Importance of Sprayer Cleanout
Proper sprayer maintenance and cleanout should be conducted to help avoid the potential for crop injury from a contaminated sprayer. Minute amounts of some herbicides can cause serious injury to susceptible crops.
Chemical particles can become lodged within small cracks in fiberglass tanks, hoses, and nozzles. Particles can remain in hidden areas and will dissolve back into solution and contaminate new loads, creating a potential for crop injury on susceptible crops.
Additionally, the corrosive nature of some chemistries can cause significant maintenance problems if sprayers are not thoroughly cleaned after each use. Cleaning should include the exterior of the machinery as well as the tank, hoses, boom, nozzles, filters, and other pieces of equipment that chemicals pass through (Figure 1).
Planning for sprayer cleanout should start well before loading the sprayer. The cleanout process must be performed in a manner that protects employees, family members, the public, livestock, pets, water supply, nearby gardens, yards, and other environmentally sensitive areas. A specific cleanout area may need to be constructed that provides necessary protection while providing the means to properly clean the spraying unit. An area enclosed by concrete, along with proper rinsate and runoff collection basins should be considered.
Cleanout in the field after concluding the application is the preferred method. This keeps the active material within the intended use area. However, precautions are required for the protection of ground and surface waters and other sensitive environmental areas. Cleanout in the field requires enough water for triple rinsing, and cleaning agents, which should be accounted for in the preplanning process. Personal protective equipment (PPE) should always be used and pesticide labels be present.
The application equipment should be calibrated and the spray prepared to cover the area to be sprayed without having excess product left over. Excessive left-over solution may result in applying more than the label allows when the rinsate is applied to the crop, or can be a challenge if collection basins are used.
Water alone may not be sufficient to thoroughly clean a sprayer unit. Common household chemicals and commercial cleaning products may be required to sufficiently clean, dissolve, and remove chemical residues from the system. Product labels should be reviewed to determine recommended products for sprayer cleaning. Rinsate should be removed and disposed of properly. Common cleaning agents include:1,2,3
- Water – may be sufficient if the same chemistry is to be applied the next day. Several rinses can dissolve and dilute residues within the system.
- Household ammonia – can raise the solubility of some herbicides by increasing the pH. It can penetrate and loosen deposits and residues. While it can make sulfonylurea herbicides more soluble and easier to remove, it does not deactivate or decompose this class of herbicides.
- Chlorine bleach – can deactivate and decompose most sulfonylurea and other herbicide products into inactive compounds; however, some tank-mix partners may inhibit decomposition. Chlorine can be dangerous as it can combine with ammonia based fertilizers to produce chlorine gas, which is irritating to eyes, nose, throat, and lungs. Rinsate containing chlorine is not labeled for cropland application.
- Detergents – can help remove water and oil-soluble products. Commercial detergents formulated for tank cleaning may perform better than household detergents.
- Kerosene or fuel oil – can be used to remove products which have an oil base, such as 2,4-D esters. The oil rinse should be followed by a detergent or ammonia rinse.
- Activated charcoal – can deactivate organic herbicides. A 3% suspension of activated charcoal and water can be flushed through the system to tie up and deactivate pesticide residues. Rinsate should be removed and disposed of properly. The system should then be flushed with water as any remaining charcoal can deactivate portions of the next pesticide.
After using cleaning agents, solids may be loosened and can clog nozzles or filters. Be sure to remove filters and nozzles to clear any potential debris that will interfere with spray patterns.
General Cleaning Process between Crops
Before starting the cleaning process, review the pesticide label of the product to be rinsed as well as the cleaning agent label to identify the required PPE. An apron and eye protection such as goggles and face shield should be used. When using the cleanout procedure described below, dispose of all rinsate in an appropriate manner according to all local, state, and federal regulations.
- Fill tank half full of water and begin flushing system for at least 5 minutes with a combination of agitation and spraying. Rinsate is best sprayed onto appropriate cropland. Interior surfaces of the tank should be thoroughly rinsed, including baffles, plumbing fixtures, and tank opening.
- Fill tank half full of water and add 2 quarts of household ammonia, 4 pounds of trisodium phosphate detergent, or a commercial tank cleaner for each 50 gallons of water and agitate for 15 minutes. Operate the booms to ensure that all lines have been filled with the solution and let stand for several hours. If a growth regulator herbicide has been in the tank, the solution should be left in the tank overnight. Agitate and spray solution onto suitable area for the rinsate.
- Add additional water and rinse the entire system again with a combination of agitation and spraying. Open the bottom tank drain to allow any residual water with possible contaminants to drain out (collect and dispose of appropriately). Nozzles, screens, strainers, and other individual components should be removed, washed in a bucket containing a solution of water and a cleaning agent, and replaced.
- System should be rinsed and flushed with water a final time.
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