Analysis and treatment of common faults and main causes of self suction centrifugal oil pumps

（1） Common faults analysis and treatment of self suction centrifugal oil pumps There are various reasons for the faults of self suction centrifugal oil pumps, including unreasonable selection and inherent equipment faults, installation, startup, and operation faults. For example, pump overpower caused by unreasonable selection; Severe pump cavitation and insufficient flow caused by design and manufacturing defects; Due to installation failure, the vibration and noise of the self suction centrifugal oil pump severely exceed the standard; Due to startup and operation failures of the self priming centrifugal oil pump, the pump cannot start normally, the water output gradually decreases, the packing heats up, and the bearings overheat. When the pump operates with abnormal sound or excessive vibration, the small unit composed of a self suction centrifugal pump and motor should be stable and the sound should be normal. If there is noise or abnormal vibration in this small unit, it is often a precursor to pump failure, and it should be stopped immediately for inspection to eliminate hidden dangers. The possible causes of malfunctions may include: imbalanced rotation of the pump or motor rotor, misalignment between the pump and motor, aging of the impeller rubber ring, incorrect impeller balance, insufficient stiffness of the pump foundation, loose anchor bolts, excessive wear of bearings or seals, resulting in rotor eccentricity, gas in the pump, failure to vacuum, improper lubrication of bearings and packing, excessive wear, bearing wear or damage, excessive or insufficient lubricating oil (grease), excessive suction head, cavitation of the impeller, bubbles appearing in the low-pressure area when the liquid passes through the impeller, and bubbles collapsing in the high-pressure area, causing collision and vibration. At this time, the installation height of the pump should be reduced, foreign objects sucked in by the pump, blockage or damage to the impeller should be stopped. The vibration caused by cleaning foreign objects or replacing damaged impellers or resonance is mainly due to the natural frequency of the rotor being the same as the pump speed, resulting in resonance, etc. If the bearing is found to be hot during the operation of the pump, the cause can be investigated in the following items: the self suction centrifugal oil pump is not concentric with the electric motor, the coupling is poorly aligned, or the axial clearance is too small. The method is to check the alignment and adjust the axial clearance, insufficient lubricating oil or poor lubricating oil circulation, poor lubricating oil quality, impurities that cause bearing rust and wear, inflexible rotation, severe bearing wear, and poor scraping of the bearing. If the bearing clearance is too small, the bearing clearance should be readjusted or scraped. If the bearing assembly is poor, the bearing assembly should be checked according to requirements. Factors that do not meet the requirements, cooling, etc. If there is a water circuit break, the cooling water device should be checked and repaired immediately. If the pump shaft is bent, factors such as the pump shaft should be corrected

(2) The main reasons for the low operating efficiency of self suction centrifugal pumps

In order to achieve energy conservation and consumption reduction in self suction centrifugal pumps during production and operation, it is necessary to improve the pump's efficiency and operate stably for a long time under optimal working conditions.

. The energy-saving measures for pumps need to be systematically considered from multiple aspects such as selection, design, manufacturing, installation, operation, operation, maintenance, and inspection. Based on the analysis of the energy-saving characteristics of the pump, consider energy-saving and renovation methods, and improve the economy and efficiency of pump operation through various renovations

1. Unreasonable selection

The main reason for the low operating efficiency of self suction centrifugal pumps is that the actual operating point is lower than the pump's rate point.

. The general model of self suction centrifugal pump relies on the throttling of the pump outlet valve to regulate the medium flow rate. Although this method is simple and convenient, it results in a significant amount of energy waste due to inefficient operation. And the motor has also been operating at a low efficiency

2. Unreasonable pump design and manufacturing

Whether the design of a self suction centrifugal pump is reasonable, the level of processing accuracy, and the quality of assembly are the determining factors of the energy utilization efficiency and energy consumption of the self suction centrifugal pump. This not only affects the rated efficiency of the self suction centrifugal pump, but also has an important impact on the selection and operation of the self suction centrifugal pump.