Each centrifugal pump is composed of hundreds of parts, and the basic structure of the centrifugal pump is composed of six parts.
Impeller
Volute Casing
Shaft
Bearing
Seal ring
Stuffing box
These components can be subdivided into the wet end and mechanical end.

Impeller

The impeller is the core part of the centrifugal pump, it has high speed and high output, the impeller on the blade and plays a major role, the impeller should pass the static balance test before assembly. The inner and outer surfaces on the impeller are required to be smooth to reduce the friction loss of water flow.

The impeller can be generally divided into single-suction and double-suction two kinds, single-suction impeller for single-sided suction, small flow pump impeller is mostly this type. Double-suction impeller is two-sided suction, large flow pump impeller are used double-suction impeller

Impeller design is the most important factor in determining the performance of a centrifugal pump. A properly designed impeller optimizes the flow rate. Centrifugal pump type water pump impeller mainly has the following 3 forms, closed type, semi-open type, open type

Closed impeller: It consists of blades and front and rear cover plates. The closed impeller is more efficient and more difficult to manufacture. It is the most used in centrifugal pumps. Suitable for conveying clean water, solutions, and other clean liquids with small viscosity and no particles.

Semi-open impeller: there are two general structures one is the front semi-open, by the back cover and blade composition, this structure impeller efficiency is low, in order to improve efficiency need to be equipped with adjustable gap sealing ring another for the back semi-open, by the front cover and blade composition, because can be applied with the closed pump impeller the same sealing ring? Efficiency and closed impeller are basically the same, and the blade in addition to conveying liquid, but also has: back blade or vice impeller sealing role. The semi-open impeller is suitable for conveying liquids containing solid particles, fibers, and other suspended matters. The semi-open impeller is less difficult to manufacture, lower cost, and is adaptable, in recent years in the refinery chemical centrifugal pump application gradually increased, and used to transport clear water and near clearwater liquid

Open impeller: only the blade and blade reinforcement, no front and rear cover impeller. The number of open impeller blades is less than 2-5 pieces. Water pump impeller efficiency is low, the application is less, mainly used for conveying high viscosity liquid and slurry liquid.

Volute Casing

Acts as a support fixation and is connected to the bracket where the bearing is mounted

Shaft

The impeller mounted on the shaft, the pump shaft is connected to the motor by coupling and transmits the torque of the motor to the impeller, so it is the main part for transmitting mechanical energy.

Bearing

Bearings constrain the relative motion of the shaft (rotor) and reduce friction between the rotating shaft and the stator

Seal ring

Sealing rings are also known as leak reduction rings prevent the leakage of the pumped liquid

Stuffing box

The stuffing box is mainly composed of packing, water seal ring, packing cylinder, packing gland and water seal tube. The function of the stuffing box is mainly to close the gap between the pump casing and the pump shaft, so that the water inside the pump will not flow outside and the air outside will not enter the pump. Always keep the vacuum inside the pump! When the pump shaft and the packing friction heat will rely on the water seal tube water to the water seal ring to make the packing cool! Keep the normal operation of the pump. Therefore, we should pay special attention to the checking of the stuffing box during the operation tour of the pump! The packing should be replaced in about 600 hours of operation.

Table of Content

Centrifugal pump definition
Centrifugal pump basic structure
The working principle of centrifugal pump
Working process of centrifugal pump
Classification of centrifugal pumps
Centrifugal pump technical parameters
Centrifugal Pump Benefits

Centrifugal pump definition

Centrifugal pumps refer to pumps that rely on the centrifugal force generated when the impeller rotates to transport liquids, and the energy for impeller rotation usually comes from diesel engines or electric motors. Applicable to various industries, such as industrial applications agricultural irrigation, municipal water supply, power station circulation water supply, urban pollution treatment, etc.

Centrifugal pump basic structure

The basic components of a centrifugal pump are a high-speed rotating impeller and a fixed worm-shaped pump casing. The impeller is fastened to the pump shaft and driven by the pump shaft with the motor or diesel engine for high-speed rotation (also see centrifugal pump parts)
The impeller is the part that does work directly on the liquid in the pump and is the energy supply device of the centrifugal pump. The suction port in the center of the pump casing is connected with the suction pipeline, and the bottom of the suction pipeline is equipped with a one-way bottom valve. The discharge port at the side of the pump casing is connected to the discharge pipeline with a regulating valve.

The working principle of centrifugal pump

Centrifugal pump in the work, relying on high-speed rotation of the impeller, the liquid in the role of inertial centrifugal force gained energy to improve the pressure. Centrifugal pump in the work before the pump body and inlet pipeline must be full of liquid media, to prevent cavitation phenomenon. When the impeller rotates rapidly, the vane prompts the medium to rotate quickly, and the rotating medium flies out of the impeller under the action of centrifugal force, and the water inside the pump is thrown out after the central part of the impeller forms a vacuum area. One side constantly inhales the liquid, and the other side constantly gives a certain amount of energy to the inhaled liquid and discharges the liquid

Working process of centrifugal pump

Before starting the pump, fill the pump with the liquid to be delivered
After the pump is turned on, the pump shaft drives the impeller to rotate at a high speed to generate centrifugal force. Under this action, the liquid is thrown from the center of the impeller to the outer periphery of the impeller, the pressure increases, and flows into the pump casing at a very high speed.
Due to the continuous expansion of the flow channel in the volute pump casing, the flow rate of the liquid slows down, so that most of the kinetic energy is converted into pressure energy. Finally, the liquid flows into the discharge pipe from the discharge port with a higher static pressure
After the liquid in the pump is thrown out, a vacuum is formed in the center of the impeller. Under the action of the pressure difference between the liquid surface pressure (atmospheric pressure) and the pressure in the pump (negative pressure), the liquid enters the pump through the suction pipe to fill the gap. Where to drain the liquid

Classification of centrifugal pumps

Centrifugal pumps are classified in various ways, including by working pressure, by a number of working impellers, by way of impeller intake, etc.

According to working pressure

Low-pressure pumps: pressures below 100 m water column
Medium pressure pump: pressure between 100 and 650 m water column
High-pressure pump: pressure higher than 650 m water column

By number of working impeller

Single-stage pumps: only one impeller on the pump shaft
Multi-stage pump: There are two or more impellers on the pump shaft when the total head of the pump is the sum of the heads produced by n impellers

By impeller inlet method

Single side inlet pump: also called single suction pump, there is only one inlet on the impeller
Double-side inlet pump: also called double-suction pump, that is, there is a water inlet on both sides of the impeller. Its flow rate is twice as large as that of single suction pumps, which can be approximated as two single suction pump impellers placed back to back.

By pump shaft position

Horizontal pumps: pump shaft in a horizontal position
Vertical pump: the pump shaft is located in a vertical position

According to the medium conveyed by the centrifugal pump

Clean water pumps
Sewage pumps
Slurry pumps

By installation height

Self-priming centrifugal pump: the pump shaft is lower than the surface of the suction pool, no need to irrigate when starting, it can start automatically
Suction centrifugal pump (non-self-irrigating centrifugal pump): the pump shaft is higher than the surface of the suction pool. Before starting, it is necessary to fill the pump casing and suction pipe with water, then drive the motor to make the impeller rotate at high speed, the water is thrown out of the impeller by the centrifugal force, the negative pressure is formed in the center of the impeller, the water in the suction pool enters the impeller under the action of atmospheric pressure, and is thrown out of the impeller into the water pressure pipe by the action of the impeller rotating at high speed.

Special construction

The pipeline pump is installed as part of the pipeline without changing the pipeline
Submersible pump and motor are submerged in water as one unit
The submerged pump body is immersed in liquid

Centrifugal pump technical parameters

Pump Terms Glossary

Flow Rate
Head
Pumping liquid temperature range
System pressure
Shaft Power

Centrifugal Pump Benefits

Compact construction
Wide range of flow and head
Suitable for mildly corrosive liquids
Multiple control options
Uniform flow rate, smooth operation, and low vibration No special vibration-damping foundation is required
Low equipment installation, maintenance, and overhaul costs

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