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Pesticide Safety Education Program (PSEP)
Part of the Pesticide Management Education Program
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Cleaning Your Sprayer

Cleaning Your Sprayer

Old Spray Nozzles Never Die

Old spray nozzles never get replaced until they're lost. You should know that new nozzles will have different rates of delivery than your old ones. Consequently, all nozzles should be replaced at one time and the sprayer should then be calibrated.

Stainless steel nozzles last three-and-a-half times longer than aluminum, brass or plastic ones. But they also cost three times as much. So, the only advantage is that you don't have to change them as often. Hardened stainless steel, on the other hand, last 10-15 times as long and only cost 3.6 times as much. This type of nozzle, then, is the best buy for the money.

Sprayer Cleaning

Sprayers need to be cleaned to prevent corrosion, to prevent cross- contamination of pesticides or other materials, and to prevent crop injury. Trace amounts of one pesticide can react with another or carry-over to the next spraying, causing damage especially with herbicides. Long exposure with even small amounts of some pesticides can damage sprayer components, including stainless steel tips and fiberglass tanks.

No cleaning method is 100% foolproof. If you want to spray crops that are very susceptible to herbicide injury, such as vegetables, fruits or ornamental, it is recommended that two sprayers be used - one for herbicides only and one for all other pesticides. Careful cleaning will usually remove all but insignificant amounts of insecticides and fungicides.

Always try to end the day with an empty tank. Mix only what is needed for that day's jobs. Choose the washing area carefully. Avoid contamination of water supplies and injury to plants or animals. Don't make puddles that might be accessible to children, pets, farm animals or wildlife. Always flush with clean water and drain even if you plan to apply the same material the next day. Also, rinse the outside of the sprayer. The use of surfactants with pesticides, when compatible with your needs, will provide some cleaning action of the sprayer. Some pesticide combinations (especially if oil is used) may produce a putty-like paste ("buttering out") in the sprayer tank, and flushing with water after each load may prevent an accumulation. If water alone does not dissolve and remove the buildup, add Stoddard solvent, kerosene, or other low flammable solvent; allow paste to dissolve; then agitate and flush. Next, flush with detergent and finally with clean water.

Whenever you change pesticides or prior to storage, sprayers should be given a thorough cleaning with a cleaning solution. The solution used depends on the pesticide to be removed from the sprayer. Check the pesticide labels for cleaning instructions or see the table on the other side of this sheet for specific recommendations.

Cleaning Agents and Rates for Cleaning Sprayers

Pesticide Used 25 Gallons
Cleaning Solution
2.5 Gallons
Cleaning Solution
Hormone herbicides, ester form.(2,4-D, brush killers, MCPA) 1 Qt. household ammonia 1/2 cup household ammonia Thoroughly agitate small amount through system, and let remainder stand in sprayer overnight and rinse. Flush.
1 lb. washing soda (sal soda) 3 Tablespoons washing soda (sal soda) Same as above except let stand for at least 2 hours.
2 lb. trisodium phosphate 1/4 lb.trisodium phosphate Same as above except let stand for at least 2 hours.
1/2 lb. fine activated charcoal and 1/2 cup powder detergent* 2 Tablespoons fine activated charcoal and 1-2 oz. powder detergent Agitate, operate sprayer for 2 min., let remainder stand for 10 min., then flush through sprayer. Rinse.
Hormone herbicides, ester form. (2,4-D, brush killers, MCPA) 1 lb. washing soda (sal soda) + 1 gal kerosene + 1/4 lb. powder detergent* 4 oz. washing soda (sal soda) +1 1/2 cups kerosene + 1 Tablespoon powder detergent* Rinse inside of tank and flush small amount through system. Let stand at least 2 hours. Flush and rinse.
Other herbicides (atrazine, simazine, alachlor) 1/4 lb. powder detergent* 1 Tablespoon powder detergent* Rinse with clean water before and after using sudsy solution.
Insecticides**, fungicides 1/4 lb. powder detergent 1 Tablespoon powder detergent Agitate, flush and and/or rinse.

*Liquid detergent may be substituted for powder detergent; mix at rate to make a sudsy solution.

**Organophosphate and carbamate insecticides may be detoxified by adding household ammonia to the cleaning solution (1 qt./25 gallons or 1/2 cup/2.5 gallons).

From Donald Daum, Extension Ag Engineer, Penn State University.