Every liquid sprayer is only as good as the nozzle that regulates the spray. A properly applied spray nozzle can last for decades if made of high quality material and properly cleaned. Plastic or aluminum spray nozzles are often purchased with a new spray rig. They are not the best spray end attachment for long term reliability.
If you are refitting nozzles on an old tank or can afford a higher grade nozzle, high quality will service you with accurate spray rates, better target area coverage and a longer life. Simply stated, using a hardened stainless steal nozzle will last 10 to 15 times as long as the cheaper aluminum variety (don't even consider plastic).
Regular stainless steel nozzles will last three-and-a-half times longer than aluminum or brass but still will cost three times as much. The major advantage here is, you don't have to change them as often. One recommendation on multi-nozzle systems is to change all nozzles at the same time and recalibrate. New nozzles will have different rates of delivery than your old ones.One Sprayer-Cleaning Caveat
The best cleaning in the world will not protect sensitive plants when different pesticides are used in the same tank. If you need to spray plants 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 Flush Sprayer After Every Use
Sprayers need to be cleaned for several reasons. A good cleaning will help prevent unwanted contamination of other pesticides used in the same tank. Many pesticides can be highly acid or alkaline and their corrosive nature will ruin nozzles, pumps and other parts. Lengthy exposure to even small amounts of some pesticides can damage sprayer components, including stainless steel tips and fiberglass tanks.
Always end your spray job with an empty tank. That means mixing only what is needed for that day's jobs. Be careful to choose the least sensitive area available to flush, use only clean water and drain even if you plan to apply the same material the next day. Using soap surfactants in your mixture also helps in overall cleaning. Remember to rinse the outside of the sprayer.Cleaning The Sprayer
Most herbicide residue can be easily cleaned with either a solution of household ammonia or sal soda (washing soda or soda crystals). Take the cleaning agent of choice and completely agitate and run a small amount (one half cup ammonia or three tablespoons of soda) with two gallons of water through the sprayer. For better results, let it stand in sprayer overnight - rinse then flush.Insecticides, fungicides and herbicides containing atrazine, simazine, alachlor need a slightly different cleaning solution. These chemicals clean best when adding a tablespoon of washing detergent to several quarts of water. Add the soap, agitate and run the solution through the nozzle to flush. A rinse is also recommended.