Centrifugal Pumps

Types of Centrifugal pumps

Centrifugal pumps are of several types depending on the number of impellers, design, construction, service, and many more. Here, we describe all the types based on several factors:

Based on the number of impellers, Centrifugal pumps are of three types:

• Single stage: In this type, one impeller is present which means it has a simple design and easy to maintain.
• Two-stage: Two impellers are present which operate side by side, used for medium head applications.
• Multi-stage: Used for high head application, this type includes three or more impellers.

On the basis of a type of impeller:

• Single Suction: It has one suction in impeller which means fluid enters in blades through only one side. Although its design is simple, it has one limitation which is impeller imbalance due to flow coming in one side.
• Double suction: It overcomes the limitation of impeller imbalance because it is double suction impeller which means fluid enters from both sides of blades.

On the basis of shaft orientation:

• Horizontal: In these pumps, the shaft is in the horizontal plane. It is popular because of easy to maintain and service.
• Vertical: In these pumps, a shaft is in the vertical plane. They require large headroom for maintenance, installation, and service.

Depending on the compliance with industry standards:

• ANSI pump: It stands for American National Standards Institute that refers to dimensional standards. The standards ANSI B73.1 and ASME B73.1 must meet by the pumps.
• API pump: American Petroleum Institute refers to the parameters of pump’s constructions. The pump must meet the requirements of API standards 610 for General Refinery Service.
• ISO pumps: Those pumps that come under ISO pumps must follow ISO 2858, 5199 specifications.
• Nuclear Pumps: The pumps follow ASME specifications.
• DIN pump: Pumps have DIN 24256 specifications, used in large flow rates, very high temperatures, or high working pressures.

On the basis of case-split:

• Axial split: In these, the volute casing splits axially and the split line is at the center line of the shaft. They are mounted horizontally because of easy to maintain and install.
• Radial split: In this, the volute casing splits radially which means the split line is perpendicular to shaft center line.

Components of Centrifugal pumps:

The components are divided mainly into two primary classes that are a wet end and the mechanical end. The wet end of the pump has those parts that determine the hydraulic performance whereas the mechanical end has those parts that help impeller to rotate within a casing. The wet end includes impeller, casing, and mechanical end includes a shaft, shaft sealing, bearings, pipes, etc.

1. Impeller: It is the most important component of centrifugal pumps. It is the rotating part of the system which is used to increase the speed of flow. It is mounted on the shaft which is connected with a motor that is used to rotate the impeller.
2. Casing: It surrounds the impeller with an airtight passage and acts as a pressure containment vessel. The main work of casing is to provide the flow of liquid in and out of a centrifugal pump. Generally, three types of the casing are used: volute casing, vortex casing, and casing with Guide blades.
3. Shaft sealing: It is the special part of centrifugal pumps as it is used to prevent the leakage of the fluid.
4. Bearings: It is used to reduce the friction between the shaft and the stator.
5. Suction pipe: It is the pipe whose one end is in the water sump and another part is connected with an inlet of an impeller. At the end of the suction pipe, strainer and foot valve are connected. A strainer is used to filter the water and block the unwanted particles.
6. Delivery Pipe: It is the pipe whose one end is in the tank where water has to deliver and one end is connected with an outlet of the pump.

Applications of centrifugal pumps:

It is true that a centrifugal pump is the most demanding choice for fluid movement which makes it useful in many industries. Here, we present some applications of centrifugal pumps:

1. Dairy Industry: Centrifugal pumps are used to transfer liquid products such as milk, buttermilk, etc.
2. Agriculture and Manufacturing: Used for drainage, wastewater processing plants, irrigation and many more.
3. Oil & energy: Pumps are used for movement of crude oil, mud, refinery plants, etc.
4. Pharma and Cosmetic Industry: Here, pumps are used to transfer glucose, lactose and other chemical substances.

Advantages of centrifugal pumps

The centrifugal pumps are the popular choice for the movement of fluids for below reasons. Get a look at them:

• The utmost advantage of a centrifugal pump is its simplicity. It is small in size and doesn't have complex parts to maintain. This means they need less space to install.
• They are not expensive which means they have a lower capital cost and easily affordable.
• The output of centrifugal water pumps is steady and uniform.
• They can handle any type of fluids which means handle with low to high viscous fluids.
• They are easily maintainable and can be cleaned very quickly.
• They can handle with corrosive and edible types of fluids.
• They are leek free that ensures safety from the toxic fluids.

Disadvantages of centrifugal pumps:

Although, centrifugal pumps are great in use but still, they have some disadvantages which are:

• The main disadvantage is that they use rotation instead of suction which means they have to be underwater to move water.
• They can’t give optimal output with high viscous fluids.
• The size of pumps is also restrictable.
• They don’t produce high pressure as per requirement.