What's missing from JD's See & Spray Nozzle Pocket Guide? - Part 7

Dear John Deere,

As requested, here is my review.

The See & Spray Nozzle Pocket Guide provides all the information to work out a per nozzle flow rate required based on "band width" for single spot (isolated nozzle) applications. There are two sets of tables that provide theoretical values which should be used in place of nozzle spacing in the final worksheet.

One of the tables is for downward directed nozzles (Page 19) and the other for 40° inclined nozzles nozzles (Page 21)

The result, when the spray width (W) is plugged into the worksheet formula at the back page, is a flow rate per minute that is the basis for selection of the nozzle at 3BAR (40 PSI) as recommended on Page 9.

That flow rate can be referenced against a standard nozzle chart to find a nozzle of the appropriate flow rate to match at 3 BAR. All good.

A reminder here that these theoretical spray widths are calculating an even fan rate. That is the nozzle output is distributed evenly across the full spray width in the worksheet calculation. There is no mention in the guide to measure and amend these theoretical values. In our App for See & Spray users we provide an "Edit Spray Width" feature to enable that.

OK so now we have a nozzle, let's say an 80° 08 at 18kmh, 70cm high with an even fan rate of 91 l/ha based on 3 BAR, 3.2 l/min and a 1.17m theoretical spray width.

Baring measuring the actual spray width and recalculating or measuring the target zone volume as we do in our Apps, these are the only numbers your customers have to work with.

So the Nozzle Pocket Guide when followed can establish a theoretical even spray result, but it gives no hint whatsoever to the most important question of all. What setting is required for the controller?

Well, we've already established above that our 8008 running at 3BAR is delivering a 91 l/ha even fan rate. What controller setting is required for the isolated nozzle to achieve that rate in isolation without overlap?

If you consider that when two or more adjacent nozzles activate the combined overlapping rate is approximately double the isolated nozzle rate (subject to nozzle height of the isolated nozzle). Therefore the rate controller must be set to approximately double the single spot rate for the isolated nozzle to have sufficient flow to do its thing. How do we improve on approximately though?

Easy, just by looking at the rate per hectare in the same table you selected the nozzle from. Follow the 08, 3 BAR line along until you hit 18 kmh and there it is, 211 l/ha. Simultaneously the blanket rate for the overlapping nozzles AND your controller setting!

With the App we have produced for See & Spray users, we only recommend tapered fan nozzles which produce a higher rate in the 50cm target zone, so the rate on target is higher than your even fan and the calculation to establish our controller setting has a bit extra math in it, but I hope you get the idea.

I trust you will find my brief analysis helpful.

Please feel free to investigate and share our App for See & Spray users from;
App Central

Simply select ExactApply/See & Spray from the menu, register and receive your access code via email.

Feel free to call anytime if questions arise.

Regards,

Dave
0422 131 123

PS: Note that the guide uses 'W' for both nozzle spacing and band (spray width). I would suggest 'W' for nozzle spacing and 'SW' for spray width in the next print.

Disclaimer - There may be other systems under development in Australia or information about potential improvements from manufacturers about which I am unaware. If any such information is available, please contact me and I will share it.

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