The centrifugal pump is the most used pump type in the world. The principle is simple, well-described and thoroughly tested, and the pump is robust, effective and relatively inexpensive to produce. There is a wide range of variations based on the principle of the centrifugal pump and consisting of the same basic hydraulic parts.
The operation principle : An increase in the fluid pressure from the pump inlet to its outlet is created when the pump is in operation. This pressure difference drives the fluid through the system or plant. The centrifugal pump creates an increase in pressure by transferring mechanical energy from the motor to the fluid through the rotating impeller.The fluid flows from the inlet to the impeller center and out along its blades.The centrifugal force hereby increases the fluid velocity and consequently also the kinetic energy is transformed to pressure.
Inlet :
The pump is connected to the piping system through its inlet and outlet flanges. The design of the flanges depends on the pump application. Some pump types have no inlet flange because the inlet is not mounted on a pipe but submerged directly in the fluid. The inlet guides the fluid to the impeller eye. The design o the inlet depends on the pump type. The four most common types of inlets are inline, endsuction, doublesuction and inlet for submersible pumps.
inline pumps are constructed to be mounted on a straight pipe – hence the name inline. The inlet section leads the fluid into the impeller eye.
Endsuction pumps have a very short and straight inlet section because the impeller eye is placed in continuation of the inlet flange.
The impeller in double suction pumps has two impeller eyes.The inlet splits in two and leads the fluid from the inlet flange to both impeller eyes. This design minimizes the axial force, In submersible pumps, the motor is often placed below the hydraulic parts with the inlet placed in the mid section of the pump. The design prevents hydraulic losses related to leading the fluid along the motor. In addition,the motor is cooled due to submersion in the fluid
The design of the inlet aims at creating a uniform velocity profile into the impeller since this leads to the best performance.
Impeller:
The blades of the rotating impeller transfer energy to the fluid there by increasing pressure and velocity. The fluid is sucked into the impeller at the impeller eye and flows through the impeller channels formed by the blades between the shroud and hub, .The design of the impeller depends on the requirements for pressure, flow and application. The impeller is the primary component determining the pump performance. Pumps variants are often created only by modifying the impeller. The impeller’s ability to increase pressure and create flow depends mainly on whether the fluid runs radially or axially through the impeller
The impeller has a number of impeller blades. The number mainly depends on the desired performance and noise constraints as well as the amount and size of solid particles in the fluid. Impellers with 5-10 channels has proven to give the best efficiency and is used for fluid without solid particles. One, two or three channel impellers are used for fluids with particles such as waste water.The leading edge of such impellers is designed to minimize the risk of particles blocking the impeller. One, two and three channel impellers can handle particles of a certain size passing through the impeller.
Impellers without a shroud are called open impellers. Open impellers are used where it is necessary to clean the impeller and where there is risk of blocking. A vortex pump with an open impeller is used in waste water application. In this type of pump, the impeller creates a flow resembling the vortex in a tornado. The vortex pump has a low efficiency
compared to pumps with a shroud and impeller sealFor More information you can review Grundfos Pump
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