• slide

Know when to change nozzles

The simplest way to optimise sprayer performance

Fitting new nozzles must be one of the simplest and most effective sprayer maintenance tasks around – but when, and how often, should it be done?

No-one could argue that sprayer nozzles are cheap… By the time you re-nozzle an entire boom, the dollar cost can really add up.

On the other hand, good nozzles are great value at almost any price. Regardless of steering accuracy, pressure management and target rate

along the boom. If you notice any asymmetry in the fan/cone shape or droplet distribution, fit a new nozzle right away. (Assuming the filters are clean, of course!)

At the minimum, individual nozzle flows should be tested every time you calibrate your sprayer – something that needs to be done at least once a season. Use a measuring jug to measure each nozzle’s output (with water) and if it is any more than 10% above the manufacturer’s quoted 

“...it’s not just your dosage rates that will be too high – your chemical bills will be over by 10% or 15% too.”

technology, any sprayer’s performance ultimately comes down to its nozzles.

The business end of your sprayer

Nozzles control

  • Chemical throughput – and therefore dosage
  • Distribution quality
  • Droplet spectrum and coverage
  • Distribution over the target
  • Retention or reflection on the target
  • The degree of drift and downwind fallout

All these factors are affected by the design, material and manufactured precision of a new nozzle. And, as with most things, price is fairly good measure of the inherent quality. But as soon as a nozzle orifice becomes eroded, nicked, burred, worn or simply out-of-round, its precision and deposition will be compromised.

Frequent checks

So how frequently should you invest in new nozzles or, at the very least, how do you tell when your current set needs replacing?  One easy check is to spray water and visually inspect the output pattern at each point 

figure then the nozzle should be replaced.

Ideally, you’ll clean your nozzles (using only a soft-bristled brush) after every week of spraying and then check the flow from at least two nozzles per boom section. Again, if any of these show a flow rate that’s more than 10% over a new nozzle, then all the nozzles need to be changed.

That may sound extreme, but remember it’s not just your dosage rates that will be too high – your chemical bills will be over by 10% or 15% too.

What’s right for you?

The rate of everyday wear and tear on your nozzles will depend on chemical abrasiveness, spraying pressures and the nozzle material itself. You’ll soon get to know what’s ‘normal’ for your operations.

Surprisingly, traditional materials like brass and stainless steel aren’t as durable as you might think. For example, SYNTAL thermoplastic is five times more durable than brass and nearly three times as durable as stainless steel. Ceramic nozzles are off the chart – which means their upfront cost can deliver lasting value, especially if you often use abrasive compounds and/or high pressures.

But whichever nozzles you choose, investing time and money in their condition will pay real dividends right through to harvest.