1. Causes and treatment of centrifugal pump air binding
The air binding is mainly due to the fact that the centrifugal pump is not filled with liquid before starting, there is air in the pump casing, and the air density is small , the centrifugal force generated is also very small, at this time, the vacuum formed at the suction port is not enough to suck the liquid into the pump, and the pump cannot transport the liquid after the pump is pneumatic.
Cause analysis:
1. Before starting, the pump was not pumped and exhausted, causing the air to enter the pump casing.
2. The sealing of the casing is not strict, allowing air to enter.
Treatment method:
1. Before starting the pump, perform priming treatment on the pump to remove the air accumulated in the pump casing.
2. Clean the filter regularly.
3. Do a good job of sealing the shell.
2. Common faults and treatment methods of centrifugal pumps
1. The pump does not absorb water
( 1) The suction valve has debris or is not opened, or the suction pipe is blocked. Treatment method: Open the suction valve, remove the sundries, and clear the suction pipe.
(2) Poor sealing of the piping system. Treatment method: Check the pipeline, especially the segmented pressure test connection flange, and plug the leakage.
(3) Inhale air from the shaft seal. Treatment method: replace the shaft seal and press the packing seal.
(4) Failure of the irrigation pump system. Treatment method: Check and repair the pump system.
2. The pump cannot be started
(1) The prime mover fails (including the power supply). Solution: Check the power supply and prime mover condition.
(2) The pump is stuck. Treatment method: crank again to determine the coupling condition.
(3) The stuffing box is too tight. Treatment: Relax the filler.
(4) The discharge valve is not closed. Treatment method: close the discharge valve and restart.
(5) The balance tube is not smooth. Treatment method: clear the balance tube.
3. The pump does not discharge liquid
(1) The pump is insufficiently filled (or the gas in the pump is not exhausted). Treatment method: Refill the pump.
(2) The direction of the pump is wrong. Solution: Check the rotation direction.
(3) The pump speed is too low. Treatment method: Check the speed and increase the speed.
(4) The filter screen is blocked and the bottom valve is not working. Treatment method: Check the filter screen to eliminate sundries.
(5) The suction height is too high, or there is a vacuum in the suction tank. Treatment method: reduce the suction height; check the suction tank pressure.
4. The pump is interrupted after discharge
(1) The suction line is leaking. Treatment method: Check the sealing of the suction side pipeline connection and stuffing box.
(2) The gas on the suction side is not exhausted when filling the pump. Treatment method: Ask to refill the pump.
(3) The suction side is suddenly blocked by foreign objects. Treatment method: Stop the pump to deal with foreign objects.
(4) Inhale a lot of gas. Treatment method: Check whether there is a vortex at the suction port and whether the submerged depth is too shallow.
5. Insufficient flow of centrifugal pump
(1) The static head of the system increases. Treatment method: Check liquid level and system pressure.
(2) The resistance loss increases. Treatment method: Check the pipeline and check valve and other obstacles.
(3) The wear ring of the casing and impeller is too worn. Treatment method: Replace or repair the wear ring and impeller.
(4) Fluid leakage from other parts. Treatment method: Check the shaft seal and other parts.
(5) The pump impeller is blocked, worn and corroded. Treatment method: cleaning, inspection and replacement.
6. Centrifugal pumpInsufficient head
(1) The impeller is reversely installed (double suction wheel). Treatment method: Check the impeller.
(2) The liquid density and viscosity are inconsistent with the design conditions. Treatment method: Check the properties of the liquid.
(3) The flow is too large during operation. Treatment method: reduce traffic.
7. Running overload
(1) The quality of the engine is poor, and the stator and rotor are rubbed. Treatment method: Check and replace the motor.
(2) There is friction between the impeller and the wear ring, the impeller and the pump casing. Treatment method: Check the parts in the pump and repair them.
(3) The density of the liquid increases. Treatment method: Check the density.
(4) The packing is pressed too tightly or rubbed dry. Treatment method: loosen the packing, check the water seal pipe.
(5) The bearing is damaged. Treatment method: Check and repair or replace the bearing.
(6) The speed is too high. Solution: Check the speed and power of the prime mover.
(7) The pump shaft is bent. Treatment method: Correct the pump shaft.
(8) The axial force balance device fails. Treatment method: Check whether the balance air and return pipe are blocked.
(9) Poor alignment of the coupling or too small axial clearance. Treatment method: Check the coupling and adjust the alignment.
(10) The viscosity of the conveying liquid is too high or the density is too high. Treatment method: replace the high-power motor.
8. The vibration or noise of the pump exceeds the standard
(1) The anchor bolts are loose or the base welding is unqualified. Treatment method: Tighten the anchor bolts, re-check the base welding, and re-weld the base if necessary.
(2) The pump has flow erosion (the flow is too large, the suction resistance increases or the liquid operating temperature is too high). Treatment method: Check the cause and eliminate it.
(3) The pump surges (the net head pressure of the system is higher than the dead pressure of the pump). Treatment method: Check whether the discharge is too high and the pressure is too high.
(4) The impeller is damaged or has foreign objects. Treatment method: disassemble the pump body for inspection, replace and remove foreign objects.
9. Bearing overheating
(1) The bearing assembly is unqualified. Treatment method: check and adjust.
(2) Insufficient lubricating oil, poor oil quality or aging. Treatment method: add enough oil or change the oil.
(3) Insufficient cooling water or open circuit. Treatment method: increase the amount of water after inspection.
10. The shaft seal is overheated
(1) The packing seal is too tight. Treatment method: adjust the sealing pressure.
(2) The mechanical seal is faulty. Treatment method: Check, repair or replace the mechanical seal.
