A Brief Analysis of the Structure of Pipeline Centrifugal Pumps

The basic structure of a pipeline centrifugal pump consists of six parts: the impeller, the pump body, the pump shaft, the bearing, the sealing ring, and the stuffing box.

1. Impeller

It is the core part of the centrifugal pump. It has a high rotational speed and large force. The blades on the impeller play a major role. Before assembly, the impeller must pass a static balance test. The inner and outer surfaces of the impeller are required to be smooth to reduce the friction loss of water flow.

2. Pump body

Also known as the pump casing, it is the main body of the water pump. It serves a supporting and fixing function and is connected to the bracket where the bearing is installed.

3. Pump shaft

The function of the pump shaft is to connect with the motor through a coupling and transfer the motor's torque to the impeller. Therefore, it is the main component for transmitting mechanical energy.

4. Bearing

It is a component that is sleeved over the pump shaft to support it, and there are two types: rolling bearings and sliding bearings. Rolling bearings use tallow as a lubricant. The amount of oil added should be appropriate, generally 2/3 to 3/4 of the volume: too much will cause heat, while too little will make noise and generate heat! The sliding bearing uses transparent oil as the lubricant. Add oil to the oil level line. If there is too much oil, it will seep out along the pump shaft and splash; if there is too little, the bearings will overheat and burn out, causing an accident! During the operation of the water pump, the temperature of the bearings is relatively high, usually around 85 degrees Celsius, and generally operates at around 60 degrees Celsius. If it exceeds this temperature, the cause should be identified (wherher there are impurities, whether the oil is black, or whether water has entered) and dealt with promptly!

5. Sealing ring

Also known as a leakage reduction ring. If the gap between the impeller inlet and the pump casing is too large, the water in the high-pressure area inside the pump will flow to the low-pressure area through this gap, affecting the pump's water output and reducing its efficiency! Too small a clearance will cause friction between the impeller and the pump casing, resulting in wear. To increase the backflow resistance, reduce internal leakage and prolong the service life of the impeller and the pump casing, a sealing ring is installed at the junction of the inner edge of the pump casing and the outer edge of the impeller. The sealing gap is preferably maintained between 0.25 and 1.10mm.

6. Stuffing box

It is mainly composed of packing, water seal ring, packing cylinder, packing gland and water seal pipe. The main function of the stuffing box is to seal the gap between the pump casing and the pump shaft, preventing the water inside the pump from flowing out and the outside air from entering the pump. Always maintain the vacuum inside the water pump! When the pump shaft rubs against the packing and generates heat, water needs to be trapped in the water seal ring through the water seal pipe to cool the packing! Keep the water pump running normally. Therefore, during the operation and patrol inspection of the water pump, special attention should be paid to the inspection of the stuffing box! The packing needs to be replaced after about 600 hours of operation.