Centrifugal Pump

About Centrifugal Pump
Centrifugal Pump

Centrifugal Pump, its is most common pump. The centrifugal pump is a simple type of pump that you can see anywhere around you, its working system is very simple. This pump creates a rotation motion by the help of prime mover and with the  help of  centrifugal force occur and that force provided flow speed to liquid.
  in other word , Centrifugal Pump's main part part impeller creates vacuum force that force provided liner motion ot fluid and hence one side of Centrifugal Pump suction forces and other side exhaust force. both force make a flow speed of material. The action of the impeller increases the fluid’s velocity and pressure and also directs it towards the pump outlet.  The pump casing is specially designed to constrict the fluid from the pump inlet, direct it into the impeller and then slow and control the fluid before discharge.
Centrifugal Pump
 Common uses include water, sewage, agriculture, petroleum and petrochemical pumping. Centrifugal pumps are often chosen for their high flow rate capabilities, abrasive solution compatibility, mixing potential, as well as their relatively simple engineering.
 are the most common type of pump used in industry, agriculture, municipal (water and wastewater plants), power generation plants, petroleum and many other industries. They are the primary pump type in the class of pumps called "kinetic" pumps and are distinctly different than "positive displacement" pumps.

Centrifugal Pump History 

The first machine that was characterized into a centrifugal pump was named as mud lifting machine. This machine was appeared in the year 1475 by the Francesco di Giorgio Martini. He is an Italian Renaissance engineer. However, the actual centrifugal pumps were not implemented until the 17th century, while Denis Papin designed the pump with the help of straight vanes. In the year 1851, the British inventor namely John Appold has launched the curved vane.

Working of  Centrifugal Pump

Working of  Centrifugal Pump

Like most pumps, a centrifugal pump converts rotational energy, often from a motor, to energy in a moving fluid. A portion of the energy goes into kinetic energy of the fluid. Fluid enters axially through eye of the casing, is caught up in the impeller blades, and is whirled tangentially and radially outward until it leaves through all circumferential parts of the impeller into the diffuser part of the casing. The fluid gains both velocity and pressure while passing through the impeller. The doughnut-shaped diffuser, or scroll, section of the casing decelerates the flow and further increases the pressure. It is important to note that the water is not pushed radially outward by centrifugal force (non-existent force), but rather by inertia, the natural tendency of an object to continue in a straight line (tangent to the radius) when traveling around circle. This can be compared to the way a spin-cycle works in a washing machine.

Types of Centrifugal Pump

Centrifugal pumps can be classified into several types depending on factors such as design, construction, application, service, compliance with a national or industry standard, etc. Therefore, one specific pump can belong to different groups and at times pump is known by its description itself. Some of these groups have been highlighted below:

Based on number of impellers in the pump,

  1. Single stage Centrifugal Pump
  2. Two-stage Centrifugal Pump
  3. Multi-stage Centrifugal Pump

Based on orientation of case-split,

  1. Axial split Centrifugal Pump
  2. Radial split Centrifugal Pump

Based on type of impeller design,

  1. Single suction Centrifugal Pump
  2. Double suction Centrifugal Pump

Based on the basis compliance with industry standards,

  1. ANSI pump – (American National Standards Institute)
  2. API pump – (American Petroleum Institute)
  3. DIN pump – DIN 24256 specifications
  4. ISO pump – ISO 2858, 5199 specifications
  5. Nuclear pump – ASME (American Society of Mechanical Engineers) specifications

Based on type of volute

  1. Single volute Centrifugal Pump
  2. Double volute Centrifugal Pump

Based on where the bearing support is,

  1. Overhung Centrifugal Pump
  2. Between-bearing Centrifugal Pump

Based on on shaft orientation

  1. Horizontal Centrifugal Pump
  2. Vertical Centrifugal Pump

Single stage Centrifugal Pump

Single stage Centrifugal Pump

 A one impeller pump, single stage Centrifugal Pump has a simple design and easy maintenance. Ideal for large flow rates and low-pressure installations. They are commonly used in pumping services of high flow and low to moderate TDH (Total Dynamic Head).

Two-stage Centrifugal Pump

Two-stage Centrifugal Pump

Centrifugal Pump  has two impellers operating side by side which are used for medium head applications.

Multi-stage Centrifugal Pump

Multi-stage Centrifugal Pump

Centrifugal Pump  has three or more impellers in series; for high head service.A centrifugal pump containing two or more impellers is called a multistage centrifugal pump. The impellers may be mounted on the same shaft or on different shafts. At each stage, the fluid is directed to the center before making its way to the discharge on the outer diameter.
For higher pressures at the outlet, impellers can be connected in series. For higher flow output, impellers can be connected in parallel.

 Main function of Centrifugal Pump

The following chief factors affect the performance of a centrifugal pump and need to be considered while choosing a centrifugal pump:
  • Working Fluid Viscosity – can be defined as resistance to shear when energy is applied. In general, a centrifugal pump is suitable for low viscosity fluids since the pumping action generates high liquid shear.
  • Specific density and gravity of working fluid – The density of a fluid is its mass per unit of volume. A fluid’s mass per unit volume and gravity of a fluid is the ratio of a fluid’s density to the density of water. It directly affects the input power required to pump a particular liquid. If you are working with a fluid other than water, it is important to consider the specific density and gravity since the weight will have a direct effect on the amount of work performed by the pump.
  • Operating temperature and pressure – Pumping conditions like temperature and pressures are an important consideration for any operation. For example - High-temperature pumping may require special gaskets, seals and mounting designs. Similarly, an adequately designed pressure retaining casing may be required for high-pressure conditions.
  • Net Positive Suction Head (NPSH) and Cavitation – NPSH is a term that refers to the pressure of a fluid on the suction side of a pump to help determine if the pressure is high enough to avoid cavitation. Cavitation refers to the formation of bubbles or cavities in liquid, developed in areas of relatively low pressure around an impeller and can cause serious damage to the impeller and lead to decreased flow/pressure rates among other things. One must ensure that the system’s net positive suction head available (NPSHA) is greater than the pump’s net positive suction head required (NPSHR), with an appropriate safety margin.
  • Vapour pressure of the working fluid – The vapor pressure of a fluid is the pressure, at a given temperature, at which a fluid will change to a vapor. It must be determined in order to avoid cavitation as well as bearing damage caused by dry running when the fluid has evaporated.

Owing to the use in the diverse range of applications, pumps come with different capacities and in various sizes. You should also consider the pressure and volume requirements of the specific operations for which you need the pump. The horsepower required is another important consideration when it comes to volume and discharge pressure.

 Main Parts of Centrifugal Pump

the  three main parts 
  1. Centrifugal Pump impeller
  2. Centrifugal Pump casing 
  3. Centrifugal Pump delivery pipe

1. Centrifugal Pump Impeller

Centrifugal Pump Impeller

It is a wheel or rotor which is provided with a series of backward curved blades or vanes. It is mounded on the shaft which is coupled to an external source of energy which imparts the liquid energy to the impeller there by making it to rotate.

Impellers are divided into 3 types,
  1. Open Impeller
  2. Semi enclosed Impeller
  3. Enclosed Impeller

2. Centrifugal Pump Casing

Centrifugal Pump Casing

It is a pipe which is connected at the upper end to the inlet of the pump to the centre of impeller which is commonly known as eye. The double end reaction pump consists of two suction pipe connected to the eye from both sides. The lower end dips into liquid in to lift. The lower end is fitted in to foot valve and strainer.

Commonly three types of casing are used in centrifugal pump,
  1. Volute Casing
  2. Vortex Casing
  3. Casing with Guide Blades

3. Centrifugal Pump Delivery Pipe

It is a pipe which is connected at its lower end to the out let of the pump and it delivers the liquid to the required height. Near the outlet of the pump on the delivery pipe, a valve is provided which controls the flow from the pump into delivery pipe.

4. Centrifugal Pump Suction Pipe with Foot Valve and Strainer

suction pipe is connected with the inlet of the impeller and the other end is dipped into the sump of water. At the water end, it consists of foot value and strainer. The foot valve is a one way valve that opens in the upward direction. The strainer is used to filter the unwanted particle present in the water to prevent the centrifugal pump from blockage.

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