ILLINOIS AERIAL APPLICATION CORE EXAMS SET
QUESTIONS AND ANSWERS FIRM A+
✔✔What are the two key factors affecting off-target drift? - ✔✔spray droplets and the
percentage of droplets within a certain size range
✔✔What is the unit of measure for the diameter of a spray droplet? - ✔✔micron
✔✔Why is a small spray droplet more susceptible to drift than a larger droplet? -
✔✔because the small droplet is lighter and therefore remains airborne much longer
✔✔There is a rapid decrease in the drift potential of droplets larger than about ____
microns. - ✔✔200 microns
✔✔What do people who study drift classify droplets that are 150 to 200 microns or
smaller? - ✔✔driftable fines
✔✔Droplets below ____ microns in diameter remain suspended in the air indefinitely or
until they evaporate. - ✔✔50
✔✔All nozzles produce a range of droplet sizes, known as the __________________. -
✔✔droplet-size spectrum
✔✔What does the volume median diameter (VMD) mean? - ✔✔half of the total spray
volume of that nozzle consists of spray droplets smaller than the VMD numerical value,
while the other half is larger than the VMD numerical value
✔✔What is another way of classifying the droplet sizes produced by a nozzle? -
✔✔identify the percentage of the total spray volume that contains droplets smaller or
larger than a specific diameter, usually 200 microns
✔✔What is the most useful way to describe the droplet sizes produced by a nozzle? -
✔✔use droplet-size categories based on the entire droplet-size spectrum of a nozzle
✔✔What is this spray-classification system? - ✔✔American Society of Agricultural and
Biological Engineers standard S-572.1: Spray Nozzle Classification by Droplet Spectra
✔✔How many categories does this classification system have? - ✔✔eight categories
✔✔You should consult what when selecting nozzles? - ✔✔the pesticide label for
specific instructions
,✔✔What three physical properties of a spray mixture have a significant effect on droplet
size in aerial applications? - ✔✔dynamic surface tension
extensional viscosity
shear viscosity
✔✔The force that keeps a droplet together. - ✔✔surface tension
✔✔True/False: Surface tension of spray droplets can change after the droplets are
formed, causing a larger droplet to split into smaller droplets. - ✔✔True
✔✔The amount of stretching or "stringiness" when the pump forces spray liquid through
a nozzle orifice before it breaks off to form a droplet. - ✔✔extensional viscosity
✔✔_____ in the system, which regulates the ejection speed of the liquid, affects the
extensional viscosity. - ✔✔Pressure
✔✔_____ pressure lowers this viscosity, therefore producing smaller droplets. -
✔✔Higher
✔✔A liquid's resistance to flow. - ✔✔shear viscosity
✔✔Spray drift control adjuvants may reduce the number of drift able droplets, but may
lose their ________ when circulated through a sprayer pump. - ✔✔effectiveness
✔✔Evaporation removes water or other carriers, making the spray droplet ____ than it
was when it left the nozzle. - ✔✔smaller
✔✔The optimum time to make an aerial application when evaporation of spray droplets
is a concern is during ___________. - ✔✔the coolest part of the day
✔✔Keep the application height between ______ feet from the target to shorten the
distance that spray droplets must fall. - ✔✔8 to 12 feet
✔✔Occurs when the pesticide contacts very hot surfaces, usually soil with no
vegetation. Pesticides leave the soil surface with water molecules during rapid
evaporation that occurs immediately after irrigation. - ✔✔co-distillation
✔✔Occur as the ground heats up, usually in the afternoon, and especially after cool
night temperatures. This causes air near the ground to rise (warmer air molecules are
spaced further apart). - ✔✔thermals
✔✔When do inversions occur? - ✔✔when an upper layer of air is warmer than the air
below it (warm air cap blocks cooler air below it, preventing cooler air below it)
, generally begin before sunset and remain into early morning or near bodies of water
✔✔What are the two factors that reduce wind shear effects? - ✔✔appropriate airspeed
proper nozzle orientation
✔✔You can minimize off-target drift by confining boom length to no more than ____
percent of the wingspan of the fixed-wing aircraft or the rotor diameter on rotary-wing
aircraft. - ✔✔75 percent
✔✔You can minimize off-target drift by _____ system pressure when flying at faster
speeds to reduce the amount of smaller droplets. - ✔✔increasing
✔✔What do you use smoke generators on the aircraft for? - ✔✔to visualize air
movement at the application height or to identify inversion conditions below the
application height
✔✔Wider spray angles typically produce _____ sprays. - ✔✔finer
✔✔___________ used for pesticide application are fast, maneuverable, and carry
heavier loads than rotary-wing craft. - ✔✔Fixed-wing aircraft
✔✔A limitation of a fixed-wing aircraft is the need for a ____________, which may not
always be close to the application site. - ✔✔designated landing area
✔✔Rotary-wing aircraft used for pesticide application are more maneuverable but
_____ than fixed-wing aircraft, and can operate over a range of speeds and in almost
any area since they do not require a runway for takeoff or landing. - ✔✔slower
✔✔What is the main function of a dispersal system? - ✔✔to allow you to apply an
accurate and uniform amount of pesticide material over the application site as efficiently
as possible
✔✔Stainless steel, fiberglass, polyethylene, and polypropylene are non-corrosive, while
_____, _____, and _________ will corrode. - ✔✔steel, iron, and aluminum
✔✔The presence of pesticide residues where could be an indicator of a leaking hose or
connection somewhere in the system? - ✔✔on the belly of the aircraft
✔✔Systems that adjust the ____ _____ according to the application air speed (referred
to as flow control) provide the greatest application volume uniformity, but can affect
droplet size. - ✔✔flow volume
QUESTIONS AND ANSWERS FIRM A+
✔✔What are the two key factors affecting off-target drift? - ✔✔spray droplets and the
percentage of droplets within a certain size range
✔✔What is the unit of measure for the diameter of a spray droplet? - ✔✔micron
✔✔Why is a small spray droplet more susceptible to drift than a larger droplet? -
✔✔because the small droplet is lighter and therefore remains airborne much longer
✔✔There is a rapid decrease in the drift potential of droplets larger than about ____
microns. - ✔✔200 microns
✔✔What do people who study drift classify droplets that are 150 to 200 microns or
smaller? - ✔✔driftable fines
✔✔Droplets below ____ microns in diameter remain suspended in the air indefinitely or
until they evaporate. - ✔✔50
✔✔All nozzles produce a range of droplet sizes, known as the __________________. -
✔✔droplet-size spectrum
✔✔What does the volume median diameter (VMD) mean? - ✔✔half of the total spray
volume of that nozzle consists of spray droplets smaller than the VMD numerical value,
while the other half is larger than the VMD numerical value
✔✔What is another way of classifying the droplet sizes produced by a nozzle? -
✔✔identify the percentage of the total spray volume that contains droplets smaller or
larger than a specific diameter, usually 200 microns
✔✔What is the most useful way to describe the droplet sizes produced by a nozzle? -
✔✔use droplet-size categories based on the entire droplet-size spectrum of a nozzle
✔✔What is this spray-classification system? - ✔✔American Society of Agricultural and
Biological Engineers standard S-572.1: Spray Nozzle Classification by Droplet Spectra
✔✔How many categories does this classification system have? - ✔✔eight categories
✔✔You should consult what when selecting nozzles? - ✔✔the pesticide label for
specific instructions
,✔✔What three physical properties of a spray mixture have a significant effect on droplet
size in aerial applications? - ✔✔dynamic surface tension
extensional viscosity
shear viscosity
✔✔The force that keeps a droplet together. - ✔✔surface tension
✔✔True/False: Surface tension of spray droplets can change after the droplets are
formed, causing a larger droplet to split into smaller droplets. - ✔✔True
✔✔The amount of stretching or "stringiness" when the pump forces spray liquid through
a nozzle orifice before it breaks off to form a droplet. - ✔✔extensional viscosity
✔✔_____ in the system, which regulates the ejection speed of the liquid, affects the
extensional viscosity. - ✔✔Pressure
✔✔_____ pressure lowers this viscosity, therefore producing smaller droplets. -
✔✔Higher
✔✔A liquid's resistance to flow. - ✔✔shear viscosity
✔✔Spray drift control adjuvants may reduce the number of drift able droplets, but may
lose their ________ when circulated through a sprayer pump. - ✔✔effectiveness
✔✔Evaporation removes water or other carriers, making the spray droplet ____ than it
was when it left the nozzle. - ✔✔smaller
✔✔The optimum time to make an aerial application when evaporation of spray droplets
is a concern is during ___________. - ✔✔the coolest part of the day
✔✔Keep the application height between ______ feet from the target to shorten the
distance that spray droplets must fall. - ✔✔8 to 12 feet
✔✔Occurs when the pesticide contacts very hot surfaces, usually soil with no
vegetation. Pesticides leave the soil surface with water molecules during rapid
evaporation that occurs immediately after irrigation. - ✔✔co-distillation
✔✔Occur as the ground heats up, usually in the afternoon, and especially after cool
night temperatures. This causes air near the ground to rise (warmer air molecules are
spaced further apart). - ✔✔thermals
✔✔When do inversions occur? - ✔✔when an upper layer of air is warmer than the air
below it (warm air cap blocks cooler air below it, preventing cooler air below it)
, generally begin before sunset and remain into early morning or near bodies of water
✔✔What are the two factors that reduce wind shear effects? - ✔✔appropriate airspeed
proper nozzle orientation
✔✔You can minimize off-target drift by confining boom length to no more than ____
percent of the wingspan of the fixed-wing aircraft or the rotor diameter on rotary-wing
aircraft. - ✔✔75 percent
✔✔You can minimize off-target drift by _____ system pressure when flying at faster
speeds to reduce the amount of smaller droplets. - ✔✔increasing
✔✔What do you use smoke generators on the aircraft for? - ✔✔to visualize air
movement at the application height or to identify inversion conditions below the
application height
✔✔Wider spray angles typically produce _____ sprays. - ✔✔finer
✔✔___________ used for pesticide application are fast, maneuverable, and carry
heavier loads than rotary-wing craft. - ✔✔Fixed-wing aircraft
✔✔A limitation of a fixed-wing aircraft is the need for a ____________, which may not
always be close to the application site. - ✔✔designated landing area
✔✔Rotary-wing aircraft used for pesticide application are more maneuverable but
_____ than fixed-wing aircraft, and can operate over a range of speeds and in almost
any area since they do not require a runway for takeoff or landing. - ✔✔slower
✔✔What is the main function of a dispersal system? - ✔✔to allow you to apply an
accurate and uniform amount of pesticide material over the application site as efficiently
as possible
✔✔Stainless steel, fiberglass, polyethylene, and polypropylene are non-corrosive, while
_____, _____, and _________ will corrode. - ✔✔steel, iron, and aluminum
✔✔The presence of pesticide residues where could be an indicator of a leaking hose or
connection somewhere in the system? - ✔✔on the belly of the aircraft
✔✔Systems that adjust the ____ _____ according to the application air speed (referred
to as flow control) provide the greatest application volume uniformity, but can affect
droplet size. - ✔✔flow volume
