What are the Core Components of a Centrifugal Pump?

In the grand landscape of fluid machinery, Omron Tech Pumps has long been deeply engaged in the field of centrifugal pumps. Centrifugal pumps occupy a dominant position due to their simple structure and wide application range. Although there is a wide variety of centrifugal pumps, ranging from miniature household booster pumps to giant industrial drainage stations with vastly different appearances, their core "organs" are strikingly similar when their casings are removed.

Today, we will conduct an in-depth analysis of the structural details and evolution logic of centrifugal pumps by combining the classic Type B pumps, modern IS pumps, and large-flow double-suction pumps.

I. Eight Core Components of Centrifugal Pumps

Regardless of pump type variations, the following main components form the basic framework of centrifugal pumps:

• Impeller: The core component that does work, converting mechanical energy into liquid kinetic energy.
• Pump body and pump cover: Form the working chamber, collect liquid and convert energy.
• Pump shaft: The transmission rod that transfers torque.
• Bearings and bracket: Support the rotor and ensure rotational accuracy.
• Seal ring: Prevent backflow of internal high-pressure liquid.
• Stuffing box (shaft seal): Prevent external leakage and air ingress.
• Coupling: The bridge connecting the motor and the pump shaft.

Analysis of Typical Centrifugal Pump Structures: Type B, IS and Single-Stage Double-Suction Pumps

After understanding the general structure of centrifugal pumps, we further explore several common types of centrifugal pumps, each with a focused structural design to adapt to different working conditions.

1. Type B Centrifugal Pump

The Type B pump is a classic centrifugal pump design, characterized by one end of the pump being supported by bearings inside the bracket, while the end fitted with the impeller extends cantilevered out of the bracket. Based on the combination of the pump body and pump cover, Type B pumps are divided into front-opening and rear-opening types. The rear-opening design offers significant advantages during maintenance: the bracket together with the impeller can be removed simply by loosening the bracket spigot nut, without disassembling the pump’s inlet and outlet pipelines, greatly simplifying the maintenance process. Most of the axial force of Type B pumps is balanced by balance holes on the impeller, and the remaining force is borne by the bearings. This type of pump is simple in structure, reliable in operation, easy to manufacture and maintain, and highly adaptable, so it was once widely used.

2. IS Centrifugal Pump

The IS pump is the mainstream single-stage single-suction centrifugal pump that is gradually replacing Type B pumps. It has been optimized on the basis of Type B pumps to improve energy efficiency and convenience. The impeller suction port diameter of IS pumps is usually larger, and the suction and discharge ports of the pump casing have also been improved, with the pump body directly supported on the base. Compared with Type B pumps of the same performance, IS pumps have a smaller rated power, reflecting their energy-saving characteristics. IS pumps also adopt a rear-opening structure, with further enhanced maintenance convenience: the rotating parts can be withdrawn for maintenance by removing the intermediate connection of the extended coupling, without disassembling the pump body, pipelines and motor. IS pumps are suitable for industrial and urban water supply and drainage, as well as agricultural irrigation, and can transport clean water or liquids with physical and chemical properties similar to clean water, with a temperature not higher than 80°C.

3. Single-Stage Double-Suction Centrifugal Pump

The single-stage double-suction centrifugal pump is structurally equivalent to combining two impellers of Type B pumps, with liquid entering from both the left and right sides of the impeller simultaneously, making its flow rate much larger than that of a single-suction pump of the same size. Its rotor is supported at both ends, and the pump casing is usually a horizontally split volute type, with two semi-helical suction chambers forming a split structure together with the pump casing. This design not only handles large flow rates but also balances the axial force of the pump by itself due to the symmetric liquid entry into the impeller, eliminating the need for an additional axial force balancing device. At the same flow rate, double-suction pumps generally have better cavitation resistance than single-suction pumps, which is particularly important for transporting easily vaporized liquids or under high suction lift conditions. The shaft seal device of the pump mostly adopts packing seal, with a water seal ring installed in the stuffing box for cooling and lubrication by introducing pressurized water.

Conclusion

From the rugged durability of Type B pumps, to the energy-saving precision of IS pumps, and to the magnificent performance of double-suction pumps, the structural evolution of centrifugal pumps has always centered on the two core themes of efficiency and maintenance convenience. Different types of centrifugal pumps, based on the general core structure, have their own structural characteristics and application advantages to meet the needs of different industrial scenarios. Omron Tech Pumps will continue to empower the R&D and application of centrifugal pumps with professional technology.