Mixed Flow Pumps

The operating principles of mixed flow pumps 

Mixed flow pumps are centrifugal pumps that are designed to combine the best characteristics of both radial flow pumps and axial flow pumps. These pumps are widely used in a variety of applications such as irrigation, drainage, cooling water circulation, and sewage treatment due to their unique capabilities. 

The impeller of a mixed flow pump has a distinct design that allows it to produce fluid flow that is a combination of both radial and axial directions. This impeller can have diameters ranging from 152 to 762 mm, and as it rotates, it creates a low-pressure zone at its center, which draws fluid into the impeller from the inlet. The low-pressure zone can reach a vacuum of up to 635 mm of mercury (inHg). The fluid then flows through the impeller blades, which push it outwards in a radial direction. However, the angled blades of the impeller also cause the fluid to rotate as it exits, imparting an axial component to the flow. The angle of rotation is typically between 20 to 45 degrees with respect to the impeller axis. 

The mixed flow pump's volute casing is designed to direct the flow from the impeller into a spiraling path that allows the fluid to exit the pump in the desired direction. The volute casing also helps to convert some of the kinetic energy of the fluid into pressure energy, which can increase the pressure of the fluid by up to 30%. The efficiency of mixed flow pumps typically ranges from 60% to 90%, depending on the design and operating conditions. Additionally, mixed flow pumps are often more compact and less expensive than axial flow pumps for the same flow rate, making them an attractive option for a wide range of pumping applications. 

Features and advantages of mixed flow pumps 

Mixed flow pumps offer several advantages and features that make them a desirable choice for various pumping applications. Some of the main advantages and features of mixed flow pumps include: 

• Unique Impeller Design: The impeller of a mixed flow pump has a distinctive design that combines characteristics of both radial and axial flow pumps. This design allows mixed flow pumps to produce fluid flow that is a combination of both radial and axial directions, resulting in high efficiency and low shear rates. 
• High Flow Rates: Mixed flow pumps typically have flow rates ranging from 200 to 38 000 liters per minute, making them suitable for a wide range of applications that require high flow rates. 
• Wide Range of Applications: Mixed flow pumps are commonly used in applications such as irrigation, drainage, cooling water circulation, and sewage treatment, among others. 
• Low Maintenance: Mixed flow pumps are known for their low maintenance requirements due to their simple design and fewer moving parts, resulting in reduced downtime and lower operating costs. 
• High Efficiency: The efficiency of mixed flow pumps typically ranges from 60% to 90%, depending on the design and operating conditions. This high efficiency results in lower energy consumption, reducing the overall operating costs. 

Industries and applications that uses mixed flow pumps 

Mixed flow pumps are used in a wide range of industries and applications due to their unique combination of radial and axial flow characteristics, as well as their ability to handle high flow rates with relatively low head. 

One common application of mixed flow pumps is in irrigation systems, where they are used to transport water from a source such as a lake or river to fields or crops. For example, a mixed flow pump with a flow rate of 15000 liters per minute and a head of 15 meters may be used to irrigate a 400000 square meters field with a sprinkler system, delivering 15 mm of water per hour. 

Mixed flow pumps are also used in drainage systems to remove excess water from low-lying areas or construction sites. In these applications, the pumps may need to handle high flow rates of up to 38 000 lpm or more, such as in a stormwater management system. For instance, a mixed flow pump with a flow rate of 30 000 lpm and a head of 4,5 meters could be used in a stormwater pumping station to remove excess water from a heavily populated area during a rainstorm. 

Another important application of mixed flow pumps is in cooling water circulation systems, where they are used to transport water through heat exchangers to remove heat generated by industrial processes. In this case, the pumps may need to handle high temperatures and corrosive fluids, such as in a power plant or chemical processing facility. For example, a mixed flow pump with a flow rate of 11500 lpm and a head of 9 meters may be used in a cooling water system for a gas turbine generator, circulating water through a heat exchanger to maintain the temperature within acceptable limits. 

In sewage treatment plants, mixed flow pumps are used to transport wastewater from one processing stage to another. The pumps may need to handle solids and other debris that can cause clogging, such as in a lift station. For instance, a mixed flow pump with a flow rate of 10 000 lpm and a head of 12 meters could be used to transfer wastewater from a primary clarifier to a secondary clarifier in a municipal sewage treatment plant. 

Important considerations when selecting mixed flow pumps 

When selecting mixed flow pumps, there are several important considerations to keep in mind. These include: 

• Flow rate: The flow rate is the amount of fluid that the pump is required to move per unit of time. It is important to choose a mixed flow pump that can handle the required flow rate for the given application. The flow rate of mixed flow pumps typically ranges from 189 to 37850 liters per minute. 
• Head: The head is the height to which the pump is required to lift the fluid. It is important to choose a mixed flow pump that can provide the required head for the given application. The head of mixed flow pumps typically ranges from a few feet to several hundred feet. 
• Efficiency: The efficiency of the pump is the ratio of the output power to the input power. It is important to choose a mixed flow pump that is efficient to minimize energy consumption and operating costs. The efficiency of mixed flow pumps typically ranges from 60% to 90%, depending on the design and operating conditions. 
• NPSH (Net Positive Suction Head): The NPSH is the amount of suction head required to prevent the formation of cavitation within the pump. It is important to choose a mixed flow pump that has a low NPSH requirement to prevent cavitation. The NPSH requirement of mixed flow pumps varies depending on the design and operating conditions. 
• Material of construction: The material of construction is important to ensure the pump is compatible with the fluid being pumped and can withstand the operating conditions. Common materials of construction for mixed flow pumps include cast iron, stainless steel, and bronze. 

Why buy mixed flow pumps from AxFlow? 

AxFlow provides mixed flow pumps that cater to an extensive variety of industries and applications. Exclusive to AxFlow, you will be provided with personalized recommendations from highly experienced process engineers, and access to the most prominent process technology manufacturers that are independent of the manufacturer. If you require assistance in selecting the appropriate pumps that satisfy your requirements, feel free to contact AxFlow without any delay. AxFlows engineers and specialists can help with the selection process, specifications, installation, and maintenance of your fluid handling equipment.