United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 2771
Research and Development
EPA/600/S8-87/034g Feb. 1988
&EPA Project Summary
Prevention Reference Manual:
Chemical Specific, Volume 7:
Control of Accidental Releases of
Chloropicrin (SCAQMD)
D. S. Davis, G. 8. DeWolf, and J. D. Quass
The South Coast Air Quality Manage-
ment District (SCAQMD) of California
has been considering a strategy for
reducing the risk of a major accidental
air release of toxic chemicals. The
strategy, which will serve as a guide to
industry and communities, includes
monitoring activities associated with
the storage, handling, and use of certain
chemicals. This manual summarizes
technical information that will assist in
identifying and controlling chloropicrin-
associated release hazards specific to
the SCAQMD.
Chloropicrin has an immediately dan-
gerous to life and health (IDLH) con-
centration of 1 ppm, making it a
substantial acute toxic hazard. Potential
causes of accidental releases from pro-
cesses that use Chloropicrin in the
SCAQMD are identified, as are specific
measures that may be taken to reduce
the risk of accidental release. Such
measures include recommendations on:
plant design practices; prevention, pro-
tection, and mitigation technologies;
and operation and maintenance prac-
tices. Conceptual costs of these mea-
sures are estimated.
This Protect Summary was developed
by EPA'* Air and Energy Engineering
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that Is fully docu-
mented In a separate report of the same
title (see Pro/ecf Report ordering In-
formation at back).
Introduction
The South Coast Air Quality Manage-
ment District (SCAQMD) conducted a
study in 1985 to determine the presence,
quantities, and uses of hazardous chemi-
cals in the SCAQMD, which comprises
Los Angeles, Orange, San Bernandino,
and Riverside Counties. The study re-
sulted in a 1985 report, "South Coast Air
Basin Accidental Toxic Air Emissions
Study," which outlined an overall strategy
for reducing the potential for a major
toxic chemical release.
The strategy involves monitoring in-
dustry activities associated with the
storage, handling, and use of certain
chemicals to minimize the potential for
accidental chemical releases or the con-
sequences of any releases that might
occur.
This volume of the manual discusses
storage and handling practices and pro-
cess operations relating to the prevention
of accidental releases of Chloropicrin as it
is used in the SCAQMD. Chloropicrin
(CC13NO2) is manufactured commercially
from bleaching powder and picric acid or
by the chlorination of nitromethane in
the presence of caustic. It is used primarily
as an insecticide, a soil fumigant, and a
warning agent in chemical fumigants. In
the SCAQMD, Chloropicrin is manufac-
tured from nitromethane and sodium
hypochlorite and is used in the formula-
tion of chloropicrin-methyl bromide.
Potential Causes of Releases
Chloropicrin releases can originate from
many sources, including leaks or ruptures
in vessels, piping, valves, instrumentation
connections, and process machinery such
as pumps. The primary hazard associated
with the manufacture of Chloropicrin is
the possibility of a runaway reaction
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caused by the exothermic nature of the
chlorination reaction. Adequate tempera-
ture control and agitation are required to
prevent a hazardous release of toxic
material.
Chloropicrin decomposes violently
when heated above its normal boiling
point, 112°C, to severely toxic gases,
including nitric oxide, phosgene, nitrosyl
chloride, chlorine, and carbon monoxide.
Most metals are corroded or tarnished to
some degree by chloropicrin. Which is
also incompatible with strong oxidizers.
Possible process causes of a chloro-
picrin release include: (1) excess nitro-
methane feed to a batch reactor, leading
to excessive exothermic reactions; (2)
excess feeds in any part of the system,
leading to overfilling or overpressuring
equipment; and (3) overpressure in chlo-
ropicrin storage vessels.
Possible equipment causes of accidental
releases resulting from hardware failures
include excessive stress caused by im-
proper fabrication, construction, or in-
stallation; or failure of vessels, pipes, or
pumps because of corrosion, external
loadings, or excessive stress.
Operational causes of accidental re-
leases resulting from incorrect operating
and maintenance procedures and operator
error include overfilled storage vessels,
errors in transfer procedures, inadequate
maintenance, improper system operation,
and lack of inspection and nondestructive
testing of vessels and piping to detect
corrosion weakening.
Hazard Prevention and Control
Prevention of accidental releases re-
quires careful consideration of the design,
construction, operation, and protective
systems of facilities where chloropicrin is
manufactured, stored, and used.
The primary consideration in the manu-
facture of chloropicrin is the prevention
of overheating resulting in boiling of the
batch reactor contents that might lead to
overpressure. Equipment failure is also
possible if corrosion has weakened pro-
cess equipment. Most metals are corroded
or tarnished by chloropicrin, but not
enough to prevent their use as construc-
tion materials. Metals also tend to have a
catalytic effect on the decomposition of
chloropicrin. Equipment used in chlo-
ropicrin service is commonly lined with
tetrafluoropolyethylene, vinylidene chlo-
ride, or polyvinylidene fluoride to prevent
corrosiion. Aluminum, magnesium, and
their alloys should not be used in chloro-
picrin service since it reacts violently
with these materials.
Release prevention for vessels includes
overpressure protection, temperature
control, and corrosion prevention. Process
vessels are usually protected by pressure
relief valves and/or rupture discs. The
correct design and use of pipe supports is
essential to reduce overstess and vibration
that could lead to piping failure. All piping
should be situated away from fire and
fire hazards since chloropicrin can explode
violently above its boiling point. If possible,
piping carrying chloropicrin should not be
routed near other processes or piping
networks that might present an external
threat. Many of the concerns and con-
siderations for chloropicrin piping also
apply to valves and pumps.
Siting and layout of facilities and equip-
ment should be designed to reduce per-
sonnel exposure in the event of a release.
Large inventories of chloropicrin should
be kept away from sources of fire or
explosion hazard, and storage facilities
should be segregated from the main pro-
cess if possible.
Protection for the containment and
neutralization of chloropicrin in the event
of a release includes enclosures and
scrubbers. Enclosures for chloropicrin
releases could be concrete block or con-
crete sheet buildings or bunkers. The
enclosure should be gaslight and have a
ventilation system designed to draw in
air when the building is vented to a
scrubber. Scrubbers appropriate for use
with chloropicrin include spray towers,
packed bed scrubbers, and Venturis.
Mitigation technologies are those that
reduce the consequences of a release if it
occurs. They include physical barriers,
water sprays and fogs, and foams. Such
techniques divert, limit, or disperse the
spilled or released chemical to reduce
the atmospheric concentration and the
area affected by the chemical. Secondary
containment systems (e.g., impounding
basins, dikes, and flotation devices and
foams) can be used to reduce the
evaporation rate of a spilled liquid.
Accidental releases of the materials
can result from deficiencies of operation
as well as of design. A sound maintenance
program would include corrosion moni-
toring and relief valve testing. Employees
should be trained in handling chloropicrin.
D. S. Davis, G. B. DeWolf, andJ. D. Quass are with Radian Corporation, Austin,
TX 78766.
T. Kelly Janes is the EPA Project Officer (see below).
The complete report, entitled "Prevention Reference Manual: Chemical Specific,
Volume 7: Control of Accidental Releases of Chloropicrin fSCAQMDj,"(Order
No. PB 87-234 522/AS; Cost: $13.95, subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 7O3-487-465O
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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