Knowledge Review: Common Pump Failure Troubleshooting Tips

Thread Content

The method for dealing with a stuck pump is to manually turn the coupling to check it; if necessary, disassemble it for inspection in order to eliminate faults in the moving and stationary parts. The pump does not discharge fluid; insufficient priming (or gas remaining inside the pump). The solution is to re-primer the pump ； The pump is not turning in the correct direction. The solution is to check the rotation direction ； The pump speed is too low. The solution is to check the rotation speed and increase it ； The filter screen is clogged, and the bottom valve is not functioning properly. The solution is to check the filter screen and remove any debris ； The suction height is too high, or a vacuum forms in the suction tank. The solution is to reduce the suction height ； Check the suction tank pressure. The pump stops discharging fluid; cause and solution: air leakage in the suction line. The solution is to check the connections in the suction side pipeline as well as the sealing of the stuffing box: the gas on the suction side was not completely exhausted during pumping. The solution is to request a re-pumping ； The inhalation side was suddenly blocked by a foreign object. The solution is to stop the pump in order to remove the foreign object ； Inhale a large amount of gas. The solution is to check whether there are vortices at the inlet and whether the submersion depth is too shallow. Insufficient flow: causes and solutions: increased system static head. The solution is to check the liquid level and system pressure ； The drag loss increases. The solution is to check for obstructions such as pipes and check valves ； The wear of the casing and impeller wear rings is excessive. The solution is to replace or repair the wear ring and impeller ； Leakage in other areas. The solution is to check areas such as the shaft seal ； Pump impeller blockage, wear, corrosion. The treatment methods are cleaning, inspection, and replacement. Insufficient head: causes and solutions: the impeller is installed in the wrong direction (double-suction impeller). The solution is to check the impeller ； The liquid density and viscosity do not match the design conditions. The treatment method is to check the physical properties of the liquid ； The flow rate is too high during operation. The solution is to reduce the traffic. Pump vibration or abnormal noises: Causes and solutions. The vibration frequency ranges from 0 to 40% of the operating speed. 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. The treatment method involves conducting inspections and taking appropriate actions, such as adjusting the bearing clearance, removing impurities from the oil, and replacing it with fresh oil ； The vibration frequency is 60%-100% of the operating speed, or the sealing gap is too large, the retaining ring is loose, or the seal is worn out. The solution is to inspect, adjust, or replace the seal ； The vibration frequency is twice the operating speed; misalignment, loose couplings, friction in sealing devices, housing deformation, bearing damage, support resonance, thrust bearing damage, shaft bending, and poor fit. The approach is to conduct inspections, take appropriate measures, and repair, adjust, or replace as necessary ； The vibration frequency is n times the operating speed. Pressure pulsation, off-centering, shell deformation, seal friction, resonance of supports or foundations, resonance of pipelines and machinery ； Reinforce foundations or pipelines ； The vibration frequency is very high. Shaft friction, sealing issues, bearings, lack of precision, bearing vibration, poor fit due to contraction, etc. Causes of bearing overheating and treatment methods: The bearing bushing has not been lapped to the required standard. The solution is to repair the bearing shells again or replace them. The bearing clearance is too small. The solution is to readjust the bearing clearance or perform scraping ； Insufficient amount of lubricant and poor quality of oil. The solution is to increase the oil volume or replace the lubricant ； The bearing is poorly assembled. The solution is to check the bearing assembly as required and eliminate any factors that do not meet the specifications ； Cooling water circuit broken. The handling method is to inspect and repair ； The bearing is worn or loose. The solution is to repair the bearing or discard it. Wakamatsu Kyō, retighten the relevant bolts ； The pump shaft is bent. The solution is to correct the pump shaft ； The oil slinger is deformed; it cannot rotate and thus cannot transfer oil. The solution is to update the oil slinger ring ； The coupling is poorly aligned or the axial clearance is too small. The solution is to check the alignment and adjust the axial clearance. Axial seal overheating: causes and solutions: the packing is too tight or there is friction. The solution is to loosen the packing and check the water seal tube ； The water seal ring is out of alignment with the water seal tube. The solution is to recheck the alignment ； Poor flushing and cooling. The solution is to check the flushing and cooling circulation pipe ； The mechanical seal is faulty. The solution is to check the mechanical seal. Reasons for large rotor play and solutions: improper operation, with operating conditions far from the pump’s design conditions. Handling method: Operate strictly to keep the pump running near its designed operating conditions at all times ； The balance is not smooth. The solution is to clear the balance tube ； The material of the balance disc and its seat does not meet the requirements. The solution is to replace the balance disc and its holder with materials that meet the requirements.