In this article we will discuss about the types of sprayers and dusters used for applying pesticides.
The equipment which is used for dispersal of pesticide (i.e. insecticide, fungicide, herbicide etc.,) in liquid form is called “Sprayer”.
The sprayers are of two types as follows:
(i) Manually operated or hand sprayer.
(ii) Power operated sprayers which are commonly termed as Power sprayer.
The sprayer consists of different parts as follows:
The tank is an important part of a sprayer in which spray materials are kept. It is generally made of galvanized iron or steel coated with anticorrosive material particularly on the inside. The tank is provided with large filler hole fitted with strainer for pouring of liquid into the tank as well as cleaning of spray material. The tank is also provided with lid.
The pump is a most essential component of the sprayer as it is needed for atomization of liquid through air.
Depending on the mechanization of action, the source of power etc., pumps in use in the sprayer may be broadly put into three categories as follows:
(b) Displacement pump. Plunger, piston, rotary and diaphragm.
(c) Centrifugal or impeller.
The agitator is usually provided in the power sprayer for maintenance of a uniform dispersion or suspensions and emulsions.
(iv) Delivery Horse:
The delivery horse is fitted with sprayer at the end and spray lance or boom on the other end and made of rubber or synthetic rubber or plastic tube or nylon. The hose is capable of withstanding high pressure.
(v) Spray Lance:
The spray lance is a bras tube of variable length. One end of the spray lance is fitted with a hose and other end with a nozzle. The nozzle end is usually bent.
The nozzle is most important part of a sprayer to break up the liquid coming out the spray tank into fine droplets. Different types of nozzles are used in the sprayer.
The trigger is provided in the sprayer to control the flow of spray materials.
Different Types of Sprayer:
(a) Manually Operated Sprayer:
(1) Foot Sprayer:
The pump in the foot sprayer consists of a pump barrel and a pressure chamber. The pump is worked by the upward and downward movement of the foot used for the purpose. The plunger with suction cup or piston drives into pump barrel, thus sucking the liquid in the pressure chamber and expelling it through the discharge line.
The return stroke of the plunger pulls the liquid in through the suction hose for the next discharge. The sprayer develops a pressure of 60-80 psi and has a provision for attaching two discharge lines. It is an ideal all-purpose sprayer suitable for small and large scale field crops, in orchard, tea and coffee plantations and rubber estate.
(2) Rocking Type Sprayer:
The rocking type sprayer consists of a lever operated pump assembly which rest on wooden platform. The plunger is operated by means of a lever that is pushed forward and backward by hand. The suction hose with a strainer is immersed in a separate container containing spray mixture and the delivery system consist of a separate pressure chamber, a flexible hose, spray lance and spray nozzle. The rocking type sprayer develops 60-80 psi pressure.
The rocking type sprayers are ideal for spraying plantations, orchards and farms.
(3) Compression Sprayer:
In compression sprayer, the tank is pressure vessel in which the liquid is filled to two-third capacity, leaving one fourth volume for the compressed air. It is then pressurised to 60 psi by means of air charge pump which is fitted vertically inside the tank (i.e. Container). A pressure gauge or safety valve may optionally fitted to the tank.
A pressure regulator may also be used when the discharge pressure needs to be strictly controlled. The compressed air forces discharge the liquid through the nozzle and desired type of spray is achieved. This sprayer is ideal for spraying all field crops and vegetables.
(4) Knap-Sack Sprayer:
In knap-sack sprayer, the tank is non-pressured and made of brass or galvanized steel. The pump may be fitted inside or outside the tank and sucks the liquid from the tank and expels it through the delivery system consisting of lance and nozzle which is connected with a pump by flexible hose. The knap-sack sprayer develops 30-40 psi pressure.
The operator operates the lever with his left hand and spraying is done by his right hand. A spray boom or rig may be attached when wider areas have to be covered. This sprayer is ideal for spraying all field crops at high pressure with low volume nozzle.
(5) Bucket Sprayer:
The bucket sprayer consists of a double action pump with a lance or nozzle outlet.
The suction hose is placed in the bucket. In the single barrel type, the plunger is hollow and act as pressure. In the double barrel type, one barrel is of smaller diameter than the other and acts a pump while the bigger serves as pressure chamber to produce more continuous spraying. Liquid is discharged in both the suction and delivery strokes. A pressure of 30-40 psi is generated.
(6) Hand Sprayer or Nursery Sprayer:
The nursery sprayer is small and simple sprayer. The sprayer produces a mist spray and can be effortlessly operated. This sprayer is generally recommended for use in nursery or private garden. Varieties with a small compressor type or plunger type sprayers are also available.
(b) Power Operated Sprayer:
(1) Hydraulic Sprayer:
The hydraulic sprayer may be engine or electric motor driven and is available with single, double and triple piston pumps which is driven by air cooled or water cooled engine. The single piston pump, double piston pump and triple piston pump develop a maximum pressure of 150 psi, 300 psi and 400 psi respectively.
The single piston pump has only two discharge line and double and triple pumps can accommodate 4-6 discharge lines. This sprayer is operated by means of 1-2 HP electric motor or 2-3 MP Petrol, petrol-kerosene or diesel engine and this spryer can also be driven power tiller or tractor.
(2) Motorized Knap-Sack Mist Blower-cum Duster:
The motorized Knap sack Mist blower cum duster is fitted with two stokes air cooled engine of 35-70CC. capacity connected to a centrifugal fan by direct drive. The spray liquid is first pressurized by air generated by blower. This air current achieves a velocity of over 275 kmp at the nozzle and spays the chemical in fine particles that can be measured by micron. The nozzle design enables even spraying at maximum efficiency.
When dusting, the air blast enters the tank from air inlet which is connected to a tube with several holes on its surface. This agitates the power which is then thrust out by velocity of air coming out of the blower through pleated hose and out through the nozzle. The blower is mounted with rubber elements on frame with back cushion and padded carrying straps and is fitted with Villiers L-34-2 stroke, 1.2 HP petrol or petrol/kerosene engine. This implement is ideal for quick application of pesticides in dust and liquid form in orchard, tea and coffee estates and other crops.
(3) Tractor Mounted Sprayer:
As the name indicates, Tractor mounted sprayer is attached to a tractor for use. The pump is driven by PTO shaft of the tractor and the sprayer unit sucks the chemicals and discharges it through the spray boom or through discharge line consisting of a delivery hose and spray gun. The boom has a swivel arm to direct the spray correctly. The main frame allows the spray boom to be adjusted accordingly to the height of crop being sprayed.
(4) Spinning Disc Sprayer:
The spinning disc sprayer consists of a battery operated motor with spinning disc, a liquid tank, a handle and a set of batteries. Liquid is fed from the tank on spinning disc by the force of gravity. The spinning disc which has 180 channels on the world and 180 teeth on its periphery, operates at 4000-5000 rmp to stir the liquid and create very fine, even particles for low volume spraying. A smooth flow of liquid with highly controlled droplets (100-165 micron) application is thus achieved. The stainless steel disc is interchangeable.
The equipment which is used for dispersal of insecticides in dust form is called ‘Duster’.
Different Types of Duster:
(1) Rotary Type Duster:
The rotary type duster is provided with an agitator which stirs the dust or powder and releases it evenly through the discharge vent. The blower sucks the dust or powder from the hopper through the connecting pipe and pushes it out forcefully to active efficient dispersal. The operator carries the duster by means of one or two shoulder straps and holds the lance in his left hand, cracking the handle with his right hand.
(2) Plunger Type Duster:
The plunger type duster operates on the presto principle by generating an air blast which passes through the dust chamber and expels the dust through discharge outlet.
(3) Bellows Type Duster:
The bellows type duster also creates a blast of air through the dust chamber to discharge the powder; the significance difference being that the force is generated by means of bellow operation. This type of duster is not popular in India.
(b) Power Operated Duster:
(1) Rotary type – In rotary type of duster, the air is sucked by a motorized blower and discharged through the blower outlet.
(2) Air Jet type – A jet of air from the blower enters the hopper which agitates the dust and blows it out simultaneously with a jet of air.