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1. Overheating of the shaft seal in fluoroplastic centrifugal pumps Causes and solutions: (1) The packing is too tight or there is friction. Loosen the packing and check the water seal tube. (2) The water seal ring and the water seal tube are out of alignment. The alignment should be checked again. (3) Poor flushing and cooling. The flushing and cooling circulation pipes should be checked. (4) The mechanical seal is faulty. All the sealing components of the machinery should be checked. 2. Excessive axial movement of the rotor in fluoroplastic centrifugal pumps Causes and solutions: (1) Improper operation; the operating conditions do not match those for which the pump was designed. Solution: Operate strictly in accordance with the procedures, ensuring that the pump runs near its designed operating conditions. (2) The balance is usually insufficient. Solution: Clear the balance pipeline. (3) The material of the balance disc and its base does not meet the requirements; solution: Replace them with ones made of materials that satisfy the specified requirements. 3. The fluoroplastic centrifugal pump will not start or requires a high starting load. Causes and solutions: (1) The prime mover or power supply is malfunctioning. Solution: Check the power supply and prime mover. (2) The pump is stuck. Solution: Rotate the coupling by hand for inspection; if necessary, disassemble it for inspection to eliminate faults in the moving and stationary parts. (3) The filler is pressed too tightly. Solution: Loosen the filler. (4) The discharge valve is not closed. Solution: Close the discharge valve and restart. (5) The balance tube is not unobstructed. Solution: Clear the balance tube. 4. Fluoroplastic centrifugal pump does not discharge fluid. The reasons and solutions are as follows: (1) Insufficient filling of the pump (or residual gas inside the pump). Solution: Refill the pump. (2) The pump is turned in the wrong direction. Solution: Check the rotation direction. (3) The pump speed is too low. Solution: Check the speed and increase it. (4) The filter screen is clogged, and the bottom valve is not functioning properly. Solution: Check the filter screen and remove any debris. (5) The suction height is too high, or a vacuum has formed in the liquid suction tank. Solution: Reduce the suction height ； Check the suction tank pressure. 5. Interruption in discharge from fluoroplastic centrifugal pump. The causes and solutions are as follows: (1) Air leakage in the suction pipeline. Solution: Check the connections of the suction side pipes as well as the sealing condition of the stuffing box. (2) The gas on the suction side was not completely exhausted during pumping. Solution: Request to refill the pump. (3) The inhalation side is suddenly blocked by a foreign object. Solution: Stop the pump to remove the foreign object. (4) Inhaling a large amount of gas. Solution: Check whether there are vortices at the inlet and whether the submersion depth is too shallow. 6. Insufficient flow rate of fluoroplastic centrifugal pumps. The causes and solutions are as follows: (1) Same as b and c. Solution: Take appropriate measures. (2) The system’s static head increases. Solution: Check the liquid level and system pressure. (3) The resistance loss increases. Solution: Check for obstructions such as pipes and check valves. (4) Excessive wear of the casing and impeller wear rings. Solution: Replace or repair the wear ring and impeller. (5) Leakage in other areas. Solution: Check areas such as the shaft seal. (6) Clogging, wear, and corrosion of the pump impeller. Solution: Clean, inspect, replace. 7. Insufficient head of fluoroplastic centrifugal pumps. The causes and solutions are as follows: (1) Same as (1), (2), (3), (4) in b, and (1) in c and (6) in d. Solution: Take appropriate measures. (2) Impeller installed in reverse (double-suction impeller). Solution: Check the impeller. (3) The liquid density and viscosity do not match the design conditions. Solution: Check the physical properties of the liquid. (4) The flow rate is too high during operation. Solution: Reduce traffic. 8. High power consumption of fluoroplastic centrifugal pumps during operation. The reasons and solutions are as follows: (1) Friction between the impeller and the wear-resistant ring, as well as between the impeller and the casing. Solution: Check and repair. (2) Same as item (4) of e. Solution: Reduce traffic. (3) The liquid density increases. Solution: Check the liquid density. (4) The filler is pressed too tightly or there is dry friction. Solution: Loosen the filler and check the water seal tube. (5) Bearing damage. Solution: Inspect, repair, or replace the bearing. (6) Excessively high rotation speed. Solution: Check the drive and power supply. (7) Pump shaft bent. Solution: Correct the pump shaft. (8) The axial force balance mechanism has failed. Solution: Check whether the balance hole and return water pipe are blocked. (9) Poor coupling alignment or too small axial clearance. Solution: Check the alignment and adjust the axial clearance. 9. Vibration or abnormal noises in fluoroplastic centrifugal pumps: The causes and solutions are as follows: (1) Same as items (4) of c, and (5), (7), (9) of f. Solution: Take appropriate measures. (2) Excessively large bearing clearance, loose bearing shells, impurities in the oil, poor oil quality (viscosity, temperature), foaming of the oil due to air or process fluids, inadequate lubrication, and damaged bearings. Solution: After inspection, take appropriate measures such as adjusting the bearing clearance, removing impurities from the oil, and replacing it with fresh oil. (3) The bearing issues are the same as those in (2), either due to an excessive sealing gap, loose retainer rings, or worn seals. Solution: Inspect, adjust, or replace the seal. (4) Misalignment, loose couplings, friction in the sealing devices, deformation of the housing, damaged bearings, support resonance, damaged thrust bearings, bent shafts, and poor fit. The approach is to conduct inspections, take appropriate measures, and repair, adjust, or replace as necessary. (5) Pressure pulsation, off-centering, shell deformation, sealing friction, resonance of supports or foundations, resonance of pipelines or machinery; the treatment methods are the same as those for (4), namely strengthening the foundations or pipelines. (6) Shaft friction, sealing issues, bearings that are not precise, bearing vibration, poor fit due to contraction, etc. The treatment method is the same as (4). 10. Overheating of bearings in fluoroplastic centrifugal pumps: The causes and solutions are as follows: (1) The bearing shells were not lapped to the required standard. The solution is to repair the bearing shells again or replace them. (2) The bearing clearance is too small. The solution is to readjust the bearing clearance or perform scraping. (3) Insufficient amount of lubricating oil and poor oil quality. The solution is to increase the oil amount or replace the lubricant. (4) Poor bearing assembly. The solution is to check the bearing assembly as required and eliminate any factors that do not meet the specifications. (5) Cooling water circuit breaker. The treatment method is inspection and repair. (6) Bearing wear or looseness. The solution is to repair the bearing or discard it. Wakamatsu Kyō, retighten the relevant bolts. (7) Pump shaft bent. The solution is to correct the pump shaft. (8) The oil slinger is deformed; it cannot rotate and thus cannot convey oil. The solution is to replace the oil slinger. (9) Poor coupling alignment or too small axial clearance. The solution is to check the alignment and adjust the axial clearance.