sprinkler irrigation final (2)

Sprinkler IrrigationBy Gautam R. Patel

Introduction

Sprinkler Irrigation is the method of applying irrigation water above the soil surface in the form of spray or droplets, similar to the natural rainfall. The spray is obtained by the flow of water under pressure through small orifices or nozzels known as sprinklers. Water is conveyed from the pump and distributed through a network of pipes, called manline, submain, laterals and sprinklers.

Sprinkler irrigation is suitable for all crops (row crops, field crops, and orchards) except jute and rice as these crops require standing water.

The area of land wetted by a sprinkler depends on the velocity head given to the water jet, the angle of flow of the jet, the type of sprinkler and its design and the wind conditions during irrigation.

Introduction

Suitable SoilsSprinkler Irrigartion is adaptable for

almost all types of soils but it is best suited to sandy loam soils with high infiltration rates and undulating topography. However, it is not suitable to very fine textured soils where infiltration rate is less than 0.4 cm/hr. The average water application rate for sprinkler system is always chosen to be less than that of basic infiltration rate of soils to avoid the surface ponding and runoff

Introduction

Advantages Suitable for complete range of topographic conditions. No requirement of land leveling. Light texture soil also can be irrigated. High irrigation efficiency due to uniform distribution of water. Accurate and precise depth of water can be applied. Application of soluble fertilizers, herbicides and fungicides can

be appled along with water. Preperation of field channels and bunds are not required.

Advantages

Introduction

Limitations High initial investment. Power requirement is usually high since sprinkler operates

with more than 1.5 kg/cm2 water pressur. Loss of water due to evaporation. High wind velocity causes uneven distribution of water. Delicate flowering plants cannot be irrigated. Fine texture solis having low infiltration rate cannot be

irrigated efficiently.

Limitations

Types of Sprinkler Irrigation Systems

On the basis of method of water application Rotating sprinklers – Impact sprinklers, gear driven,

reaction type and fixed head sprinkler Perforated Pipe system

On the Basis of Principle of operation Whirling sprinkler Turbo Hammer Sprinkler Propeller sprinkler Mini sprinkler


On the basis of Movement Set move irrigation system

a) Hand move b) Tow move c) Side roll d) Gun type

Solid set System Continous Move systems

a) Center-pivot sprinkler systemb) Linear move systemc) Traveller sprinkler systems


On the basis of Portability Portable system Semi-portable sysetm Semi-permanent system Permanent system

On the basis of precipitation rates Low volume sprinkler Medium volume sprinkler High volume sprinkler


Impact Sprinkler Gear Driven Sprinkler


Whirling SprinklerTurbo Hammer Sprinkler


Propeller SprinklerMini Sprinkler

Types of Sprinkler Irrigation SystemsTravelling Gun type Sprinkler

Types of Sprinkler Irrigation SystemsPortable Solid-Set Sprinkler System

Types of Sprinkler Irrigation SystemsCentre-pivot Sprinkler System

Types of Sprinkler Irrigation SystemsSpray Pad Sprinklers

Nozzle

Smooth Deflector Pad Serrated Deflector Pad

Types of Sprinkler Irrigation SystemsPop up Part Circle Sprinkler

Layout of Sprinkler Irrigation SystemsLayout

Pump

NRV

Filter

PVC pipe

HDPE pipeRiser

Sprinkler

End plugService saddle

Basic components of sprinkler irrigation system

A sprinkler system usually consists of following components.

1) Pumping Unit 2) Filters3) Main Lines 4) Submain Lines5) Lateral Lines 6) Sprinkler heads7) Riser pipe 8) Non-return valve9) Air release valve 10) Vacumm release

valve11) Pressure Regulators 12) Booster pump13) Fertilizer applicator 14) Other accessories


Pumping Unit : Pump is required to carry water from

source to main line and laterals up to sprinkler head or nozzle from where it is spray applied to crops. A high speed centrifugal or turbine pump can be used for operating sprinkler irrigation system. Centrifugal pump is used when the vertical distance from the pump inlet to water surface is less than 8m. Fro pumping water from deep wells or more than 8 m a turbine pump is suggested.

Pumping Unit


Filters: Filter is called the heart of micro irrigation system. A filter

removes the suspended impurities from the irrigation water and prevent the blocage of sprinkler nozzles. The type of filtration depends upon the source of water used and size of nozzle. The measurement of pressure before and after the filters will be done for control purposes. A drop in pressure indicates the extend of clogging and need for cleaning. Automatic filters are self cleaned by the process of back flusing.

Three different types of filters are used viz.a) Sand filter b) Screen Filter c) Disc filter

Filters


Sand Filter:

Sand Filter

This filter is effective against both ingorganic and organic suspended solids. This type of filter is essentional for using water from open sources. In most of the sand filters the media material is uniform sized crushed sand. When water is allowed to pass through this filter dirt and alge present in the water are trapped and watel alone passes throught the interconnected voids formed in the sand then to mushrooms to outlet .These Filters are cleaned by back flushing action, in which the flow of water is forced in back ward direction; due to which the deposited materials inside filter gets lift and become free, which are finelly removed by opening the flush valve.

Inlet

Outlet

Uniform sized Crushed sand

Candle/ mushroom


Screen Filter:

Filter

This filter is compulsory for every sprinkler irigation system. This filter cleans sand and other foreign particles from water. Mesh of screen size varies between 20 to 200 mesh. The larger the number smaller the particle size screen will filter out.


Disc Filter:

Filter

This filters are very effective to remove the particles like sand and organic matters. This filter consists of a stack of round disks. The face of each disc is covered with small bump of differemt sizes, which forms a tiny pyramid shaped sharp point at the top. Between series of disks there are small size spaces through which the water gets flow. For cleaning the disks are seperated from each other and debries are flushed through a flush outlet.


Disc Filter:

Filter

Basic components of sprinkler irrigation systemSprinkler head

Spreader Nozzle

Range (Drive) Nozzle

Bearing

Trajectory Angle Spreader Nozzle

Bearing

Spreader Nozzle

Bearing

Impact Arm

Sprinkler head

Basic components of sprinkler irrigation systemSprinkler head

Sprinkler head: Impact sprinkle heads make use of a mechanical arm to impact the stream of water that comes out of the head. This impact mechanism is the reason behind its name. Impact sprinkler heads can cover a radius of 45-feet average and is perfect for wide garden, lawn, or landscaped areas. The impact arm helps in the distribution of water to produce finer sprays. Perhaps the greatest disadvantage of this sprinkler head is its open design. Pieces of debris might get tangled in the sprinkler head and disrupt its rotary and impact mechanism. When using this type of sprinkler head, it is best to clean the head regularly to maintain smooth spraying mechanism. Impact sprinkler heads can be set up at different distances (12-inches or more) from the ground to protect it from the interruption of debris. This type of sprinkler head can cover a radius of 15-feet average.


Sprinkler head: It is the most important component of the system. It may rotate or remain fixed. The operating pressure of the sprinkler ranges from 1.5 to 7 kg/cm2. the operating pressure ranging from 1.5 to 4 kg/cm2 is considered most practical.the rotating head sprinklers may have 1 to 2 nozzels. One nozzel applies water at considerable distance from the sprinkler and another nozzel cover the area near the sprinkler head.

Sprinkler head


Risers: The sprinkler head is attached to the laterals

by means of riser, the height of which must be adjusted according to the crop irrigated. In field crops, the sprinkler must be above the canopy of the crops at all times, but in case of big orchads riser should be as small as possible. The riser must be perpendicular to the lateral line because any deviation will adversely affect the distribution pattern of the sprinkler. Risers used for field crops are made from metals having diameter of about 12 to 32 mm and for orchars are made from plastic material placed below the canopy.

Risers


Schematic view of mini sprinkler

Schematic view of mini sprinkler


Main and Submain lines: In sprinkler irrigation system generally main and submain lines are made of HDPE, in very rare case people use PVC or aluminum. HDPE type lines are movable while other two are fixed. Main line carries water from pumpuing source and supplies to submain and to laterals. The fixed type main line or submain line are burried in groung upto 45 to 60cm depth. The velocity flow in mainline should not be greater than1.5m/sec and friction head loss should be less than 5m per 1000m running length of pipe.

Main and Submain lines

HDPE pipes Aluminum pipesPVC pipes


Lateral : Lateral conveys water from mainline or submain to individual sprinkler head. Laterals are generally portable. They might be made up of lightweigt aluminum or HDPE and are generally equipped with coupling devices.

Non-Return Valve: The function of non-retutn valve is to prevent flow of water. The valve projects pump and prevents the return flow of water injected with fertilizer solution to the portable water system. This valve must be installed in head unit at the point just before the fertigation equipment.

Lateral and Non-Return Valve


Air release valve: Air release valve is a normally-open valve. Until your system is

pressurized, the valve is simply open, and air is present. As pressure builds within the system, unwanted air is forced to the highest point in the system i.e., the normally open air-release valve. When pressure within the system exceeds atmospheric pressure, air is expelled. As liquid rises, the poppet becomes buoyant and eventually closes. It is possible that trace amounts of air will remain in the system, depending on the rapidity with which the valve closes. It is also likely that some trace amounts of process liquid will be emitted. At system pressure of 10 psi, the poppet will seal bubble tight against the orifice. When pressure and liquid level drop, the valve will automatically re-open.

Air release valve


Air release valve:

Air release valve


Air release valve:

Air release valve

OPENAir under pressure

flows out

CLOSINGLiquid causes poppet to rise:air under pressure still flows

out

CLOSEDAs liquid continues to

rise, poppet seals against orifice


flows out

CLOSINGLiquid causes poppet to rise:air under pressure still flows

out


flows out


Fertilizer applicator:

Fertilizers may be applied through sprinkler systems. By three ways fertilizers are injected.

1) Venturi2) Fertilizer tank3) Injection pump

Fertilizer applicator


Venturi:

Fertilizer applicator-Venturi


The principle behind the operation of the Venturi is the Bernoulli effect

Fertilizer applicator-Venturi

The pressure differential follows Bernoulli's Equation.


Venturi : The fluid, either liquid or gaseous, enters the Venturi at the

location with a cross-sectional area A1, pressure P1, and velocity v1. These properties form the potential and kinetic energy of the fluid at one location. Energy is conserved in a closed system, that is, the sum of potential and kinetic energy at one location must equal the sum of the potential and kinetic energy at any another location in the system. If potential energy decreases at one location, the kinetic energy must proportionally increase at that location. The fluid now enters the throat of the Venturi with a new area A2, which is smaller than A1. In a closed system, mass can be neither created nor destroyed (law of conservation of mass, simply, what goes in, must come out), and as such, the volumetric flow rate at area A1 must equal the volumetric flow rate at area A2. If the area at location A2 is smaller than A1, the fluid must travel faster to maintain the same volumetric flow rate. This increase in velocity results in a decrease in pressure which follows Bernoulli's equation After the pressure difference is generated, the fluid is passed through a pressure recovery exit section where up to 80% of the differential pressure generated at the throat is recovered.

Fertilizer applicator- Venturi


Fertilizer tank

Fertilizer applicator- Fertilizer tank


Other Accessories

Other Accessories

Service Saddle Bend


Other Accessories

Other Accessories

Tee

PCN

End CAp


Design of Sprinkler irrigation systems:1. Inventory of resources and conditions

a. Map of the area (Survey map)b. Water supply- source, availability and dependabilityc. Climatic conditions: sprinkler system is designed for the

daily peak rate of consumptive use of the crops.d. Depth of irrigatione. Irrigation intervalf. Water application rate (limited by infiltration capacity)g. Sprinkler spacingh. Power source

Design Of Sprinkler Irrigation

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sprinkler irrigation final (2)

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