As the sprayer is the equipment that most comes into the cultivation during the harvest and one of the biggest costs of the crop is spent on the spray tips, which are pesticides, it is extremely important to have the sprayer well regulated and calibrated, to guarantee the success of the crop. Agriculture.

Adjustment refers to the act of preparing the sprayer to meet the desired requirements. Calibration refers to checking whether the sprayer is performing as expected by the adjustment.

Before starting adjustment, it is important to know some conversion factors (table 1).

         Tabela 1: fatores de conversão

Some essential steps that must be followed for regulation and calibration:

TO CHOOSE THE TIP

1º: Definição da taxa de aplicação (seguir instrução do fabricante do defensivo ou do engenheiro agrônomo);

Example: 100 L/ha

2nd: Determine the speed of travel of the sprayer, timing the time it takes for the tractor/sprayer to travel 50 meters at normal working speed and speed.

Para obter a velocidade em km/h, basta realizar o seguinte cálculo:
V=180/T , onde: T = tempo gasto (s) para percorrer 50 metros.

Example: The sprayer took 18 seconds to travel 50 meters, therefore:

V=180/18;
V= 10 km/h.

3º: Calcular qual a vazão necessária na ponta, através da seguinte fórmula: L/=(Lha*kmhr*E )/60000

Where:
L/min = vazão necessária na ponta;
L/ha = taxa de aplicação desejada;
km/h = velocidade de deslocamento do pulverizador;
E = espaçamento entre bicos (cm).

Example: pulverizador com espaçamento de 50 cm entre bicos.

L/=(100*10*50 )/60000;

L/=0,833 .

4th: Choose the spray tip according to the nominal flow rate and working pressure of the tip, using information from the manufacturer, as for example in the figure below, where we see information about Turbo Teejet tips:

Figure 1: Nozzle flow data according to the pressure used. Source: (TeeJet Technologies)

Note: The initial letters (TT) correspond to the nozzle model, the first 3 numbers (110) correspond to the opening angle of the application fan and the remaining numbers correspond to the flow rate (gallons/min) at a pressure of 40 PSI. As exemplified in Figure 2.

Figure 2: Spray tip identification pattern. Source: (TeeJet Technologies)

The colors of the tips are defined by ISO 10625, with the standard being orange for tips 01, green for 015, yellow for 02 and so on, as represented in Figure 1.

Following the example, as calculated in the 3rd step, there could be several tip options to use close to the calculated flow rate of 0.833 L/min. A) Tip TT110015, with 6 bar pressure, offers 0.83 L/min forming a Fine drop pattern (F). B) TT11002 tip, with 3.5 bar pressure, offers approximately 0.85 L/min with medium drop (M). C) TT11003 tip, with 1.5 bar of pressure, offers approximately 0.84 L/min with a thick droplet (C).

For sprayers with an automatic rate control system, based on pressure changes, it is recommended to choose the tip that, at the average working speed of the sprayer, works at the desired rate at an approximate pressure of 3 bar. This way there is a range of pressure variation to always guarantee the same application rate.

If you do not have a spray tip reference table, you can calculate the flow rate based on the desired pressure, using the following formula: q_x * p_y√p_x  = q_y

Or find out the target pressure, based on the desired flow rate, using the following formula below: q_y * p_xqx  = p_y

Where:

q_x = Vazão nominal da ponta (L/min)
q_y = Vazão alvo (L/min)
p_y = Pressão alvo (PSI)
p_x = Pressão nominal (essa é sempre 40 PSI)

Example: A yellow tip, has a nominal flow rate of 0.2 US gallons per minute at 40 PSI pressure, or 0.76 L/min. You want to know what working pressure should be used to reach 0.83 L/min. Soon:

0,76 * Py√40 = 0,83
Py=0,83* 400,76
Py=6,90
Py=47,7 PSI

That is, the target pressure (P_y) to reach 0.83 L/min with the yellow tip (02) it is 47.7 PSI. It is worth mentioning that it is recommended that the tips are new to infer the target pressure based on the nominal flow rates of the tips. As they are used, wear and tear occurs, which may cause changes in the actual flow rate.

TO CALIBRATE THE SPRAYER

In the steps above we learned how to choose a spray tip according to its nominal flow rate, classified by color according to ISO 10625.

Below we will list a step-by-step guide to check the volume of spray that the sprayer is delivering per hectare.

1st – Measure the flow rate of the tips using a measuring cup.

To do this, the tractor must be at normal working speed (TDP at 540 rpm) and the sprayer must be at the desired pressure. The flow of at least 2 nozzles must be collected per session, for one minute each and the average between them must be collected. If the sprayer has no more sessions, it is recommended to collect the flow from at least 6 nozzles.

Note: It is recommended to change the tips if there are tips that show a variation greater than 5% of the average.

Example: Average flow collected: 960 mL/min or 0.96 L/min.

2nd – Use the following equation to find out the application rate:

Q =q*60.000V * E

Where:
Q = Taxa (L/ha)
q = Vazão (L/min)
V = Velocidade (km/h)
E = Espaçamento entre bicos (cm)
60.000 = Constante

Example:

Q =q*60.000V * E
Q =0,96*60.00010 * 50
Q=115,2 L/ha

Thus, we find that the sprayer adjusted under these working conditions delivers a rate of 115.2 liters per hectare. If you wish to change the rate delivered using the same tip, it is possible to change the pressure or working speed of the machine, and then carry out the same step by step to assess the new working condition of the machine.

HOW MUCH PRODUCT DO YOU USE IN THE TANK?

Once the sprayer has been adjusted and calibrated, the amount of product to be used in the tank must be defined. To do this, you must first find out the amount of area sprayed by each tank. To do this, simply divide the maximum tank capacity (L) by the application rate (L/ha).

Example: A 1500 liter tank, with a rate of 115 L/ha results in a capacity of 13 hectares per tank.

Assuming that the application recommendation is 3 liters per hectare of glyphosate, simply multiply the dose of product per hectare by the tank capacity (3 * 13 = 39 L glifosato por tanque). When mixing directly in the tank, it is recommended to fill half the tank's capacity with water, add the commercial product, shake the mixture well and then top up the remaining volume with water.

CONCLUSION

Checking the sprayer is quick and easy, and is a fundamental step to guarantee the quality of the application and success at harvest time. For more information, consult an agronomist.