United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/073 Jan. 1 988
&EPA Project Summary
Sampling Oil-Water Mixtures
at OHMSETT
Michael Borst
This report describes procedures
developed for sampling oil and water
mixtures.
Two procedures for sampling in con-
tainers are discussed: grab and stratified
sampling. Both of these techniques
require stripping free-standing water
from the container bottom. The grab
sample technique requires that the
remaining fluids be thoroughly mixed
before immersing a bottle through the
resulting homogeneous emulsion. The
stratified sampling procedure uses a
sample thief to capture a segmented
cross-section of the remaining fluids.
Two procedures for sampling flowing
fluids were tested. The two sampling
tubes tested were installed immediately
downstream of a series of static mixers
and a centrifugal pump. The sampling
ports were a simple slotted tube and a
pilot-shaped tube.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, 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).
Discussion
In the documentation of oil spill skim-
mer performance, a measure of the rela-
tive oil/water makeup of collected fluids
is essential. The U.S. Environmental
Protection Agency (EPA) conducted tests
at the Oil & Hazardous Materials Simu-
lated Environmental Test Tank (OHMSETT)
in Leonardo, New Jersey to determine
the usefulness of several techniques to
obtain and analyze representative sam-
ples of oil/water mixtures. Two methods
of sampling containers holding the mixed
fluids and two methods of sampling
flowing streams of the mixed fluids were
tested.
Complete statistical studies were not
conducted, but the tests indicate that the
two methods for sampling containers of
the fluids would give a precision of 3%
oil. The first method entailed thoroughly
mixing the oil and water to form a homo-
geneous emulsion. The sample was then
taken by lowering a bottle through the
emulsion to obtain a 100 ml sample for
later analysis. The second method used a
stratified sampling thief to capture a
representative cross-sectional core of the
fluids. The entire sampler was then sent
to the laboratory for analysis. Tests were
conducted using the stratified sampler to
determine if the complete analysis could
be abbreviated for field application, where
speed rather than accuracy may be the
prime consideration. These tests showed
that, while order-of-magnitude results
could be obtained, significant deterioration
of precision should be expected. The
selection of the method used in the field
would depend on the use of the sample
and support facilities available as well as
the shape of the container sampled.
Two methods of sampling flowing
streams were investigated. One method
used a slotted sampling port; the second
method used a pitot-shaped tube for the
sampling port. In both cases, the sampling
port was located immediately downstream
of an in-line static mixer. The analysis of
samples taken through the two ports
each gave results within the precision of
the comparison technique. The use of the
static mixer to eliminate radial nonsym-
metry in the flowing liquid appears to
make the selection of samples purely
arbitrary.
These tests were performed using only
OHMSETT Circo X medium oil and salt
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water as the immiscible fluids. Highly
viscous mixtures may affect the results
of future application of either of the
stationary techniques. When sampling
materials other than oil and water, chemi-
cal compatibility of the materials with the
sampling device must be considered.
Michael Borst is with Mason & Hanger-Silas Mason Co., Inc.. Leonardo, NJ
07737.
Richard A. Griffiths is the EPA Project Off Jeer (see below}.
The complete report, entitled "Sampling Oil-Water Mixtures at OHMSETT,"
(Order No. PB 88-102 892/AS: Cost: $11.95. 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:
Releases Control Branch
Hazardous Waste Engineering Research Laboratory—Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837
United Slates
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGES FEES PAID
EPA
PERMIT No G-35
Official Business
Penally for Private Use S300
EPA/600/S2-87/073
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