Submersible axial flow pumps are crucial components in various industries, including water treatment, irrigation, flood control, and industrial processes. These pumps are designed to operate while fully submerged in the fluid they are pumping, making them ideal for applications where traditional pumps might be impractical or less efficient. The choice of materials used in the construction of these pumps is critical to their performance, durability, and longevity. 

Pump Casing

The pump casing, also known as the pump housing or volute, is the outer shell of the pump that contains the impeller and directs the flow of liquid. It plays a crucial role in maintaining the pump's structural integrity and efficiency. The choice of material for the pump casing depends on factors such as the nature of the fluid being pumped, the operating environment, and cost considerations.

For general water pumping applications, cast iron is a popular choice for pump casings due to its strength, durability, and cost-effectiveness. Cast iron casings are resistant to wear and can withstand moderate corrosion, making them suitable for many municipal and industrial applications. However, when dealing with more corrosive fluids or environments, stainless steel is often preferred.

Stainless steel, particularly grades like 316 or 304, offers excellent corrosion resistance and is widely used in pump casings for applications involving seawater, chemical processing, or food and beverage industries. Stainless steel casings are also favored in situations where contamination of the pumped fluid must be avoided, such as in pharmaceutical or semiconductor manufacturing processes.

In some specialized applications, such as handling highly corrosive chemicals or abrasive slurries, more exotic materials might be used for pump casings. These can include duplex stainless steels, super duplex stainless steels, or even non-metallic materials like fiber-reinforced plastics (FRP) or high-performance thermoplastics. These materials offer superior resistance to corrosion and abrasion but come at a higher cost.

Aluminum alloys are sometimes used for pump casings in applications where weight is a critical factor, such as in portable pumps or in certain marine applications. However, their use is less common in large industrial submersible axial flow pumps due to concerns about long-term durability in harsh environments.

Impeller

The impeller is the heart of the submersible axial flow pump, responsible for imparting kinetic energy to the fluid and creating the flow. The material choice for the impeller is crucial as it directly impacts the pump's efficiency, wear resistance, and overall performance.

Stainless steel is a common material for impellers in submersible axial flow pumps. Grades such as 316 or 304 stainless steel offer a good balance of strength, corrosion resistance, and cost-effectiveness. These materials perform well in a wide range of applications, from clean water pumping to moderately corrosive environments.

For more demanding applications involving highly corrosive fluids or abrasive slurries, harder and more resistant materials may be used. These can include duplex stainless steels, super duplex stainless steels, or even specialized alloys like Hastelloy or Inconel. These materials offer superior resistance to corrosion and erosion but come at a significantly higher cost.

In some cases, especially for smaller pumps or less demanding applications, bronze impellers may be used. Bronze offers good corrosion resistance and is often less expensive than stainless steel. However, it may not be suitable for all applications due to its lower strength compared to steel alloys.

For pumps handling extremely abrasive slurries, such as in mining or dredging applications, hard-faced or rubber-lined impellers may be used. These impellers have a base material (often steel) that is coated or lined with a highly wear-resistant material to extend the life of the impeller in harsh conditions.

In recent years, there has been growing interest in using advanced composite materials for impellers. These materials, such as fiber-reinforced polymers, offer excellent corrosion resistance and can be engineered to have specific properties suitable for certain applications. However, their use in large industrial pumps is still relatively limited due to concerns about long-term durability and cost.

Shaft

The pump shaft is a critical component that transmits power from the motor to the impeller. It must be strong enough to withstand the torque and bending forces involved in pump operation, as well as resist corrosion and fatigue.

Stainless s teel is the most common material used for pump shafts in submersible axial flow pumps. Grades such as 316 or 410 stainless steel offer excellent strength and corrosion resistance. The specific grade chosen often depends on the application and the level of corrosion resistance required.

For pumps handling particularly corrosive fluids, more resistant alloys may be used for the shaft. These can include duplex stainless steels, super duplex stainless steels, or nickel-based alloys like Inconel. These materials offer superior corrosion resistance but are more expensive than standard stainless steels.

In some cases, especially for larger pumps or those operating at high speeds, high-strength alloy steels may be used for the shaft. These materials offer excellent strength and fatigue resistance but may require additional corrosion protection, such as a stainless steel sleeve or coating.

For pumps used in applications where even tiny amounts of contamination must be avoided, such as in pharmaceutical or semiconductor manufacturing, solid stainless steel shafts are often preferred over carbon steel shafts with stainless steel sleeves.

Seals

Seals play a crucial role in submersible axial flow pumps, preventing the pumped fluid from entering the motor housing and ensuring the longevity of the pump. The choice of seal materials is critical and depends on factors such as the nature of the pumped fluid, operating temperature, and pressure.

Mechanical seals are commonly used in submersible axial flow pumps. These seals typically consist of two main components: the stationary seat and the rotating face. The materials for these components are chosen based on their compatibility with the pumped fluid and their wear characteristics.

For the rotating face, materials such as silicon carbide or tungsten carbide are often used due to their excellent hardness and wear resistance. These materials can withstand the high pressures and temperatures often encountered in pump operations.

The stationary seat is often made from materials like carbon, ceramic, or silicon carbide. The choice depends on the specific application requirements. Carbon, for example, offers good self-lubricating properties but may not be suitable for all fluids or temperatures.

The elastomers used in the seals, such as O-rings, are also critical components. Common materials include Viton (FKM), EPDM (Ethylene Propylene Diene Monomer), and Nitrile (NBR). The choice depends on the chemical compatibility with the pumped fluid and the operating temperature range.

Submersible Axial Flow Pump For Sale

When selecting a submersible axial flow pump, it's crucial to choose a reputable manufacturer that can provide high-quality equipment tailored to your specific needs. Tianjin Kairun offers submersible axial flow pumps that have passed the ISO 9001 Quality Management System certification, ensuring reliability and performance. If you're in the market for a submersible axial flow pump, you can reach out to Tianjin Kairun at catherine@kairunpump.com for more information and assistance in selecting the right pump for your application.

References:

1. Karassik, I. J., Messina, J. P., Cooper, P., & Heald, C. C. (2008). Pump Handbook (4th ed.). McGraw-Hill Education.

2. Gülich, J. F. (2020). Centrifugal Pumps (3rd ed.). Springer.

3. Tuzson, J. (2000). Centrifugal Pump Design. John Wiley & Sons.

4. Nelik, L. (1999). Centrifugal and Rotary Pumps: Fundamentals with Applications. CRC Press.