Short Answer:

Pumps are mechanical devices used to move fluids such as liquids or slurries from one place to another by adding energy to the fluid. They are commonly used in industries, irrigation systems, and household water supply. Pumps operate by converting mechanical energy from an external source into hydraulic energy of the fluid.

The pumps are mainly divided into two broad categories: positive displacement pumps and dynamic pumps. Positive displacement pumps transfer a fixed amount of fluid during each cycle, while dynamic pumps use velocity and pressure changes to move the fluid continuously. Each type has specific applications based on flow rate, pressure, and fluid characteristics.

Detailed Explanation :

Types of Pumps

Pumps play an essential role in mechanical systems, as they help in transporting fluids efficiently. They are used in various applications like water supply, fuel injection, hydraulic systems, chemical processing, and sewage treatment. The classification of pumps is mainly based on their working principles and how they add energy to the fluid. The two main types of pumps are Positive Displacement Pumps and Dynamic Pumps.

1. Positive Displacement Pumps

A positive displacement pump works by trapping a definite volume of fluid in a chamber and then forcing it out into the discharge pipe. The flow of fluid is constant regardless of the pressure on the discharge side. These pumps are suitable for high-pressure and low-flow applications.

Types of Positive Displacement Pumps:

1. Reciprocating Pumps:
   These pumps use a piston or plunger that moves back and forth in a cylinder to draw in and discharge the liquid.
   • Piston Pump: It uses a piston moving inside a cylinder to create suction and discharge strokes.
   • Plunger Pump: It works similarly to a piston pump but has a longer stroke and is suitable for high-pressure systems.
   • Diaphragm Pump: It uses a flexible diaphragm to move fluids, often used for corrosive or hazardous liquids.

Working Principle:
During the suction stroke, the piston moves backward, creating a vacuum and allowing fluid to enter the cylinder. During the discharge stroke, the piston moves forward, pushing the fluid out through the discharge valve.

Advantages:

1. • High pressure can be achieved.
   • Accurate and consistent discharge.
   • Suitable for viscous and corrosive fluids.

Disadvantages:

1. • Complex design with many moving parts.
   • Requires regular maintenance.
   • Limited flow rate.
2. Rotary Pumps:
   These pumps use rotating elements like gears, screws, or vanes to move fluid.
   • Gear Pump: Consists of two meshing gears that trap fluid and move it through the pump casing.
   • Screw Pump: Uses one or more screws that rotate to move fluid along the screw axis.
   • Vane Pump: Has sliding vanes mounted on a rotating rotor that traps and moves fluid.

Advantages:

1. • Smooth and uniform flow.
   • Can handle viscous fluids.
   • Compact and efficient.

Disadvantages:

1. • Not suitable for large flow rates.
   • Sensitive to wear and tear.

2. Dynamic Pumps

Dynamic pumps add energy to the fluid continuously by imparting velocity, which is then converted into pressure energy. These pumps are used in applications where a large volume of fluid is required at a relatively low pressure.

Types of Dynamic Pumps:

1. Centrifugal Pump:
   This is the most common type of dynamic pump. It consists of an impeller that rotates inside a casing. The impeller imparts velocity to the liquid, and the casing converts this velocity into pressure.

Working Principle:
When the impeller rotates, it creates a low-pressure area at the eye of the impeller, drawing fluid in. The fluid gains velocity as it passes through the impeller and is pushed outward into the casing, where velocity energy is converted into pressure.

Advantages:

1. • Simple design and easy maintenance.
   • Suitable for large flow rates.
   • Operates smoothly with low noise.

Disadvantages:

1. • Not suitable for very viscous fluids.
   • Efficiency decreases with varying discharge pressure.
2. Axial Flow Pump:
   The fluid flows parallel to the pump shaft, similar to a propeller. It is used for applications that require a high flow rate and low head, such as flood control and circulation systems.
3. Mixed Flow Pump:
   In this type, the fluid flow is partly radial and partly axial. It combines the advantages of both centrifugal and axial flow pumps. These pumps are used in irrigation and drainage systems.

Comparison Between Positive Displacement and Dynamic Pumps:

• Positive Displacement Pumps: Deliver a fixed volume of fluid per cycle; suitable for high pressure and viscous liquids.
• Dynamic Pumps: Deliver continuous flow; suitable for large volumes and low viscosity fluids.

Applications of Pumps:

• Water supply systems.
• Oil and gas industries.
• Hydraulic systems.
• Chemical and process industries.
• Sewage and wastewater treatment.

Conclusion:

Pumps are vital components in many mechanical and industrial systems. They ensure smooth and reliable movement of liquids by converting mechanical energy into hydraulic energy. The two major types, positive displacement and dynamic pumps, serve different needs based on flow and pressure requirements. Understanding the types and functions of pumps helps in selecting the right pump for specific industrial and mechanical applications, ensuring better efficiency and system performance.