Importance of maintaining internal sprayer systems in the off-season

The off-season comprises the period between the end of the main harvest and the beginning of the next crop, and is, in general, a period in which the soil is fallow or cultivated with cover crops. Normally, the off-season period takes place between the months of May and September and the duration of this period varies greatly depending on the growing region, the type of crop and the number of harvests throughout the year.

The most important thing is not when this period actually happens, but what to do during this period when there are no crops in the field. It is extremely important to inspect agricultural machinery during this period, as preventive maintenance, in addition to having a lower cost than corrective maintenance, helps to extend the useful life of the machinery and, above all, to prevent the machine from breaking down during operation in the field. .

The need for maintenance is justified by the greater demand for the use of sprayers during the crop cycle, and also in order to not miss the timing of the application. As an example, spraying equipment is used at least three times, as occurs in corn cultivation, on average eight times in the coffee harvest and more than ten times in cotton cultivation. And unfortunately, it is very common to find sprayers with broken bars held together by cords or wires, worn out nozzles or with different flow rates on the same bar, encrusted dirt and leaks. This shows, in a way, that the main concern is greater with pesticides, and not with the way they are applied.

In the case of sprayers and turbo atomizers, the review normally includes the operating part of the machines, parts, oils, air and fuel filters, but does not include the internal spraying system (cleaning of the tank, hoses, pipes, flow meters, line filters and nozzles).

Part of the problems arising from phytotoxicity occur due to the presence of agrochemical residues in the spraying system, when washed with just water. These residues are only detected when the system is internally cleaned. In some regions, it is already a reality to use specific products to clean sprayers, such as “tank cleaners”, as well as constant cleaning of this equipment.

Another serious problem resulting from dirt embedded inside the machine is the clogging of spray tips. The filters in the sprayer are designed to retain dirt, preventing the tips from clogging during application. However, when this dirt is not removed, it can accumulate throughout the system, from the tank to the tip itself.

The dirt in the spray system has several origins: the water intake source, from the supply tank; of the premix tank, which also needs to be cleaned frequently. But the main source of waste occurs due to product mixtures in tanks. In this case, it is relevant to consider the incompatibility between products, which can be chemical or physical. When it is just chemical, no changes in the quality of the spray are normally observed, but the effect is visible in the field after application, when there is not good target control effectiveness. But when this incompatibility is physical, in addition to being possible to observe control failures, there is the formation of precipitates and the presence of residues in the tank or pre-mix tanks. In this way, such residues adhere to the tank walls, hoses, filters and flow meters, anti-drip valves and tips, causing wear of parts, clogging and leaks.

Most of this residue is not removed with water alone, especially if it has accumulated for a long time in the equipment and comes from the use of powdered products, which have low solubility, very oily and silicone products. Therefore, it becomes necessary to use specific products for tank cleaning. It is important to note the active ingredient in these products, as bleach, sulfuric acid, gasoline and diesel, for example, are not recommended for this purpose. Products based on dodecyl benzene sulfonic acid, sodium lauryl ether sulfate and surfactants are most recommended for deep cleaning of the spraying system, as they are non-corrosive and do not harm machine components.

HOW TO CARRY OUT CLEANING

There are different ways to clean spray equipment internally, but in general the procedure follows a standard, changing only the time for which the product will be agitated in the tank, the amount of water for cleaning and the dose, which vary according to each manufacturer's recommendation.

The following box presents suggestions for cleaning/decontaminating spray equipment. This cleaning process can also be carried out on turbo atomizers, aircraft, knapsack sprayers and pre-mix tanks, simply adapt the sequence to the operating process of each of these pieces of equipment, as well as following each manufacturer's recommendation.

It is important to highlight that cleaning and decontamination of the sprayer must preferably be carried out in the phytosanitary product decontamination yard. On rural properties that do not have one, it is recommended to choose an isolated area, inaccessible to children and animals, far from watercourses and places where people circulate. Finally, the use of PPE is also mandatory during the cleaning process, in order to avoid poisoning problems.

How to clean/decontaminate spray equipment

The cleaning process can also be carried out in turbo atomizers, aircraft, knapsack sprayers and premix tanks. Just follow the steps and adapt them to each piece of equipment.

1st) Add clean water to the spray tank (following the water volume recommended by the manufacturer). For deep cleaning, half the tank capacity is suggested.

2nd) During refueling, remove the filters and spray tips and soak them in buckets with clean water and cleaning product.

3rd) Add the cleaning product in the recommended dose, preferably by the equipment eductor (when equipped). When added by the eductor, the product helps to clean the tank return piping.

4) Stir the cleaning solution in the tank for at least 30 minutes. The cleaning time depends on the amount of scale and residue inside the spray system, if there is a large amount it may be necessary to increase the agitation time.

5th) After homogenizing the product in the tank (between five and ten minutes of agitation), open the sections and let the product pass through all the nozzles quickly. This process aims to place the product in contact with the spray bar circulation system to facilitate the removal of scale.

6) If the machine's return system is not activated automatically during the stirring process, turn it on (approximately five minutes) at least once.

7º) Once the stirring time is over, start draining the liquid. Remove the drainage covers/ends of the sessions and open session by session so that the liquid exits through the pipes (Photo A). After this process, replace the covers.

8º) To use up the remaining liquid, open it again session by session and drain the liquid through the nozzles (Photo B). If there is a lot of water in the tank and the system is clean, drain the remaining water through the valve at the bottom of the tank.

9) If there is residue on the walls and bottom of the tank, jet clean water into the tank, with the valve at the bottom of the tank open so that this dirty water can be discarded.

10th) To finish, add clean water back to the tank, approximately 1/5 of the capacity, shake for approximately five minutes and drain through the bar nozzles.

Mariana Rodrigues Bueno,
UFVJM
Mateus Aparecido Vitorino Gonçalves de Oliveira,
JC&F/Bayer
César Henrique Souza Zandonadi,
Forchemistry
Sérgio Macedo Silva,
UFVJM