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United States
Environmental Protection
Agency
Municipal Environmental Research^
Laboratory ""
Cincinnati OH 45268
Research and Development
EPA-600/S2-82-029 July 1982
Project Summary
Evaluation of Foams for
Mitigating Air Pollution from
Hazardous Spills
S. S. Gross and R. H. Hiltz
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Water-based foam is investigated
and evaluated as a means of mitigating
vapor hazards posed by spills of
hazardous materials. The study ex-
amines the use of foams on both
individual chemicals and classes of
these. Characteristics of foams that
influence chemical compatibility and
vapor control are also studied.
Results indicate that foam is an
effective mechanism for mitigating
the vapor hazard from most volatile
hazardous materials. Different chemi-
cal classes require different types of
foam. For long-term control of vapor,
a high-expansion foam is desirable,
whereas a low-expansion foam is best
for short-term situations. Expansion is
the ratio of the volume of foam to the
volume of foam-forming fluid. For
low-expansion foam, this ratio is
about 10:1; for high-expansion foam,
100:1.
This Project Summary was devel-
oped by EPA's Municipal Environ-
mental Research Laboratory. Cincin-
nati, OH. to announce key findings of
the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
In the last few years, significant
advances have been made in the control
and containment of hazardous material
spills. These advances minimize dam-
age to the land and water, but they do
not address the significant air pollution
problem that can be caused by such
spills. This problem is particularly acute
for the personnel assigned to clean up
and dispose of the spilled material, but it
can also pose a serious threat to all life
and property in the spill area.
Water-based foams have been known
for some time to be effective in con-
trolling the vapor released from some
volatile chemicals. Foam blankets
retard evaporation by insulating the
bulk material from heat sources (air,
solar radiation) and further act as
barriers between flammable materials
and ignition sources. Vapor release is
further reduced because of the limited
permeability of the foam, its capacity to
absorb the chemical, and by dilution of
the surface layer. For materials that boil
below 0°C and whose gas density is less
than air, foam actually assists in vapor
dispersion since the temperature of the
vapors increase as they permeate the
foam layer and thus disperse better.
Problems posed by water-reactive
chemical spills can also be mitigated by
foams. Foams allow the gentle applica-
tion of water to the surface to effect
dilution and/or conversion to less
hazardous chemical species without
violent reaction.
At the time this study was initiated,
some data already existed to show that
foam could be effectively used with
spills of hydrocarbon fuels. Limited
information was also available on the
use of foam with liquefied natural gas,
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vinyl chloride monomer, ammonia,
chlorine, and sulfur trioxide. This
program aimed to better define the
capabilities of foam as a mechanism of
vapor mitigation. Three separate tasks
were identified. The first task investi-
gated and evaluated the use of foams to
mitigate air pollution from spills of
hazardous materials as a general class.
The second task assessed the use of
foams and foam-generating equipment
against individual chemicals. The third
task defined the characteristics of
foams that influenced chemical com-
patibility and vapor control.
Results and Conclusions
Results of the program show that
application of foam is an effective
mechanism for mitigating the vapor
hazard from most volatile hazardous
materials. Different chemical classes
require different foam types, with the
foam expansion ratio as an additional
variable. Table 1 provides a basic
selection guide for a range of chemical
classes. As a basic rule, the better the
water retention of the foam (i.e., low
drainage rate), the better its perform-
ance, regardless of other factors. Thus
drainage (the rate at which the foam
releases water) should be a primary
consideration when selecting a foam
concentrate for spill use.
As indicated in the table, certain gen-
eralizations can be drawn. For nonpolar
liquids that are not water reactive, any
high quality foam cover, regardless of its
chemical type, can provide mitigation of
the vapor hazard. Only those foams
designed for use with polar liquids are
applicable to that class of chemicals.
Other types of foam rapidly collapse. For
vapor mitigation, polar solvent foams
based on metal stearates are superior to
those that use a gelling polysaccharide.
For liquids that are extremely water
reactive (such as sulfur trioxide), only
high-expansion foam should be used
because of the high heat of reaction.
Low-expansion foams contain too much
water to gently dilute these water-
reactive liquids. For liquefied gases that
are lighter than air at ambient tempera-
tures, high-expansion foam provides a
heat source. Vapors passing through
the foam are warmed, and upon release,
they tend to rise rather than drift down-
wind at ground level. For those that are
heavier than air, no foam could effec-
tively mitigate the vapor hazard, since
warming does not result in a positive
buoyancy. For reactive liquefied gases
(such as NH3), high-expansion foam pro-
vides a reasonable vapor mitigation.
High-expansion foam warms and scrubs
the vapors as they pass through the
foam layer. Low-expansion foams add
too much water to the liquefied gas,
resulting in large vapor clouds.
The program has shown further that
laboratory tests can predict the behavior
of foams for spill control under field con-
ditions. Atmospheric conditions, wind,
and rain can be a factor in selecting the
correct expansion ratio for optimum
vapor control.
For long-term control, a high-expan-
sion foam is the better selection. High-
expansion foam mitigates the hazard by
containing the vapors and reducing the
vaporization driving force. Low-expan-
sion foam operates by acting as a barrier
to vapor release, and it is best suited to
short-term situations.
The full report was submitted in fulfill-
ment of Contract No. 68-03-2478 by
MSA Research Corporation under spon-
sorship of the U.S. Environmental Pro-
tection Agency.
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Table 1. Preliminary Matrix of Foam Capabilities on the Spilled Hazardous Chemicals Listed
Recommend 1* 2 3 4
Organics-Aliphatic
Acids - Acetic Acid
' Caproic Acid
Alcohols - Amy! Alcohol
• Butanol
- Butyl Cellosolve
- Methanol
- Octanol
- Propanol
Aldehydes & - Acetone
Ketones - Methyl Butyl Ketone
- Methyl Ethyl Ketone
Esters - Butyl Acetate
- Ethyl Acetate
- Methyl Acrylate
- Methyl Methacrylate
- Propyl Acetate
Halogenated - Butyl Bromide
- Methyl Bromide
- Tetrachloroethane
Hydrocarbons - Heptane
- Hexane
- Octane
Nitrogen Bearing - Dimethyl Formamide
Organics-Aromatic
Hydrocarbons - Benzene
• Tetrahydronaphthalene
• Toluene
Orggnics-Alicyclics • Cyclohexane
Organics-lndustrial - Gasoline
- Kerosene
- Naptha
- Paint Thinner
Organics-Cryogens - Liquefied Natural Gas
Inorganics - Silicon Tetrachloride
- Sulfur Trioxide
Inorganics -Cryogens - Ammonia
- Chlorine
Type of foam: 1. Surfactant Low Expansion; 2.
Film-Forming Foam
/V0+
ND
NO
R
ND
R
R
R
R
R
R
ND
ND
ND
ND
ND
ND
ND
ND
R
R
R
ND
R
R
R
R
R
R
R
R
R
R
R
R
R
Surfactant
ND
U
U
E-
ND
E-
U
E-
E-
E-
U
U
U
U
U
U
U
U
U
C+
c+
c+
U
c+
U
c+
B+
C+
C+
c+
c+
c-
E.
E-
C+
C+
ND
ND
U
E-
ND
E-
U
E-
E-
E-
U
(1
U
U
U
U
U
U
U
B+
B+
B+
E-
B+
U
B+
A+
B+
B+
B+
B+
A+
A +
A+
A +
C+
High Expansion; 3,
ND
ND
ND
E-
U
E-
U
E-
E-
U
U
U
U
ND
ND
U
ND
ND
ND
B+
B+
B+
ND
B+
U
8+
8+
8+
8+
8+
8+
E-
E-
E-
C+
C+
Protein; 4,
ND
ND
ND
E-
ND
E-
U
E-
E-
ND
ND
U
U
U
U
U
ND
ND
ND
B+
B+
8+
ND
B+
ND
8+
B+
B+
B+
8+
8+
E-
E-
E-
C+
C+
ND
ND
ND
A+
ND
A+
U
A+
A +
A+
A+
ND
ND
ND
ND
ND
ND
ND
ND
A+
A+
A+
ND
A+
ND
A+
C+
A+
A+
A+
A+
E-
E-
E-
E-
E-
Fluoroprotein; 5, Alcohol;
ND
ND
ND
E-
ND
E-
ND
E-
E-
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
C+
C+
C+
ND
C+
U
C+
C+
C+
C+
C+
C+
E-
E-
E-
C+
E-
6. Aqueous
*U Limited data available - capabilities uncertain
NO No data
R Foam use recommended over spill
A+ Best foam formulation
B+ Next best foam formulation
C+ Acceptable in some situations
F- Unsuitable foam formulation
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S. S. Gross andR. H. Hiltz are with MSA Research Corporation, Evans City. PA
16033.
John E. Brugger is the EPA Project Officer (see below).
The complete report, entitled "Evaluation of Foams for Mitigating Air Pollution
from Hazardous Spills," (Order No. PB 82-227 117; Cost: $10.50, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Oil and Hazardous Materials Spills Branch
Municipal Environmental Research Laboratory—Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
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