Water-Lifting Devices – Pumps - Practices of Irrigation and On-farm Water Management - page 437

supply pipe also starts flowing in reverse direction and the water valve is opened
due to its own weight and the water again starts running in supply pipe. This action
continues unless the action of waste valve is stopped. The magnification factor of
head and efficiency of hydraulic ram can be known by the following formula:

q × h = Q × H × e

where

q = amount of water lifted by the ram,

h = head to which water is lifted,

Q = amount of water supplied to supply pipe,

H = head due to which water enters the supply pipe, and

e = efficiency of the ram.

12.1.4 Mechanically Powered Water-Lifting Devices

Mechanically powered water-lifting devices are usually termed as pumps, which
are operated with the help of auxiliary power sources such as engine or electric
motor. These pumps are capable of lifting large quantity of water to higher heads
and are usually employed for the irrigation of field and horticultural crops, city water
supply, etc.

12.2 Definition, Purpose, and Classification of Pumps

12.2.1 Definition of Pump

There are different definitions of pump. Simply speaking, it is a device or machine
which is used for transferring fluids and/or gases from one place to another, or
to increase the pressure of a fluid, or to create a vacuum in an enclosed space.
Common definition of pump in the literature is that pump is a device which converts
mechanical energy into pressure energy.

12.2.2 Pumping Purpose

The primary function of a pump is to transfer energy from a power source to a fluid,
and as a result to create flow, lift, or greater pressure on the fluid. A pump can impart
three types of hydraulic energy to a fluid: lift, pressure, and velocity. In irrigation
and drainage systems, pumps are commonly used to lift water from a lower elevation
to a higher elevation and/or add pressure to the water. Most pumps are used to take
water from a standing (or non-pressurized) source and move it to another location.
For example, a pump might take water from a lake and move it to a sprinkler system.