Basic Construction of Centrifugal Pumps

Centrifugal pumps operate by utilizing the rotation of the impeller to create centrifugal motion in water. Prior to starting the pump, it is essential to fill the pump casing and suction pipe with water. Then, activate the motor to drive the pump shaft, causing the impeller and water to rotate at high speed. This generates centrifugal motion, propelling the water outward to the edge of the impeller. The water then flows through the spiral casing's channel into the pump's discharge piping.

The basic structure of a centrifugal pump consists of six main components: impeller, pump housing, shaft, bearings, seal ring, and stuffing box.

The impeller is the core component of the centrifugal pump, characterized by its high speed and powerful force. The blades on the impeller play a crucial role. Before assembly, the impeller must undergo a static balance test. The inner and outer surfaces of the impeller must be smooth to minimize frictional losses in water flow.

2. The pump body, also known as the pump housing, is the main part of the pump. It serves as a support and fixing element, connecting to the bracket that accommodates the installed bearings.

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

4. The sliding bearings use transparent oil as the lubricant, filling it up to the oil level line. Too much oil will leak out along the pump shaft, while too little can cause the bearing to overheat, burn out, and lead to accidents! During the operation of the water pump, the temperature of the bearing can rise to as high as 85 degrees, with normal operation around 60 degrees.

5. The sealing ring, also known as the leak reduction ring.

The stuffing box is primarily composed of packing, water seal ring, packing cylinder, packing cover, and water seal pipe. Its main function is to seal the gap between the pump housing and the shaft, preventing the flow of water inside the pump from escaping and preventing external air from entering the pump, thereby maintaining a vacuum inside the water pump. When friction between the pump shaft and the packing generates heat, water is injected into the water seal ring by the water seal pipe to cool the packing, ensuring the normal operation of the water pump. Therefore, during the routine maintenance checks of the water pump, it is particularly important to inspect the stuffing box. A replacement of the packing should be considered after approximately 600 hours of operation.