Article • Agronomic Insights, WUC - Insights

Keeping Your Spray on Target – Nozzle Calibration and Replacement

Oct 28, 2022
WinField United Canada
Spray Clinic

Featuring: Martin Carr, PAg, CCA, 4R-NMS, Agronomy Manager West, -WinField United Canada

You’ve pumped your water, mixed your products, and prepped your coffee and you’re ready to hit the field for a round of spraying. But have you missed one of the key steps to ensuring your investment of time, money and effort will pay dividends?

The condition and “acreage” of your spray nozzles are important considerations in the success of a pesticide application. Worn or damaged nozzles can result in a portion of your spray being wasted or overapplied. Taking the time to ensure your sprayer is applying the product correctly, evenly and at the correct rate, will save you time and money in the long run.

Just like a river carving out the riverbank, over time, spray nozzle tip openings are worn by liquid flow. This erosion means worn-out tips have the opening of a larger size nozzle and result in:
  1. Uneven product distribution – as you apply the product on the field, you will have spots that get a large variation in dosage.
  2. Increased droplet size – as nozzles wear out, they become coarser, so even though you are applying more product than needed, you may still see reduced performance due to poor coverage.
  3. Wasted product – the output rate at the nozzle will be greater than the flow rate the nozzle was designed for, resulting in the over-application of your product.

Image Source: TeeJet Technologies – Catalogue 51A

Knowing how many acres you’ve put through a set of nozzles can save you a lot of time in determining if you should calibrate or install a new set.

Nozzle tips made of polymers/plastics or stainless steel have a life span of 20,000 to 30,000 applied acres (or 200 to 300 application hours). If your tips are in this end-of-active-life range, we recommend installing new nozzles. A fresh set of nozzles will ensure your product is distributed evenly, at the right rate, to the right place and in the right quantity to achieve the desired result.

If your nozzles have been used for application on 10,000 - 20,000 acres, they will already have experienced some wear and you will want to take the time to calibrate them to optimize your application. The purpose of calibrating your nozzles is to ensure they are applying the correct amount of product in the right spot. You have invested in the crop protection products you need to get the job done - make sure you take the time to get those products where they need to go.

Tips and Tricks for Calibrating
  • When calibrating, be sure to test the actual pressure at the nozzle, and don’t just go off the sprayer monitor.  Depending on the age of the sprayer, these at-the-nozzle numbers can vary as high as five to seven PSI. 
  • A worn tip will show up when you test the flow of the nozzle at 40 PSI since all nozzles are calibrated for their flow rate at 40 PSI. The expected flow rate is listed on the nozzle (eg. a red TeeJet AIXR11004 indicates 0.4 USG/min at 40 PSI). If the nozzle is more than ± 5% of the listed flow rate, it should be changed.
  • Typically worn nozzles will over-apply and blocked or pressure-affected nozzles will under-apply.
  • If you have more than 30,000 acres through your spray tips, don’t waste time calibrating them, they are worn out and should be replaced.
  • Use a SpotOn sprayer calibrator for quick, easy and accurate calibrating. You can achieve the same measurement with a stopwatch and a metered jug; however, this technique can be cumbersome.   
  • If a nozzle has a spray pattern that doesn’t look quite right, replace it. If you can see a visible difference this indicates the nozzle is damaged not just worn. A nozzle can be extremely worn out and not visibly different.
  • If one nozzle in a section is worn out, swap for a new one and carry on; if two or more are worn in a section, it’s appropriate to change every nozzle within the section.
Interested in learning more? Find a WinField United Canada retailer and attend a spray clinic in your area.
Spray Tip Wear Pattern
Image Source: TeeJet Technologies – Catalogue 51A

Featuring: Martin Carr, PAg, CCA, 4R-NMS, Agronomy Manager West - WinField United Canada

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