Axial flow pumps, known for their high flow rate and low head characteristics, are widely used in water conservancy projects, irrigation and drainage systems, and power plant circulating water systems. The quality of their cast components directly affects the pump's efficiency, vibration levels, and service life.
Below are the main cast components of an axial flow pump and their related technical considerations:
1. Main Casting Components
Impeller: The core component of an axial flow pump, typically featuring spatially twisted blades and classified as a complex curved surface casting.
Diffuser/Guide Vane: Installed behind the impeller to convert the rotational kinetic energy of the liquid into pressure energy, while also providing structural support.
Pump Casing/Elbow: Includes the inlet elbow, pump body casing, and outlet elbow. For large axial flow pumps, the casing is usually cast in sections and assembled on-site.
Bearing Housing/Support: Structural components used to support the drive shaft and bearings.
Cone/Suction Bell: A component that guides water smoothly into the impeller.
2. Key Casting Materials
Material selection varies depending on operating conditions (freshwater, seawater, sediment abrasion, etc.):
Gray cast iron (e.g., HT200, HT250): Low cost and good vibration damping, suitable for general-purpose pumps.
Ductile cast iron (e.g., QT400-18, QT500-7): Superior strength and toughness compared to gray cast iron, ideal for components subjected to higher loads.
Stainless steel (e.g., ZG0Cr13Ni4Mo, a super martensitic stainless steel): Excellent resistance to cavitation, corrosion, and wear, making it the preferred material for high-quality axial-flow pump impellers.
Bronze/aluminum bronze (e.g., ZCuAl10Fe3): Outstanding resistance to seawater corrosion, commonly used in marine applications and seawater circulation pumps.