Centrifugal pump type selection and application
Centrifugal pumps are widely used in many different industries due to their simple construction and cost-effectiveness. The pump uses the centrifugal force created by a rotating impeller to add kinetic energy to the liquid to increase the flow rate and pressure. The type of pump chosen is usually based on the flow rate, pressure, and liquid viscosity, which depends on the application. Therefore, selecting the correct centrifugal pump is essential for achieving optimal performance. This article examines centrifugal pump types and the factors to consider when selecting them.
Types of pumps
Centrifugal pumps are classified into two main types: radial-flow and axial-flow pumps. The main difference between the two pumps is the flow path of the fluid. In radial-flow pumps, the fluid enters the eye of the impeller and is directed outward by the centrifugal force, where it is discharged tangentially from the impeller. In axial pumps, the fluid enters the eye of the impeller, is generally accelerated in the axial direction, and is discharged through a different outlet than the feed port.
There are various other types of centrifugal pumps, such as volute and barrel pumps, among others. Each type has its own advantages and disadvantages and is suitable for specific applications.
Volute pumps are designed with an expanding volute casing that increases the flow rate and reduces pressure drops along the impeller. This design is typically used in large-flow applications and is preferred over barrel pumps due to its higher efficiency.
Barrel pumps have a narrow volute casing that restricts the flow and increases the pressure. This design is usually used in smaller-flow applications, such as pumping fluids with higher viscosities.
There are also other types of centrifugal pumps, such as mixed-flow pumps, multi-stage pumps, and self-priming pumps. Each type of pump is suitable for a different application and should be considered based on the specific requirements of the project.
Factors to consider
The performance of a centrifugal pump is likely to be affected by a variety of factors, such as viscosity, pump speed, diameter of the impeller, housing type, and casing material.
Viscosity: One of the most important factors to consider is the viscosity of the fluid to be pumped. High-viscosity liquids, such as oil and sludge, require a pump that can handle high viscosity and turbulence. On the other hand, low-viscosity fluids, such as water and other liquids, can be pumped with a standard centrifugal pump.
Pump speed: The pump speed, measured in revolutions per minute (RPMs), is also an important factor to consider. The average centrifugal pump operates at speeds from 3600 to 7000 RPMs, and the speed should be adjusted according to the flow rate required for the application.
Diameter of the impeller: The diameter of the impeller determines the amount of fluid that can be pumped per revolution of the pump shaft. Smaller impellers usually increase the flow rate, while larger impellers increase the pressure.
Housing type: The housing and casing must be designed to withstand pressure and be compatible with the liquid being pumped. The types of housing and casing materials used vary depending on the application. Common materials used include brass, cast iron, stainless steel, and plastics.
Casing material: The casing material should also be selected according to the liquid pressure, temperature, and corrosion resistance requirements of the application. Common materials used include stainless steel, bronze, aluminum, and thermoplastics.
Selecting the right pump
When selecting a centrifugal pump, it is important to consider the specific requirements of the application, such as flow rate, pressure, and viscosity, as well as the factors mentioned above. Different types of pumps may be used for different applications and their performance can be affected by a variety of factors that should be taken into consideration. Taking the time to select the right pump can ensure optimal performance of the system.
