Correct cleaning and decontamination of sprayers

The sprayer cleaning and decontamination procedure is part of the equipment adjustment and is a relatively simple and very important practice, as it avoids problems with phytotoxicity and extends the useful life of the sprayer.

When it comes to preparing sprayers for an application, many technicians and operators believe that it is just a matter of marking an area on the ground, checking the volume of spray that the equipment is applying and making the necessary adjustments to the work speed and/or pressure. of operation. I'm mistaken! A well-done spraying requires much more than that.

For everything to go well and the application objectives to be achieved, work with the sprayer must begin well before checking the volume of spray applied. Therefore, it is important that everyone involved in the spraying operation understands the difference between two very different terms: regulate and calibrate. In short, regular is preparing the sprayer for calibration and subsequent use. To do this, the sprayer must be maintained up to date. Calibration involves checking the volume of syrup applied and adjusting it to what is desired. At this stage, the amount of product that will be placed in the spray tank is also determined.

In this way, it is possible to state that, if a sprayer is not well adjusted, it runs a serious risk of not being calibrated properly and causing serious problems for the crops, for the useful life of the equipment itself and even for the operators. Currently, several studies carried out on Brazilian crops indicate a lack of care given to sprayers. Data from the IPP (Periodic Inspection of Sprayers from Unesp in Botucatu-SP) points to a loss of around 23% due to the lack of maintenance on sprayers.

Good adjustment involves adequate knowledge of how the sprayer works, but you must also understand the interaction that the products used have with the sprayers. Many products are capable of encrusting in hard-to-reach parts and remaining there for a long time, contaminating crops and altering the chemical and physical composition of other products. They can also cause obstruction of piping, registers, filters and tips. In more severe cases, they can cause corrosion in important parts of the equipment's hydraulic system. Therefore, during adjustment, the sprayer must also be thoroughly cleaned. To do this, specific cleaning agents must be used and a suitable location must be designated for this operation. Correct cleaning must be carried out following some basic procedures that may vary according to each specific situation. Below, some actions that can be adopted will be described.

PROPER CLEANING

After finishing the application, if there is still product remaining in the tank, it must be emptied completely, preferably over the sprayed crop. The best option is to carry out a calibration so as not to leave any product left in the tank after finishing the application across the entire area. If you use the same product the next day, it is advisable to put clean water in the spray tank and spray until it runs out again. This will help prevent waste from drying out at the bottom of the tank. If by chance a different product is used the next day, deeper cleaning is recommended immediately after use.

In this case, you must take the sprayer to a suitable location on the farm and carry out decontamination. Currently, one of the norms for establishing legal standards for adapting sprayer cleaning locations on farms is the one that deals with the decontamination of agricultural planes (Normative Instruction 02 of 3/1/2008 of Mapa, Article VII). Whenever possible, some of the recommendations in this Normative Instruction should be suitable for other sprayers.

In general, the cleaning site or yard must be large enough to house the sprayer, must be open, fenced and have a pumping system for pressurizing clean water with a manual pressure control nozzle. The floor must be waterproof and have a minimum slope of 3% directed to the channel for conveying phytosanitary effluent or washing water to a specific location for treatment..

Currently, some companies have developed systems for treating these effluents, aiming to meet standards of good agricultural practices. One of them consists of capturing the effluent from the cleaning yard and channeling it to an evaporation tank. This tank must be built on an impermeable concrete floor, covered with resistant canvas, and may have a solar heating system to accelerate the effluent evaporation process. After complete evaporation of the liquid part, the tarpaulin must be folded to collect the solid part, identified and discarded with the other empty agrochemical packaging. The end of these solids are usually the furnaces of specialized incineration industries.

Every cleaning location must be adequately marked to indicate that it is an area with potential risk of contamination, preventing frequent access by people other than those involved in the sprayer cleaning process. During the entire cleaning procedure, the operator must be appropriately dressed in PPE.

It is important to clean the sprayer inside and out. Currently, there are products on the market sold for the specific purposes of cleaning and decontaminating sprayers and, in general, agrochemical manufacturers provide on their leaflets or labels which bases or active principles of the cleaning agents are most suitable for each specific product.

EXTERNAL CLEANING

For external cleaning, pressurized water can be used to remove residues that fall on the equipment during fueling or movement. Frequent cleaning generally prevents the formation of large scale. However, sometimes it becomes necessary to use some cleaning agents on the outside as well. In this case, they must be added to the water that will be pressurized.

Some parts of the sprayer must receive special attention when cleaning, such as: filters, tips, valves and valves. Filters and tips must be removed and washed using clean water at low pressure or a soft bristle brush.

After cleaning, pressurized clean water must be applied to all parts of the sprayer, in addition to placing at least ¼ of water in the tank and draining it. This will prevent cleaning agent residues from causing phytotoxicity problems in crops. It should also be noted that the sprayer, like all agricultural equipment, must receive the necessary lubrication care, indicated by the manufacturer's lubrication map.

Products used to clean the tank

In general, cleaning agents based on ammonia are the most recommended. This occurs because they promote an increase in the pH of the rinsing solution, making some agrochemical residues more soluble and easily removed by water pressure. Chlorine is also another widely used cleaning agent base. However, it is important to note that chlorine-based cleaning agents should never be directly mixed with ammonia or liquid fertilizers that contain ammonia. Because the two materials together react to form ammonium chloride gas, which is

toxic and can cause irritation to the eyes, nose, throat and lungs. Agrochemical residues from oily formulations can be removed with localized applications of diesel or kerosene.

Regardless of the cleaning agent used, the sprayer must be left running for a few minutes with only the syrup agitator turned on with the cleaning agents, before allowing the product to pass to the spray nozzles.

Renato Adriane Alves Ruas, João de Deus Godinho Júnior, Guilherme Andrade Gontijo, José Márcio de Souza Júnior, UFV

Article published in issue 157 of Cultivar Máquinas.