Positive Displacement Pumps

One of the first pieces of powered machinery to be invented at the dawn of the industrial age was a crude form of pump. The pump has since evolved into an endless variety of types, sizes, and applications. A functional understanding of pumps, their use, and application, is essential to understand how most processes are handled in process plants today.

Introduction

Pump is a machine or mechanical equipment which is required to lift liquid from low level to high level or to flow liquid from low pressure area to high pressure area or as a booster in a piping network system. Principally, pump converts mechanical energy of motor into fluid flow energy.

Pump also can be used in process operations that requires a high hydraulic pressure. This can be seen in heavy duty equipment’s. Often heavy duty equipment’s requires a high discharge pressure and a low suction pressure. Due to low pressure at suction side of pump, fluid will lift from certain depth, whereas due to high pressure at discharge side of pump, it will push fluid to lift until reach desired height.

Classification of Pumps

Pumps may be classified on the basis of the applications they serve, the materials from which they are constructed, the liquids they handle, and even their orientation in space. All such classifications, however, are limited in scope and tend to substantially overlap each other. A more basic system of pump classification is based on the principle by which energy is added to the fluid. Under this system, all pump types generally fall into two main categories:

Dynamic (Centrifugal) Pumps – Energy is continuously added to increase the fluid velocities within the machine.

Positive Displacement Pumps – Energy is periodically added by application of force to one or more movable boundaries of enclosed, fluid-containing volumes.

These are further divided into many forms. For simplification of article we will discuss these many forms separately in separate articles.

The Function of a Pump

A pump is any device meant to facilitate the motion of a fluid. Pumps displace fluids, causing it to move down or out of a pipe. Most pumps use some sort of compressional action to displace the fluid. This compressional action sometimes necessitates a motor that acts to put pressure on the fluid in order to displace it. This motor can be powered by a variety of fuels, as long as it has the necessary power to displace the fluid. Most pumps are either positive displacement or rotodynamic.

Positive Displacement Pumps

Positive displacement pumps function by trapping and displacing amounts of a fluid. This causes the fluid to be displaced and move along the length of the pump and through its discharge. The fluid must be continually displaced in order for fluid to keep being discharged from the pump.

Rotodynamic Pumps

Rotodynamic pumps use motion to generate more energy in a fluid and then cause the fluid to move along a pipe. Pumps such as these generally use a motor to turn a device that will increase pressure on a fluid or will increase the flow rate of the fluid using centrifugal force.

Different pumps can be used for different places and usages, for example, there are Slurry Pump, Dredge Pump, Gravel Pump, Froth Pump, Sump Pump and so on. And they are always equipped with other Pump Parts to get a expected effect.