Plant Protection Equipment Sprayers
Depending upon the quantity of spray fluid required per unit area, the sprays are described as i) High volume sprays ii) Low volume sprays and iii) Ultra – low volume sprays. The spray fluid of 450 to 1000 liters; 12 to 125 liters and 0.5 to 6 liters will be required to cover one hectare of field crop with above mentioned sprays respectively. However the droplet size of these three sprays varies from 250 to 500, 150 to 250 and 70 to 150 microns respectively.
Types of Sprayers:
I) High Volume Sprayers:
A) Manually Operated Hydraulic Sprayers:
1. Hand Syringe:
It consists of a cylinder and a plunger, spray fluid has to be contained in a separate tank. The liquid is drawn on return stroke of the plunger and ejected during the compression stroke. After each ejected the spray fluid has to be drawn in. It is useful for small scale spraying in kitchen gardens and pot plants.
2. Bucker Sprayer or Stirrup Pump:
It may consist either of a double acting pump with two cylinders or a single acting pump with one cylinder. The other parts of the sprayer are the plunger assembly, foot value assembly, hose, lance and nozzle, a stirrup and an adjustable foot rest. The pump has to be put in a bucket of any container having the spray fluid. In the single acting pump the spray discharge is discontinuous since the fluid is ejected only during the downward compression stroke, while in the double acting pump the discharge is continuous as the fluid is discharged during both sucdon and pressures strokes. This type of sprayer is useful for spraying small trees. Area covered per day is 0.5 to 0.8 ha.
3. Knapsack Sprayer:
This type of sprayer has a flat or bean shaped tank. The tank has a capacity of 10 to 30 liters and is made of galvanized iron, brass stainless steel or plastic. It is similar to bucket type in principle. It is operated by a lever handle provided inside the tank and it moves up and down inside the container due to the movements of the pump lever. It is user for spraying field crops vegetables and nurseries. The area covered per day is 0.8 to 1 ha.
4. Rocker Sprayer or Gatoor Pump:
It consists of a pump assembly, a rocking lever, pressure chamber, and suction hose with a strainer, delivery hose, cut-off valve and spray lance with nozzle. By rocking movement of the lever pressure can be built in the pressure chamber and this helps to force the liquid through the nozzle. There is no built in tank. It can be used for spraying trees and tall field crops. It covers about 1.5 to 2 hectares of area in a day.
5. Foot Sprayer or Pedal Pump:
A pedal pump consists of a vertical pressure chamber mounted on to a stand and a plunger assembly with the plunger rod attacked to a pedal in addition to a suction hose with a strainer, a delivery hose with an extension rod and spray nozzle. It has no built in tank. It works on the same principle as the rocker sprayer except that the pedal is worked up and down by foot in this case where the rocker in a rocker sprayer is operated forward and backward by hand. In both cases continuous operation of pedal or rocker is required to maintain high pressure for uniform spraying. It is used for spraying agricultural crops as well as small fruit trees. About 1 to 1.5 ha area can be sprayed in a day.
B) Manually Operated Pneumatic Sprayers:
In the sprayer working with air compression system, the pressure is developed on the air contained in the spray tank, hence some air should be allowed to remained in the tank which therefore, should not be filled with spray fluid completely. They do not have agitators and hence are not useful spraying materials which settle down quickly.
1. Hand Sprayer or Ganesh Pump or Atomizer:
The container for the spray fluid also acts as the pressure chamber. An air pump attacked to the chamber projects inside. The inner end of the discharge pipe runs down to the bottom of the container and its outlet terminates in a nozzle. The tank is filled about 3/4th of it and the pump is worked force air into the space to build sufficient pressure upon the spray fluid. These sprayers are used extensively in kitchen gardens, in glasshouses and in doors against house-hold insects. The capacity of tank is up to one liter, if used in field it can cover an area of 0.1 ha in a day.
2. Knapsack Sprayer:
They are adopted for spraying large quantities of liquids. It comprises a tank for holding the spray as well as compressed air, a vertical air pump with a handle, filling hole with a strainer, spray lance with nozzle and release and shut-off devices. The tank is provided a convenient rest with the back of the operator and has shoulder straps that allow it to be carried by him. These sprayers are used against agricultural pests and mosquito control operations. The capacity of tank is 12 to 16 liters. This pump covers an area of about 0.8 to 1.2 ha in a day.
C) Power Operated Hydraulic Sprayer:
A power operated hydraulic sprayer generally consists of a petrol engine and a framework. The following are some of the power operated hydraulic sprayer.
1. Stretcher sprayer
2. Wheel-barrow sprayer
3. Traction sprayer
4. Power take off sprayer
D) Power Operated Pneumatic Sprayers:
It consists of the following sprayers
1. Portable sprayers
2. Traction sprayers
II) Low Volume Sprayers:
Since in these sprayers the spray fluid is atomized with the help of an air stream at high velocity, they are called mist blowers or power sprayers. The tank in these is made of a thick polyethylene and has a capacity of 10 liters. The fuel tank capacity is 1.0 to 1.5 liters. It is provided with 1.2 to 3.0 hp petrol engine. This can also be used for dusting provided suitable accessories. The area covered by these sprayers is about 2 ha in a day.
III) Ultra Low Volume Sprayers:
The pesticide in ULV formulation is used undiluted at a quantity less than 6 liters/ha and usually at 0.5 to 2.0 liters/ha for field crops. The droplet size varies from 20-150 micron with ground spraying equipment for ULV spray an area of 5 ha can be covered in a day. E.g. Controlled Droplet Applicator (CDA)