Pumps

 The Pump is used to import energy to a fluid in a fluid system. It is run by using an external source such as electric motor.

PUMPS

1. Introduction

The Pump is used to import energy to a fluid in a fluid system. It is run by using an external source such as electric motor. So that it can import pressure energy of kinetic energy or both energies to the fluid. In a pump the fluid flow takes place from the low pressure side to the high pressure side of the pump. By rotating the pump impeller by external source the fluid flow is accelerated to enable it to move from low pressure side to the high pressure side. According to the operating principles, the pumps can be classified as

(i) Reciprocating pump

(ii) Centrifugal pump

(iii) Rotary positive displacement pumps.

Reciprocating pump is a positive displacement pump which has a piston that executes reciprocating motion in a closely fitting cylinder.

Centrifugal pump operates by rotating rotor blades called impeller inside a casing filled with water, there by imparting energy to the flowing water. A cent fugal pump operates similar to Francis turbine, but is operates in reverse way. In Francis turbine, water with pressure energy drives a runner wheel where as in centrifugal pump, an impeller is driven by external source and it imparts motion to the water. The delivery head is generated by the centrifugal pump by centrifugal acceleration imposed to the water by the rotating impeller.

2. Definition of Pump

The hydraulic machines which convert the mechanical energy into hydraulic energy are called pump. It is used to raise or transfer of liquids from a lower level to a higher level through increase the pressure energy of the liquids. Pump utilizes the mechanical energy given by an outside source and it provides this energy to a fluid to increase the pressure of kinetic energy or both the energies of the fluid.

3. Types of Pumps.

Two main types of pumps are,

(i) Positive-displacement pump.

(ii) Non-positive displacement pump.

(i) Positive displacement pump

In a positive displacement pump, the liquid is sucked and then it is actually pushed (or) displaced due to the thrust exerted on it by a moving member, which results in lifting the liquid to the required height.

Example: Reciprocating pumps, Rotary pumps.

(ii) Non Positive displacement pump.

In non-positive displacement pump the liquid is subjected to whirling motion by an impeller(Rotating element), the kinetic energy of the liquid is converted into pressure energy. It is also called as Roto-dynamic pump (or) dynamic pressure pump.

Example: Centrifugal pump