Experiment

Hypothesis
    As the hypothesis for this experiment, we expect that the higher the spray pressure and the lower amount of gallons sprayed, the more drift there will be.  The goal of our experiment is to determine what type of nozzles have the least amount of drift on average (flat fan, Turbo TeeJet, air induction).  We also want to determine if it is worthwhile to upgrade to the more expensive and newly developed air induction nozzles, opposed to staying with the cheaper and more recognizable extended range or flat fan nozzles.
 

Procedure
    Below is a table of the types of  nozzles that were used in our experiment:

 
Gallons Sprayed Per Minute (At 40 PSI)
0.15 gallons 0.20 gallons 0.30 gallons 0.80 gallons
XR110015VS XR11002VS XR11003VS XR11008VS
TT110015-VP TT11002-VP TT11003-VP TT11008-VP
AI110015-VS AI11002-VS AI11003-VS AI11008-VS
 
    This table states the amount of gallons sprayed per minute at 40 PSI for the following nozzles.  All nozzles that spray 0.15 gallons under these conditions are colored green, nozzles that spray 0.20 gallons are colored yellow, nozzles that spray 0.30 gallons are colored blue, and nozzles that spray 0.80 gallons are colored white.  We included the 0.80 gallon per minute nozzles, because of the reason that these nozzles are used for desiccating broadleaf crops in harvest time (which requires a large amount of water to sprayed in a short time span).  These three nozzles types were chosen because they are designed specifically for the various farming practices that confront agriculture producers in the northern great plain states and Saskatchewan.  The main uses of these nozzles are in the application of insecticides, herbicides and other pesticides over a wide range of cereal and broadleaf crops.   These nozzles also spray at a 110 degree angle.  Below are pictures of these nozzles:
 
 
XR TeeJet Nozzles
XR110015VS
XR11002VS
XR11003VS
XR11008VS
 
 
Turbo TeeJet Nozzles
TT110015-VP
TT11002-VP
TT11003-VP
TT11008-VP
 
 
Air Induction Nozzles
AI110015-VS
AI11002-VS
AI11003-VS
AI11008-VS
 

    The first step in this experiment was to set up the area where the nozzles were tested.  We tested the nozzles with our ATV sprayer set, as shown in the picture below:
 
 
 

ATV Sprayer Unit
ATV Sprayer Controls
 
 

     When we set up the spray unit for the experiment, we made sure that the distance of the air hose (wind) was the same distance (12 inches) and angle from the nozzle for each trial. The temperature in the shop was set at 59ºF / 15ºC, to stimulate ideal spraying conditions (night spraying).  We also made sure that the boom height was the same (around 22 inches) for every observation.

 
 
    Obviously, what we measured in this experiment was the drift of the spray.  Ideally, the area most prone to drift is the fan of spray coming out of the nozzles along the boom.  If the spray drifts toward the front of the sprayer from a wind at the back, the implications of that spray is not very serious, since most of the drift is stopped by the sprayer.  Thus, the spray is most prone to damage (more contact with wind) when it drifts to the opposite direction of the boom (behind the sprayer).  Since the sides of the of the spray fan cover a relatively small surface area, and are well defined, they are seldom prone to drift.  We used an air compressor, with a wind meter to detect the wind speed, to create a controlled wind environment for the spray (as seen below). The distance of the spray mist was determined to the point in which it could be barely detected on the back of a person's hand, and not be readily be detected beyond that point (the mist was so fine, that it could not be measured).  This was the most effective and accurate way of measuring the distance of the spray drift droplets.  Since TeeJet is a multinational company, and quite possibly the world leader in agricultural spray products, a person can basically guarantee that all new spray nozzles with the TeeJet name will perform exceptionally well with uniform spray coverage across the boom under all / most circumstances.
 
 
    For this experiment, we tested the nozzles under different wind speeds (0 mph, 10 mph, 20 mph, 30 mph and 40 mph).  We also controlled the spray pressure, which was either 20 PSI, 40 PSI, 60 PSI or 80 PSI.  After the experiment, we recorded our observations.
 

Observations
 

Measuring spray drift
 
 
Observations for Nozzles under Different PSI Pressures
20 PSI
 40 PSI 
60 PSI
80 PSI
Averaged Results
 

Conclusion
    As the conclusion for this experiment, we found the nozzles that sprayed the less liquid drifted more than the nozzles that sprayed more.  We also found that spray drift was more common as the spray pressure increased, but not with the Air Induction (AI) nozzles.  Therefore, the XR TeeJet nozzles drifted the most on average, with the Turbo TeeJet nozzles drifting the second most drift, and the Air Induction nozzles drifting the lowest amount of mist.  These nozzles seemed to have the same drift measurements under all spray pressures.  The Air Induction nozzles seemed to work better under higher spray pressures, while the XR TeeJet (Flat Tip) nozzles seemed to operate better under lower spray pressures.  For most spraying uses, the normal XR TeeJet nozzles might be the best, because most farmers do not need them for crops that require higher spray pressures, unlike custom spraying (the higher the PI pressure, the faster the application time).  These nozzles are also the cheapest, at around $3.50 per nozzle tip (or less), and are readily available in most rural areas.  The Air Induction nozzles worked the best under averaged conditions, but they cost around $10.00 per nozzle tip, and are hard to get a hold of.  Under specific circumstances, however, the performance of the nozzles varied.  Under conditions where the wind speed does not exceed 20 mph, the Turbo TeeJet nozzles appear to perform the most ideal, with the least amount of drift out of the three nozzle types (at a cost of around $5.00 per nozzle tip).
    Ideally, most sprayers have a 90 foot boom width.  Since nozzles are spaced 20 inches apart, that means that there would be around 54 spray nozzles/caps on the sprayer.  The cost of just buying the nozzle tips for the sprayer (not including the cap or filter, and taxes) would be around $190.00 for XR TeeJet nozzles, and $540.00 for the AI TeeJet nozzles.  A difference of $350.00 is merely a drop in the bucket, compared to the cost of spray and other agricultural inputs.  Therefore, the cost of the nozzle tips should not be used factor in determining what nozzle tip to purchase.  One may also point out, that it is very unethical to spray in winds above 10 mph, because of the risk in damaging the neighbor's crop.
    With all this said, we have concluded that for custom spraying, the best choice would be to purchase air induction nozzles.  However, the use of air induction nozzles should not be needed in spraying.  For the application of pesticides under perfect, no wind conditions, the use of regular extended range nozzles is sufficient (because the finer mist of these nozzles make better contact for the spray of the pesticide, compared to the courser droplets of air induction nozzles).  Depending on the spray application, it is important to note, that all nozzles have practical uses which make them outperform the other nozzle types (contact, systemic contact, etc.).

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