if you are needing to get the spray to just fall down and coat the exterior that is one thing, but if you need to do more of a covering of entire vines and under leafs, and on top of leafs. then i would guess, you might want a few extra nozzles. more nozzles means more GPM, and/or the spray heads will need to be set closer to the fence rows/vines rows. one set (left side spraying down wards), another set of nozzles (left side spraying upwards), then same on right side. when i say upwards/downwards, i mean more of an angle. for the spray pattern of the nozzles to hit tops and bottoms of the leafs and vines.
pending on what you are spraying, either a mist, to more of a rain droplets, along with how much drifting of chemicals you want. if you point the nozzles straight out (perpendicular) to tractor, then a lot of the chemicals may blow straight through the vines and onto the other side of the fence row / vine row. if you angle the nozzles forward, you will more likely take a chemical bath, if you aim them say 45 degrees behind you. then you may end up spraying just the outside of the leafs, and not get a good injection of chemicals deeper into were the vines are.
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you will most likely want to stop the spray as you reach end of row, and then start the spray backup as you enter a new row.
---ability to turn off left or right side spray nozzles, for outside rows, or getting the ends.
---a way to use roller pump to fully "mix" both chemicals and water together. before applying
---a way to drain and clean the 50 gallon drum.
---a filter between pump and tank, to keep stuff from damaging pump. (either make it a dry chemical that needs to be mixed first to other). to a filter to keep small stuff out from clogging up nozzles.
---guessing upper set of nozzles (high up nozzles) abilty to turn some of them off, for vines/rows that are shorter vs others.
---replaceable nozzles / spray heads. ((some have a miniature final filter in the nozzles / spray heads.)) to keep nozzles from clogging up, same nozzles that i have seen allow one to replace a spray nozzle with a "cap" to turn off the spray head/nozzle.
---a way to keep air from creating a "air lock in the system", and a way to fully drain all the hoses/pipes of chemicals/water.
--- hard plastic pipe (pvc, abs) i do not recommend the hard piping, it will vibrate and crack, instead make sure to use metal piping, or use of rubber or like hoses only.
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---easy to reach valves (1/4 turn valves) only takes 1/4 turn of handle to either close or fully open valves. might be suggested. or use of 12v electrical valves.
---valve to mix chemicals, valves for spray nozzles. these 2 valves work in tandem with each other, controlling amount of GPM/pressure going to spray heads/nozzles
---((individual valves each spray nozzle or a set of nozzles)), by default you should try to keep same amount and type of fittings/hose length between each spray head/nozzle. if you start putting longer pieces of hoses here or there with shorter ones. the shorter length hose nozzles are more likely to get more GPM/pressure vs the nozzles with longer hoses on them.
---lower nozzles will see more GPM/pressure than higher placed nozzles as well.
---you can attempt to overcome some of the difference with more Pressure / GPM, within reason.
---if you go with 12v electrical valves, you have more of an option (at a price), to use a hand wand / hand gun spot sprayer setup. 12v sensor open/closes valves as needed to put pressure/GPM to hand gun when ya pull the trigger. 12v electrical pumps generally have sensor built directly into pump, for on demand. but a roller pump setup does not.
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you can create a "spray bar" using a piece of pipe and drilling say 1/32" to 1/16" hole into it to create a spray bar. and then mount the spray bar inside the drum, this can aid in cleaning drum out and also mixing chemicals/water together. a drill press helps here putting holes in a row. take say a 2x4 piece of lumber, and saw out a V in it. to make yourself a pipe holder. if you can not figure out how to get wand to stay put, along with getting an end cap on it. run the entire spray wand clear through drum. (bulkhead on each side of drum), and then place end cap on one side, and hose/piping on the other side (on outside of the drum).
--to note it, this is not ment to replace actual spray heads/nozzles, but only for inside the drum, to help clean and/or mix chemicals/water.
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you can use electrical fittings (water tight seals for pipes), that connect electrical boxes to electrical pipe, ((normally come with a gasket for threaded connection to box (((err drum))), then just get yourself some thread fittings to go onto the bulkhead per say.
---they also make a "beh forget name" it looks like a "rubber pulley" like belts and pulleys. but rubber. ya drill a hole and push this rubber piece into the hole on the drum. and then use a little bit of Vaseline or some other slicker upper, and push pipe through drum. the pipe causes the rubber to expand just enough to make a really tight water proof seal. and being rubber it forms to the curvature of the drum!.
www.koiphen.com you should be able to find some suppliers there for this pulley looking rubber piece.
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2", 3", or 4" shower drain. (for diy showers and like), can be used like a man hole for drums. they generally come with a little rubber gasket / o-ring / washer. that creates a water tight seal.
instead of getting a threaded on cap.... run a short piece of pipe into shower drain. and then take a "dremal" or like a put a small grove into end of pipe. and then slip a rubber 0-ring into the grove with some Vaseline, and then take dremal again, and sand the inside of a end cap a little bit, so it simply slips over the 0-ring and end of pipe. pvc like fittings generally have a "taper to them" so when ya primer/glue them together a tight fit happens. the sanding of the inside removes this taper, electrical fittings generally do not have this taper. but you still may need to do a little bit of sanding on the inside.
www.koiphen.com search for "stand pipes" as on/off valves. same basic principle but just used for a man hole / clean out hole per say.
drill i don't know 1/4" hole into top of the end cap, to so air can enter drum while in use. possibly adding a small chain via bolt to end cap. so if it does come off, ya don't loose end cap.
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the outlet on drum that goes to pumps inlet....
when ya do a sink full of dishes and go and remove the drain plug... as the water begins draining, you end up getting a vortexing / whirl pool of water, and most likely some "sucking noises" as air goes down the drain as well. if you put your hand over the whirl pool or a dish or like. you end up stopping the whirl pool and more so sucking of air!....
---this is what known as "anti vortex", or anti whirlpool, or some sort... basically all they are is a piece of plastic or metal. that sets off say 1/2" or so off the end of pipe coming into the tank. and basically directs the suction around the pipe. vs directly above the end of the pipe. this helps you suck out the last bit of chemicals/water in the tank. vs leaving say a few gallons of stuff in the tank, that you can not get, even if it means sucking in air with the water/chemicals.
---pointing you to
www.koiphen.com for "diy bottom drains" that have a dome on them.
---you have a bulkhead or like fitting going through drum, on the outside of the drum, instead of going directly to a metal pipe or hose. put a Tee, (the leg of a T pointing down in this text, connects to the hose or pipe), the other 2 ends of T, one connects to bulkhead, the other gets an end cap. drill a hole into center of end cap, and use some threaded rod, to extend up into drum / tank, were you can use a couple nuts to hold a piece of plastic or metal. just above the pipe end, (inside of the drum), use a couple more nuts, with some silicon to attach to end cap.
alternative... simply attach a "end cap" inside the drum/tank. and drill a bunch of larger holes around the sides of the end cap. this can also act like an anti vortexing like setup. though it may leave a little bit of stuff in the tank.
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100's of ways going about something, mix and match what ya think will work for ya!
Not really, but the whole point of an airblast sprayer is to spray both sides of the leaves in one pass. That airblast gets the leaves moving and flopping around for more complete spray coverage and doesn't hurt the vines at all. It has nothing to do with creating air droplets or anything like that. Its about moving the leaves and about penetrating the canopy to get spray coverage into the center of the vines and to get spray on the fruit (fruit can be hidden behind leaves). 