How to Choose Optimal Spray Tips

Each type of spraying requires a different size of droplets that can be generated by the most diverse models of spray nozzles.

The choice of the appropriate droplet size depends on the target to be reached, the type of product to be applied, the crop and the weather conditions present during the process. However, it is important to understand the appropriate management of droplet size during an application day, especially in applications where fine to very fine droplets are required, as is the case with fungicide and insecticide applications at the end of the soybean cycle.

In the case of applying herbicides for desiccation or pre-emergence, the use of tips with Ultra Coarse drops is the best option in order to obtain excellent performance and excellent drift control. The TTI spray tip is the tip with the largest droplet size on the market, having the best drift control over a wide pressure range with a potential drift risk of less than 3%. Figure 1 shows the spectrum of drops from the TTI11002-VP tip at 3 bar pressure, in which it is possible to observe ultra-thick and uniform drops.

For contact herbicide applications, where coverage needs to be greater, it is recommended to use thick to medium drops, this way it is possible to have adequate coverage with reduced drift. In figure 2 it is possible to observe the spectrum of drops from the TTJ60-11002VP spray tip at 3 bar pressure. It is a double turbo jet tip, with pre-orifice and formation of two jets by deflection, characteristic of the Turbo family, patented tips from TeeJet Technologies. In the sprayed jet, the formation of both jets is clear with a very high number of drops, which guarantees excellent coverage. A detail that is not possible to observe in laboratories or in the field is the formation of smaller diameter droplets in the middle of the two jets. This makes it possible to increase coverage in cases of applications where there is an umbrella effect or the coverage requirement is very high.

Fungicide and insecticide applications at the end of the soybean cycle are the most demanding in relation to the use of application technology concepts. This is due to the need for the drops to reach the lower third of the plant in a phenological stage in which the soybean plant has a very high leaf index, where the plant barrier that the drops must cross is quite dense, making it difficult to reach the target and requiring the maximum of the application technique.

One of the most used models for end-of-cycle applications in soybeans or dense crops is the TXA empty conical jet nozzle, as it produces fine to very fine droplets with very high uniformity, which favors penetration into the canopy. of the plant with high coverage potential in the lower third. In figure 3 it is possible to observe the TXA8002VK tip at a pressure of 3 bar. Something clear in the image that was possible to observe in the droplet dynamics is that even though it is an empty conical jet tip, there are drops inside the cone, this happens due to the turbulence formed in the jet, causing the smaller drops to concentrate inside the cone, with this the potential for penetration and coverage increases.

DRIFT

When the context of the application technique is involved, whether in applications of herbicides, insecticides or fungicides, it is important to take into account the monitoring of climatic conditions due to the negative effect they can have on the droplets and their transport process from the nozzle exit to the target. Wind is one of the biggest problems and causes losses in applications. When the application is carried out with fine drops and the wind reaches the maximum speed and limit for that tip model and/or droplet size, there are two procedures to be followed. The first is to stop the application and wait until conditions improve, a fact that happens in some South American countries mainly due to the chosen application technique, which is low volume. The other procedure is to continue the application but with a change in droplet size. This change must be carried out by choosing a cutting-edge model with droplet classification as Medium, this way there will be a reduction in losses and an increase in the potential for reaching the target. One of the biggest mistakes that are observed in the field is not managing the droplet size appropriately, that is, although the weather conditions are unfavorable, applications continue. Thus the loss percentage increases exponentially. In figure 4, the TXA8002 tip can be seen with fine to very fine drops at a pressure of 3 bar under the effect of wind at a speed of 10 to 11 km/h. It is possible to observe that approximately 40% of the product is being dragged and causing losses and contamination. There are cases where the product can be deposited in the same field (endoderivative) or outside the field (exoderift) in both cases the deposition of the product is out of control and is not correct. 

For cases where the application cannot stop and it is necessary to manage the droplet size, an excellent option is to use the TTJ60 spray tip. For fungicide and insecticide applications at the end of the cycle in soybeans, the recommendation is to use the TTJ60 tip with pressures above 3 bar. With this it is possible to obtain a spectrum of drops classified as medium with a significant reduction in the drag of the drops by the wind and a high potential for penetration and arrival at the target. In figure 5, the TTJ60-11002VP tip can be seen at a pressure of 3.5 bar, where it is possible to observe the small drag of the drops and the high concentration of drops arriving at the target due to the high number of drops produced by the double jet.

The TTJ60 tip, as well as the TT tip, are models that provide farmers with versatility in applications due to their construction and technology that allow them to work in a wide pressure range with different droplet size classifications in the same model. However, it is important for the farmer to understand that there are different models of spray tips that produce droplet sizes according to the needs of the crop, the product to be applied and the weather conditions, thus understanding the management of droplet size and adequate selection of the spray tip model for different applications, are indispensable factors that will contribute significantly to the success of applications and subsequent plant health of the crop.

Demo for producers

In the last edition of the Coopavel Rural Show, TeeJet Technologies provided visitors to its stand with a demonstration of droplet dynamics in real time with different wind conditions and appropriate drift management depending on droplet size. This dynamic was possible with the use of equipment to read the spectrum of drops with a wide-angle lens positioned on the laser cannon in order to emit a beam capable of covering the entire sprayed jet, thus enabling total observation of the drops, the formation of the jet, drops and all the dynamics involved in the spraying process.

 

Rodrigo Alandia Roman, Teejet Technologies

Article published in issue 160 of Cultivar Máquinas.