United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S8-88/069 July 1988
^EPA Project Summary
Construction and
Operation of a 10 CFM
Sampling System with a 10:1
Dilution Ratio for Measuring
Condensable Emissions
William J. Steele, Ashley D. Williamson, and Joseph D. McCain
This report describes a trans-
portable sampling apparatus de-
signed to sample incineration
sources at municipal and hazardous
waste disposal facilities,and to
provide non-contaminated samples
of condensable materials. The sam-
ple gas, at a flowrate of 10 cfm (283
Ipm), passes through a modified
Source Assessment Sampling Sys-
tem (SASS) cyclone and is then
diluted with clean air at 100 cfm
(2830 Ipm) by a novel, perforated
cone assembly. Rapid uniform dilu-
tion takes place through the vigorous
mixing of the sample and clean air
streams in the dilution chamber. The
resultant gas, cooled to approx-
imately atmospheric conditions, is
passed'through a mixing section that
provides a residence time of
approximately 3 sec. The resulting
aerosol particles are collected on a
Teflon-coated glass-fiber filter.
These solids, along with those col-
lected in the cyclone, are subse-
quently provided for chemical and
biological assay analysis.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research
Triangle Park, NC, 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
The primary design objective of this
apparatus was to provide (for bioassay)
non-contaminated samples of con-
densable materials from stack discharges
at municipal incinerators and hazardous
waste disposal facilities. Two opposing
design constraints were: (1) to provide
sufficient quantities of particulate matter
within a reasonable sampling time
(i.e.,<1 day), and (2) to provide a
portable instrument that could be
operated at various sites. For microbial
mutagenicity (Ames) assays, sufficient
particulate to obtain 10-100 mg of
extractable organic material is desirable.
This resulted in the design of a 10 cfm
(283 Ipm) sampling system with a 10:1
dilution ratio.
System Description
The main flow paths within the dil-
ution system are: 1) dilution air, 2) sam-
ple gas, 3) diluted gas, and 4) outlet gas.
The dilution air is extracted from the
ambient atmosphere and conditioned
with a condenser system, High Efficiency
Particulate Air (HEPA) filter, and a
charcoal bed. A heater raises the dilution
air temperature to 70°F (21 °C) when
necessary. An in-line orifice is used to
measure the dilution air flowrate
(nominally 100 cfm or 2830 Ipm).
The sample gas is extracted from the
stack through a 3/4-in. (1.9 cm) ID
glass-lined probe. The probe introduces
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the stack gas to a modified Source
Assessment Sampling System (SASS)
cyclone which has a D$Q of 1.8 ^m for a
10 cfm flowrate at about room
temperature (75°F or 24°C). The probe
and cyclone are heated to maintain the
sample gas at the existing flue gas
temperature.
The sample gas is diluted by the
dilution air at a 10:1 ratio in the dilution
cone. The sample gas is introduced at
the throat of the cone, and the dilution air
is forced through the perforations on the
outer surface of the cone. The combined
gas (called diluted gas) enters a dwell
chamber where a residence time of
approximately 3 sec allows for the
formation of condensable emissions. The
resulting paniculate materials are then
collected on a Teflon-coated glass-
fiber filter.
An outlet transform below the filter
directs the filtered gas to the exhaust
pump. The flow of the outlet gas is
measured by an orifice upstream of the
pump.
The support assembly for the
dilution system provides a cradle for
supporting the dilution manifold and the
associated probe. The cradle can be
adjusted vertically to position the probe
at the selected sampling port. The critical
temperatures and pressures of the
dilution system are regulated by the
control and monitoring assembly.
System Assembly
The first step in assembling the
system is to construct the dilution
manifold inside the support structure.
Three wooden cradles support the
assembled dilution manifold; heavy-
duty elastic cords hold the transform on
the cradles. Once the manifold is
supported, the outlet transform may bo
removed and the filter placed in the
recessed surface of the filter flange. The
cyclone may then be attached to the
face of the diluter. The rear of the
cyclone is supported with a clamp
attached to a front rail of the support
structure. A second clamp supports one
end of the probe; this clamp is attached
to a side rail for horizontal probe access
or to a rail directly under the cyclone for
vertical probe access.
The HEPA filter and charcoal bed
used to condition the dilution air should
be replaced prior to each test. During a
run, the probe and cyclone should be
kept as near to stack temperature as
feasible. The cyclone should not be
heated above 375°F (191°C) to avoid
damaging the internal finish. Care should
be used during leak tests and sampling
to apply and release pressures and/or
vacuums gradually to avoid rupturing the
sample filter. At the completion of a run,
the sample filter should be handled
carefully (surgical gloves are suggested)
and sealed in a glass or Teflon container
to prevent external contamination
William J. Steele, Ashley D. Williamson, and Joseph D. McCain are with
Southern Research Institute, Birmingham, AL 35255-5305.
Sharon L No/en is the EPA Project Officer (see below).
The complete report, entitled "Construction and Operation of a 10 CFM
Sampling System With a 10:1 Dilution Ratio for Measuring Condensable
Emissions," (Order No. PB 88-198 551/AS; Cost: S12.95, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S8-88/069
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