What gripes a nozzle guy!

There are many types of broad-acre boom sprayer in the market. Big and small, trailed and self propelled, PWM, PWFM, 3TS, 7TS; a bewildering array of very high tech spraying machinery.

Apart from a few exotic exceptions, the common denominator among them all is that they have hydraulic nozzles. Enter Nozzle Guys, those of us that make a living out of advising about or selling spray nozzles for the plethora of machines.

Nozzles, and the various things about them are explained with words. Important amongst those words are certainly ‘droplet size’ and more importantly, Spray Quality. They are not the same thing.

Spray Quality is the more important because it is used in legislation and on chemical labels to determine what you can or cannot do. Actual droplet sizes and the percentage volume of them are a handy thing to know, especially when it comes to very small ones. That information is useful in terms of nozzle selection, but has absolutely nothing to do with controlling things in the field.

The nozzles in question at any given pressure produce a range of droplet sizes, anything depending on size and type from UC, XC, VC, C, M, and F. Spray Quality is a measure of the ‘droplet size’ of the middle sized droplet and where that falls on a graph. It is derived by a process that is fully explained here: https://www.fantasticnozzles.com.au/articles/spray-quality-standard-asabe-S572.1

The gripe, at least for me is the use of the term ‘droplet size’ by enthusiastic sellers and marketers implying that it can be precisely controlled when it simply cannot. Perhaps it's a lack of understanding or just a poor choice of words, but it brings on a sigh to the nozzle guy every time.

What is actually being controlled in manipulating pressures or flows with duty cycles and frequencies with a nozzle, or a switch to another nozzle, is the shift from one Spray Quality, meaning one mixup of droplet sizes to another. Please call it precise Spray Quality management instead.

Marketers and sellers, I beseech thee, cease and desist! Repent you droplet sizers and get with the program. It’s Spray Quality!

That’s it!


4 October 2023

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