ASTM F1737/F1737M-23
(Guide)Standard Guide for Use of Oil Spill Dispersant Application Equipment During Spill Response: Boom and Nozzle Systems
Standard Guide for Use of Oil Spill Dispersant Application Equipment During Spill Response: Boom and Nozzle Systems
SIGNIFICANCE AND USE
3.1 This guide provides information, procedures, and requirements for management and operation of dispersant spray application equipment (boom and nozzle systems) in oil spill response.
3.2 This guide provides information on requirements for storage and maintenance of dispersant spray equipment and associated materials.
3.3 This guide will aid operators in ensuring that a dispersant spray operation is carried out in an effective manner.
SCOPE
1.1 This guide covers considerations for the maintenance, storage, and use of oil spill dispersant application systems.
1.2 This guide is applicable to spray systems employing booms and nozzles and not to other systems such as fire monitors or single-point spray systems.
1.3 This guide is applicable to systems employed on ships or boats and helicopters or airplanes.
1.4 This guide is applicable to temperate weather conditions and may not be applicable to freezing conditions.
1.5 This guide is one of five related to dispersant application systems. Guide F1413/F1413M covers design, Practice F1460/F1460M covers calibration, Test Method F1738 covers deposition, Guide F1737 covers the use of the systems, and Guide F2465/F2465M covers the design and specification for single-point spray systems. Familiarity with all five standards is recommended.
1.6 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.7 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F1737/F1737M − 23
Standard Guide for
Use of Oil Spill Dispersant Application Equipment During
Spill Response: Boom and Nozzle Systems
This standard is issued under the fixed designation F1737/F1737M; 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 2. Referenced Documents
1.1 This guide covers considerations for the maintenance, 2.1 ASTM Standards:
storage, and use of oil spill dispersant application systems. F1413/F1413M Guide for Oil Spill Dispersant Application
Equipment: Boom and Nozzle Systems
1.2 This guide is applicable to spray systems employing
F1460/F1460M Practice for Calibrating Oil Spill Dispersant
booms and nozzles and not to other systems such as fire
Application Equipment Boom and Nozzle Systems
monitors or single-point spray systems.
F1738 Test Method for Determination of Deposition of
1.3 This guide is applicable to systems employed on ships
Aerially Applied Oil Spill Dispersants
or boats and helicopters or airplanes.
F2465/F2465M Guide for Oil Spill Dispersant Application
Equipment: Single-point Spray Systems
1.4 This guide is applicable to temperate weather conditions
and may not be applicable to freezing conditions. F2532 Guide for Determining Net Environmental Benefit of
Dispersant Use
1.5 This guide is one of five related to dispersant application
systems. Guide F1413/F1413M covers design, Practice F1460/
3. Significance and Use
F1460M covers calibration, Test Method F1738 covers
3.1 This guide provides information, procedures, and re-
deposition, Guide F1737 covers the use of the systems, and
quirements for management and operation of dispersant spray
Guide F2465/F2465M covers the design and specification for
application equipment (boom and nozzle systems) in oil spill
single-point spray systems. Familiarity with all five standards
response.
is recommended.
3.2 This guide provides information on requirements for
1.6 Units—The values stated in either SI units or inch-
storage and maintenance of dispersant spray equipment and
pound units are to be regarded separately as standard. The
associated materials.
values stated in each system may not be exact equivalents;
therefore, each system shall be used independently of the other.
3.3 This guide will aid operators in ensuring that a disper-
Combining values from the two systems may result in non- sant spray operation is carried out in an effective manner.
conformance with the standard.
4. Background to the Use of Dispersants and Spray
1.7 This standard does not purport to address all of the
Systems
safety concerns, if any, associated with its use. It is the
4.1 Primary Considerations:
responsibility of the user of this standard to establish appro-
4.1.1 Use of dispersants, particularly in a specific area, may
priate safety, health, and environmental practices and deter-
be subject to regulatory approval. Net Environmental Benefit
mine the applicability of regulatory limitations prior to use.
Analysis is used for dispersant decision-making (Guide
1.8 This international standard was developed in accor-
F2532). Dispersant response is for use in the early stages of a
dance with internationally recognized principles on standard-
spill; so, it is strongly recommended that a pre-approval
ization established in the Decision on Principles for the
mechanism, or rapid approval, be part of response planning.
Development of International Standards, Guides and Recom-
4.1.2 Nature of Oil Slick(s) to Be Treated:
mendations issued by the World Trade Organization Technical
4.1.2.1 The effectiveness of dispersants is dependent (as-
Barriers to Trade (TBT) Committee.
suming proper application) on two factors; the oil composition
and the sea surface energy. The primary factor is the oil
This guide is under the jurisdiction of ASTM Committee F20 on Hazardous
Substances and Oil Spill Response and is the direct responsibility of Subcommittee
F20.13 on Treatment. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 1, 2023. Published March 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1996. Last previous edition approved in 2019 as F1737/F1737M – 19. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/F1737_F1737M-23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1737/F1737M − 23
composition. Heavier oils, those that contain large amounts of 5.5 Dispersant application systems on single-engine air-
components such as asphaltenes, disperse poorly, and those planes have a built-in tank and pump, with the booms attached
which have only a small amount of these disperse more easily. to the wings. Dispersant capacity varies with the airplane
As oil weathers on the sea surface, its composition changes and design but is about 400 to 4000 L [100 to 1000 U.S. gal].
it generally becomes less dispersable. Some oils can also form
5.6 Dispersant application systems can also be installed on
highly viscous water-in-oil emulsions, known as “chocolate
large multi-engine airplanes. These must be designed for each
mousse,” particularly in areas of high energy waves. Once
type of aircraft, and will include one or more pumps,
mousse has formed, dispersants may not be effective.
flowmeters, dispersant storage tanks, and spray booms with
4.1.2.2 Viscosity is an indicator of the oil composition, but
nozzles. The airplane type and payload capability will deter-
affects dispersion by its influence on the amount of dispersant
mine the available dispersant capacity from about 2000 to
penetrating into and mixing with the oil. Dispersant can run off
20 000 L [500 to 5000 U.S. gal].
the surface of highly viscous oils or will mix only slowly with
them. Traditionally, oils of a viscosity between 2000 and
6. Equipment Configuration for Vessels and Aircraft
10 000 mPa were thought to be un-dispersable. However,
6.1 Vessels—Dispersant spray systems for boats have been
viscosity may not be as much a limitation as is composition as
designed for many types of craft. Most systems use water-
noted above, especially for dispersants which are not quickly
compatible dispersants diluted with seawater during applica-
lost to the water column. Viscosity may have its largest effect
tion. These dispersants are mixed with seawater by use of an
on the time required for mixing with the oil.
eductor or metering pump to allow for the dispersant to be used
4.1.2.3 Natural weathering affects the composition and vis-
at the desired concentration (generally 10 %). Some systems
cosity of the oil. Much of the oil evaporated will usually
spray dispersants neat (without dilution with water) and thus
consist of the most dispersable fraction. Also, loss of the lighter
eliminate the need for seawater.
fractions by evaporation increases the viscosity. This combined
6.1.1 Mounting the spray booms as far forward as possible
effect may rapidly reduce the dispersability of some spilled
is optimal, so that the spray is applied in front of the bow wave,
oils. Some oils may not be effectively dispersed after only 24
because this wave can push oil out of reach of the spray at
h on the surface.
typical boat speeds. Nozzles and extensions should be
4.1.2.4 Sea surface energy can be an important factor in
downward-pointing and stable relative to the boom. Spray
dispersant effectiveness. Higher sea energy is needed to dis-
booms with multiple nozzles should be arranged to produce
perse oil of less favorable composition. Very low sea energies
flat, fan-shaped spray patterns, striking the water (oil) surface
often result in poor dispersant performance. Very high seas can
in a line perpendicular to the direction of travel of the vessel.
be detrimental since they can promote water-in-oil emulsion
Nozzles producing a hollow-cone shaped spray pattern should
formation and can cause oil slicks to become discontinuous or
not be used. Spray pressure should not be excessive so that the
submerged. Attempting to spray such slicks is likely to be
droplets do not break the oil surface. The dispersant-water
ineffective resulting in significant dispersant loss.
mixture should be delivered to the oil surface in the desired
4.1.3 Environmental Conditions, Including Wind, Sea State,
pattern, with a minimum amount of energy. The spray should
Visibility, and Temperature of Air and Water—It is essential to
strike the oil in small droplets of 300 to 500-μm volume
minimize dispersant loss in aerial application due to wind drift
median diameter (VMD). The droplets should be visually
and air turbulence. Large droplets assist in this, but, in addition,
larger than a fog or mist and smaller than heavy rain drops. The
the aircraft should be flown as low as safety considerations
fan-shaped sprays from adjacent nozzles should overlap just
allow. It is also best to fly into the wind while spraying, so as
above the oil surface. The height of the nozzles should ideally
to limit wind drift.
not exceed 1 metre from the water surface.
5. Equipment Types For Vessels and Aircraft 6.1.2 Relatively small spills may be treated by vessels, but
vessels are limited on large offshore spills by their spray swath
5.1 A boom and nozzle spraying system consists of one or
and speed. For example, a boat operating at 10 km/h [5 knots
more pumps, flowmeters, storage tanks, spray booms, and
or 6 mph], and spraying a 12-m [40-ft] swath, can only treat
nozzles that are mounted in various configurations depending
2 2
about 1.3 km [0.5 miles ] of an oil spill surface in about 12 h.
on the platform.
6.2 Helicopters—Spraying systems on helicopters are either
5.2 Single-point spray systems are not covered by this
integral (attached to the airframe) or external units that have a
standard. See Guide F2465/F2465M.
combined tank, pump, and spray boom assembly suspended
5.3 Dispersant application systems on ships or boats may be
below the aircraft from a cargo hook, as specified by the
portable or permanently installed. Vessels may have built-in
manufacturer of the bucket. Sufficient room must be allowed
dispersant storage tanks and on-board pumps for use with the
between the helicopter and the spray unit to allow for safe
spraying system.
connection and release. Spraying is controlled from the cockpit
5.4 Dispersant application systems on helicopters are most with an electrical remote-control unit, attached by cable to the
commonly slung beneath the aircraft, with remote controls spray system. Nozzles should be oriented parallel to the
available to the pilot. Some specially configured helicopters direction of travel and pointed aft on the spray boom. Only
have integral tanks and pumps. Helicopter spraying systems dispersants applied without dilution are suitable for aerial
are available with dispersant capacity of about 400 to 3000 L spraying. The spray-boom altitude, when spraying, should
[100 to 800 U.S. gal]. typically be 10 m [30 ft].
F1737/F1737M − 23
6.2.1 Helicopters are limited in the volume of dispersant recording instrumentation. To ensure safety in such a case, all
they can carry, typically under 2000 L [500 U.S. gal]. They the aircraft must have planned for, and maintained, continuous
have greater speed than vessels, however, and if working near communications.
the source of dispersant supply, helicopters provide very
7.2 Personnel in the controller (spotter) aircraft can identify
efficient dispersant application on small areas. Helicopters are
the heavier concentrations of oil (or those slicks posing the
best close to shore and should not work further than 20 km [15
greatest threat), direct spray aircraft or boats to the target,
miles] from shore, unless there are available offshore platforms
request spraying to be started and stopped, and assess the
on which to land, refuel, and load dispersants. Certain specialty
accuracy of the application. This guidance is important for
helicopters may have a greater range.
spraying operations since observation from a vessel or a spray
plane is limited. Air support is essential when large multi-
6.3 Small Airplanes—Small single-engine airplanes will
engine aircraft are used for spraying. Even when using heli-
have a pump that draws dispersant from a tank to feed the spray
copters and small airplanes for spraying, it is not reasonable to
booms, that are usually fitted close to the trailing edge of the
rely on pilot observation, since all of the sprayed area is behind
wing. The dispersant is discharged through nozzles (spaced at
the aircraft. It is recommended that a separate spotter aircraft
intervals along the boom) that are designed to generate droplets
be utilized. Consequently, the area of coverage and the effect of
within the required size range. The dispersant pump should be
the dispersant is better seen by a qualified observer in a control
capable of spraying at a rate that is required for a surface
plane at a higher altitude, who also can better direct the spray
coverage of 20 to 100 L/hectare [2 to 10 U.S. gal/acre]. The
plane on the next pass, in the same or a different treatment area.
pump rate should be variable in flight, and regulated and
monitored with a pre-calibrated flowmeter or pressure gage.
7.3 With the advent and use of GPS flight assist and
Air shear, which affects droplet size, may be a problem for
recording instrumentation, it is possible for aircraft to map,
lower viscosity dispersants of less than 60 mPas [cP], at
spray, observe, and document the oil slick, the dispersant
aircraft velocities exceeding about 200 km/h [100 knots or 120
application, and the visual dispersant effectiveness.
mph]. The spray-boom altitude during application should not
be over 10 to 30 m [30 to 100 ft].
8. Storage, Handling, and Maintenance of Dispersant
6.3.1 Small airplanes generally have limited load capacity,
and Dispersant Application Systems
about 400 to 3000 L [100 to 800 U.S. gal]. This size of aircraft
8.1 Dispersants are to be handled and stored in accordance
may provide rapid response to small spills, and has longer
with information provided by the manufacturer’s (Material)
range and greater speeds than a helicopter system.
Safety Data Sheets (MSDS or SDS), labels, and user-specified
6.4 Large Airplanes—Large multi-engine airplanes
...
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: F1737/F1737M − 19 F1737/F1737M − 23
Standard Guide for
Use of Oil Spill Dispersant Application Equipment During
Spill Response: Boom and Nozzle Systems
This standard is issued under the fixed designation F1737/F1737M; 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 guide covers considerations for the maintenance, storage, and use of oil spill dispersant application systems.
1.2 This guide is applicable to spray systems employing booms and nozzles and not to other systems such as fire monitors or
single-point spray systems.
1.3 This guide is applicable to systems employed on ships or boats and helicopters or airplanes.
1.4 This guide is applicable to temperate weather conditions and may not be applicable to freezing conditions.
1.5 This guide is one of five related to dispersant application systems. Guide F1413/F1413M covers design, Practice
F1460/F1460M covers calibration, Test Method F1738 covers deposition, Guide F1737 covers the use of the systems, and Guide
F2465/F2465M covers the design and specification for single-point spray systems. Familiarity with all five standards is
recommended.
1.6 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from
the two systems may result in non-conformance with the standard.
1.7 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
F1413/F1413M Guide for Oil Spill Dispersant Application Equipment: Boom and Nozzle Systems
This guide is under the jurisdiction of ASTM Committee F20 on Hazardous Substances and Oil Spill Response and is the direct responsibility of Subcommittee F20.13
on Treatment.
Current edition approved Aug. 1, 2019March 1, 2023. Published August 2019March 2023. Originally approved in 1996. Last previous edition approved in 20152019 as
F1713/F1713M – 15.F1737/F1737M – 19. DOI: 10.1520/F1737_F1737M-19.10.1520/F1737_F1737M-23.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1737/F1737M − 23
F1460/F1460M Practice for Calibrating Oil Spill Dispersant Application Equipment Boom and Nozzle Systems
F1738 Test Method for Determination of Deposition of Aerially Applied Oil Spill Dispersants
F2465/F2465M Guide for Oil Spill Dispersant Application Equipment: Single-point Spray Systems
F2532 Guide for Determining Net Environmental Benefit of Dispersant Use
3. Significance and Use
3.1 This guide provides information, procedures, and requirements for management and operation of dispersant spray application
equipment (boom and nozzle systems) in oil spill response.
3.2 This guide provides information on requirements for storage and maintenance of dispersant spray equipment and associated
materials.
3.3 This guide will aid operators in ensuring that a dispersant spray operation is carried out in an effective manner.
4. Background to the Use of Dispersants and Spray Systems
4.1 Primary Considerations:
4.1.1 Use of dispersants, particularly in a specific area, may be subject to regulatory approval. Net Environmental Benefit Analysis
is used for dispersant decision-making (Guide F2532). Dispersant response is for use in the early stages of a spill; so, it is strongly
recommended that a rapid approval pre-approval mechanism, or pre-approval, rapid approval, be part of response planning.
4.1.2 Nature of Oil Slick(s) to Be Treated:
4.1.2.1 The effectiveness of dispersants is dependent (assuming proper application) on two factors; the oil composition and the
sea surface energy. The primary factor is the oil composition. Heavier oils, those that contain large amounts of components such
as asphaltenes, disperse poorly, and those which have only a small amount of these disperse more easily. As oil weathers on the
sea surface, its composition changes and it generally becomes less dispersable. Some oils can also form highly viscous water-in-oil
emulsions, known as “chocolate mousse,” particularly in areas of high energy waves. Once mousse has formed, dispersants may
not be effective.
4.1.2.2 Viscosity is an indicator of the oil composition, but affects dispersion by its influence on the amount of dispersant
penetrating into and mixing with the oil. Dispersant can run off the surface of highly viscous oils or will mix only slowly with them.
Traditionally, oils of a viscosity between 2000 and 10 000 mPa were thought to be undispersable.un-dispersable. However,
viscosity may not be as much a limitation as is composition as noted above, especially for dispersants which are not quickly lost
to the water column. Viscosity may have its largest effect on the time required for mixing with the oil.
4.1.2.3 Natural weathering affects the composition and viscosity of the oil. Much of the oil evaporated will usually consist of the
most dispersable fraction. Also, loss of the lighter fractions by evaporation increases the viscosity. This combined effect may
rapidly reduce the dispersability of some spilled oils. Some oils may not be effectively dispersed after only 24 h on the surface.
4.1.2.4 Sea surface energy can be an important factor in dispersant effectiveness. Higher sea energy is needed to disperse oil of
less favorable composition. Very low sea energies often result in poor dispersant performance. Very high seas can be detrimental
since they can promote water-in-oil emulsion formation and can cause oil slicks to become discontinuous or submerged.
Attempting to spray such slicks is likely to be ineffective resulting in significant dispersant loss.
4.1.3 Environmental Conditions, Including Wind, Sea State, Visibility, and Temperature of Air and Water—It is essential to
minimize dispersant loss in aerial application due to wind drift and air turbulence. Large droplets assist in this, but, in addition,
the aircraft should be flown as low as safety considerations allow. It is also best to fly into the wind while spraying, so as to limit
wind drift.
5. Equipment Types For Vessels and Aircraft
5.1 A boom and nozzle spraying system consists of one or more pumps, flowmeters, storage tanks, spray booms, and nozzles that
are mounted in various configurations depending on the platform.
5.2 Single-point spray systems are not covered by this standard. See Guide F2465/F2465M.
F1737/F1737M − 23
5.3 Dispersant application systems on ships or boats may be portable or permanently installed. Vessels may have built-in
dispersant storage tanks and on-board pumps for use with the spraying system.
5.4 Dispersant application systems on helicopters are most commonly slung beneath the aircraft, with remote controls available
to the pilot. Some specially configured helicopters have integral tanks and pumps. Helicopter spraying systems are available with
dispersant capacity of about 400 to 3000 L [100 to 800 U.S. gal].
5.5 Dispersant application systems on single-engine airplanes have a built-in tank and pump, with the booms attached to the wings.
Dispersant capacity varies with the airplane design but is about 400 to 4000 L [100 to 1000 U.S. gal].
5.6 Dispersant application systems can also be installed on large multi-engine airplanes. These must be designed for each type of
aircraft, and will include one or more pumps, flowmeters, dispersant storage tanks, and spray booms with nozzles. The airplane
type and payload capability will determine the available dispersant capacity from about 2000 to 20 000 L [500 to 5000 U.S. gal].
6. Equipment Configuration for Vessels and Aircraft
6.1 Vessels—Dispersant spray systems for boats have been designed for many types of craft. Most systems use water-compatible
dispersants diluted with seawater during application. These dispersants are mixed with seawater by use of an eductor or metering
pump to allow for the dispersant to be used at the desired concentration (generally 10 %). Some systems spray dispersants neat
(without dilution with water) and thus eliminate the need for seawater.
6.1.1 Mounting the spray booms as far forward as possible is optimal, so that the spray is applied in front of the bow wave, because
this wave can push oil out of reach of the spray at typical boat speeds. Nozzles and extensions should be downward-pointing and
stable relative to the boom. Spray booms with multiple nozzles should be arranged to produce flat, fan-shaped spray patterns,
striking the water (oil) surface in a line perpendicular to the direction of travel of the vessel. Nozzles producing a hollow-cone
shaped spray pattern should not be used. Spray pressure should not be excessive so that the droplets do not break the oil surface.
The dispersant-water mixture should be delivered to the oil surface in the desired pattern, with a minimum amount of energy. The
spray should strike the oil in small droplets of 300 to 500-μm volume median diameter (VMD). The droplets should be visually
larger than a fog or mist and smaller than heavy rain drops. The fan-shaped sprays from adjacent nozzles should overlap just above
the oil surface. The height of the nozzles should ideally not exceed 1 metre from the water surface.
6.1.2 Relatively small spills may be treated by vessels, but vessels are limited on large offshore spills by their spray swath and
speed. For example, a boat operating at 10 km/h [5 knots or 6 mph], and spraying a 12-m [40-ft] swath, can only treat about 1.3
2 2
km [0.5 miles ] of an oil spill surface in about 12 h.
6.2 Helicopters—Spraying systems on helicopters are either integral (attached to the airframe) or external units that have a
combined tank, pump, and spray boom assembly suspended below the aircraft from a cargo hook, as specified by the manufacturer
of the bucket. Sufficient room must be allowed between the helicopter and the spray unit to allow for safe connection and release.
Spraying is controlled from the cockpit with an electrical remote-control unit, attached by cable to the spray system. Nozzles
should be oriented parallel to the direction of travel and pointed aft on the spray boom. Only dispersants applied without dilution
are suitable for aerial spraying. The spray-boom altitude, when spraying, should typically be 10 m [30 ft].
6.2.1 Helicopters are limited in the volume of dispersant they can carry, typically under 2000 L [500 U.S. gal]. They have greater
speed than vessels, however, and if working near the source of dispersant supply, helicopters provide very efficient dispersant
application on small areas. Helicopters are best close to shore and should not work further than 20 km [15 miles] from shore, unless
there are available offshore platforms on which to land, refuel, and load dispersants. Certain specialty helicopters may have a
greater range.
6.3 Small Airplanes—Small single-engine airplanes will have a pump that draws dispersant from a tank to feed the spray booms,
that are usually fitted close to the trailing edge of the wing. The dispersant is discharged through nozzles (spaced at intervals along
the boom) that are designed to generate droplets within the required size range. The dispersant pump should be capable of spraying
at a rate that is required for a surface coverage of 20 to 100 L/hectare [2 to 10 U.S. gal/acre]. The pump rate should be variable
in flight, and regulated and monitored with a pre-calibrated flowmeter or pressure gage. Air shear, which affects droplet size, may
be a problem for lower viscosity dispersants of less than 60 mPas [cP], at aircraft velocities exceeding about 200 km/h [100 knots
or 120 mph]. The spray-boom altitude during application should not be over 10 to 30 m [30 to 100 ft].
F1737/F1737M − 23
6.3.1 Small airplanes generally have limited load capacity, about 400 to 3000 L [100 to 800 U.S. gal]. This size of aircraft may
provide rapid response to small spills, and has longer range and greater speeds than a helicopter system.
6.4 Large Airplanes—Large multi-engine airplanes offer increased payload, range, and speed for the treatment of large spills.
Some large cargo airplanes have a rear cargo or personnel door that can be opened in flight, can accommodate portable tank
systems, and have extendable booms that can be deployed in flight. Such a system can be permanently fitted to a dedicated airplane,
or installed as needed in an airplane of opportunity. These systems may require specific certification by aviation authorities for use
on a particular type of aircraft.
6.4.1 These larger aircraft will generally fly at altitudes of 15 to 30 m [50 to 100 ft] when applying dispersant to the oil.
6.4.2 The largest dispersant liquid capacity for such aircraft is 20 000 L [5000 U.S. gal]. Aircraft range and payload characteristics
can limit the dispersant volume. Application rates from 10 to 100 L/hectare [1 to 10 U.S. gal/acre] can be achieved. Typical
coverage for these systems is 20 hectares/min [50 acres/min] at 130 to 150 knots.
7. Control of Spraying Operations
7.1 Whichever method is employed to apply dispersants, an objective assessment is required to ensure that a vessel or aircraft
spraying operation is conducted properly and effectively. Direction of the operation and observation of its effectiveness can best
be conducted from another controller
...
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