ASTM E642-91(2014)
(Practice)Standard Practice for Determining Application Rates and Distribution Patterns from Aerial Application Equipment
Standard Practice for Determining Application Rates and Distribution Patterns from Aerial Application Equipment
ABSTRACT
This practice covers uniform procedures for determining and reporting application rates and distribution patterns from agricultural aircraft. The procedures covered deal with both fixed and rotary-wing aircraft equipped with either liquid or dry material distribution systems. The physical characteristics of the liquid or dry material have an effect on the application rate and the distribution patterns. If inert test solutions for materials are substituted for the materials to be applied, they shall have physical characteristics similar to those of the material to be applied. If toxic materials are used in the tests, all safety precautions prescribed. A complete procedure shall consist of five parts: the first part is the determination of the output rate from the aircraft system, the second part involves the determination of the swath distribution pattern by recovery of the applied materials from suitable collectors, the third part covers the determination of usable swath width for field applications, the fourth part discusses the determination of the rate of application of the spray mixture or dry material, and the fifth and last part is the determination of the uniformity of distribution of several swaths.
SCOPE
1.1 This practice covers uniform procedures for determining and reporting application rates and distribution patterns from agricultural aircraft. This practice should not be used for making biological performance tests.
1.2 The procedures covered deal with both fixed and rotary-wing aircraft equipped with either liquid or dry material distribution systems.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E642 − 91 (Reapproved 2014)
Standard Practice for
Determining Application Rates and Distribution Patterns
from Aerial Application Equipment
This standard is issued under the fixed designation E642; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope the materials to be applied, they shall have physical character-
istics similar to those of the material to be applied. If toxic
1.1 Thispracticecoversuniformproceduresfordetermining
materials are used in the tests, all safety precautions prescribed
and reporting application rates and distribution patterns from
by the manufacturer and governmental authority for handling,
agricultural aircraft. This practice should not be used for
loading, application, and disposal of toxic materials shall be
making biological performance tests.
observed.
1.2 The procedures covered deal with both fixed and rotary-
3.2 Pattern tests shall be conducted, with wind speeds not
wing aircraft equipped with either liquid or dry material
exceeding 16 km/h (10 mph), measured 2.5 m (8.2 ft) above
distribution systems.
the land surface or crop canopy. If wind occurs, flights shall be
1.3 The values stated in SI units are to be regarded as
made both into and with the wind to minimize the effects of
standard. The values given in parentheses are mathematical
wind velocity on ground speed. Flights shall be made parallel
conversions to inch-pound units that are provided for informa-
to or within 20° of the direction of the wind to minimize errors
tion only and are not considered standard.
due to crosswinds.These restrictions do not apply to the output
1.4 This standard does not purport to address all of the
rate tests.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Procedure
priate safety and health practices and determine the applica-
4.1 A complete procedure shall consist of five parts:
bility of regulatory limitations prior to use.
4.1.1 Determination of the output rate from the aircraft
system.
2. Referenced Documents
4.1.2 Determination of the swath distribution pattern by
2.1 ASTM Standards:
recovery of the applied materials from suitable collectors.
E726 Test Method for Particle Size Distribution of Granular
4.1.3 Determination of usable swath width for field appli-
Carriers and Granular Pesticides
cations.
2.2 ASAE Standard:
4.1.4 Determination of the rate of application of the spray
ASAE S327.1 Terminology and Definitions for Agricultural
mixture or dry material, and
Chemical Application
4.1.5 Determination of the uniformity of distribution of
3. Test Conditions several swaths.
3.1 The physical characteristics of the liquid or dry material
4.2 Output Rate Determination:
have an effect on the application rate and the distribution
4.2.1 Liquid Materials—Determine the output rate by the
patterns. If inert test solutions for materials are substituted for
amount of liquid discharged from the tank for a measured time
interval while the aircraft is in flight under normal conditions.
The time interval shall be sufficient to permit accurate mea-
This practice is under the jurisdiction of ASTM Committee E35 on Pesticides,
surement of liquid discharged and to minimize errors due to
Antimicrobials, and Alternative Control Agents and is the direct responsibility of
Subcommittee E35.22 on Pesticide Formulations and Delivery Systems.
turning the system on and off. Run the system for at least 30 s
Current edition approved Oct. 1, 2014. Published December 2014. Originally
and measure to the nearest 0.5 s. Measure the amount of liquid
approvedin1978.Lastpreviouseditionapprovedin2008asE642 – 91(2008).DOI:
used by either refilling the tank to the initial level or by
10.1520/E0642-91R14.
measuring the amount remaining in the tank and subtracting
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
from the initial amount. Measurement precision shall be 62%
Standards volume information, refer to the standard’s Document Summary page on
of the amount discharged in the test. If the liquid dispersal
the ASTM website.
system can be operated with the aircraft stationary, the test can
Available from American Society of Agricultural and Biological Engineers
(ASABE), 2950 Niles Rd., St. Joseph, MI 49085, http://www.asabe.org. be accomplished without actually flying the aircraft. Report
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E642 − 91 (2014)
output rate in litres per minute (gallons per minute), and note numbers, an appropriate area must be scanned to obtain a true
the nozzle (boom) pressure. representation of the droplet-size distribution in the sample.
4.2.2 Dry Materials—If venturi distributors are used, deter- 4.3.3.5 Qualitative Spray Distribution Pattern
mine the output rate by measuring the amount of material Measurement—A qualitative measure of the distribution pat-
dischargedfromthehopperoveragiventimeintervalwhilethe
tern may be used to diagnose and correct distribution system
aircraft is in flight under normal conditions. Precision of deficiencies (plugged or worn nozzles, improper size nozzles,
measurement of time and materials as specified in 4.2.1 shall
system leaks, improperly placed nozzles, and so forth). Quali-
apply here. Run tests with the aircraft hopper filled to at least tative distribution pattern measurement techniques may em-
25 % of capacity. Report the output rate, in kilograms per
ploy discrete sample targets or a continuous collector placed
minute (pounds per minute), and the control settings used to
across the flight line of the aircraft. The measurement tech-
achieve this rate.
nique used should provide a relative or absolute measure of the
deposition on the sample surfaces across the flight line.
4.3 Swath Distribution Pattern Test:
4.3.4 Dry Material Test Procedure and Collectors:
4.3.1 Conduct this test by flying the aircraft over the center
4.3.4.1 Granular materials are normally tested by capturing
of a collection line placed at a right angle to the line of flight.
samples of the swath in buckets or collectors that are high
The collection line may be placed on the land surface or crop
enough to prevent the particles bouncing into or out of the
height (or any other height consistent with the purpose of the
containers. Collect dust or other small particles on greased
test), and shall permit collection of a representative sample of
boards or other sticky surfaces, or in shallow pans. Weigh or
the distribution pattern for the dispersed material. Fly the
count the material collected in these devices, or dissolve in a
aircraftataheightsuitedtothetypeofmaterialappliedandthe
solution for analysis as appropriate.
purpose of the application. The airspeed shall be that for the
intended application and the flight shall be level and straight. 4.3.4.2 The area of the top opening of the collectors shall be
2 2
0.1 m (1 ft ) or larger, to provide a representative sample of
Extend the collection line at least 3 m (10 ft) beyond the ends
of the pattern being tested. Measure ambient temperature, the deposit. Spacing of the collectors along the swath shall not
exceed1m(3 ft).
humidity,andwindspeedanddirection(withrespecttotheline
of flight) at 1 to3m(3to10ft) above the land surface or crop
4.4 Sample Analysis and Conversion of Swath Distribution
canopy. Note the height of flight and the airspeed.
Pattern Data:
4.3.2 Turn on the distribution equipment in the aircraft at
4.4.1 Spray Pattern Test:
least 100 m (300 ft) prior to crossing the collection line, and
4.4.1.1 For quantifying spray deposits using tracer
continue operating it the same distance beyond. Run three
materials, any type of sample analysis may be used that is
replications of each test. Make each replication with a separate
compatible with the spray tracer. Examples are photoelectric
single pass of the aircraft. Note the direction of flight with
colorimetry, absorption or emission spectroscopy, and liquid or
respect to wind direction.
gas chromatography, where the sensitivity of the analysis shall
4.3.3 Spray Test Procedure and Target Collectors:
be at least 2 ppm. After a collector is washed in accordance
4.3.3.1 An inert chemical or dye tracer material may be
with 4.3.3, the concentration of tracer may be determined by
added to the contents of the spray tank, or the active chemical
use of a standard calibration curve developed for the tracer and
may be used as a tracer for the spray pattern tests. If inert
the analytical method employed. The rate of spray deposit in
materials are used, include suitable amounts of emulsifier,
litres per hectare (gallons per acre) may then be determined for
spreader-stickers, and other solvents and carriers to closely
each location across the collection line as follows:
simulate the material to be applied.
D 5 K 3 V 3 C / C 3 A (1)
~ ! ~ !
t t s
4.3.3.2 The spray collection line may be composed of
where:
discrete targets or a narrow continuous surface. Quantitative
analysisofthespraydepositedonthetargetcollector(s)maybe
D = deposit rate, L/ha (gal/acre),
accomplished by electronic scanning or by washing tracer
K = constant, 10 (or 1657),
2 2
material from the collector surface(s). A = collector area, cm (in. ),
= volume of solvent used to wash tracer from target, mL,
4.3.3.3 If the pattern is determined from the amount of t
C = concentration of tracer washed from collector, mg/L,
t
tracer material recovered from the line, the surface of the
and
collector(s) shall permit all or a constant percentage of the
C = concentration of collector in original spray solution,
s
tracer to be removed by washing. If the tracer used degrades
mg/L.
due to exposure to sunlight, age, or other factors, the results
should be corrected to compensate for the degradation. If
4.4.1.2 Quantifying spray deposits using image scanning of
discrete targets are used, they may be flat sheets, or have raised
discrete or continuous sample surfaces shall utilize sufficient
edges to facilitate washing.The exposed flat surface (exclusive
size classes, preferably at least 20, to accurately define the
2 2
of raised edges) shall have an area of at least 50 cm (7.8 in. ).
droplet size distribution. A droplet size versus spread factor
Spacing of descrete targets across the swath shall not exceed 1
function covering the droplet size range encountered under test
m (3.3 ft).
conditions (temperature and relative humidity) shall be devel-
4.3.3.4 For samples that are electronically scanned to mea- oped for the sample surface material and test liquid and used in
suredepositiononthesamplesurfacebasedondropletsizeand calculating the deposit volume per unit of area.
E642 − 91 (2014)
4.4.2 Dry Material Test—If the dry material deposited in the swath patterns are skewed due to crosswind, simulated field
collection device at each location across the line of collectors distributions for back-and-forth applications may indicate ar-
is weighed, the deposit rate may be determined in kg/ha tificial irregularities. Determination of the effective swath
(lb/acre) as follows: width from the simulated field distribution data is accom-
plished by calculating the coefficient of variation (CV) in
D 5 K 3 W /A (2)
~ !
accordance with 4.7.3, for overlapped rates of deposit obtained
where:
from sampling intervals from one swath center line to the next
D = deposit rate, kg/ha (lb/acre),
for one-direction application, or from two swath spacings for
K = constant, 10 (13 829),
back-and-forth application. Field distribution simulations will
W = weight collected, g, and
be made and CV’s calculated for swath center line spacings
2 2
A = area of collector opening, cm (or in. ).
ranging from one sampling interval width to the total width of
the single swath pattern. Swath increments for the CV calcu-
If the collected material is of a nature to make counting of
lations shall not be greater than the sampling interval (or one
individual particles desirable, express the results as the number
2 2 2 2 2
meter for continuous sampling) across the swath. The largest
of particles per unit area, such as cm , 0.1 m,m (in.,ft ). If
swath width associated with the minimum acceptable CV for
the material collected is a dust, it may be desirable to use
the intended application shall be considered the effective swath
greased boards or other sticky surfaces, or shallow pans
width.
holding a solute as collectors. Procedures similar to those
outlinedin4.4.1maybeusedforanalysisofdustdepositsifthe
4.6 Rate of Application—Calculate the overall rate of appli-
dust itself can serve as the tracer material, or a suitable tracer
cation as follows:
material is mixed with the dust. Express the deposit rate in
R 5 ~Q 3 K!/~V 3 S! (3)
kilograms per hectare (pounds per acre) at each location across
the line of collectors.
where:
R = rate of application, L/ha or kg/ha (gal/acre or lb/acre),
4.5 Plotting the Distribution Curve and Evaluating Swath
Q = output rate, L/min or kg/min (gpm or lb/min),
Widths—Data for each test replication from 4.4.1 or 4.4.2 will
K = constant, 600 (495),
be plotted with the rate of deposit on the ordinate and the
V = velocity over ground, km/h (mph), and
location of deposit with respect to the aircraft center line on the
S = usable swath width, m (ft).
abscissa. This data, or the resulting plot, or both, will be used
4.7 Uniformity of Distribution—Use the coefficient of varia-
to determine the maximum effective swath width for each
tion to express the uniformity of distribution of application
replication either by inspection as described in 4.5.1 or by
resulting from multiple adjacent swaths. The multiple swaths
simulated overlapping of swaths and statistical analysis as
can be simulated for each distribution pattern replication
described in 4.5.2. The usable swath width will be obtained by
plottedin4.5orfromactualflighttestsusingasufficientlylong
averaging the maximum effective widths determined for the
collection line. Also plot the resulting distribution to permit
individual replicates and will be used in calculating the rate of
visual examination for deposit peaks and low points that may
application as described in 4.6.
occur.
4.5.1 Effective Swath Width by Inspection—The distribution
4.7.1 Simulated Field Distribution:
pattern for most aerially applied materials should approximate
4.7.1.1 Determine the simulated
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E642 − 91 (Reapproved 2008) E642 − 91 (Reapproved 2014)
Standard Practice for
Determining Application Rates and Distribution Patterns
from Aerial Application Equipment
This standard is issued under the fixed designation E642; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers uniform procedures for determining and reporting application rates and distribution patterns from
agricultural aircraft. This practice should not be used for making biological performance tests.
1.2 The procedures covered deal with both fixed and rotary-wing aircraft equipped with either liquid or dry material distribution
systems.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions
to inch-pound units that are provided for information only and are not considered standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
E726 Test Method for Particle Size Distribution of Granular Carriers and Granular Pesticides
2.2 ASAE Standard:
ASAE S327.1 Terminology and Definitions for Agricultural Chemical Application
3. Test Conditions
3.1 The physical characteristics of the liquid or dry material have an effect on the application rate and the distribution patterns.
If inert test solutions for materials are substituted for the materials to be applied, they shall have physical characteristics similar
to those of the material to be applied. If toxic materials are used in the tests, all safety precautions prescribed by the manufacturer
and governmental authority for handling, loading, application, and disposal of toxic materials shall be observed.
3.2 Pattern tests shall be conducted, with wind speeds not exceeding 16 km/h (10 mph), measured 2.5 m (8.2 ft) above the land
surface or crop canopy. If wind occurs, flights shall be made both into and with the wind to minimize the effects of wind velocity
on ground speed. Flights shall be made parallel to or within 20° of the direction of the wind to minimize errors due to crosswinds.
These restrictions do not apply to the output rate tests.
4. Procedure
4.1 A complete procedure shall consist of five parts:
4.1.1 Determination of the output rate from the aircraft system.
4.1.2 Determination of the swath distribution pattern by recovery of the applied materials from suitable collectors.
4.1.3 Determination of usable swath width for field applications.
4.1.4 Determination of the rate of application of the spray mixture or dry material, and
4.1.5 Determination of the uniformity of distribution of several swaths.
This practice is under the jurisdiction of ASTM Committee E35 on Pesticides, Antimicrobials, and Alternative Control Agents and is the direct responsibility of
Subcommittee E35.22 on Pesticide Formulations and Delivery Systems.
Current edition approved Oct. 1, 2008Oct. 1, 2014. Published November 2008December 2014. Originally approved in 1978. Last previous edition approved in 20022008
as E642 – 91(2002).(2008). DOI: 10.1520/E0642-91R08.10.1520/E0642-91R14.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American Society of Agricultural and Biological Engineers (ASABE), 2950 Niles Rd., St. Joseph, MI 49085, http://www.asabe.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E642 − 91 (2014)
4.2 Output Rate Determination:
4.2.1 Liquid Materials—Determine the output rate by the amount of liquid discharged from the tank for a measured time interval
while the aircraft is in flight under normal conditions. The time interval shall be sufficient to permit accurate measurement of liquid
discharged and to minimize errors due to turning the system on and off. Run the system for at least 30 s and measure to the nearest
0.5 s. Measure the amount of liquid used by either refilling the tank to the initial level or by measuring the amount remaining in
the tank and subtracting from the initial amount. Measurement precision shall be 62 % of the amount discharged in the test. If
the liquid dispersal system can be operated with the aircraft stationary, the test can be accomplished without actually flying the
aircraft. Report output rate in litres per minute (gallons per minute), and note the nozzle (boom) pressure.
4.2.2 Dry Materials—If venturi distributors are used, determine the output rate by measuring the amount of material discharged
from the hopper over a given time interval while the aircraft is in flight under normal conditions. Precision of measurement of time
and materials as specified in 4.2.1 shall apply here. Run tests with the aircraft hopper filled to at least 25 % of capacity. Report
the output rate, in kilograms per minute (pounds per minute), and the control settings used to achieve this rate.
4.3 Swath Distribution Pattern Test:
4.3.1 Conduct this test by flying the aircraft over the center of a collection line placed at a right angle to the line of flight. The
collection line may be placed on the land surface or crop height (or any other height consistent with the purpose of the test), and
shall permit collection of a representative sample of the distribution pattern for the dispersed material. Fly the aircraft at a height
suited to the type of material applied and the purpose of the application. The airspeed shall be that for the intended application
and the flight shall be level and straight. Extend the collection line at least 3 m (10 ft) beyond the ends of the pattern being tested.
Measure ambient temperature, humidity, and wind speed and direction (with respect to the line of flight) at 1 to 3 m (3 to 10 ft)
above the land surface or crop canopy. Note the height of flight and the airspeed.
4.3.2 Turn on the distribution equipment in the aircraft at least 100 m (300 ft) prior to crossing the collection line, and continue
operating it the same distance beyond. Run three replications of each test. Make each replication with a separate single pass of the
aircraft. Note the direction of flight with respect to wind direction.
4.3.3 Spray Test Procedure and Target Collectors:
4.3.3.1 An inert chemical or dye tracer material may be added to the contents of the spray tank, or the active chemical may be
used as a tracer for the spray pattern tests. If inert materials are used, include suitable amounts of emulsifier, spreader-stickers, and
other solvents and carriers to closely simulate the material to be applied.
4.3.3.2 The spray collection line may be composed of discrete targets or a narrow continuous surface. Quantitative analysis of
the spray deposited on the target collector(s) may be accomplished by electronic scanning or by washing tracer material from the
collector surface(s).
4.3.3.3 If the pattern is determined from the amount of tracer material recovered from the line, the surface of the collector(s)
shall permit all or a constant percentage of the tracer to be removed by washing. If the tracer used degrades due to exposure to
sunlight, age, or other factors, the results should be corrected to compensate for the degradation. If discrete targets are used, they
may be flat sheets, or have raised edges to facilitate washing. The exposed flat surface (exclusive of raised edges) shall have an
2 2
area of at least 50 cm (7.8 in. ). Spacing of descrete targets across the swath shall not exceed 1 m (3.3 ft).
4.3.3.4 For samples that are electronically scanned to measure deposition on the sample surface based on droplet size and
numbers, an appropriate area must be scanned to obtain a true representation of the droplet-size distribution in the sample.
4.3.3.5 Qualitative Spray Distribution Pattern Measurement—A qualitative measure of the distribution pattern may be used to
diagnose and correct distribution system deficiencies (plugged or worn nozzles, improper size nozzles, system leaks, improperly
placed nozzles, and so forth). Qualitative distribution pattern measurement techniques may employ discrete sample targets or a
continuous collector placed across the flight line of the aircraft. The measurement technique used should provide a relative or
absolute measure of the deposition on the sample surfaces across the flight line.
4.3.4 Dry Material Test Procedure and Collectors:
4.3.4.1 Granular materials are normally tested by capturing samples of the swath in buckets or collectors that are high enough
to prevent the particles bouncing into or out of the containers. Collect dust or other small particles on greased boards or other sticky
surfaces, or in shallow pans. Weigh or count the material collected in these devices, or dissolve in a solution for analysis as
appropriate.
2 2
4.3.4.2 The area of the top opening of the collectors shall be 0.1 m (1 ft ) or larger, to provide a representative sample of the
deposit. Spacing of the collectors along the swath shall not exceed 1 m (3 ft).
4.4 Sample Analysis and Conversion of Swath Distribution Pattern Data:
4.4.1 Spray Pattern Test:
4.4.1.1 For quantifying spray deposits using tracer materials, any type of sample analysis may be used that is compatible with
the spray tracer. Examples are photoelectric colorimetry, absorption or emission spectroscopy, and liquid or gas chromatography,
where the sensitivity of the analysis shall be at least 2 ppm. After a collector is washed in accordance with 4.3.3, the concentration
of tracer may be determined by use of a standard calibration curve developed for the tracer and the analytical method employed.
The rate of spray deposit in litres per hectare (gallons per acre) may then be determined for each location across the collection line
as follows:
E642 − 91 (2014)
D 5 K 3V 3C / C 3A (1)
~ ! ~ !
t t s
where:
D = deposit rate, L/ha (gal/acre),
K = constant, 10 (or 1657),
2 2
A = collector area, cm (in. ),
= volume of solvent used to wash tracer from target, mL,
t
C = concentration of tracer washed from collector, mg/L, and
t
C = concentration of collector in original spray solution, mg/L.
s
4.4.1.2 Quantifying spray deposits using image scanning of discrete or continuous sample surfaces shall utilize sufficient size
classes, preferably at least 20, to accurately define the droplet size distribution. A droplet size versus spread factor function
covering the droplet size range encountered under test conditions (temperature and relative humidity) shall be developed for the
sample surface material and test liquid and used in calculating the deposit volume per unit of area.
4.4.2 Dry Material Test—If the dry material deposited in the collection device at each location across the line of collectors is
weighed, the deposit rate may be determined in kg/ha (lb/acre) as follows:
D 5 ~K 3W!/A (2)
where:
D = deposit rate, kg/ha (lb/acre),
K = constant, 10 (13 829),
W = weight collected, g, and
2 2
A = area of collector opening, cm (or in. ).
If the collected material is of a nature to make counting of individual particles desirable, express the results as the number of
2 2 2 2 2
particles per unit area, such as cm , 0.1 m , m (in. , ft ). If the material collected is a dust, it may be desirable to use greased boards
or other sticky surfaces, or shallow pans holding a solute as collectors. Procedures similar to those outlined in 4.4.1 may be used
for analysis of dust deposits if the dust itself can serve as the tracer material, or a suitable tracer material is mixed with the dust.
Express the deposit rate in kilograms per hectare (pounds per acre) at each location across the line of collectors.
4.5 Plotting the Distribution Curve and Evaluating Swath Widths—Data for each test replication from 4.4.1 or 4.4.2 will be
plotted with the rate of deposit on the ordinate and the location of deposit with respect to the aircraft center line on the abscissa.
This data, or the resulting plot, or both, will be used to determine the maximum effective swath width for each replication either
by inspection as described in 4.5.1 or by simulated overlapping of swaths and statistical analysis as described in 4.5.2. The usable
swath width will be obtained by averaging the maximum effective widths determined for the individual replicates and will be used
in calculating the rate of application as described in 4.6.
4.5.1 Effective Swath Width by Inspection—The distribution pattern for most aerially applied materials should approximate
either a triangular or a trapezoidal pattern with the maximum rate of deposit under the flight path of the aircraft. The rate of deposit
should taper off evenly at the edges of the pattern. The effective swath width may be determined as the distance between points
on either side of the pattern where the rate of deposit equals one half of the maximum rate for the pattern. If a pattern contains
spurious peak deposit rates or other irregularities, it should either not be used to determine effective swath width or such
irregularities should be discounted.
4.5.2 Effective Swath Width by Simulated Overlapping and Statistical Analysis—The single swath patterns shall be plotted
around the aircraft center line as multiple adjacent swaths, with additive deposits in the overlapped regions to obtain a composite
plot showing simulated field distribution. Since the distribution patterns often are not perfectly symmetrical, plots may be prepared
to simulate both the one-direction and back-and-forth methods of application. Enough patterns must be overlapped to ensure a
representative simulated field distribution that would be unaffected by additional swaths (a minimum of four swaths for
one-direction or five for back-and-forth application, if the tails of the distribution pattern extend beyond the center line of adjacent
swaths). If the single swath patterns are skewed due to crosswind
...
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