When operators winterize their sprayers, they should remove all the tips and store them separately. Many store them in large pails with lids. Calibrating the sprayer just prior to winterizing will indicate if the nozzles should be stored, or replaced. Let’s assume the tips are still within 5% of the average output, and 5% of the manufacturer’s pressure tables.
Just like any other part of the sprayer that comes in contact with spray mix, nozzles should be cleaned regularly. And, just like any other part of the plumbing, the best way to do that is to dilute any residues via a series of rinses. One of the intermediate rinses should include a detergent, and soaking during this step is an excellent practice.
The orifice of any nozzle is very delicate, either machined or moulded to exacting standards. Even small changes to the orifice shape results in distorted spray (e.g. spray comes out at undesirable angles), and a change to the rate (typically more volume per minute) and the spray quality (typically larger median droplet size). If foreign objects or residues remain in the tips, the subsequent spray job may be less accurate and even damage the tips.
In the case of air induction nozzles, which are essentially the standard on most boom sprayers and even some airblast sprayers, debris and weed seeds can plug the air-intake ports. When that happens, the nozzle will not function as intended. So, while the occasional soaking of nozzles does a great deal of good, they also have to be scrubbed. There are nozzle cleaning tools out there, but they’re basically toothbrushes. Soft bristles are the way to go for removing stubborn residues and cleaning any tip orifices. Don’t use picks or reamers.
Here’s a step by step:
- Wearing gloves, remove all nozzles, rubber gaskets and tips from the sprayer.
- Put them in a large plastic pail and cover them in warm water. Leave them to soak.
- Drain the pail, but be aware that the rinsate will have pesticide residue.
- Fill a second pail with a solution of the same commercial detergent used to clean the sprayer.
- With a toothbrush, scrub the caps, gaskets and nozzles to remove any residue. Some nozzles can be pulled apart to expose the mixing chamber and facilitate cleaning.
- Once scrubbed, leave all the parts to soak in the detergent solution.
- Drain the solution, which will contain trace amounts of pesticide, rinse the parts with water and reassemble the nozzles.
This may seem extreme, but of all the technology on a sprayer, the nozzle has the biggest impact on the effectiveness and efficiency of the spray job. Take the opportunity over the winter months to clean and inspect the tips for damage so the sprayer is ready for calibration in the spring.
Thanks to Jason Boersma (@RVFBoys), Ridge Valley Farms, Ontario, who sparked this article with his tweet: “Great job for a cold winter day, soak & clean all your tips to be ready for spring also saves on down time!”