United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S2-91/056 Dec. 1991
EPA Project Summary
Manual for Non-CFC Aerosol
Packaging: Conversion from
CFC to Hydrocarbon Propellants
K.M. Adams, K.E. Hummel, T.P. Nelson, and S.L. Wevill
Because stratospheric ozone pro-
vides protection from biologically dam-
aging ultraviolet-B radiation, and
because chlorofluorocarbons (CFCs)
have been strongly implicated in the
thinning of the Earth's stratospheric
ozone layer, there is an urgent need to
eliminate production and use of the.
CFCs. In the U.S., CFCs were banned
for use as propellants from nearly all
aerosol products as early as 1978. In
place of the CFC propellants, liquefied
hydrocarbons such as propane, n-bu-
tane, and isobutane were found to be
acceptable substitutes for the majority
of aerosol products. This report pro-
vides technical assistance to aerosol
product marketers and fillers in other
nations now faced with eliminating CFCs
under the terms of the Montreal Proto-
col. The report addresses the Issues of
hydrocarbon propellant supply, prod-
uct reformulation, equipment conver-
sion, and safety concerns for both the
manufacturing plants and the aerosol
products themselves.
This Project Summary was devel-
oped by EPA's Air and Energy Engi-
neering Research Laboratory, Research
Triangle Park, NC, to announce key find-
ings of the research project that Is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Recent concern about depletion of the
stratospheric ozone layer has focused on
synthetic chemicals known as chlorofluo-
rocarbons (CFCs). Scientists have con-
cluded that destruction of the ozone layer
by CFCs will allow too much harmful ultra-
violet radiation to reach the Earth's sur-*
face, with potentially catastrophic results.
The most serious consequences include a
higher incidence of skin cancer and cata-
racts, suppression of the human immune
system, damage to plant and animal life,
and global warming.
In response to these concerns, coun-
tries around the world have agreed to phase
out the production and use of CFCs by the
year 2000. The Montreal Protocol, drafted
under the auspices of the United Nations
Environment Programme (UNEP), has
been ratified as of October 1990 by 68
countries and the European Economic
Community (EEC). Work is now underway
to find substitutes and alternatives to re-
place CFCs, as well as to decrease CFC
emissions in areas for which substitutes
are currently unavailable.
Many alternatives exist for replacing
the CFC-propelled aerosol package. This
manual does not discuss the strengths
and weaknesses of the many potential
options. A brief list of the alternatives, how-
ever, follows:
• Hydrocarbon propellants;
Other liquefied gas propellants such
as dimethyl ether (DME);
Compressed gas propellants such as
carbon dioxide, nitrous oxide, and
nitrogen;
Hydrochlorofluorocarbons (HCFCs)
such as HCFC-22, HCFC-123, and
HCFC-142b;
Printed on Recycled Paper
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• Hydrofluorocarbons (MFCs) such as
HFC-152a and HFC-134a; and
• Non-aerosol packaging such as me-
chanical finger pumps, trigger spray-
ers, and other alternative packaging.
This manual provides manufacturers of
aerosol products with the technical infor-
mation that will enable them to convert
from CFC propellants to hydrocarbon pro-
pellants. Hydrocarbon propellants are pri-
marily mixtures (or pure components) of
butane and propane, along with pentane,
and to a much lesser extent, ethane.
For the reasons listed below, if manu-
facturers choose to continue to use aero-
sol dispensers instead of non-aerosol
alternatives, hydrocarbon propellants are
the most feasible near-term alternative to
CFC aerosol propellants:
• Hydrocarbons can be treated and
blended to obtain the physical and
chemical properties that make them
suitable aerosol propellants;
• Most hydrocarbons are essentially
nontoxic, making them suitable for
use in a variety of personal care and
household products;
• Hydrocarbon propellants are less ex-
pensive than CFCs, enabling manu-
facturers to produce aerosols at a
tower unit cost;
• Hydrocarbons are compatible with
properly selected container materi-
als and formulations, thus preserving
shelf life and product stability; and
• Since the banning of CFC aerosol
propellants, hydrocarbons have be-
come the dominant aerosol propel-
lant in many developed and
developing countries and useful ex-
perience is available that can mini-
mize the conversion cost for other
countries.
Hydrocarbons also have two limitations
or disadvantages:
• Hydrocarbon propellants are flam-
mable; therefore, precautions must
be taken by producers, distributors,
and end-users to ensure that the
aerosol products are handled safely.
• Hydrocarbon propellants belong
in a class of compounds known
as volatile organic compounds
(VOCs), which are natural and
synthetic compounds that contrib-
ute to the formation of what is
known as photochemical "smog."
In some urban areas where smog
formation is a health and envi-
ronmental problem, regulations
have been proposed to reduce
the amounts of VOCs in con-
sumer products.
Properties and Availability of
Hydrocarbon Propellants
A replacement aerosol propellant must
have properties that allow the aerosol pack-
age to function: 1) the aerosol propellant
must provide the pressure to expel the
product from the container; 2) the propel-
lant may serve as a solvent to aid in keep-
ing the active ingredients in solution; and
3) the propellant must vaporize after leav-
ing the container, producing a spray or
foam. Other important properties of aero-
sol propellants are toxicity, stability, den-
sity and flammability. Table 1 compares
the properties of the most common CFC
propellants (CFC-11 and CFC-12) and the
hydrocarbon propellants (isobutane, n-bu-
tane, and propane).
Either liquefied gases or compressed
gases can provide pressure to expel prod-
uct from the container. Hydrocarbon and
CFC aerosol propellants are both liquefied
gases. Throughout the life of the aerosol
product, they generally provide a more
uniform internal pressure.
The solubility of the propellant is impor-
tant since it determines whether the over-
all contents are uniformly blended
("homogeneous"), or whether the contents
exist in separate phases ("heterogeneous").
The hydrocarbon compounds are all non-
polar, which renders them insoluble with
many polar solvents (including water). How-
ever, in some cases co-solvents such as
ethanol can be used to provide single-
phase blends of hydrocarbons, alcohol,
and water.
The toxicity of propellants may be com-
pared by using the threshold limit value
(TLV, a trademark of the American Confer-
ence of Governmental Industrial Hygien-
ists—ACGIH). The TLV is the maximum
level of exposure for a person working 8
hours a day, 40 hours a week throughout a
normal working career without adverse
health effects. The occupational exposure
guidelines for CFC-11, CFC-12, and hy-
drocarbon propellants are roughly compa-
rable.
The corrosion properties of propellants
may be compared by testing their hydro-
lytic stability. These tests measure the rate
of hydrolysis (decomposition) in the pres-
ence of a steel test coupon in water. CFCs
are generally less stable than the hydro-
carbons. However, contaminants in "field-
grade" hydrocarbons (water, and sulfur
compounds) may have a major effect on
corrosion.
No discussion of the properties of hy-
drocarbons would be complete without con-
sidering flammability. The flammability of
an aerosol spray is a combined function of
the composition of the product inside the
container and of the design of the valve.
Frequently, other major ingredients of the
formula (e.g., alcohols or petroleum distil-
lates) are also flammable.
Hydrocarbon propellants are derived
from liquefied petroleum gases (LPGs)
which come from the ground as constitu-
ents of wet natural gas or crude oil or as a
by-product of petroleum refinjng. LPG usu-
ally refers to a mixture of propane and
butane, although other hydrocarbons may
also be present (ethane at the light end,
and pentanes at the heavy end). The
amount of LPG used for aerosol propellant
is very small (less than 0.1% in the U.S. in
1981). Aerosol grade hydrocarbon propel-
lants are prepared by first distilling the
LPG to separate the various species. The
distillation of hydrocarbon propellant is nor-
mally carried out at a specially designed
plant that serves the regional aerosol in-
dustry. These plants are generally quite
sophisticated and would be too large for
any single aerosol filler.
Some aerosol products may use so-
called "natural blend" LPG instead of dis-
tilled hydrocarbons. The primary advantage
of natural blend LPG is that it is less ex-
pensive because there is less processing
of the hydrocarbon. The natural blend pro-
pellant is suitable in products where odor
is not as important (i.e., where the concen-
trate itself is quite odorous as in some
degreasers or spray paints) or where the
spray characteristics are not critical (such
as wet sprays in some residual insecti-
cides). A disadvantage of natural blend
hydrocarbon propellant is that the quality
varies, resulting in inconsistent pressure.
Because the natural blend is produced by
a coarse distillation, the amount of pro-
pane, butane, and pentanes may differ
from one lot-to the next, and this will affect
the spray pattern. Natural blend propel-
lants are likely to contain larger quantities
of impurities (such as water, sulfurous com-
pounds, olefins, or reactive particulates).
The presence of water can be tolerated in
water-based products, but not in products
intended to be anhydrous.
Some types of aerosol products re-
quire a purer hydrocarbon propellant than
other types. The most demanding aerosol
products are aerosol perfumes and fra-
grances. Other products which require a
highly refined hydrocarbon propellant in-
clude personal care products, food prod-
ucts, medicinal or pharmaceutical products,
some household products, certain paints
and coating sprays, and certain automo-
tive and industrial sprays.
Before the propane and butanes are
suitable for these aerosol propellant appli-
cations, they must be purified further to
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Table 1.
Physical Properties of CFC and Hydrocarbon Propellants
Name
CFC-11
CFC-12
Propane
Isobutane
n-Butane
Formula
CCI3F
CCIf,
C3H$
C4H10
CtHw
Molecular
Weight
137.4
120.9
44.1
58.1
58. 1
Vapor
Pressure
@21°C
(kPa)
89
586
855
317
221
Specific
Gravity
1.476
1.311
0.5077
0.5631
0.5844
Solubility
in Water
(Kauri-
Butanol)
60
18
15.2
17.5
19.5
Toxicity
(TLV)
9 1000
1000
1000
'
800 (est.)
_
600
Stability
(g/L per year)
(w/steel 30PC,
101.3 kPa)
10
0.8
—
—
—
Flammability
(explosive range)
Nonflammable
Nonflammable
Flammable
(2.18 - 9.5 vol%)
Flammable
(1.86- 8.5 vol%)
Flammable
(1.86 - 8.5 vol%)
remove odorous and reactive compounds
such as unsaturated hydrocarbons (for ex-
ample, 1-butylene or propylene), as well
as sulfur compounds and water. The pro-
cesses used include: dehydration (for re-
moving moisture); acid gas removal (for
removing sulfur compounds); and sulfuric
acid treatment or desiccant treatment (for
removing unsaturated compounds). Con-
tacts with industry experts and limited pub-
lished data suggest that the most common
type of hydrocarbon propellant purification
is the solid adsorbent process. The solid
adsorbent process can use such materials
as silica gel, activated aluminas, or mo-
lecular sieve adsorbents for water or sulfur
compounds (dehydration or acid gas re-
moval). Unsaturated compounds can be
removed using activated carbon or mo-
lecular sieves. The nonregenerable sys-
tem is simpler and less expensive than a
regenerable system, but the adsorbent(s)
must be replaced periodically. The disad-
vantage of a non-regenerable adsorbent
system is that, once the adsorbent be-
comes saturated, the impurities will no
longer be removed, and contaminated pro-
pellant will enter the system.
An alternative to on-site purification is
to use a central purification facility in con-
junction with a distillation system. The cen-
tral purification facility can operate with
multiple beds that are alternated between
purification and regeneration. Such a com-
bined facility would comprise the basic
elements of a regional hydrocarbon pro-
pellant supply.
Countries can import purified hydrocar-
bon propellant or LPG by overland or ocean
shipment in bulk containers. Containers for
shipping LPG include tank trucks, rail tank
cars, and containerized pressure vessels
(International Organization of Standardiza-
tion containers) for ocean shipment.
Safety in Using Hydrocarbon
Propellants
Hydrocarbon gases are used primarily
as fuels. Because of their flammability,
they must be handled with great care. In
the U.S., the National Fire Protection As-
sociation (NFPA) has issued standards for
manufacturing and storing aerosol prod-
ucts (NFPA Code SOB), and for storing
and handling LPG (NFPA Code 58). In
addition to these codes, which relate di-
rectly to the safety of aerosol products,
many other NFPA codes are relevant. Im-
portant safety measures include:
Locating manufacturing buildings and
flammable propellant storage tanks
at a safe distance [7.6 m (25 ft) or
more] from the property fenceline and
from other areas of the plant that
could become sources of ignition or
shrapnel.
Providing for a blast wall between
flammable propellant charging rooms
and other areas.
Providing a well-ventilated gas house
that gives positive ventilation (at both
normal and emergency rates).
Routing all discharge vents from
vacuum pumps, propellant pumps,
and building ventilation systems no
less than 3 m (10 ft) above the roof to
ensure adequate dispersion.
Complying with the 1990 U.S. Na-
tional Electrical Code (NEC) for haz-
ardous atmospheres, which requires
that equipment be isolated so that
these potential ignition sources are
enclosed in "explosion proof" hous-
ings. The NEC Code specifies that
approved fixtures be used on electric
. motors, switches, lamps, and other
electrical equipment. The minimum
ratings for the gas house and pump
room where flammable hydrocarbon
propellants are used are Class I, Di-
vision 1, Group D.
Installing blowout walls or ceiling ("de-
flagration venting") to allow a con-
trolled release of pressure if an
. explosion occurs. If venting is not
possible or if personnel will be present
when filling is underway, a specially
engineered "explosion suppression"
system is required. This type of sys-
tem often employs pressurized halon,
which is an ozone-depleting sub-
stance, and its production will be
phased out under the Montreal Pro-
tocol.
Providing automatic sensing systems
to measure flammable gas concen-
trations in the gas house, sound
alarms, and activate the emergency
ventilation system and interlocks to
cut off the propellant supply from the
tank farm.
Again, this is only a partial list of the Code
requirements. Other important areas cover
such topics as fire sprinkler systems,
standpipes, fire hoses, and fire extinguish-.
ers.
A fully enclosed gas house with two-
speed ventilation and an explosion sup-
pression system may not be necessary in
warm climates, where an "open-air filling"
area may be possible. The open-air filling
technique has several advantages, such
as reduced capital expenditures for install-
ing or retrofitting an aerosol-filling plant.
In addition to the general safety consid-
erations for hydrocarbon storage and build-
ing construction, other engineering safety
measures apply to the hydrocarbon con-
tainer valves and accessories, piping, and
safety relief devices.
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Labeling Requirements and
Flammabillty Testing
Manufacturers normally place warnings
on labels of aerosol products to ensure
that the products are used safely and for
thoir intended purposes. Among the most
important labeling statements are the words
FLAMMABLE and EXTREMELY FLAM-
MABLE. These warnings do not generally
discourage purchases of useful products
except on baby products, foods, and some
Pharmaceuticals.
In the U.S., two tests are used to deter-
mine when FLAMMABLE or EXTREMELY
FLAMMABLE labels are required: 1) the
Modified Flash Point Test, and 2) the Flame
Projection/Flashback Test.
Equipment Conversion of
Hydrocarbon Filling Operations
Automated Filling Lines
The large aerosol filling operation uses
an automated production line that can pro-
duce 14,000 to 28,000 units per shift, which
equals approximately 35 to 70 units per
minute. The equipment that must be modi-
fied to convert from CFG aerosols includes
the propellant supply, the gassing area,
and possibly the main production area,
depending on the location of the gassing
area.
Automated filling lines typically use bulk
storage of the hydrocarbon propellant. One
of the most important guidelines is ensur-
ing that the distance between the tanks
and charging pumps and the production
and gassing area meets the specifications
in NFPA 30B. For tanks under 7.6 m3 (268
ft3), at least 8 m (25 ft) from the nearest
production facility is recommended. For
tanks over 7.6 m3, at least 15 m (50 ft) is
recommended. If existing fixed storage
tanks are reused, they must be thoroughly
cleaned (sandblasted) and hydrostatically
tested at 2 times their maximum working
pressure to ensure they can safely store
the hydrocarbon propellant.
In addition to the storage area, modifi-
cations may be needed for the gassing
and production areas. The gassing room
should be constructed outside the main
production area. The modifications required
include increased ventilation, combustible
gas detectors, isolation of electrical equip-
ment in "explosion proof" housings, and
possibly an explosion suppression system.
The walls and roof of the gas house should
be made blast proof, and blowout panels
should be provided to allow a controlled
release of pressure.
If a facility is not able to make the
modifications suggested above, then an
open-air gassing room may be an alterna-
tive. The main feature of the open-air gas
house is the use of natural ventilation to
keep any escaped hydrocarbon vapors
below flammable or explosive limits. The
gassing apparatus is located outside of the,
main production facility, with a solid roof,
wire mesh walls on three sides, and a solid
wall between the gassing area and the
main production facility.
The costs for converting an automated
aerosol filling line are difficult to estimate
without site-specific details. One example
is the Mexico Case Study, which estimated
the cost to convert an automated filling line
(producing 8 million cans per year) from
CFCs to LPG to be $566,000 for capital
investment (machinery and filling lines) and
$793,000 for auxiliary equipment (gas de-
tectors, fire extinguishing systems, and
alarms), resulting in a conversion cost of
$1.36 million U.S. dollars. However, the
estimated propellant savings from using
less expensive hydrocarbons in place of
CFCs would be $1.69 million U.S. per
year. Therefore, the cost savings from con-
verting to hydrocarbons would more than
offset the initial capital investment.
Manual Filling Lines
Small- to medium-sized aerosol-filling
operations typically use a manual produc-
tion line capable of producing 6,000 to
8,000 units per shift with two persons (lim-
ited to filling, gassing, crimping only), which
would equate to approximately 15 units
per minute. On the basis of one 8-hour
shift per day and a 5-day work week, such
a plant could conceivably produce nearly 2
million units per year. Other operations,
such as labeling containers with paper la-
bels or packing, would either slow the rate
or require additional labor.
Atypical manual aerosol filling line uses
air-operated and manually actuated equip-
ment. Each container must be transferred
manually from one step to the next. Cold
filling is nor appropriate with hydrocarbon
propellants and should be replaced by pres-
sure filling. A single-station pressure filling
machine may cost up to $30,000.
Required equipment modifications
would typically be limited to the propellant
supply and the gassing area. The hydro-
carbon storage used for small manual fill-
ing lines are typically several 53-kg (117-lb)
cylinders manifolded together or a 385-kg
(849-lb) container. Cylinders not in use
should be stored in the open air or in well-
ventilated areas. No more than six cylin-
ders should be stored together with a
minimum distance of 3 m (10 ft) between
the storage and a boundary, building, or
fixed ignition source (such as pumps, elec-
trical motors, or vehicles). All cylinders
should be stored upright, with protective
valve caps in place, and securely chained.
In addition to the propellant supply,
equipment modifications for manual lines
must be made to the gassing area. Many
small filling operations are located in
crowded urban areas, and the use of an
open-air gassing area would not be pos-
sible. One way to significantly reduce the
hazards associated with hydrocarbon pro-
pellants would be to locate the gassing
and crimping operations within a labora-
tory fume hood. These types of hoods
have been successfully used for labora-
tory-scale, manual filling operations that
closely correspond to cottage-size produc-
tion facilities.
The exhaust from the fume hood should
be connected to a flue or pipe duct that
uses an explosion-proof fan motor. The
end of the duct or piping should exit di-
rectly through the roof of a one-story build-
ing or to an adjacent outside wall if the
filling room is located in a multi-story build-
ing. The location of any ignition sources
that may be near the exhaust duct should
be considered. The fume hood, fan-motor,
and any equipment used within the fume
hood (such as lighting) should be Class I,
Division 1, Group D explosion-proof equip-
ment.
The costs for converting a'manual aero-
sol filling line are also difficult to estimate
without site-specific details. The estimated
cost to convert a hypothetical manual fill-
ing line (producing 500,000 cans per year)
from CFCs to LPG is at least $12,000 U.S.
dollars. This includes purchase of explo-
sion-proof motors, starters, and solenoid
valves; installation of explosion-proof fume
hoods for gassing equipment and test
baths; and construction of a covered,
fenced hydrocarbon storage area. This ini-
tial capital investment would be more than
recovered by the material cost savings of
using hydrocarbon propellants instead of
CFC propellants.
Aerosol Product Storage
Since hydrocarbon propellants are flam-
mable (containing butane, propane, or a
mixture of- these two, or less frequently,
pentane or ethane), producers, distribu-
tors, and end users must take extra care to
handle them safely. Aerosol products can
be classified into three levels according to
their perceived flammability. hazard. The
classification considers the percentage of
flammable base material and flammable
propellant. Materials that mix with water,
such as ethanol, isopropanol, propylene
glycol, and acetone, would dissolve in the
water from sprinklers and fire hoses during
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afire and be rendered nonflammable. Wa-
ter immiscibje materials, on the other hand,
such as toluene and aliphatic petroleum
distillates would not dissolve and could
spread as a burning top layer as water was
directed at a fire.
Level 1 aerosol products are those
whose base products contain up to 25%
by weight of materials with flash points of
260°C (500°F) or less. Level 1 aerosol
products do not require special fire pro-
tection measures. These "water-based"
aerosol products may be stored as a
Class III commodity as defined in NFPA
Standard 231 for Rack Storage of Materi-
als; i.e., equivalent to paper, cardboard,
and wood products.
Level 2 products are those whose base
product contains either 1) more than 25%
by weight of water miscible materials with
flash points of 260°C (500°F) or less, or 2)
more than 25% but less than 55% of water
immiscible materials with flash points of
260°C (500°F) or less. Level 3 products
are those whose base product contains
more than 55% of water miscible materials
with flash points of 260°C (500°F) or less,
or the flammable propellant equals or ex-
ceeds 80% of the net container weight.
Level 2 and Level 3 aerosol products
may be stored in a general purpose ware-
house that either has no sprinklers or is
not protected in accordance with NFPA
306, but the quantity is limited to 1135 kg
(2,500 Ib). Storage of greater amounts of
Level 2 and Level 3 aerosol products in
general purpose warehouses requires com-
pliance with the protection guidelines for
automatic sprinklers and palletized, solid
pile, or rack storage arrangements as listed
in NFPA 30B.
Aerosol 'storage in sales display areas
and backstock storage areas is also ad-
dressed in NFPA 306.
Product Reformulation
The characteristics of hydrocarbon pro-
pellants as they relate to formulations and
performance are discussed. Dispersion,
one major attribute of aerosol propellants,
is the efficiency with which a propellant
can produce a fine spray or acceptable
foam. The dispersive effect is not linear
but is modified by vapor pressure and
solubility factors, ft normally can be used
as a general guideline to determine equiva-
lencies when changing from one propel-
lant to another.
After a concentrate has been tenta-
tively developed, the correct type and
amount of propellant must be added, and
an aerosol valve must be used that will
develop the desired spray pattern or foam
puff. One of the most important character-
istics that the formulator looks for is par-
ticle size distribution. There are several
techniques to decrease the droplet size if it
is too coarse. One approach is to use a
vapor-tap valve.
Approximately 40-50% of the world's 8
billion aerosol products use vapor-tap
valves. Such valves have an orifice ex-
tending through the side or bottom wall of
the valve body and into the head space
area. The orifice may be enlarged to de-
crease particle size. However, this has
several negative effects.
To devise a good aerosol product, a
formulator must minimize the risks of flam-
mability and possible explosivity. It is a
tribute to the excellence of the aerosol
packaging form that extremely flammable
products can be safely dispensed, if the
user follows label directions, and if the
formulator is able to make allowances for
reasonably foreseeable consumer misuse.
Most U.S. aerosols are formulated to a
pressure as low as is consistent with good
operational performance across the antici-
pated temperature range of their use. For
example, hair sprays are expected to work
well between 13°C and 37°C, and reason-
ably well just outside these limits.
The formulator's job is not complete
when an acceptable product and packag-
ing system have been developed. Test
packing is always needed to establish data
on weight loss rates, can and valve com-
patibility, etc. Several options are discussed
to correct corrosion problems, such as ad-
dition of corrosion inhibitors, increasing the
pH, or minimizing the presence of chloride
ion.
•&U.S. GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40119
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K.M. Adams, K.E. Hummel, T.P. Nelson, and S.L Wevill are with Radian Corp., Austin, TX
78720-1088
N. Dean Smith is the EPA Project Officer, (see below).
The complete report, entitled "Manual for Non-CFC Aerosol Packaging: Conversion from
CFC to Hydrocarbon Propellants," (Order No. PB92-101344/AS; Cost: $35.00, 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:
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
BULK RATE
POSTAGE & FEES PAID
EPA PERMIT NO. G-35
Official Business
Penalty for Private Use $300
EPA/6QO/S2-91/056
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