United States
Environmental Protection
Agency
Office of Solid Waste
and Emergency Response
(5104)
EPA550-F-98-017
August 1998
www.epa.gov/ceppo
SEPA
HAZARDS OF AMMONIA RELEASES
AT AMMONIA REFRIGERATION
FACILITIES
The Environmental Protection Agency (EPA) is issuing this Alert as part of its ongoing
effort to protect human health and the environment. EPA is striving to learn the causes
and contributing factors associated with chemical accidents and to prevent their
recurrence. Major chemical accidents cannot be prevented solely through command and
control regulatory requirements, but by understanding the fundamental root causes,
widely disseminating the lessons learned, and integrating these lessons learned into
safe operations. EPA will publish A/erts to increase awareness of possible hazards. It
is important that personnel who operate refrigeration systems, managers of facilities,
SERCs, LEPCs, emergency responders and others review this information and take
appropriate steps to minimize risk.
PROBLEM
Anhydrous ammonia is used as
a refrigerant in mechanical
compression systems at a
large number of industrial facilities.
Ammonia is a toxic gas under ambi-
ent conditions. Many parts of a
refrigeration system contain ammo-
nia liquefied under pressure. Re-
leases of ammonia have the potential
for harmful effects on workers and
the public; if the ammonia is under
pressure, larger quantities may be
released rapidly into the air. Also,
some explosions have been attributed
to releases of ammonia contaminated
with lubricatingjoil, This Alert further
discusses these potential hazards and
the steps that can be.,taken.to mini-
mize risks. This Alert should be
reviewed by personnel who operate
and maintain refrigeration systems,
managers of facilities, and emergency
responders (e.g., haz mat teams).
ACCIDENTS
A numberof accidental-releases
of ammoniaJiave occurred
from refrigerationifacilities in
the past. Causes of theseTreleases" .
include plant upsets;leading to the "
lifting of relief valves; leaks in rotat-
ing seals; pipeline failures; vehicular
traffic hitting pipes, valves, and
evaporators; and failures during
ammonia delivery, such as hose leaks.
Some of these releases have killed
and injured workers, caused injuries
off site, or resulted in evacuations.
The following describes several
recent incidents in more detail.
A specific incident demonstrates the
need for mechanical protection to
protect refrigeration equipment from
impact. In a 1992 incident at a meat
packing plant, a forklift struck and
ruptured-a-pipe-earr-ying-ammonia
for refrigeration.'Workers were
evacuaied-whenlhe leak was de-
tected. A-shorttirrie laFer,,an explo-
sion occurred'thafcaused extensive
damage, including large holes in two
sides of the building. The forklift was
believed to be the source of ignition.
In this incident, physical barriers
would have provided mechanical
protection to the refrigeration system
and prevented:a release.
Another ihadehthighlights the need
for anadequate preventive mainte-
nance program and scheduling. In a ,
1996 incident in a produce cold
storage facility, oil pressure-got low
Chemical Emergency Preparedness and Prevention Office
@> Printed on recycled paper
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HAZARDS OF AMMONIA RELEASES AT AMMONIA REFRIGERATION FACILITIES
AUGUST 1998
over a long weekend in an older ammonia refrig-
eration system. The low oil pressure cutout switch
failed and the compressor tore itself apart, resulting
in a significant ammonia release. The periodic
testing of the low oil pressure cutout switch against
a known standard would have prevented this
incident.
Two other incidents illustrate the potential for
serious effects from accidental releases from ammo-
nia refrigeration systems, although the causes of
these releases were not reported. In a 1986 incident
in a packing plant slaughterhouse, a refrigeration
line ruptured, releasing ammonia. Eight workers
were critically injured, suffering respiratory burns
from ammonia inhalation, and 17 others were less
severely hurt. A1989 ammonia release in a frozen
pizza plant led to the evacuation of nearly all of the
6,500 residents of the town where the plant was
located. The release started when an end cap of a
16-inch suction line of the ammonia refrigeration
system was knocked off. Up to 45,000 pounds of
ammonia was released, forming a cloud 24 city
blocks long. About 50 area residents were taken to
hospitals, where they were treated with oxygen
and released, while dozens of others were treated
with oxygen at evacuation centers.
HAZARD AWARENESS
Ammonia is used widely and in large quanti-
ties for a variety of purposes. More than
80% of ammonia produced is used for
agricultural purposes; less than two percent is used
for refrigeration. Use of ammonia is generally safe
provided appropriate maintenance and operating
controls are exercised. It is important to recognize,
however, that ammonia is toxic and can be a
hazard to human health. It may be harmful if
inhaled at high concentrations. The Occupational
Safety and Health Administration (OSHA) Permis-
sible Exposure Level (PEL) is 50 parts per million
(ppm), 8-hour time-weighted average. Effects of
inhalation of ammonia range from, irritation to
severe respiratory injuries, with possible fatality at
higher concentrations. The National Institute of
Occupational Safety and Health (NIOSH) has-
established an Immediately Dangerous to Life and
Health (IDLH) level of 300 ppm for the purposes of
respirator selection. Ammonia is corrosive and can
burn the skin and eyes. Liquefied ammonia can
cause frostbite.
The American Industrial Hygiene Association
(AIHA) has developed Emergency Response
Planning Guidelines (ERPGs) for a number of
substances to assist in planning for catastrophic
releases to the community. The ERPG-2 repre-
sents the concentration below which it is believed
nearly all individuals could be exposed for up to
one hour without irreversible or serious health
effects. The ERPG-2 for ammonia is 200 ppm. EPA
has adopted the ERPG-2 as the toxic endpoint for
ammonia for the offsite consequence analysis
required by the Risk Management Program (RMP)
Rule under section 112(r) of the Clean Air Act.
In refrigeration systems, ammonia is liquefied
under pressure. Liquid ammonia that is acciden-
tally released may aerosolize (i.e., small liquid
droplets may be released along with ammonia gas)
and behave as a dense gas, even though it is
normally lighter than air (i.e., it may travel along
the ground instead of immediately rising into the
air). This behavior may increase the potential for
exposure of workers and the public.
Although pure ammonia vapors are not flam-
mable at concentrations of less than 16%, they may
be a fire and explosion hazard at concentrations
between 16 and 25%. Mixtures involving ammo-
nia contaminated with lubricating oil from the
system, however, may have a much broader
explosive range. A study conducted to determine
the influence of oil on the flammability limits of
ammonia found that oil reduced the lower flam-
mability limit as low as 8%, depending on the type
and concentration of oil (Fenton, et al., 1995).
An important property of ammonia is its pungent
odor. Odor threshold varies with the individual
but ammonia can be usually detected at concentra-
tions in the range of about 5 pprn-to 50 ppm.
Concentrations above about 100 ppm are uncom-
fortable to most people; concentrations in the
range of 300 to 500'ppm will cause people to leave
the area immediately.
HAZARD REDUCTION
The Chemical Accident Prevention Group'of
"EPA's Region III (Pennsylvania, Maryland,
Virginia, West Virginia, Delaware, and:the
District of Columbia) has been evaluating facilities
in Region HI with ammonia refrigeration systems
to gather information on safety practices and -:
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HAZARDS OF AMMONIA RELEASES AT AMMONIA REFRIGERATION FACILITIES
AUGUST 1998
technologies and to share its knowledge with
these facilities. Region IH has conducted more
than 120 audits from 1995 to the present of both
large and small facilities using ammonia for
refrigeration. To share their findings from the
audits, including both the deficiencies observed
and the actions that facilities are taking to increase
safety, Region in has made presentations to the
Refrigerating Engineers and Technicians Associa-
tion (RETA). ThisAkrt is intended to communicate
these findings to a wider audience.
Ammonia refrigeration facilities should be aware
of the potential hazards of ammonia releases and
of the steps that can be taken to prevent such
releases. They should be prepared to respond
appropriately if releases do occur. Here are steps
that ammonia refrigeration facilities could take to
prevent releases and reduce the severity of re-
leases that do occur include:
Establish training programs to ensure that the
ammonia refrigeration system is operated and
maintained by knowledgeable personnel.
Consider using a spring-loaded ball valve
(dead-man valve) in conjunction with the oil
drain valve on all oil out pots (used to collect
oil that leaks through seals) as an "emergency
stop valve."
Develop written standard operating proce-
dures for removing oil from the oil out pots.
Consider developing an in-house checklist to
guide mechanics through the procedure.
Remove refrigeration oil from the refrigera-
tion system on a regular basis. Never remove
oil directly from the refrigeration system
without pumping down and properly isolat-
ingJttat.component.... .. . _"".'.-'
Provide barriers to protect refrigeration
equipment, i.e., lines, valves, and refrigeration
coils, from impact in areas where forklif ts are
used.. Consider, starting a forklift driver
training program.
Develop and maintain awiitten preventive
maintenance program and schedule-based on
the manufacturer's recommendations for all
of the refrigeration equipment. The preven-
tive maintenance program should include,
but not be limited-to: '--
a) compressors
b) pumps
c) evaporators
d) condensers
e) control valves
f) all electrical safety(s), including
1) high pressure cutouts
2) high temperature cutouts
3) low pressure cutouts
4) low temperature cutouts
5) low oil pressure cutouts
g) ammonia detectors
h) emergency response equipment, including,
1) air monitoring equipment
2) self-contained breathing apparatus (SCBA)
3) level A suit
4) air- purifying respirators
Perform vibration testing on compressors.
Document and analyze results for trends.
Maintain a leak-free ammonia refrigeration
system. Investigate all reports of an ammonia
odor and repair all leaks immediately. Leak test
all piping, valves, seals, flanges, etc., at least four
times a year. Some methods which can be used
for leak testing are sulfur sticks, litmus paper,
or a portable monitor equipped with a flexible
probe.
Consider installing ammonia detectors in areas
where a substantial leak could occur or if the
facility is not manned 24 hours/day. The am-
monia detectors should be monitored by a local
alarm company or tied into a call-down system.
Ensure that the ammonia detectors are cali-
brated regularly against a known standard.
Check the operation of ammonia sensors and
alarms regularly.
Replace pressure relief valves (PRVs) on a five-
year schedule; document replacement dates by
stamping the replacement date onto each unit's-
tag.
Replace single PRVs with dual relief valves. A
dual relief-valve installation consists of one
three-way dual shut-off valve with two pres-
sure safety relief-valves. -
For largesysterns.with many.PRVs, consider-
using the arrangement shown in Exhibit 1 for
detecting leakage. This arrangement includes
installation of a rupture disc upstream of each
PRV with a gauge port or transducer in be-
tween the disc and PRV and installation of an
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HAZARDS OF AMMONIA RELEASES AT AMMONIA REFRIGERATION FACILITIES
AUGUST 1998
ammonia sensor in the PRV common mani-
fold. In case of leakage from a PRV, the
sensor would set off an alarm. A check of
either the pressure gauge or transducer signal
would permit easy identification of which
PRV has popped.
EXHIBIT 1
RUPTURE DISC/DUAL RELIEF VALVE ASSEMBLY
To common
manifold tying
in all PRVs,
NH3
sensor Vr
PRV-
. . ^-PRV
Gauge
port
Rupture
disc
Three-way valve
Consider installing a low water level probe
with an alarm in the water sump for the
evaporative condenser(s) to warn of water
supply failure.
Ensure that the ammonia refrigeration system
is routinely monitored. Consider using a
daily engine room log, recording process
parameters (e.g., temperature and pressure
levels) and reviewing the log on a regular
basis. Consider having the chief engineer and'
the refrigeration technician sign the daily ., ,
engine room log. In designing new systems
or retrofitting existing systems, consider the
use of computer controls to monitor the
process parameters.
Keep an accurate record of the amount of
ammonia that is purchased for the initial
charge to the refrigeration system(s) and the
amount thatis replaced. Consider keeping a .
record of the amount of lubricating oil added
to the system and removed from the system.
Ensure that good housekeeping procedures
are followed in the compressor rooms.
Ensure that refrigeration system lines and
valves are adequately identified (e.g., by color
coding or labeling) by using an in-house
system.
Properly post ammonia placards (i.e. NFPA
704 NH3 diamond) and warning signs in
areas where ammonia is being used as a
refrigerant or being stored (for example,
compressor room doors). Properly
identify the chemicals within the piping
system(s); label all process piping, i.e.
piping containing ammonia, as "AM-
MONIA." Label must use black letters
with yellow background. (This require-
ment is not the same as the in-house
color coding system.)
Periodically inspect all ammonia
refrigeration piping for failed insulation/
vapor barrier, rust, and corrosion.
Inspect any ammonia refrigeration
piping underneath any failed insulation
systems for rust=and corrosion. Replace
all deteriorated refrigeration piping as
needed. Protect all un-insulated refrig-
eration piping from rust and/or corro-
sion by cleaning, priming, and painting
with an appropriate coating.
Carry out regular inspections of emergency
equipment and keep respirators, including
air-purifying and self-contained breathing
apparatus (SCBA), and other equipment in
good shape; ensure that personnel are trained
in proper use of this equipment. For SCBA, it
is important to ensure that air is bone dry. For
air-purifying respirators, replace cartridges as
needed and check expiration dates.
Consider using the compressbr.room-ammo-
nia detector to control the ventilation fans.
Identify the king valve and other emergency
isolation valves with a large placard so that
they can easily be identified by emergency
responders, in case of an emergency. These
valves should be clearly indicated on the
piping and instrumentation diagrams
(P&IDs) and/or process flow diagrams.
Establish emergency shutdown procedures
and instructions on what to do during and
after a power failure.
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HAZARDS OF AMMONIA RELEASES AT AMMONIA REFRIGERATION FACILITIES
AUGUST 1998
Establish written emergency procedures and
instructions on what to do in the event of an
ammonia release.
Mount a compressor room ventilation fan
manual switch outside of the compressor room
and identify it with a placard for use in an
emergency. Good practice would be to have
ventilation switches located outside and inside
of each door to the compressor room.
Mount windsocks in appropriate places and
incorporate their use into the facility emergency
response plan. In addition to the emergency
response plan, consider developing additional
materials (posters, signs, etc.) to provide useful
information to employees and emergency
responders in case of an emergency.
Keep piping and instrumentation diagrams
(P&IDs), process flow diagrams, ladder dia-
grams, or single lines up-to-date and incorpo-
rate them into training programs for operators.
Stage a realistic emergency response spill
exercise with the local fire company.
References
Fenton, D.L., K.S. Chapman, R.D. Kelley, and A.S.
Khan. 1995. Operating Characteristics of a flare/
oxidizer for the disposal of ammonia from and
industrial refrigeration facility. ASHRAE Transac-
tions, 101 (2), pp. 463-475. Atlanta, GA: American
Society of Heating, Refrigeration, and Air-Condition-
ing Engineers.
INFORMATION RESOURCES -
General References
The Alaska DEC fact sheet on preventing accidental
.releases of anhydrous ammonia is available at: ~
http://es.inel.gov/techinfo/facts/alaska/aTc-fsQ3.html
CEPPO has prepared a general advisory on ammo-
nia (OSWER 91-008.2 Series 8 No. 2), available
at: http://www.epa.gov/ceppo/acc-hisrhtml.
Statutes and Regulations
,The~following are a list of federal statutes and '
regulations-related to process-saf ety/ accident
prevention, emergency planning, and-release
reporting. .......
EPA
Clean Air Act (CAA)
General Duty Clause [Section 112(r) of the
Act]- Facilities have a general duty to prevent
and mitigate accidental releases of extremely
hazardous substances, including ammonia.
Risk Management Program (RMP) Rule [40
CFR 68]- Facilities that have anhydrous
ammonia in quantities greater than 10,000
pounds are required to develop a hazard
assessment, a prevention program, and an
emergency response program. EPA has
developed a model guidance to assist ammo-
nia refrigeration facilities comply with the
RMP rule,
Emergency Planning and Community Right-to-
Know(EPCRA)
Emergency Planning [40 CFR Part 355] -
Facilities that have ammonia at or above 500
pounds must report to their LEPC and SERC
and comply with certain requirements for
emergency planning.
Emergency Release Notification [40 CFR Part
355]- Facilities that releaselOO pounds or more
of ammonia must immediately report the
release to the LEPC and the SERC.
Hazardous Chemical Reporting [40 CFR Part
370]- Facilities that have ammonia at or above
500 pounds must submit a MSDS to their
LEPC, SERC, and local fire department and
comply with the Tier V Tier II inventory
reporting requirements1,--
Toxic Chemicals Release-Inventory [40 CFR
Part 372]:- Manufacturing businesses with ten
or more employees that manufacture, process,
or otherwise use ammonia above an appli-
cable threshold must file annually a Toxic
Chemical Release form with EPA and the
state.
Comprehensive Environmental Response/
Compensation,and,;LiabilityAct (CERCLA)
Hazardous Substance Release Reporting [40
CFR Part 302]- Facilities must report to the
National Response-Center (NRC) any
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HAZARDS OF AMMONM RELEASES AT AMMONIA REFRIGERATION FACILITIES
AUGUST 1998
environmental release of ammonia which
exceeds 100 pounds. A release may trigger a
response by EPA, or by one or more Federal or
State emergency response authorities.
OSJIA
Process Safety"Management (PSM) Standard [29
CFR1910] Ammonia (anhydrous) is listed as a
highly hazardous substance. Facilities that have
ammonia in quantities at or above the threshold
quantity of 10,000 pounds are subject to a number
of requirements for management of hazards,
including performing a process hazards analysis
and maintaining mechanical integrity of equip-
ment.
Hazard Communication [29 CFR 1910.1200] -
Requires that the potential hazards of toxic and
hazardous chemicals be evaluated and that
employers transmit this information to their
employees.
For additional information, contact OSHA
Public Information at (202) 219- 8151. .
Web site: http://www.osha.gov
Codes and Standards
There are a number of American National Standards
Institute (ANSI) Standards available for refrigeration
systems. Some examples are given below.
ANS1/ASHRAE Standard 15-1994 - Safety Code for
Mechanical Refrigeration
Available for purchase from the American Society of
Heating, Refrigerating and Air-Conditioning Engi-
neers (ASHRAE) International Headquarters,
1791 Tullie Circle, NE, Atlanta, GA 30329-2305.
Customer service: 1-800-527-4723 ,;'
ANSI/EAR 2-1992 - Equipment, Design, and Installa-
tion of Ammonia Mechanical Refrigeration Systems
Available from the International Institute of Ammonia
Refrigeration (EAR)
120019th Street, NW
Suite 300
Washington, DC 22036-2422
(202) 857-1110
Web site: http://www.iiar.org
ISO 5149-1993 - Mechanical Refrigerating Systems
Used for Cooling and Heating - Safety Requirements
Available from the American National Standards
Institute (ANSI)
11 West 42nd Street
New York, NY 10036
(212) 642-4900
Web site: http://www.arisi.org
FOR MORE INFORMATION...
CONTACT THE EMERGENCY PLANNING AND
COMMUNITY RIGHT-TO-KNOW HOTLINE
(800) 424-9346 OR (703) 412-9810
TDD (800) 553-7672
MONDAY-FRIDAY, 9 AM TO 6 PM, EASTERN TIME
VISIT THE CEPPO HOME PAGE ON THE WORLD
WIDE WEB AT:
HTTP://WWW.EPA.GOV/CEPPO/
NOTICE
The statements in this document are intended solely as guidance. This document does rtofsubstitute for EPA's
or other agency regulations, nor is it a regulation itself. Site-specific application of the guidance may vary
depending on process activities, and may not apply to a given situation. EPA may revoke/modify, or suspend this
guidance in the future, as appropriate-
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