Sprayers and types of sprayers
Types of dusters
Uses of sprayers and dusters
Power sprayer operated sucking trap
Plant protection equipments
- Pests and disease incident on the crops / plants
are to be overcome by the application of poisonous chemicals.
- As the technology advances and newer crop varieties
are introduced newer insects, pests and diseases are also growing
up and methods are deviced to control them.
- Many chemicals used for plant protection cannot
be handled by human operators directly.
- Also, that needs to be applied in fine particles.
- This necessitates the use of suitable machines.
- The Sprayer is one which atomises the spray
fluid (which may be a suspension, an emulsion or a solution) into
a small droplets and eject it with little force for distributing
- It also regulates the amount of pesticide
to avoid excessive application that might prove wasteful or harmful.
- The mechanical appliances that are used
for distributing the dust formulations of pesticides are called
Types of sprayers
- Sprayers are classified into four categories
on the basis of energy employed to atomise and eject the spray
- hydraulic energy sprayer
- gaseous energy sprayer
- centrifugal energy sprayer and,
- kinetic energy sprayer
Hydraulic energy sprayer
- Hydraulic Energy Sprayer is one which the
spray fluid is pressurised either directly by using a positive
displacement pump or by using an air pump to build the air pressure
above the spray fluid in the air tight container.
- The pressurized fluid is then forced through
the spray lance, which controls the spray quantity and pattern.
Gaseous energy sprayer
- In Gaseous Energy Sprayer high velocity
air stream is generated by a blower and directed through a pipe
at the end of which the spray fluid will be allowed to trickle
by the action of gravity through a diffuser plate.
Centreifugal energy sprayer
Types of dusters
- Depending on the source of power it can
be classified as manually operated and power operated dusters.
- The manually operated dusters are (i) package
duster (ii) plunger duster (iii) bellow duster and (iv) rotary
(i) Package dusters
- In some pesticide dusts are packed in containers
that serve as a hand applicators and may be discard after use.
- They are mostly provided with rubber, leather
or plastic section which, on getting squeezed, provides a puff
of air that emits the dust in a small cloud.
- The simplest type of package duster is
worked by pressing it between the fingers.
(ii) Plunger dusters
- The consists of an air pump of the simple
plunger type, a dust chamber, and a discharge assembly consisting
of a straight tube or a small exit pipe whose discharge outlet
can be increased or decreased by moving a lid provided at the
end of the dust chamber.
- The air from the pump is directed through
a tube into the container where it agitates the dust and eject
it from a discharge orifice or tube.
- The amount of dust can be controlled by
the speed of the operation of the pump.
- These are useful for spot application in
restricted areas and for controlling ants, poultry pest and pest
of farm animals.
(iii) Bellow duster
- In the below may be made from rubber, leather
- On squeezing, it puffs the air that expels
the dust in a small cloud.
- Hand held bellow duster has containers
of capacity from 30 g to 500 g.
- The bellows can be operated either directly
by hand or by handle provided for that purpose.
- The knapsack duster has the container capacity
of 2.5 to 5.0 kg.
- The air blast developed by the bellow draws
the dust from the hopper and discharges through the delivery spout
- These dusters are suitable for spot treatments.
(iv) Rotary duster
(v) Power dusters
- The resemble the rotary duster is construction,
except that the power to drive the blower through the gear box
is tapped from an external power source which may be an engine
or P.T.O. shaft of the tractor or flywheel of the power tiller.
- The power operated centrifugal energy knapsack
sprayer also can be converted into a power duster, by allowing
the dust fluid into the air stream, near the point of attaching
the pleated hose, in the blower elbow.
Uses of spraying and dusting equipments
- The spraying and dusting equipments are
used for the following purposes
- For the insecticides application to control
insect pests on crops and in stores, houses, kitchen, poultry
farms, barns, etc.
- For the insecticides application to control
insect pests on crops and in stores, houses, kitchens, poultry
farms, barns, etc.
- For the acarices application to control
- For the fungicides and bactericides application
to control the plant diseases.
- For the herbicides application, to kill
- For the harmone sprays application to increase
the fruit set or to prevent the premature dropping of fruits.
- For the application of plant nutrients
as foliar spray.
- For applying the powdery formulation of
poisonous chemicals on the crops and for any other purposes.
- The hand sprayer is a small,
light and compact unit.
- The capacity of the container varies from 500
to 1000 ml.
- This is generally used for spraying small areas
like kitchen garden and experimental laboratory plots.
- It is a hydraulic energy sprayer.
- It has a hydraulic pump inside the container,
with cylinder, plunger and a plunger rod.
- By operating the plunger up, the spray fluid
in the container is sucked into the cylinder through a ball valve
assembly and then pressurised during the downward stroke.
- The pressurised fluid is then let out through
a nozzle, and sprayed into fine droplets.
- If the pressure to be built inside the container
an air pump with cylinder, plunge and plunger rod is required.
- When the plunger is pulled up, the air is sucked
into the cylinder and when pushed down the air bubble is releases
into the container with 80% of its volume filled with the fluid.
- The air reaches the space above the free fluid
surface and presses the fluid.
- The pressurised fluid is drawn up through a trigger
cut of valve to the nozzle, where is atomized and sprayed.
- In some other type, air pump and the container
are separate pieces and the pump is attached to the container
is such a way to release the pressurised air through an orifice
at the top of the container.
- The fluid is lifted through an office at the
top of the container.
- The fluid is lifted through a capillary tube
due to surface tension developed by the high velocity air at the
outlet and sheared away by the air and sprayed as droplets.
- Any sprayer which is carried on the back
of the operator is called a knapsack sprayer.
- The commonly used manually operated knapsack
sprayer will have one hydraulic pump working inside the container.
- The plunger works inside the replacement
well attached at the bottom of the container, for easier maintenance.
- The pump can be operated through the appropriate
linkages by oscillating the handle, with the sprayer carried on
- An agitator is also provided with the pressure
chamber to agitate the fluid so that the particles in suspension
will not be allowed to settle down.
- A delivery tube is attached on the other
end of the pump which carries the pressurises fluid to the spray
- The flow to the nozzle is controlled by
a trigger cut-off valve.
- In the case of compression knapsack sprayer,
an air pump is used to build air pressure above the free surface
of the spray fluid in the container and normally the pumping of
the air will be done by keeping the unit on ground and then sprayed
til the air pressure comes down.
- The unit is again brought back to the ground
for pumping air and then the spraying is contained as before.
- The spray fluid, which does not enquire
any agitation only can be sprayed by using this type of sprayers.
- The rocking sprayer has a pump assembly,
fixed on a wooden platform with an operating lever, a valve assembly
with two ball valves, a pressure chamber, suction hose with strainer,
and delivery hose with spray lance.
- When the plunger is pulled behind by pulling
the lever way from the pump, the spray fluid from the container
is sucked through the strainer and pushes the bottom ball valve
above and enters the pump.
- The movement of the lower ball valve is
arrested by the upper valve seat.
- When the lever is pushed towards the pump,
the sucked fluid is forced to enter the pressure chamber by opening
the upper ball valve.
- The operation is continued till the entire
suction pipe, ball valve assembly, delivery hose and a portion
of pressure vessel is fitted with spray fluid and the pump operator
finds it difficult to push the piston forward, due to the downward
pressure developed by the entrapped compressed air in the pressure
- Thereafter, the trigger cut off valve will
be opened to allow the spray fluid to rush through the nozzle
and get atomized.
- Usually 14 to 18 kg/cm2 pressure can be
built in the pressure chamber and hence can be conveniently used
for free spraying.
- The bucket sprayer is designed to pump
the spray fluid directly from, the open container, usually a bucket.
- The hydraulic pump will be put inside the
bucked and held properly with the help of foot rest.
- As the plunger is pulled up, the fluid
enters through the suction ball valve assembly and when the plunger
is pressed down, the suction valve closes and the fluid enters
the pressure chamber through a ball valve assembly.
- As the plunger is continuously worked,
pressure is built in the pressure chamber and the delivery hose.
- As soon as the required pressure is built
up, the spraying will be done.
- A pressure of 4 kg / cm2 is developed in
most of the models.
This is a modified version of rocker sprayer.
The pump is fixed in a vertical position with necessary braces.
The plunger moves up and down when operated by the pedal.
A ball valve is provided in the plunger assembly itself to allow
the fluid to cross the plunger and getting pressurized in the
During the upward motion of the piston fluid is sucked in and
pressurized into the pressure vessel and during downward movement,
the sucked fluid crosses the plungers and enter the pump.
The pressure developed is about 17-21 kg/cm2.
- All the sprayers which impart the mechanical
energy developed by an I.C. Engine, on the spray fluid before
spraying is called as a power sprayer.
- The most commonly used type of power sprayer
in India is a gaseous energy type knapsack sprayer.
- In construction, it has a back pack stand on
which a blower with a S.I.
- Engine of 1.2 to 3 hp capacity, the spray fluid
tank and the petrol tank are fixed rigidly.
- A pleated hose is attached to the blower elbow
to carry the high velocity air and at the end of that a shear
nozzle is fixed to allow the spray fluid to trickle in from the
spray fluid storage tank, with a valve control.
- From the top of the blower casing, an air hose
is taken into the spray fluid tank, which carries little quantum
of air to press the spray fluid during operation.
- In operation, the engine is started by keeping
the unit on the ground and then carried by the operator.
- The blower sucks the air behind the backrest
and forces it into the pleated hose.
- The valve of the shear nozzle is opened or the
shear nozzle with selective opening and discharged through the
- The high velocity air shears off the droplets
and atomizes by the impact of diffuse and delivers it on the plant
- An air current of 2.7 to 9.1 m2 / minute is delivered
at a velocity of 175 to 320 kmph.
- The spray fluid tank capacity varies from 7 to
- The fuel tank capacity varies from 0.75 to 2.25
- The spray fluid discharge can be varied
from 0.5 to 5 lit / minute.
A power sprayer can be used as a power duster
by making the following changes.
Chemical filler cap is removed to dismantle
that strainer with the air pipe.
The liquid delivery pipe below the chemical
tank is dismantled and removed with the shear nozzle.
The tank is thoroughly cleaned to remove
possible traces of moisture left inside.
The dust agitator tube is fixed at the
bottom of the chemical tank.
This tube has holes at the bottom to prevent
the entry of dust into the agitator and clogging it.
Dust intake tube is inserted into the
chemical tank at the discharge and this tube has no. of large
size holes on its periphery.
Dust intake tube and the blower elbow
are connected by using the dust outlet pipe, which is a pleated
Battery / ULV sprayer
- ULV sprayer was invented as a result of
the desire to reduce the quantum of chemical carried by the man
for application and to eliminate the water as a medium to carry
The basic requirements of ULV spraying are
The narrow and controllable droplet spectrum
(100-250 µm for fine sprayers, 50-100 µm for mist
sprayers and 0.1 to 50 µm for aerosols)
The accurately controllable emission rate
The non-volatile pesticide formulation
of suitable viscosity and density.
The reduction in volume of the spray fluid
decreases the time spent in travelling to recharge sprayer,
in fetching water, in mixing the pesticide and filling the tank.
In a day of 8 hour about 8 ha can be covered in ULV spraying
against 3 ha with power sprayer.
A battery operated ULV sprayer has a long
handle at the horse power D.C. motor is fitted with a spinning
disc and a cover.
A HDPE bottle is fixed close to the motor,
in such a way that spray fluid is allowed to trickle at the
centre of the spinning disc in operation.
Centrifugal energy imparted fluid comes
out of the nozzle and atomizes.
The hand held ULV applicators are so designed
to release the spray droplets at 1 m away from the body of the
Further, it is recommended that they should
be operated only when the spray cloud would be blown away from
him by the breeze so as to minimize the risk of contamination.
After spraying, the atomizer must be flushed
with paraffin to remove the residual pesticide.
- Inefficient cleaning would leave the pesticide
deposit in the feeder stem to completely of partially block the
flow of the pesticide.
Power sprayer operated suction trap
- This consists of a metal elbow matching
the suction opening and the blower and the outer diameter of the
- This unit is closely fitted with the blower
suction opening with the help of an extension frame work identical
to the back pack stand.
- To the pleated hose attachment opening
of the elbow a pleated hose is attached rigidly.
- In between the two pleated hoses a screen,
an insect collector and valve to control the size of the opening
are provided in a Tee section.
- In operation the low pressure created at
the blower inside is transmitted through the below and pleated
hose which helps in sucking the lighter objects like insects and
dust from a distance of 0.5 to 1.0 m away from it.
- The sucked insect of dust will be filtered
by the screen and dropped into the collection bowl.
- Drain off any liquid still in the tank.
- Add 1 kg of washing soda per 45 litres
of water, which will serve as a cleaning detergent.Spray this
liquid through the nozzle on waste land.
- Add fresh water in the tank and spray with
and then without nozzle on the waste land.
- Wash the outside of the sprayer.Remove
the nozzle and filters and store safety after cleaning.
- Ensure the absence of water in the pump
and lubricate the parts.