Posted 4/7/2021 11:23 (#8937990 - in reply to #8937939) Subject: RE: What kind of nozzles do you suggest?
Eh, 110° will give you greater overlap, but keep in mind a flat fan pattern kind needs close to that 100% overlap as there is a different mix of spray droplets (finer towards the outside, and coarser towards the inside of the spray pattern) as well as volume as you'd have more volume towards the middle of the pattern than the outsides. If you are 'way over' 100% overlap, you end up almost doubling up some of the 'heavier volume' areas in the spray swath, and kind of missing the mark. Again, there is a whole lot of chaos that happens once the spray leaves the tip, so a lot of it will still blend together to a more even swath rate, BUT, the more extreme it is before the spray leaves the tip, the greater variability.
Pretty much, on the extreme sides for an example, you wouldn't want to have an 8GPA application turn into valleys and peaks of 5GPA to 11GPA down the length of your sprayer.
As far as using an ultra-coarse tip with that kind of situation, it'd still be darn nasty. To compare what I'd like to see for 'ideal spray coverage' for systemic products (provided the driftable fine % isn't too high for the chem) would be like having an 80%+ <600µ, if you are familiar with Wilger charts on that side of things. If not, to visually get to that kind of 'coverage level', you might be looking for a nozzle with this kind of profile:
The ~80% mark usually gets hit right as a nozzle is transitioning from ASABE COARSE to ASABE VERY COARSE categories. So, being on the upper coarser side of COARSE would be a good telltale sign of when you are over and above 80% 'coverage factor'. That 80% is used as a ball park rule of thumb as it means 80% of your spray is small enough to be 'effective' for coverage. the other 20% over 600µ is coarse enough that it might hit a leaf and roll off and do nothing for you. (Its okay for soil-applied systemics, but not systemic herbicides that rely on plant contact and translocation).
The other factor would be on the driftable side of things, which you wouldn't want to be going willy-nilly on either.
To give a benchmark for that Coarse-Very Coarse transition, you'd be likely around the 5-10% driftable fines at that 80% coverage mark, which is a pretty nice mix.
Again, for some systemics they are going to require VERY COARSE spray quality right on the chemical label, which kind of determines that you'd want to stay on the coarse side. At the point the decision is made for you, so its just a matter of following the label.
If you are talking some Dicamba-tolerant chem, then you are kind of stuck in spraying that kind of coarseness due to the label.
As far as your question on what it might look like if you are using an ULTRA COARSE nozzle:
Typically as soon as a nozzle transitions from the EXTREMELY COARSE to ULTRA COARSE spray quality, your drift/coverage profile would look something like this:
5-7% drift on the high side of things
59% 'coverage' factor on the high side of things.
The UC category is the bottom end, so a nozzle in it can also get down to the point where you are like 1% driftable fines, and like 35% coverage factor as well, so a VERY steep drift reduction to coverage balance.
So, to answer your question, I like to see systemics applied at closer to 80% 'coverage factor', whereas as soon as you get into the UC spray quality, you are already maxed out at like the 60% coverage factor, which is a big difference in coverage. If your chem label is requiring UC spray quality, then you straight up have to follow it. Typically the label for those chemicals are talking like a 15 Gal/acre rate to try overcome the shortage of coverage factor with more water.
For the twin tip in a -025 size, I'd be thinking the same thing. If it is split into a -01 and -015 nozzle size with extra mechanisms (e.g. air induction) to reduce drift as I wouldn't want you to be trying for a conventional flat fan twin tip (that'd be like 30% drift), that'd be another factor that might plug that size of nozzle quicker as well.
Yeah, depending on chem, atrazine has be to mixed in correct order for sure, otherwise you'll be cleaning filters for an afternoon