Equipments Used for Application of Herbicides – Spray Equipments
Spray Equipments:
Herbicides are largely applied as spray. Several types of sprayers are available from small hand operated to large ground and aerial sprayers.
Components of Sprayers:
Herbicides are largely applied as sprays. The important components are:
1. Pump
2. Power source
3. Tank
4. Agitator
5. Distribution system
6. Pressure gauge
7. Pressure regulator.
1. Pump:
Any spray liquid must be atomized before it leaves the spray nozzle. The pump provides the necessary pressure for this purpose.
Types of Pumps:
a. Air Compression or Pneumatic pumps:
The pumps force air into an air tight tank containing spray liquids thus moving the spray liquid under pressure through the nozzle for its atomization.
b. Hydraulic or Positive Displacement Pump:
These pumps take in a definite volume of spray liquid and force it through the delivery system under pressure. The pump differs in pressure they produce.
2. Source of Power:
It is needed to run the spray pumps.The source of power may be either
a) Manual
b) Traction
c) Motor
d) Tractor and air craft engines.
3. Spray Tank:
A sprayer may have either built in tank or a separate tank to carry spray liquid. The tank should be large enough to avoid frequent refilling but not unhandy to carry. The tank is provided with a large opening fitted with a strainer and cap to fill in the liquid. Small openings have difficult to fill in liquid an clean the tank.
4. Agitator:
It may be either mechanical or hydraulic purpose, to keep liquid spray homogenous. Mechanical agitators may be of metal fan or rod etc. Hydraulic agitator consists of a pipe with several side holes and closed at its free end is placed in the tank and it is fed with spray liquid from the pump. From these holes the liquid emerses as jets to provide agitation to the whole body of the liquid. This is called as ‘By pass system’. Hydraulic agitation is not thorough but it is more convenient in power sprayers using on large tank size. Sprayer without agitator should not be used to apply pesticide emulsion and suspension.
5. Distribution System:
It includes
i) Nozzle
ii) Spray lance
iii) Spray boom
iv) House
i) Nozzle:
The function of spray nozzle is to break pressurized spray liquid into droplets for application to the target Nozzles are identified by
a) Droplet size
b) Delivery and
c) Spray pattern that they produce spray pattern is fixed for a herbicide work, eight kinds of spray nozzles are common e.g.
1. Flat fan
2. Solid cone
3. Flooding
4. Tripe action
5. Broadcast fan
6. Blast
7. Low volume
8. Centrifugal (Sprinkler rotary).
The “Flat fan” nozzles are available in two spray patterns viz. the tapped edge pattern and rectangular pattern. Tapped edge pattern to apply pre and post emergence herbicide broadcasting, while rectangular pattern for the pre emergence bank application of herbicides.
Solid cone nozzle produces medium size droplets. Good for pre and post emergence spray. Also used for surface application of herbicides which gives fan like spray.
Triple action nozzles-diameter of the sprays can be easily changed during operating to produce either coarse or fine spry.
Broad cast fan nozzles are used for spraying on unwanted vegetation, road side fence, rows etc. it gives wide coverage of 5 to 8 m with coarse droplets on emulsion to avoid drift.
Motorized sprayers blowers employ blast nozzles. These nozzles feed the spray liquid into the air steam to split it into droplets and carry the droplets by the velocity of the wind.
ii) Lance:
It is brass rod or 90 cm length attached to a delivery hose pipe of sprayer and fitted to its free and with a replaceable nozzle. A herbicide spray lance is bent at its nozzle to form a goose neck. At the hose end it is provided with trigger mechanism to control flow liquid for specific purpose. The spray lance may be fitted with plastic shields to prevent chemical from drifting.
iii) Spray bar or Boom:
It consists of a horizontal pipe on which 2 or several nozzles are fitted and spaced at 50 cm apart. Boom length varies from 1 to 15 m. Short boom with 2-3 nozzles is used with manual sprayers, while longer ones with tractor sprayers. The main advantage of spray boom over spray lance is wide swath it covers in each trip of the sprayer over the field. Total width of land wetted by a boom can be adjusted to get either (i) Uniform spray (ii) Directed spray or (iii) Band spray
6. Pressure regulator:
It is fitted to heavy duty sprayers and tractor driven sprayers so as to run the sprayers at constant pressure. Pressure gauge is provided to check pressure.