4.Current is too large. 1、Pipe and impeller are blocked. 1、Clean the block in pipes and impellers.
  2、 The density or viscosity of the pumped liquid is high. 2、 Change the density or viscosity of the pumped liquid.
  3、 The selected pump head greatly exceeds the actual needs, or the use of conditions change, device head greatly reduced, so that the pump exceeds the recommended flow operation. 3、 Turn down outlet valve, reduce capacity or lath the small impeller, or replace the pump with lower head.

 

3.Common Faults and Elimination Methods of Double Suction Pump

Fault Performance The Possible Reasons Elimination Methods
（一）.The pump does not absorb water, and the pointer of the pressure gauge and vacuum gauge beats violently. 1.Injected water insufficient. 1.Fill the pump with water again.
 
 2.Pipe or instrument leakage. 2.Tighten to block the leakage.
 
    
（二）Pump does not absorb water, vacuum gauge shows high vacuum. 1．Bottom valve is not open or has silted up. 1．Calibrate or replace the bottom valve.
  2．The resistance of suction pipe is too large. 2．Clean or replace the suction pipe.
  3．The height of suction head is too high. 3．Lower the suction head.
     
（三）The pump is not pumping water, the pressure gauge shows pressure. 1．There is too much resistance in the outlet pipe. 1．Check or shorten outlet pipes.
  2．Wrong direction of rotation. 2．Correct the direction of motor rotation.
  3．Impeller is blocked. 3．Clean the impeller.
  4．Rotation speed is insufficient. 4．Check voltage to improve the speed.
  5．Suction pipe is too small or debris blocked. 5．Increase suction diameter to remove the block.
     
     
（四）The pump consumes too much power. 1.Impeller or inlet pipe blocked. 1．Clean impeller or pipe.
  2.Double suction wear ring wears too much, or impeller damage. 2．Replace the damaged spares.
  3.The speed is below the rated value. 3．Adjust to the rated speed.
  4.Inlet or outlet valves are not fully open. 4．Fully open.
  5.Air leakage into the suction line. 5．Seal off the leakage.
  6.The pipe has blockage. 6．Clean the blockage.
  7.Medium density does not conform to pump requirements. 7．Recalculate or replace the motor with right power.
  8.The equipped head does not conform to pump head. 8．Try to lower the installation height of pump.
     
（五）Abnormal sound inside the pump, the pump does not take in water. 1.The stuffing is too tight。 1.Screw off the stuffing gland.
  2.Friction between impeller and double suction wear ring. Excessive flow. 2．Check the reason and eliminate the mechanical friction.
 
 3.The equipped head does not conform to pump head. 3．Reduce gate valve opening.
     
（六）Pump vibration is abnormal. 1．The pump has cavitation. 1．Adjust the outlet gate valve to operate within the specified performance range.
  2． Impeller unbalance. 2． The static balance will be carried out to the impeller.
  3． The pump shaft has misalignment with the motor shaft. 3． Calibrate the concentricity of pump shaft and motor shaft.
 
 4． The anchor bolt is loose. 4． Tighten the anchor bolt.
  5． Shaft is bending. 5． Replace new shaft.
  6． Bearing friction. 6． Replace bearing.
  7． There is friction between the rotating part and the stationary part. 7． Repair or improve pump operation. 8． Open the inlet valve and adjust the outlet valve
  8． Turn down the inlet.  
 
 
    
（七）Bearing is excessively hot. 1．There is no oil in the bearing. 1．Check and clean the bearing housing. Add lubricating oil..
  2．The lubricating oil is inevitable. 2．Drain and clean the tank and refill it.
  3．Pump shaft and motor shaft are not on the same center line 3．Calibrate the concentricity of the two axes to be on the same center line.
  4．Vibration 4．Check the balance of the rotor or operate at low flow rates.
 
    
（八）Severe seal leakage 1．Improper selection of sealing material. 1．Explain the medium condition to the pump supplier to replace with appropriate seals.
  2． Friction pair is severely worn. 2． Replace friction component and adjust the spring pressure.
  3． Coincide of stationary and static ring are uneven. 3． Readjust sealing assembly.
 
 
 4． Friction pair is too large, and static ring is rupture. 4． Remove and change the static ring so that the perpendicularity error between the ring and the axis is less than 0.10. Install the sealing assembly as required.
 
 5． O ring is damaged. 5． Replace O ring.
     
（九）Motor overload. 1．Pump and motor is misalignment. 1．Adjust the alignment of the pump and motor.
  2． The relative density of medium becomes large. 2． Change the operation process.
  3． Friction occurs in the rotating part. 3． Repair the friction part.
  4． The device resistance becomes low so that the operating point is biased towards high flow. 4． Check the pressure of inlet and outlet lines and adjust it.

 

4.Common Faults and Elimination Methods of Type DG High Pressure BFP

 

Fault Performance The Possible Reasons Elimination Methods
(一).When the feed pump is running, the water does not come out and the pressure gauge does not show the pressure. 1. The pressure of the water in the inlet pipe is below the pressure of vaporization at the specified temperature. 1．Check and take action to increase inlet pressure.
 
 2. The pump turns in the wrong direction. 2．Correct the rotation direction.
 
    
(二).The water supply and pressure of the pump are insufficient in the working process. 1．Same with the above page. 1．Same with the above page.
  2. The filter of impeller flow channel and inlet pipe is blocked. 2. Check the intake strainer and try to remove it.
  3. Air in inlet pipe and pump is not released. 3. Release all the air.
  4. The gap wear of the stationary and rotating ring is large, exceeding the allowable value. 4. Disassembly inspection to ensure drawing requirements.
  5. The clearance of the balancing device exceeds the specified value. 5. Disassembly to have inspection and reparation.
     
(三).Motor Overload 1．The value of pump flow is greater than specified one. 1．Inspect by using flowmeter.
  2. The dynamic and static parts of the pump are ground. 2．Adjust it flexibly. Reasonably warm the pump.
     
(四).Pump vibration: 1）The vibration peak increases gradually and never disappears. 1）1.Pump warm-up is not reasonable. Pump and motor is misalignment. 1) 1.Warm the pump reasonably, and readjust the center.
2）The vibration peaks rise and fall, and disappears sometimes.      2. The impeller balance is too bad.      2.Readjust the impeller balance.
3）Large horizontal vibration value of coupling bearing bush.      3.The rotor dynamic balance is too bad.      3.Re-balance the impeller.
       4.Grind the dynamic and static parts of the pump.      4.Disassemble and check, and repair it.
       5.The pipes forces on the pump to make the pump displacement.      5.Reduce line pressure and realignment the pump.
  2）1.The dynamic and static clearance of the pump is too large 2). 1.It is best to disassemble the pump and reduce the dynamic and static clearance.
       2. External disturbances, such as piping or system vibration.      2.It is best to eliminate external interference and reduce the possibility of resonance.
  3）1. Pump and motor coupling is misalignment. 3). 1．Align the coupling center.
       2. Connect the shaft.      2．Replace the coupling rubber ring.
     
(五).The balancing assembly is badly worn. 1.The radial clearance of the balancing device is too small.
1.Enlarge radial clearance and increase balance force.
  2. Pump vaporization. 2.Avoid vaporization accident, increase the hardness of balance plate and hardness of balance plate.
     
(六).The pump section is not tightly sealed. 1. The tension bolts were not tightened. 1．Stop pump, tighten after cooling.
  2. Joint surface is damaged. 2．Treatment, grinding.
  3. The water temperature drops. 3．Control the deaerator temperature drop gradient.
     
(七).Shaft end seal is not sealed tightly to hold the stuffing. 1.Stuffing abrasion. 1．Fine the reason of stuffing abrasion.
  2. Pump vibration. 2．Eliminate pump vibration.
  3. Stuffing gland is not tightened. 3．Tighten stuffing gland.
  4. Shaft sleeve is worm that cannot hold the stuffing. 4．Replace shaft sleeve.
     
(八).Bearing operation is abnormal. 1. Misalignment to the center of pump and motor. 1．Realign the center on code condition.
  2. Bush clearance is too small or too large. 2．Guarantee drawing requirements.
  3. Oil is dirty. 3．Replace new oil.
     
(九).Pipes vibration 1.Suction and discharge pipes are not reinforced. 1．Reinforce pipes.
  2. The empty displacement of feed pump is small. 2．Improve the discharge valve.
     
(十).Bearing operation is abnormal. 1.Pump empty capacity is less than the allowable value. 1．Increase pump displacement value.
  2. Main equipment is loss of load. 2．The deaerator should be automatically adjusted according to the pressure and water level.
    3．The deaerator has an adequate steam source.
    4．Increase the deaerator level.
    5．The deaerator air release valve is closed.