Table of Contents
• Firbimatic's Uncompromising Policy
• Firbimatic is a world leader in the Drycleaning industry
• Firbimatic's Clean Still Feature
• Exposure to Perchloroethylene in Commercial Drycleaning
Control of Exposure to
Perchloroethylene in Commercial Drycleaning (Machine Design)
Perchloroethylene (PERC) is the most commonly used drycleaning
solvent. PERC can enter the body through respiratory and dermal
exposure. Symptoms associated with exposure include: depression of
the central nervous system; damage to the liver and kidneys;
impaired memory; confusion; dizziness; headache; drowsiness; and
eye, nose, and throat irritation. Repeated dermal exposure may
result in dermatitis. NIOSH considers PERC a potential human
To reduce exposure to drycleaning
solvents, a comprehensive control approach should be followed
involving engineering measures, work practices, and personal
protection. Engineering measures are the most effective means of
control and should generally be considered first. Modern
drycleaning machines can dramatically reduce exposures, save money
in solvent costs, and permit easier compliance with safety, health
and environmental regulations.
TYPES OF DRYCLEANING MACHINES
Drycleaning machines have evolved
over time to better protect worker safety and health and the
environment. Drycleaning machines encompass five "generations"
which are currently used in the United States.
1st Generation: transfer machines
These older and less expensive machines require manual transfer of
solvent-laden clothing between a separate washer and dryer.
Transfer machines were used exclusively until the late 1960s.
2nd Generation: dry-to-dry (vented)
These machines are nonrefrigerated, dry-to-dry machines, using a
one-step process that eliminates clothing transfer. Clothes enter
and exit the machine dry. Second generation machines vent residual
solvent vapors directly to the atmosphere or through a form of
vapor recovery system during the aeration process.
3rd Generation: dry-to-dry (nonvented)
Dry-to-dry machines with refrigerated condensers were introduced
in the late 1970s and early 1980s. These nonvented machines are
essentially closed systems, which are only open to the atmosphere
when the machine door is opened. They recirculate the heated
drying air through a vapor recovery system and back to the drying
drum. These machines provide considerable solvent savings
and reductions in PERC emissions over their predecessors.
4th Generation: dry-to-dry (nonvented
with secondary vapor control) "Fourth generation" drycleaning
machines are essentially "third generation" machines with controls
to reduce residual PERC in the machine cylinder at the end of the
dry cycle. These machines rely on both a refrigerated condenser
and carbon absorber to reduce the PERC concentration at the
cylinder outlet below 300 ppm at the end of the dry cycle. These
machines are much more effective at recovering solvent vapors than
machines equipped with a carbon adsorber or refrigerated condenser
5th Generation: dry-to-dry (nonvented
with secondary vapor control and drum monitor) "Fifth generation"
machines, widely used in Germany but seldom in the United States,
have the same features as "fourth generation" machines. However,
they also have a monitor inside the machine drum and an
interlocking system to ensure that the concentration is below
approximately 300 ppm before the loading door can be opened.
EXPOSURES AND OCCUPATIONAL LIMITS
The current OSHA permissible
exposure limit (PEL) for PERC is 100 ppm, as an 8-hr timeweighted
average (TWA). The acceptable ceiling concentration is 200 ppm for
5 min in any 3-hr period, not to exceed a maximum peak of 300 ppm.
"4th and 5th generation" machines,
unlike their predecessors, can maintain worker exposures below the
OSHA maximum peak of 300 ppm.
IMPORTANT MACHINE DESIGN FEATURES
The following drycleaning machine design features are important
for shop owners to consider when purchasing new equipment to
minimize worker exposures to PERC.
I. Dry-to-dry design that eliminates clothing transfer
II. Primary & secondary vapor control systems
A. The primary vapor control
on each machine should have the following features:
1. A refrigerated condenser
that can achieve outlet temperature of 45F, within 10 min of
initiation of cool-down
2. The ratio of machine
capacity to compressor size should be 12 or less
B. The secondary vapor
control on each machine should have the following features:
1. A carbon adsorber capable
of reducing the PERC concentration in the cylinder at end of
the dry cycle below 300 ppm
2. Carbon capable of holding
200% of maximum quantity of PERC that it is designed to
3. Carbon desorption that
does not involve contact between steam or any other form of water
III. A drying sensor that
automatically controls the dry cycle by monitoring the solvent
IV. A door locking mechanism that prevents the loading and
unloading door of the drycleaning machine from opening before the
end of the dry cycle.
Vapor phase of the "4th and 5th
Generation" dry-cleaning machines. The large, regenerable, carbon
filter is used to reduce concentrations in the drum below
approximately 300ppm during the final phase of the dry cycle.
Retrofitting is a less expensive option than purchasing new
equipment. Retrofitting is not always practical and can be fairly
difficult depending on the machine. A refrigerated condenser could
be retrofitted on many machines currently using a water- or air
-cooled condenser. This retrofit lowers short-term exposures by
approximately 50% and increases solvent mileage. A carbon adsorber
could be retrofitted onto a 3rd Generation machine. This retrofit
lowers short-term exposures by
OTHER MACHINE FEATURES
Other machine features that help reduce occupational exposures to
PERC include: safety switches to insure closed-door operation;
safety interlocks for heating, cooling and still system failures;
emission-free still cleaning devices; regenerable solvent
filtration systems; emission free solvent filling devices; seals
and fittings with tighter tolerances that resist deterioration;
process controls that lower garment residuals after drying
process; and controls that reduce vapors escaping from the button
and lint traps.
To obtain more information about
controlling this hazard or for information about other
occupational health and safety issues:
-- call NIOSH* at 1-800-35-NIOSH
-- visit the NIOSH Home Page on the World Wide Web at
A NIOSH technical report, Control of
Health and Safety Hazards in Commercial Drycleaners:
Chemical Exposures, Fire Hazards,
and Ergonomic Risk Factors, has been published on this subject.
This document is one in a series of seven HAZARD CONTROLS
concerning control of hazards in the drycleaning industry that are
available free upon request.
*NIOSH is the Federal agency
responsible for conducting research and making recommendations for
work-related illnesses and injuries. All HAZARD CONTROLS are based
on research studies that show how worker exposures to hazardous
agents or activities can be significantly reduced.