ASTM F2534-06

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Designation:F2534–06
Standard Guide for
Visually Estimating Oil Spill Thickness on Water
This standard is issued under the fixed designation F2534; 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 3.1.4 Estimating volume for legal or prosecution purposes,
such as for an illegal discharge, and
1.1 This guide provides information and criteria for estimat-
3.1.5 Developing spill control strategies.
ing the thickness of oil on water using only visual clues.
1.2 This guide applies to oil-on-water and does not pertain
4. Summary of Thickness Estimation Results
to oil on land or other surfaces.
4.1 Table1hasbeensummarizedfromavarietyofliterature
1.3 This guide is generally applicable for all types of crude
sources (see Appendix X1).
oils and most petroleum products, under a variety of marine or
fresh water conditions.
TABLE 1 Visibility Characteristics (Appearance)
1.4 The thickness values obtained using this guide are at
best estimates because the appearance of oil on water may be Minimum Onset Thickness (µm)
Minimum
Observable
affected by a number of factors including oil type, sea state,
Dark
A
Silvery Rainbow Dark
Thickness
Rainbow
visibility conditions, and weather.
Typical 0.08 0.1 0.5 3 > 3
1.5 This standard does not purport to address all of the
Range 0.05 to 0.2 0.1 to 0.3 0.2 to 3 > 3
safety concerns, if any, associated with its use. It is the
A
This color is sometimes called ‘oil-like,’ ‘dark colored,’ ‘brown,’ ‘black,’ or
responsibility of the user of this standard to establish appro-
‘metallic.’
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4.2 It should be noted that the only physical change in
2. Referenced Documents
appearance that is reliable is the onset of rainbow colors, at 0.5
to 3 µm thickness. All other appearances vary with weather,
2.1 ASTM Standards:
visibility conditions, look angle, oil type, water conditions and
F1779 Practice for Reporting Visual Observations of Oil on
color, presence of waves, and the presence of other material on
Water
the water surface. Therefore it is important to treat these as
3. Significance and Use
estimates and where possible give ranges of thicknesses. If
volume is to be calculated, it should also be given as a range of
3.1 Estimations of oil slick thickness are useful for:
values.
3.1.1 Estimating amount (volume) of oil in an area,
3.1.2 Positioning oil spill countermeasures in optimal loca-
5. Summary
tions,
5.1 The change in visual appearance of an oil slick on water
3.1.3 Evaluating a spill situation,
provides a means to estimate oil slick thickness. Only the
appearance of rainbow colors at 0.5 to 3 µm is an indication of
This guide is under the jurisdiction of ASTM Committee F20 on Hazardous
slick thickness and only in the range noted. Other appearances
Substances and Oil Spill Response and is the direct responsibility of Subcommittee
change with the variables noted and thus should be used with
F20.16 on Surveillance and Tracking.
Current edition approved June 1, 2006. Published June 2006. DOI: 10.1520/ caution.
F2534-06.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6. Keywords
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1 oil observations; oil thickness; oil thickness estimation;
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. oil visibility; slick thickness
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2534–06
APPENDIX
(Nonmandatory Information)
X1. SUMMARYAND BACKGROUND OF SLICK THICKNESS DATA
X1.1 Introduction interference of light waves reflected from the air-oil interface
with those reflected from the oil-water interface (Fingas et al.,
X1.1.1 An important tool for working with oil spills has
1999) (1). The difference in optical path lengths for these two
been the relationship between appearance and thickness. Little
waves depends on the refractive index of the oil.The refractive
research work has been done on the topic in recent times
indices of given wavelengths results in different optical path
because thickness charts were available for many years (Prac-
lengths. This difference can be given as:
tice F1779) (Fingas et al., 1999) (1). In fact, present thickness
2 2 1/2
charts actually date from 1930 (Congress, 1930) (2).Itwas
DL 5 2t~µ – sin I! (X1.1)
recognized before 1930 that slicks on water had somewhat
where:
consistent appearances. A series of experiments were con-
DL = the difference in optical path length,
ducted in the 1930s and resulted in charts that are still used.
t = the film thickness,
Only a few experiments have been done in recent years. This
µ = the refractive index of the film, and
Appendix will summarize this development of slick appear-
I = the angle of light incidence.
ance charts.
X1.2.1.2 Horstein points out that if DL contains an even
X1.1.2 The early work may not have accounted for several
number of wavelengths, then maximum destructive interfer-
factors:
ence will occur. Destructive interference occurs when light
X1.1.2.1 Effect of Slick Heterogeneity—Oils, especially
waves are in a phase alignment that they annul each other and
heavier ones, do not form slicks of consistent thickness on the
thus the resulting amplitude of light is less. Constructive
water surface. Even visual examination shows a type of ‘fried
interference is the opposite. If DL contains an odd number of
egg’vertical profile. This effect is, however, not as relevant on
wavelengths, then maximum constructive interference will
largerslicksandwithlessviscousproducts.Manyslicksdonot
occur.
cover the entire area. The effect of surface tension is to pull
X1.2.1.3 Thenthemaximumdestructiveinterferencesoccur
some oils together so that slicklets are formed rather than one
uniform slick. at:
X1.1.2.2 Effect of Evaporation—The early experiments ig-
l5DL/x (X1.2)
nored the effect of evaporation on mass balance.
where:
X1.1.2.3 Effect of View Angle—View angle is critical to
l = the wavelength under consideration, and
observing slicks on water, especially with respect to the sun.
x = an even integer such as 2, 4 etc.
How this affects appearance thresholds is not fully explored.
X1.2.1.4 The maximum constructive interferences occur at:
X1.1.2.4 EffectofWavesontheSurface—Theappearanceof
oil slicks on calm water versus that with different wave
l5 2DL/x (X1.3)
conditions may be different.
where:
X1.1.2.5 Effect of Atmospheric and Viewing Conditions—
x = an odd integer such as 1, 3, 5, 7 etc.
Factor that may be important are haze and cloud cover. Haze
X1.2.1.5 Tablesofconstructiveanddestructivewavelengths
strongly reduces visibility. Slicks are often less visible in the
resulted in a color chart for visible oil as: thickness less that
absence of a cloud cover. Glitter or reflection from the sea is
known to cause viewing problems. 0.15µm—nocolorapparent,thicknessof0.15µm—warmtone
apparent, thickness of 0.2 to 0.9 µm—variety of colors (for
X1.1.2.6 Effect of Oil Type—Dark oils are more visible on
the surface than gasoline or diesel fuel. example, rainbow), and for thickness greater than 0.9 µm—
colorsoflesspurity,headingtowardgrey.Thecolorgeneration
X1.2 Slick Visibility
by constructive and destructive interference provides the only
physical measure that
...