What is a Centrifugal Pump?

Working principle of the centrifugal pump

The principle that a centrifugal pump can transport liquid is that a high-speed rotating impeller exerts a centrifugal force to the liquid. That's why it is called a centrifugal pump. Before start-up, it is firstly required to fill the pump casing and suction line from the funnel with liquid. When the impeller rotates rapidly, the liquid in the impeller rotates as well under the driving force of the impeller blade, so that the liquid obtains centrifugal force and moves outward from the center of the impeller along the vane flow passage. Afterwards, it is tossed out of the end of the blade, and thrown into the volute or diffusion pipe of the pumping shell(or guide wheel). When the liquid flows to the diffusion tube, the flow speed slows down because the sectional area of the liquid flow expands gradually, and a part of the kinetic energy is converted into a static energy head, the pressure is raised, and eventually pushed out of the discharge tube. At the same time, a partial vacuum is generated at the center of the impeller because the liquid is thrown away, so that the liquid in the sump is continuously sucked into the pump from the source of the suction pipe under the action of the liquid surface pressure. The impeller keeps on rotating, and the liquid is continuously sent from the suction tank to the high level tank or pressure vessel.

Types of centrifugal pump

1. Classify by the number of the working impellers

Single-stage pump: have only one impeller on the pump spindle.

Multiple-stage pump: have two or more than two impellers on the pump spindle. Then, the total head of the pump is the sum of the heads of the n impellers.

2. Classify according to the working pressure

Low-voltage pump: pressure below 100m water column.

Middle-voltage pump: pressure within 100~650 m water column.

High-voltage pump: pressure higher than 650m water column.

3. Classify according to the impeller's water feeding means

One-sided water feeding pump: namely, the single suction pump, the impeller has only one water feeding inlet.
Two-sided water feeding pump: namely, the double suction pump, the impeller has one water feeding inlet on each side. Its flow doubles that of the single-suction pump. It can be approximately regarded that two single-suction impellers are placed back to back.

4. Classify according to the pump shell combining means

Horizontal middle-open pump: have the combination seam on the horizontal surface passing.
Vertical combination surface pump: combination surface is vertical to the axial lead.

5. Classify according to the pump spindle position

Horizontal centrifugal pump: the pump spindle is in the horizontal position.
Vertical centrifugal pump: the pump spindle is in the vertical position.

6. Classify according to the means of leading the water out of the impeller to the delivery chamber.

Volute shell: the water directly goes into the pump shell with the spiral line shape after coming out of the impeller.
Guide vane pump: the water enters the externally set guide vane after coming out of the impeller, and then enters the next stage or flows into the outlet.

7. Classify according to the application

Include the sewage pump, hot water pump, anti-corrosion chemical pump, explosive oil pump and so on.

Centrifugal pump applications
Centrifugal pump is suitable for high-rise building pressurized water supply, garden sprinkler irrigation, cooling tower water feeding, long-distance water delivery, air conditioning, refrigeration and washing, bathroom, circular pressurizing of the cold and hot water. The operation temperature is below 80 ℃.Centrifugal pump is applicable to the hot-temperature hot water pressurizing circulation of the heating, boiler and other industries. The operation temperature is below 130℃.
Centrifugal pump is suitable for conveying corrosive media in the process of food, pharmaceutical, wine making, chemical and other industries. The operation temperature is below 80 ℃.
Centrifugal pump is suitable for transporting non-corrosive liquids. It is applicable to the industrial sites with methane or underground coal mine fixed equipment I category and factory IIA and IIB grades, with the temperature groups of T1, T2,T3 and T4, or other explosive mixtures. The operation temperature is below 80℃.
Centrifugal pump is suitable for transporting chemical, pharmaceutical, petrochemical, food, national defense and other industrial corrosive liquids. It is applicable to the industrial sites with methane or underground coal mine fixed equipment I category and factory IIA and IIB grades, with the temperature groups of T1, T2,T3 and T4, or other explosive mixtures. The operation temperature is below 150 ℃.