Herbicide Applicator (sprayer)


Active Member
Everyone at some point has used an ATV Sprayer and not all sprayers are created equal. What makes a difference is usually the type of tips used, and this goes for ATV and larger 3 point sprayers alike. For a good all around sprayer look at something you can put a small boom on and run flat fan nozzles. They Flat fan nozzles are economical and are excellent in applying contact herbicides that we typically use. In this thread I will give my opinions on why one type of tip is better than another and simple modifications that can be done to make your sprayer even better.

Since nozzles are so important lets start there. Some will say they want a boomless nozzle but, for me the risk is not worth the reward. Boomless nozzles rely on putting out very large droplets where flat fan nozzles put out many smaller droplets. What this means is when you drive across a known area, in this case lets look at a square foot, applying the same amount of mixture from each, one square foot (boomless style) would have a lot of space between very large drops while the other will have less space between many more smaller drops. What this means while we are applying our herbicides is the larger droplets are more likely to bounce off of the plant you are trying to spray, large droplets have to travel further in the air before making contact with target plant material, and lots of tightly spaced target plants may not receive any herbicide. Smaller droplets provide more surface area contact leading to more area for plant to absorb herbicide, drops travel very short distances before making contact, and small drops have less surface area to be effected by wind. This can be the difference between success and failure especially when plants are under stress or more mature than recommended.

There are nozzles for a boom referred to as broadcast tips or Deflecto nozzles. These are common on many commercially purchased sprayers considered a Boom Nozzle. The replaceable tips are easily identified as the liquid is forced through a single orifice onto a slanted surface. The tips are usually oriented in a horizontal position and are spaced between 28 to 40 inches apart with PSI ratings around 20 PSI and spray heights between 12 and 18 inches.. The stream is deflected at an angle where the pattern fans out like a thin sheet of liquid. Due to their spray pattern large leaves and thick vegetation can block herbicides from making contact with target plants. These tips are great for spraying preplant herbicides onto bare ground but lack when spraying under normal conditions.

The next spray tip I will discuss are the flat fan types. While I will specifically talk about the flat fan, there are some different patterns based on a similar design that differ in overlap coverage between tips. Flat come in two different spray angles, 90 degree and 110 degree. The difference between these two tips is how high the boom needs to be above the target weeds. 80 degree tips need a taller boom setting (28 to 30 inches) while the 110 degree need 18 to 20 inches of height. Regular flat fan nozzles usually need lower Pressures. Tip sizes are based on the orifice size with smaller orifices applying less product per acre than the larger ones. Tips are generally color coded by orifice size only so be careful not to mix and match. There are tips size selection charts that provide approximate output based on pressure and speed. While small drops are better than large drops try to keep your selections in the Med to Coarse size and shy away from the fine size. The fine size floats around like a mist and can lead to drifting. This is your basic 110 degree flat fan tip. Nothing fancy, no ceramic orifice or brass. Just plastic and it works. The tip is seated in a cap used in a quick connect system. See the yellow residue?


Flat fan tips are commonly spaced 20 inches apart to keep a boom as close to the target weed as practical. The wider spaced the tips are, the higher a boom needs to run for good coverage. 20 inch spacing and a boom height of 20 inches is right about perfect for most 110 degree tips. Too tall and the areas between tips get no or too little herbicide coverage. Too short and you will have strips receiving no herbicide.

We can mention the Air Inducted fat fan nozzles which cost more than the regular nozzles but the air inducted nozzles are designed to perform better under a wider range of pressures.. One can see where the air inducted nozzles would be a better fit on a PTO powered pump where Pressures can be significantly higher than pressures achieved by a 12 volt electric pump. Looking deeper at air inducted nozzles we find drops are formed around bubbles of air. This lets us utilize bigger droplets for drift control while retaining less herbicide mix in proportion to droplet size. Droplets hit target weeds with less force and once droplets hit and splatter, the droplets will not bounce or run off when applied correctly.
Booms can be made out of readily accessible items or purchased. Many smaller ATV booms still need modification to perform up to expectations. Some quick and easy way to raise and lower the boom height is necessary as when we talk about boom height we are not talking about ground to boom but about top of canopy to boom. This allows consistent coverage across the length of the boom. Basically a boom is nothing more than a horizontal pipe or tube and a way to attach to the vehicle of your choice while allowing some up and down height adjustment. A boom can be as short or as long as you want but depending on the tips you select has to have a total output less than the pump you have driving the system. Some do not like booms because they don’t want to hit anything. Short booms will not hit anything but if you want a little more reach, having break away booms is very important. Basically break away booms have a spring that pulls them back into operating position if you hit an object. Some booms will have a large shield in front of the boom to block air. This is not needed really.

A section control valve allows my boom on the large 3 point sprayer to manually be set to center, right/left/center, right/center, left center, or re-circulation. This allows a 28 foot boom to spray as little as an 8 foot section. This option is handy in small plots or on the last pass when the remaining area is narrower than the full boom width. It basically allows you to not waste chemical or over apply more chemical than necessary with some more touchy chemicals.



The two most common pumps used by food plotters are the 12 volt electric pumps and roller pumps. The 12 volt pumps are necessary on everything without a power take off (PTO). 12 V pumps are limited in output, most will be rated in the 1.5 to 2.5 gallon per minute range but some can be found in the 5 gallon per minute range with max PSI between 30 and 60. These pumps create a lot of heat and having a pump with thermo protection in the electrical system is best especially when spraying plots larger than 2 acres. Having to stop and refill will give the pump time to cool slightly. Some have had issues with the 12v pumps but they are available at most tractor supply stores.

The roller pumps are rated by the number of rollers. A 4 roller pumps will deliver enough for most applications but generally are rated around 7 to 9 GPM with max pressure around 150 PSI. A 6 roller pump is generally rated around 22 GPM with max pressures around 300 PSI. If you have a tractor for spraying that has a PTO shaft this is the best route to go. Remember any sprayer can use different types of pumps and the only limitation is having a pump large enough to exceed the spraying capacity of your particular spray rig. With a PTO pump activating/deactivating the tractor’s PTO will turn on/off the sprayer without the need of high priced electric butterfly valves and controllers. If purchasing a roller pump for the first time you will also need a quick coupler that mates to the shaft of your particular roller pump and your tractor’s PTO shaft, making it quickly removable. Here is a picture showing a roller pump installed on tractor with the quick coupler attached also.


There is also an option of using a free standing small engine with a pump attached. This would be very rare in the food plot world so I will only mention this option as I have not had experience with this type of system.
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Tanks are mostly plastic anymore and come in a vast range of sizes, shapes, and colors. When looking at tanks I look at the following aspects. Deep well, well centered in tank, large opening to access tank, and all openings/connection points having good structural support. We are all familiar with the shape of many ATV tanks and some of these same tanks are mounted on carriers turning them into 3 point hitch mounts. Most of these types of tanks do not have very deep wells, if any well at all. Suction lines are usually an inch off the bottom of the tank and this can create problems spraying on side hills as the tank gets near empty. Here is a picture showing the well in my large sprayer.


I like having return lines that provide some agitation. Lots of these ATV tanks do not offer this option without some type of modification. One type of modification I am not a fan of is drilling into the top of the tank and running a line back into the tank. These create stress points within the tank’s inherent structure and through minimal use can lead to cracks. If doing this type of modification I would suggest plastic welding a thicker piece over the area or somehow beefing up the area around the drilled hole. These ATV tanks connections are generally molded into the tank and are threaded with a garden hose thread. Having the connections molded in can create problems when connecting and removing hoses. Be careful not to over tighten connections and use rubber seals in every connection. I have modified the tank drain on my tank and it now acts as the tank return. There is wear showing on the plastic threads from disconnecting the fitting to drain the tank. The next step will be to add a small banjo fitting inline to allow quick disconnect without having to screw on and off the fitting.

Here is my return to my ATV spray tank.


The tank on my large sprayer has a good sized well and draining the tank was the only aspect I did not like. The modification I did to work around this was adding a T to the connection under the tank. Using one leg to go to the filter and one leg to the tank left one leg where I added enough hose to reach around the tank and hold it in place in a mounted fashion. Adding an on/off valve allows me to completely empty the tank.
The nozzles are important but they are held in place by spray bodies and hangers. Hangers are available in different sizes to fit either square or round tube booms and square or round spray bodies. If you go out and spray one area then have to travel to the next spot or across ground you do not want sprayed, the addition of a diaphragm spray body is a great addition. A diaphragm spray body keeps solution from dripping, or leaking, out of the nozzles when the sprayer is turned off or drops below 5 PSI. Any time you flow a liquid through a hose or fitting you will have a loss in pressure and flow. While this amount may not be perceivable, it is there. Adding diaphragm spray bodies is adding additional restrictions that need to be accounted for in determining the total flow needed from your pump.

Spray bodies like the ones from Teejet and some others have a quarter turn disconnect. This makes it easier to get to screens also in the spray bodies. One huge benefit to the quick disconnect type of cap is it will perfectly align your spray tips each time you tighten them.

Here is a diaphragm spray body (Hypro)

Here is what the diaphragm look like when removed


Here is what a hanger looks like (in two pieces and held in place with friction)


And here is a picture showing the different componets necessary to attach a tip to a spray body. They are from left to right: Cap, Filter, rubber washer, spray tip (all caps will not work for all tips)

Had a couple minutes yesterday and took some pictures of modification I have made to my large sprayer. While there are differences between the large sprayer and my ATV sprayer, the basic principal is the same. So lets start at the bottom of my tank. Here is a picture showing the T added to create a tank drain.


Suction side from Pump and adding the T and some hose I have effectively done two things for myself. First the ability to drain most of the tank, but the second is having the the extra product stored low (can make a difference when sloshing around as spray is uninterrupted as tank nears empty) . The second line, on the left of the T, is the tank return.

Now here is where my extra hose goes to to provide me a drain from the T. It stays secured by a banjo fitting cap attached to the upright on my boom frame. Also note the added shutoff valve in the drain line.


Noticed it was difficult to get all the tank drained as the tank return line held quite a bit of product. Solution was to add another smaller banjo fitting in line and presto, now able to completely drain the tank. From the manifold the line on the farthest left is the tank return, or re-circulation, line. See the banjo fitting sitting low

The pump is by far the most important part of any sprayer but the second most important part is the manifold. The PSI gauge is really important as it will allow you to repeat application settings. On this Teejet model the grey knob to the left is what changes pressure. Pressure is changed by how much product is allowed to return to the tank (true with any system). the more product returning to the tank, the lower pressure you will have available at spray tips while you will have more tank agitation (or product returning to tank).


Having an easy to read gauge is important so it can be easily monitored from the tractor seat.

I should also note one other modification. to take the manifold easier to reach from the seat, we extended the mounting arm holding the bracket.

Here is a picture of the main tank filter. It is between the tank and the pump. Notice the shut off readily available in case maintenance is necessary.


So we have a path as follows: Tank to filter, filter to pump, pump to manifold, manifold back to tank. Now off the manifold we have the ability to regulate pressures and regulate where our product goes (boom, wand, so on so forth). Any sprayer built should have the same path. You can have some small differences but the basic foundation will be the same.
I am going to modify my boomless nozzle sprayer to a boom with flat fan spray tips. My concern is with clogging of the tips. Any recommendations on keeping the tips from clogging?
I am going to modify my boomless nozzle sprayer to a boom with flat fan spray tips. My concern is with clogging of the tips. Any recommendations on keeping the tips from clogging?

Use clean water first and foremost. 2nd triple rinse the tank at the end of the day or after use (including booms/tips by running with clean water briefly). Usually it is not the tip that gets clogged. It is usually the screen and this can happen fast if tank is ran "dry" and allowed to sit for a couple days or of left with mix over night.

If I know I am going to spray the same mix again within the next couple of days I stop with triple rinsing my tank and boom and leave a small amount of water in bottom of tank with booms full (Note I use spray bodies that do not allow my tips to leak out and dry)

Keep some extra in line screens handy that go in with the tips. If blockage where you believe too is blocked, swap screen with new and put other in cleaning solution as it likely will be gunked up. I have only had tips plug after leaving for long times without any cleaning. Soaking over night in tank cleaner and using compressed air to blow out has worked for me the one time when I left it setting with Gly mixed for a couple weeks without cleaning.