United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-021 May 1981
Project Summary
Vapor Pressure
Distribution of Selected
Organic Chemicals
Robert C. Weber, Phillip A. Parker, and Melanie Bowser
The objective of this project was to
prepare a consistent tabulation of
physical property data for organic
chemicals for use by the Emission
Standards and Engineering Division of
EPA's Office of Air Quality Planning
and Standards. The data reported for
450 selected organic chemicals are
melting point, boiling point, physical
state at 20°C, and vapor pressure at
20°C and 101.3 kPa where available.
From these data, physical state and
vapor pressure summaries and distri-
butions were prepared.
The 450 chemicals covered in this
report generally represent high-volume
industrial organic chemicals.
This Project Summary was developed
by EPA's Industrial Environmental
Research Laboratory, Cincinnati, OH,
to announce key findings of the re-
search project that is fully documented
in a separate report of the same title
(see Project Report ordering informa-
tion at back).
Introduction
EPA's Office of Air Quality Planning
and Standards, Emission Standards and
Engineering Division (ESED), is cur-
rently developing regulations for the
control of fugitive volatile organic com-
pound (VOC) emissions from organic
chemical production facilities. Studies
of emissions from these sources indicate
that emission rates are correlated with
the vapor pressure of the organic mate-
rial in the system. In general, equipment
in gas service contributes more to the
total emissions than equipment in liquid
service. Further, equipment in liquid
service handling relatively volatile
material contributes more to the total
problem than equipment containing
chemicals with low volatility. Therefore,
it is important to have a quantitative
assessment of the vapor pressure distri-
bution of chemicals potentially covered
by EPA regulations.
As a result, -the Emission Standards
and Engineering Division requested the
Organic and Inorganic Chemicals and
Products Branch of the Industrial Envi-
ronmental Research Laboratory in Cin-
cinnati to prepare a consistent tabula-
tion of vapor pressures for organic
chemical products currently considered
for inclusion in fugitive emissions
regulations. This special report presents
the results of this analysis.
For each of the 378 chemicals (or
groups of chemicals) identified by the
Emission Standards and Engineering
Division, the following data have been
collected: (a) physical state at 20°C and
101.3 kPa (1 atmosphere); (b) vapor
pressure at the same conditions; and (c)
references for each vapor pressure.
From these data, physical state and
vapor pressure summaries and distri-
butions have been prepared. Data used
in preparing these summaries is pre-
sented in tabular form in the Project
Report.
Finally, it is important to note that the
vapor pressure data used in this project
do not represent experimentally deter-
mined values at 20°C. Rather, they are
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estimates developed from primary
references for the purpose of generating
reasonable vapor pressure distributions
using the most widely accepted and
accurate methods.
Discussion and Procedure
Most of the vapor pressures were
estimated with one of several variations
of the Antoine Equation in which the
logarithm of the vapor pressure is
proportional to the inverse of the abso-
lute temperature. Other references
which report data at 20°C were also
used on occasion. It must be pointed out
that for many chemicals, especially
solids, 20°C is outside the temperature
range at which the reported coefficients
apply.
The specific equations are summarized
in the Project Report.
Results and Conclusions
The following tables present a sum-
mary of the physical state and vapor
pressure information collected for the
378 organic chemical products (or
chemical groups) provided by ESED. All
of the data are based on the following
"standard" conditions: 20°C and 101.3
kPa (1 atmosphere). For those entries of
the 378 which are actually groups of
chemical products, attempts were made
to identify several specific chemicals in
the group. This resulted in a total of 450
discrete chemicals.
Table 1 summarizes the information
on the physical state of the 450 chemi-
cals at the defined conditions. The
physical state was unavailable in readily
accessible literature for one chemical,
glycerol tri(polyoxypropylene)ether. Six
percent of the chemicals are gases, 60
percent are liquids, and 34 percent are
solids.
Within certain constraints, a vapor
pressure distribution was developed for
liquids. For liquids, vapor pressures
were not available for 6 out of 269
chemicals (2 percent). The frequency
distribution for liquids is presented in
Table 2.
From Table 2,43 percent of the liquids
(26 percent of the total) have vapor
pressures less than or equal to 0.3 kPa
at 20°C. Assuming solids generally
have very low vapor pressures, then
about 60 percent of the chemical
would be expected to have vapor pros
sures equal to or less than 0.3 kPa. Thi
is likely an underestimate, since th
majority of the remaining chemicals fc
which vapor pressures were not foun
probably have very low vapor pressure
at 20°C also.
Table 2. Vapor Pressure Distribution - Liquids"
Vapor Pressure
fkPaJ
Number
of Chemicals
Percent
of Liquids
Percent
of Total Chemicals
Less than or equal
to 0.3
0.31 - 1.4
1.41 - 10.3
10.31 - 101.3
Not available (NA)
116
40
62
45
6
43
15
23
17
2
26
9
14
10
1
*At 20°C.
The EPA authors Robert C. Weber, Phillip A. Parker, and Melanie Bowser are
with the Industrial Environmental Research Laboratory, Cincinnati, OH 45268
45268.
The complete report, entitled "Vapor Pressure Distribution of Selected Organic
Chemicals," (PB No. 81-171 233; Cost: $6.50, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA22161
Telephone: 703-487-4650
The EPA authors can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
Table 1. Physical State Distribution"
Number of
Chemicals
Gases
Liquids
Solids
Unknown
TOTAL
26
269
154
1
450
Percent of
Total
6
60
34
0.2
"At20°Cand101.3kPa.
0 U.S. GOVERNMENT PRINTING OfFlCE 1981 -757-OU/7092
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