The Structure And Function Of Centrifugal Pumps

The working principle of a centrifugal pump is that the reason why it can send water out is due to the action of centrifugal force. Before the water pump starts working, the pump body and inlet pipe must be filled with water to form a vacuum state. When the impeller rotates rapidly, the blades promote the water to rotate quickly. The rotating water flies away from the impeller under the action of centrifugal force. After the water inside the pump is thrown out, the central part of the impeller forms a vacuum zone. The water from the source is pressurized into the inlet pipe through the pipeline network under the action of atmospheric pressure (or water pressure). By continuously circulating in this way, continuous pumping can be achieved. The basic structure of a centrifugal pump consists of six parts, namely: impeller, pump body, pump shaft, bearings, sealing ring, and packing box.
1. The impeller is the core part of a centrifugal pump, with high rotational speed and large output force. The blades on the impeller play a major role, and the impeller needs to undergo static balance experiments before assembly. The inner and outer surfaces of the impeller are required to be smooth to reduce friction losses caused by water flow.
2. The pump body, also known as the pump casing, is the main body of the water pump. Plays a supporting and fixing role, and is connected to the bracket for installing bearings.
3. The function of the pump shaft is to connect the coupling with the electric motor, transmitting the torque of the electric motor to the impeller, so it is the main component for transmitting mechanical energy.
4. Bearings are components that are placed on the pump shaft to support the pump shaft, and there are two types of bearings: rolling bearings and sliding bearings. When using butter as a lubricant for rolling bearings, it should be added appropriately. Generally, if the volume is too large, it will heat up, and if it is too small, there will be noise and heat up! The sliding bearing uses transparent oil as a lubricant and is filled to the oil level line. Too much oil will seep out and drift along the pump shaft, and too little bearing will overheat and burn out, causing accidents! During the operation of the water pump, the maximum temperature of the bearings is 85 ° C, usually around 60 ° C. If it is too high, the cause should be investigated (whether there are impurities, whether the oil quality is black, whether water is entering) and dealt with in a timely manner!
5. Sealing ring, also known as leak reducing ring. Excessive clearance between the impeller inlet and the pump casing can cause water in the high-pressure area of the pump to flow towards the low-pressure area through this clearance, affecting the pump's water output and reducing efficiency! A small gap can cause friction and wear between the impeller and pump casing. In order to increase reflux resistance and reduce internal leakage, delay the service life of the impeller and pump casing, a sealing ring is installed at the junction of the inner edge of the pump casing and the external support of the impeller, and it is advisable to maintain a sealing gap between 0.25 and 1.10mm.
6. The packing box mainly consists of packing, water seal ring, packing cylinder, packing gland, and water seal pipe. The main function of the packing box is to seal the gap between the pump casing and the pump shaft, preventing the water flow inside the pump from flowing outside and the air from outside from entering the pump. Always maintain vacuum inside the water pump! When the friction between the pump shaft and the packing generates heat, it is necessary to use the water seal pipe to inject water into the water seal ring to cool the packing! Maintain the normal operation of the water pump. So during the operation and inspection of the water pump, special attention should be paid to the inspection of the packing box! The packing needs to be replaced after about 600 hours of operation.
7. During the operation of a centrifugal pump, the axial force balancing device generates axial thrust pointing towards the inlet direction due to the fact that the liquid enters the impeller at low pressure and flows out at high pressure, resulting in unequal pressure on both sides of the impeller. This can cause axial displacement, wear, and vibration of the rotor. Therefore, axial thrust bearings should be installed to balance the axial force.