Precautions for selecting the particle size of the new version of the centrifugal sprinkler for agricultural drones -

Precautions for selecting the particle size of the new version of the centrifugal sprinkler for agricultural drones

2023-08-09

1. Differences between old and new centrifugal nozzle selection range

Before the version update, the selection range of the centrifugal nozzle is "coarse, coarse, medium, thin, and thinnest", and the corresponding range of the centrifugal nozzle is about 50-160μm.

After the version is updated, you can directly set the particle size of the centrifugal nozzle, the range is 50-500μm, and the corresponding particle size description is "very fine, very fine, fine, medium, coarse, very coarse".

That is to say, choosing "thickest" in the previous version can only correspond to "medium" in the new version.

Note that T40/T50/T20P/T25 are equipped with double-layer centrifugal spray heads as standard, if the single-layer spray disc is replaced, the "spinner type" needs to be changed.

2. Reasons for widening the selection range of centrifugal nozzles

With the increase of the application range of agricultural drones, the risk of drifting phytotoxicity is also increasing.

Once the herbicide liquid drifts to vulnerable crops, it may cause drifting phytotoxicity accidents.

The drift distance of the centrifugal nozzle is closely related to the wind speed, particle size and height of the centrifugal nozzle.

The faster the wind speed, the smaller the particle size and the higher the height, the farther the drift distance will be.

In this update, the upper limit of the particle size of the centrifugal nozzle is adjusted from 160 μm to 500 μm, which provides more technical means to reduce the drift distance.

3. Selection of particle size of different centrifugal nozzles

The size of the particle size of the centrifugal nozzle has an impact on the operation effect and drift, and should be selected according to the type of operation, type of agent, and environmental factors.

The same amount of liquid medicine, the diameter of the centrifugal nozzle is reduced by half, and the number of centrifugal nozzles will increase by 8 times.

It is precisely because of the use of small centrifugal nozzles that agricultural drones can achieve low-capacity spraying conditions to ensure the operation effect.

1. The effect of the type of agent on the particle size selection of the centrifugal nozzle
The contact killing of gastric poisoning agents requires smaller centrifugal nozzles, because only a sufficient number of centrifugal nozzles can improve the coverage and ensure the killing effect.

Regardless of the drift factor, the 30-50μm centrifugal nozzle will have a better insecticidal effect. However, the centrifugal nozzle is small, and the problem of drift and evaporation of the centrifugal nozzle will be aggravated, especially in the case of high temperature and strong wind above 35°C, the number of centrifugal nozzles that actually reach the target will be greatly reduced.
Therefore, agricultural drones are generally used for insecticide and sterilization at 100-150 μm.

If it is a systemic insecticide or fungicide, since it can be absorbed by the plant and transmitted to the whole plant, the centrifugal nozzle can be allowed to be thicker.

2. The effect of operation type on the particle size selection of centrifugal nozzle
Most of the herbicides are systemic herbicides, and considering their own risk of drifting phytotoxicity, it is generally recommended to have a particle size of more than 200 microns.

For fruit tree operations, because of the thick canopy and many branches and leaves, the fine centrifugal sprinkler head is conducive to the diffusion of the centrifugal sprinkler head to achieve a higher proportion of coverage, so it is generally recommended to choose a very fine to very fine centrifugal sprinkler head of 50-100 μm.
For the insecticidal and bactericidal operations of ordinary field crops, considering the balance of the operation effect and avoiding drift, it is generally recommended to be 100-150 μm.
3. The influence of environmental factors on the particle size selection of centrifugal nozzles
The faster the wind speed, the more obvious the drift.

Therefore, in an environment with wind and risk of drift, centrifugal nozzles below 100 μm are generally not selected.

If it is an operational herbicide, in order to effectively reduce the drift distance, even a centrifugal nozzle with a diameter of 200 μm or more will be selected. Therefore, if it is a systemic herbicide and there is a risk of drift, you can choose a 200-500μm centrifugal nozzle.

4.the wrong way to choose

The particle size of the centrifugal nozzle has a great influence on the operation effect and operation safety, so do not choose the wrong one.
1. Operate herbicides in a windy environment and choose the finest centrifugal nozzle
In a windy environment (wind speed above 5 m/s) with the finest particle size, the centrifugal nozzle may drift hundreds of meters.

If there are vulnerable crops in the downwind direction, drifting phytotoxicity will inevitably occur.
Similar situations include operating pesticides in a windy environment, and there are mulberry trees and fish ponds in the downwind direction.

Strong winds are the main cause of the problem of drifting pesticides and poisoning.

When working, it is necessary to see clearly whether there is a risk of drifting in the downwind direction.

2. When working on fruit trees, choose a medium centrifugal nozzle with a diameter of 200 μm or more
Fruit trees are generally treated with insecticide and bactericidal operations, and generally there is no weeding operation.

Fruit trees are usually planted in mountainous areas, far away from other crops.

Fruit trees are generally luxuriant and even have a certain canopy, and it is more difficult to cover with liquid medicine.

Therefore, in order to increase the coverage rate and coverage area of fruit trees, finer centrifugal nozzles and higher per-acre dosage are generally used.

Taking citrus as an example, the dosage per mu can even reach 15 liters per mu, and the centrifugal nozzle is 50-80 μm.

If 200μm or even 500μm centrifugal nozzles are used for fruit tree operations, compared with 50-80μm, the number of centrifugal nozzles will be drastically reduced, because the same amount of liquid medicine, double the particle size, the number of centrifugal nozzles will be 1/8 of the original. The effect will also be reduced accordingly. .

3. Centrifugal nozzles above 200 μm are selected for contact killing and stomach poisoning insecticidal and sterilizing operations
Take the Xinjiang cotton defoliant as an example. The defoliant is a contact agent. During operation, the flying speed is required to be slowed down and the centrifugal nozzle is small to ensure the operation effect.

If you choose a large centrifugal nozzle with a diameter of 200-500 μm, the number of centrifugal nozzles will also decrease sharply, and the operation effect will also decrease accordingly.