Centrifugal Pump Classification: Types, Standards, and Practical Applications
Centrifugal pumps are among the most widely used fluid handling machines in industries such as oil & gas, water treatment, chemical processing, and power generation. To ensure proper selection and operation, pumps are classified based on several parameters including flow type, number of stages, design codes, volute type, shaft position, suction arrangement, case design, and impeller position.
1. Classification by Flow Type
- Radial Flow Pumps – Fluid exits the impeller at a 90° angle to the shaft.
Example: Boiler feed pumps requiring high discharge pressure.
- Axial Flow Pumps – Fluid moves parallel to the shaft, like a propeller.
Example: Flood control and irrigation systems needing high volume, low pressure.
- Mixed Flow Pumps – Fluid exits at an angle between 0° and 90°.
Example: Cooling water circulation in power plants, balancing flow and pressure.
2. Classification by Number of Stages
- Single-Stage Pumps – One impeller, simple design, used for low to moderate head.
Example: Domestic water supply pumps.
- Multi-Stage Pumps – Multiple impellers in series, generating very high pressure.
Example: High-pressure boiler feed pumps in thermal power plants.
3. Classification by Design Code
- API 610 – Standard for petroleum, petrochemical, and natural gas industries.
- ISO 2858 / DIN 24256 – End suction centrifugal pumps, standardized dimensions.
- ISO 5199 – Technical specifications for industrial centrifugal pumps.
4. Classification by Volute Type
- Single Volute – One flow passage, simpler design, lower cost.
- Double Volute – Two flow passages, reduces radial thrust, improves reliability.
Practical Example: Double volute pumps are common in large water treatment plants to minimize shaft deflection.
5. Classification by Shaft Position
- Horizontal Pumps – Shaft is horizontal, easy to install and maintain.
- Vertical Pumps – Shaft is vertical, saves floor space, ideal for deep well pumping.
6. Classification by Suction Arrangement
- Single Suction – Fluid enters from one side of the impeller.
- Double Suction – Fluid enters from both sides, balancing axial thrust.
Practical Example: Double suction pumps are widely used in HVAC systems for balanced flow.
7. Classification by Case Design
- Axial Split Case – Casing splits along the shaft axis, easy maintenance.
- Radial Split Case – Casing splits perpendicular to the shaft, stronger design for high pressure.
8. Classification by Impeller Position
- Overhung Pump – Impeller mounted at the end of the shaft.
- Between Bearing Pump – Impeller supported between two bearings, suitable for heavy-duty applications.
Practical Example: Between bearing pumps are common in oil refineries for handling large volumes at high pressures.
Conclusion
The classification of centrifugal pumps helps engineers select the right design for specific applications. From radial-flow single-stage pumps for domestic use to multi-stage API 610 pumps for petrochemical plants, understanding these categories ensures efficiency, reliability, and compliance with industry standards.
