Disclosure: This post may contain affiliate links, meaning we get a commission if you decide to make a purchase through our links, at no cost to you. Please read our disclosure for more info.
Centrifugal pumps are used to move water in many industrial applications. For example, paper mills use them to move pulp through their machinery.
The rapid rotation of the pump impeller imparts velocity to the fluid being pumped. This velocity passes through stationary volutes within the casing, which convert most of the increased rate into pressure.
In This Post:
Flow Rate
Centrifugal pumps offer a wide range of flow rates. Their energy efficiency also saves on operating costs. They are also capable of delivering precise volumes of water. Their smooth flow prevents pulsing, which can be problematic with other pumps.
Water enters the pump through the suction nozzle and encounters an impeller fitted in a casing. This fan-like rotor spins fast and whips the water radially, converting its kinetic energy into pressure. This energy is transferred to the delivery nozzle, which delivers water at a specific height.
Water entering the pump must be drained occasionally, a process called priming. It helps prevent the pump from losing momentum or slurping water and damaging itself.
Pressure
The centrifugal pump is capable of producing a great deal of pressure. This pressure results from the kinetic energy imparted to the liquid by the spinning impeller vanes. This increased velocity creates tension that is transferred to the discharge side of the pump.
Fluid enters the pump at its axis (known as the eye) and is drawn into the rotating impeller, consisting of a series of curved vanes sandwiched together. The speed of the impeller, as well as its size and shape, determines how much energy it transfers to the liquid.
This information helps determine what pump to purchase. Shop performance tests typically include six data points analyzed to find the best pump for an application.
Temperature
In many cases, centrifugal pumps can transport liquids that have varying temperatures. They can also handle abrasive particles without damage, which is not always possible with positive displacement pumps. Corrosion is another important factor to consider when choosing a pump type. Chemicals can cause the pumps to deteriorate quickly, so they should be made of corrosion-resistant materials.
A centrifugal pump comprises an arrangement of curved vanes attached to the impeller, which is mounted on a shaft connected to a motor and rotated at high speed. This rotational force imparts velocity to the fluid flow, which builds up pressure in the casing and is discharged at a required height. Before a centrifugal pump is started, it must be filled with water in priming.
Materials
Centrifugal pumps have a crucial role in managing water treatment tasks. They are responsible for pumping raw wastewater, influent wastewater, primary and secondary sludge, and treated water to distribution systems and water towers. Proper maintenance and regular testing are crucial to ensure the efficient functioning of these pumps. It helps meet diverse water treatment demands while maintaining the quality of water.
Pumps should be run in a shop for at least six points of performance to ensure that the characteristic curve remains rising for a continuous range of heads. Pumps that do not meet this standard may droop or loop.
The whirling motion of the impeller in a centrifugal pump increases mechanical energy within the liquid. This energy is transferred to the fluid through the blade rows and deposited between the vanes. Pressure is then gradually increased in a diffuser casing or a spiral case, depending on the design of the container.
Design
The centrifugal pump consists of a fan-like impeller in a watertight casing mounted on an electric motor’s shaft. When it starts to rotate, the impeller imparts velocity to the water that enters from its suction nozzle. This kinetic energy is then slowed down when it enters a volute or diffuser design, converting it to fluid pressure.
The pumped liquid is then delivered at a predetermined head. Corrosion can deteriorate the pump and its components over time, but regular maintenance and corrosion-resistant materials can help prolong their lifespans.
Pumps have special properties that allow them to convey media with up to 30% gas proportions. This makes them ideal for water treatment in applications such as ozone disinfection. They also have self-priming capabilities and can be ATEX-rated.
