Agriculture Reference
In-Depth Information
12.1.1.3 Archimedean Screw
It consists of a helical screw mounted on spindle, which is rotated inside a wooden
or metallic cylinder. One end of the cylinder remains submerged in water and is
placed at an inclined position at an angle of 30 degrees. It is used for lifting of water
from a depth of 0.6-1.2 m and may discharge 1,600 l/h.
12.1.1.4 Paddle Wheel
It is also known as Chakram and is mostly used in coastal regions for irrigating
paddy fields. It consists of small paddles mounted radially to a horizontal shaft,
which moves in close fitting concave trough, thereby pushing water ahead of them.
The number of blades depends on the size of wheel, which may be 8 for 1.2 m
and up to 24 for 3-3.6 m diameters. The wheel having 12 blades may lift about
18,000 l/h from a depth of 0.45-0.6 m.
12.1.2 Animal-Powered Devices
Animal power is available in Indian subcontinent, but decreasing day by day. They
are used for lifting of water, besides other field operations and processing works. A
pair of bullocks may develop approximately 0.80 hp. They can lift water from the
depth of 30 m or more. Of course the rate of discharge will go down with increase
in lift. Some of the devices used for irrigation operated by animal power are Persian
wheel, rope-and-bucket lift, self-emptying bucket, two bucket lift, chain pump, etc.
12.1.3 Kinetic Energy Powered Device
12.1.3.1 Hydraulic Ram
Hydraulic ram is a device to lift the water without any prime mover by utilizing
the kinetic energy of flowing water. In this system the impact of water is converted
into shock waves, which is called water hammer. This energy is utilized for lifting of
water. The essential components of the system are check dam, supply pipe, hydraulic
ram, storage tank, and discharge pipe. Except for changing of washers in the valves,
there is no repair and maintenance required and the ram can operate 365 days in a
year without any trouble. For fixing a hydraulic ram, a check dam is constructed on
flowing water of a river or streams to create low head. Due to velocity and pressure
of the water, the valve of the ram closes suddenly which creates a water hammer in
the system. This causes building up of high pressure, which opens the tank valve and
water rushes to the tank. The tank is enclosed from all sides and the air present in it
creates further pressure on the water, which enters the tank and closes the valve of
tank, thus discharging water from it. This discharged water is lifted by the hydraulic
ram to higher head than the supply head. During this action, part of the water in the
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