United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park, NC 27711
EPA-453/R-94-073
October 1994
Air
Perchloroethylene Dry Cleaning Facilities -
General Recommended Operating and
Maintenance Practices for Dry Cleaning
Equipment
(Only for Use When Manufacturers'
Information Is Unavailable)
ENVIRONMENTAL
PROTECTION
AGENCY
DALLAS, TEXAS
UBRARY
GOT
-------
GENERAL RECOMMENDED OPERATING AND MAINTENANCE
PRACTICES FOR DRY CLEANING EQUIPMENT
1.0 INTRODUCTION
On September 22, 1993, the United States Environmental
Protection Agency (EPA) finalized the national emission standards
for hazardous air pollutants (NESHAP) for perchloroethylene dry
cleaners (58 FR 49354) . This regulation set standards for the
reduction of perchloroethylene (PCE or perc) emissions from dry
cleaning operations. Included in the NESHAP were requirements that
owners or operators of dry cleaning machines and control devices
follow their manufacturers' instructions for the proper operation
and maintenance of machines and control devices. Owners or
operators are required to keep a copy of any manufacturers'
specifications or operating and maintenance recommendations at the
dry cleaning facility.
The EPA realizes that some dry cleaners may no longer have
equipment manuals for older dry cleaning machines and control
devices. Owners or operators of such dry cleaning machines and
control devices should make every reasonable effort to obtain these
manuals. This would include contacting manufacturers, if the
manufacturers are still in business, and contacting local, state,
and national trade associations in an effort to locate and obtain
manuals.
The purpose of this manual is to outline general recommended
operating and maintenance practices for owners or operators of dry
cleaning machines and emission control devices, only where efforts
to obtain manufacturers' manuals are unsuccessful. This document
serves only as a last resort when other information is not
available. It is never to be used to supersede available
manufacturers' information. This document is only for use when
manufacturers' information is completely unavailable.
Section 2.0 of this manual presents general recommended
operation and maintenance practices for dry cleaning machines and
auxiliary equipment. This section includes a brief description of
-------
the basic components in dry-to-dry and transfer machine systems,
along with recommended operation and maintenance practices derived
from sources with expert knowledge of the dry cleaning industry.
(See references 1 through 5 listed at the end of this document.)
Section 3.0 provides similar information for control devices.
Section 4.0 presents a brief discussion of some of the most common
causes of PCE vapor loss from dry cleaners.
This manual is not intended to replace specific
recommendations included in existing equipment operating manuals
available from manufacturers of equipment. The EPA strongly
recommends that dry cleaners obtain equipment operating manuals for
each machine and control device they operate, if such manuals are
available from the manufacturers.
2.0 PROPER DRY CLEANING EQUIPMENT OPERATION AND MAINTENANCE
Two basic types of dry cleaning machine are discussed in this
section: dry-to-dry machines and transfer machine systems.
Specific information on the major components for each of these
machine types is discussed in further detail in the remainder of
this section.
Dry-to-dry machines clean and dry articles within the same
cylinder (or drum or basket). Transfer machine systems clean and
dry articles in separate machine cylinders. The remaining
components of the two dry cleaning machine systems are the same.
These components are as follows: heating and condensing (cooling)
coils, button trap, fan, water separators and lint traps.
During the wash cycle on either machine, the machine cylinder
is filled with soiled garments and then filled with PCE. Then the
machine cylinder usually rotates clockwise and counterclockwise to
clean garments. During extraction, the cylinder rotates at a high
rate of speed, forcing excess PCE from the garments through the
perforated cylinder.
The difference between dry-to-dry and transfer machine systems
is that, in a dry-to-dry system, the garments remain in the same
-------
machine for drying, whereas in a transfer machine system the wet
garments must be transferred to another machine for the drying
process.
Heating and condensing coils are associated with the drying
(reclaiming) phase of the process. For dry-to-dry machines, this
step occurs in the same cylinder as washing and for transfer
machine systems it occurs in a separate machine from washing.
During the drying cycle, hot air (from heating coils) is passed
over the garments, volatilizing (evaporating) liquid PCE remaining
in the garments. This air stream is then cooled
by the condensing coils, condensing PCE vapor out of the air
stream. The air stream is then reheated and recirculated over the
garments. Condensing coils can utilize either water or a
refrigerant as the means for cooling the circulating air. Older
dry cleaning systems are more likely to use water-cooled condensing
coils.
PCE overflowing from the dry cleaning machine cylinder during
the wash/drain/extract cycle flows through a button trap before
reaching the pump. The button trap contains a strainer and keeps
buttons, pins, lint, and other small items from reaching the PCE
tank, filters, and pump.
A fan provides power to circulate heated air through the
machine cylinder to evaporate PCE from clean, wet garments. Proper
operation of the fan is needed to ensure complete drying of the
garments, as well as proper temperatures and properly cleaned
heating and cooling coils which will provide positive air flow.
Lint filters are located in several places in the dry cleaning
machine system. Each machine has lint collection points before the
PCE pump (button trap, ) in the machine cylinder air flow system
(prior to the heating and condensing coils) used for drying the
clothes, and if used, there should be a collection point before the
carbon adsorber. Some pumps have their own lint and foreign object
strainer.
The proper operation and maintenance of dry cleaning machines
is important to reduce PCE loss. In addition to checking for leaks
3
-------
and mechanical failure of the equipment mentioned above, correct
operational procedures can also reduce PCE liquid .or vapor loss.
Proper operational procedures include, correct weight loading of
the machine, adequate drying temperature, sufficient drying time,
adequate cooling water or refrigerant temperature, proper water
separation and adequate air flow. These procedures are discussed
in greater detail in section 4.0.
2.1 Maintenance of Machine Components
Table 1.0 provides a summary of recommended maintenance
practices for dry cleaning machine components. The remainder of
this section discusses those practices in more detail.
Dry-to-dry machine cylinder. Although dry-to-dry machines
wash and dry garments in one cylinder, potential PCE emissions can
come from many sources which include the cylinder, leaking door and
other gaskets and the unloading of garments that are not adequately
dried (reclaimed.) Liquid and vapor PCE leaks should be detected
and repaired during a weekly inspection program. If a liquid leak
is detected, the seal should be replaced immediately since
significant PCE loss can occur. Vapor leaks can sometimes be
detected by running a finger along the entire perimeter of the door
seal while the machine is operating or by placing a liquid bubble
solution around the door seating and looking for bubbles. An
electronic halogen leak detector is capable of locating vapor leaks
that other methods might miss.
Vented dry-to-dry machines and dryers (those with add-on
refrigerated condensers or carbon adsorbers) have exhaust dampers
to control the flow of hot air. These exhaust dampers should be
checked monthly to ensure they are functioning properly. This can
be accomplished by placing and sealing a collapsed, inflatable
plastic bag over the ductwork used to vent the dry-to-dry machine
at point downstream from the direction of flow past the exhaust
damper. If the exhaust vent outlet can not be used, some minor
modifications to the ductwork may need to be made, such as drilling
a small, resealable test hole (resealable with a leak proof plug or
-------
TABLE 1. MAINTENANCE SCHEDULE FOR DRY CLEANING EQUIPMENT
COMPONENT
MACHINE COMPONENT:
Dry-to-dry machine cylinder
Transfer washer/extractor
Transfer dryer/reclaimer
Heating and condensing coils
Button trap
Fan
Lint traps
AUXILIARY EQUIPMENT:
Filters
Distillation unit or
Muck ooker
Water separator
CONTROL DEVICE:
External refrigerated condenser
FREQUENCY
weekly
monthly
weekly
weekly
monthly
monthly
annually
daily
weekly
annually
daily
weekly
monthly
monthly
*
weekly
semi-annually
weekly
monthly
daily
weekly
MAINTENANCE PROCEDURE
leak check of door seatings and gaskets
leak check of exhaust damper (vented machines)
leak check of door seatings and gaskets
leak check of door seatings and gaskets
leak check of exhaust damper
check for lint build up
clean coils
clean strainer
check lid for leaks
check for lint buildup and need for lubrication
clean lint bag
dry clean or launder lint bag
check ductwork for leaks
check lint build up on temperature probe
clean and change filters (filters drained and muck stored in sealed containers)
leak check of seals and gaskets
clean steam and condensation coils if necessary
clean separator tank
check vent
clean any lint filters in air stream
measure temperature on exhaust for dry-to-dry machines/transfer dryer reclaimer
Carbon adsorber
weekly
moDthly
annually
daily or before saturation
weekly
daily or accordingly
monthly
measure temperature on inlet and exhaust for transfer washer
leak check of seals, gaskets, and diverter valve
check refrigerant coils for lint build up
clean refrigerant coils
desorb
measure concentration of PCE in exhaust air stream or in machine drum
clean all lint filters
leak check of gaskets and ductwork
Clean and change filters according to manufacturer or media supplier's specifications or recommendations. If unavailable, see Attachment A.
-------
tape) in the ductwork or the addition of new ductwork and/or a
manual damper for the testing. The plastic bag. is placed and
sealed over the test hole during the beginning portion of the
drying cycle. During the beginning portion of the drying cycle,
the vent to the control device should not be in use, but should be
shut off with the exhaust damper. To test to see if the exhaust
damper is leaking, the plastic bag is placed over the exhaust
outlet vent or test hole to see if it will inflate. If it
inflates, then there is a leak and the exhaust damper will need to
be repaired. It is common to find these dampers stuck in position
that does not allow them to close all the way and thus leak.
Dampers are also known to wear and will need parts repaired so that
they will seal properly again.
Transfer washer/extractor cylinder. Potential emissions from
the. washer cylinder come from leaking door gaskets. Liquid PCE
leaks and leaks from door seatings and gaskets should be detected
and repaired during a weekly inspection program. These leaks
should be detected in the same manner as discussed above for leaks
from the dry-to-dry machine cylinder.
Transfer dryer (reclaimer). As with the washer cylinder, one
source of potential PCE emissions from a dryer (reclaimer) is
through leaking gaskets on the door. These leaks should be
detected in the same manner as discussed above for leaks from the
dry-to-dry machine cylinder. In addition to leaking door gaskets,
a main source of potential PCE emissions for dryers is through
intake and exhaust dampers on exhaust systems. The machine damper
gaskets should be checked monthly to ensure proper operation. It
is quite common for these dampers to "stick" in a partially open
position and not completely close. As a result, it is very
important to check the operation of the damper and its closed
position very closely to ensure the damper swings freely and closes
completely when not in use.
Heating and condensing coils of dry cleaning machines
(dryers). There are several sets of heating and condensing coils
-------
typically in use at dry cleaning facilities. Coils are associated
with the dry cleaning machines themselves (dryers), distillation
units, muck cookers, and add-on refrigerated vapor condensers that
also become part of the reclaiming section of the dry cleaning
machine. This section addresses the heating and condensing coils
of the dry cleaning machines themselves. The condensing section of
the dry cleaning machine is often referred to as the "reclaiming"
section. Heating and condensing coils should be checked for lint
build up every month and thoroughly cleaned on an annual basis.
Special emphasis should be placed on the fins surrounding the
heating and condensing coils. Heating and condensing coils on
older tilt back dryers (transfer systems only) should be cleaned
daily. (See reference 2.)
As mentioned above, the coils should be cleaned annually at a
minimum. However, if the coils appear covered with lint that is
difficult to remove when cleaned annually, the owner or operator
should clean the coils on a more frequent basis (semi-annually).
Heating coils can be cleaned by blowing compressed air or steam
over the coils. Condensing coils can be cleaned by brushing the
coils with a stiff brush to loosen lint, then picking up the
residue with an industrial vacuum, or by the use of compressed air.
Button trap. The button trap lid and strainer need regular
servicing. The strainer should be cleaned daily, and the lid
checked for a vapor leak proof seal during the weekly leak
inspection program.
Fan. Inspection and lubrication need to be performed annually
to ensure that fans are functioning properly.
Lint traps. The lint trap located in the air flow system
usually contains a removable lint bag or filter. This bag or
filter should be cleaned daily and washed or dry cleaned weekly (a
second lint bag or filter should be used while the first is being
cleaned.) Never run a dry-to-dry machine or dryer without a lint
bag or filter. Once a day the ductwork in front of and behind the
lint bag or filter should be checked for lint buildup. Also,
machines with heat sensor probes located under or behind the lint
-------
bag or filter should be checked for lint buildup on the probe on a
daily basis.
2.2 Auxiliary Dry Cleaning Equipment
In addition to the components of dry cleaning machine systems
described in sections 2.0 and 2.1 above, all dry cleaning
facilities have auxiliary equipment used in the dry cleaning
process. This equipment is also covered by the NESHAP and includes
filters, distillation units, water separators, and pumps. Spotting
and pressing activities are not covered under the NESHAP and the
equipment used for these activities will not be discussed in this
manual. Table 1.0 provides a summary of recommended maintenance
practices for auxiliary equipment. The remainder of this section
provides a more detailed discussion of this auxiliary equipment and
recommended maintenance practices to prevent PCE loss.
Filters. Filters are used to remove suspended particles and
dyes from the PCE. There are several types of filters used at dry
cleaning facilities. Those filters currently found at dry cleaning
facilities include constant pressure powder, regenerative powder,
cartridge, and spin disk filter systems (powder and powderless.)
Most dry cleaning facilities currently use cartridge or disk filter
systems of one type or the other. Guidelines on how to maintain
proper operation of constant pressure and regenerative filter
systems are provided in Attachment A, in the event manufacturers
information in not available for these filters. (See reference 3.)
Distillation unit. The purpose of a distillation unit is to
purify and recover used PCE to recycle it back into the dry
cleaning system. Distillation units typically consist of steam and
condensation coils. PCE and water retrieved from the distillation
process go to a water separator. Operation and maintenance of the
water separator will be discussed separately. Potential PCE loss
from these units can be due to leaks in seals and gaskets, build up
of still bottoms on the heating coil and improper water or steam
temperatures.
Seals and gaskets in the distillation unit should be checked
8
-------
for leaks and repaired at least every two weeks. The steam and
condensation coils for the distillation unit should be checked
monthly and cleaned semi-annually to avoid lint build up. They may
be cleaned in the same way as the coils used in the dry cleaning
machine. Some stills do not require coil removal.
The following practices are recommended to achieve optimum
still performance and minimize PCE in the still residue:
Never exceed 75 percent of the still kettle capacity, or
the level recommended by the manufacturer;
Condenser water flow should be set up countercurrent to
PCE flow; and
Keep the PCE return temperature at maximum of 32°C
(90°F) to minimize evaporative loss through the PCE
storage tanks. (See reference 1.)
Muck cooker. Older dry cleaning systems with tubular powder
filtration systems (constant pressure and regenerative) use muck
cookers to distill the residue from these systems. Muck cookers
recover PCE from filter muck, which is a combination of water, PCE,
filter powder, carbon, detergent, and soils. Muck cookers operate
the same as regular distillation units, except they stir the muck
in order to speed up the distillation process. Maintenance
procedures for muck cookers are the same as for distillation units,
except that at least annual lubrication of the motor and gear box
is needed.
Water separator. Water separators partition PCE from the PCE-
water mixture that comes from the distillation unit, as well as any
water that condenses out with the PCE in the drying process.
Water, which is less dense (i.e., lighter) than PCE, floats to the
top of the separator tank and drains into a covered container, and
PCE sinks to the bottom, where it should be routed back to the PCE
base tank or a covered storage tank.
To function properly, water separators are vented to the
atmosphere. This vent can become clogged and should be checked
each month. In addition, the separator tank should be cleaned
weekly. It should be noted that separator water contains minor
9
-------
amounts of PCE and should be disposed of properly. It should not
be poured down a drain or flushed down a toilet. It should be
treated as a hazardous waste. Disposal of hazardous waste is
usually best accomplished through the use of an EPA licensed
hazardous waste hauler. Proper disposal of separator water may be
accomplished by using an evaporator, provided the separator water
does not contain a layer of separated PCE.
3.0 CONTROL DEVICE OPERATION AND MAINTENANCE
The NESHAP allows for two types of control devices on machines
installed prior to December 9, 1991 (1) refrigerated condensers and
(2) carbon adsorbers (if installed prior to September 22, 1993}.
Machines installed after September 22, 1993 must install
refrigerated condensers. In addition, existing major source
facilities must keep their transfer machine systems inside a room
enclosure and new major source dry cleaning facilities must install
a refrigerated condenser and a secondary carbon adsorber.
Table 1.0 provides a summary of recommended maintenance
procedures for refrigerated condensers and carbon adsorbers. Those
maintenance procedures are discussed in further detail below.
Refrigerated condensers. The air stream coming from a vented
dry-to-dry machine or dryer during the end of the drying cycle is
directed through a refrigerated condenser and back to the machine.
The condenser cools the air stream to remove and recover PCE
vapors. When the cycle is complete and the machine door is opened,
most refrigerated condensers exhaust any remaining air out of the
machine into the atmosphere. Some refrigerated condensers do not
exhaust the air remaining in the machine. Both methods are
permitted by the NESHAP, except for new major sources which must
exhaust through a secondary carbon adsorber.
In addition to the temperature monitoring requirements of the
NESHAP, all gaskets and seals should be checked for leaks during a
weekly leak detection and repair program. All lint filters in the
ductwork associated with refrigerated condensers should be cleaned
on a daily basis.
10
-------
Carbon adsorbers. Carbon adsorbers remove PCE from the vapor
stream in a process called adsorption. During adsorption, exhaust
from the machine is passed through the carbon adsorber where PCE is
adsorbed onto carbon particles. PCE is removed from the carbon bed
during a process called desorption. During desorption, steam is
passed through the carbon bed, removing the PCE from the carbon
particles. The steam and PCE then go to a condenser where the PCE
is condensed out of the air stream. The PCE is routed to the base
tank or a covered storage container after passing through a water
separator.
The effectiveness of carbon adsorbers depends upon proper
desorption. If carbon adsorbers are not desorbed properly, PCE
vapor in the air stream will pass through the carbon adsorber
without being adsorbed. This means that the carbon adsorber must
be desorbed (or "stripped") on a regular basis. The frequency of
desorption depends to a great extent upon the amount of dry
cleaning performed and the concentration of PCE in the air stream.
It is recommended that owners or operators determine the maximum
quantity of PCE that the carbon adsorber can hold, and then desorb
the carbon adsorber daily, unless the daily return of PCE from the
carbon adsorber is less than 50 percent of that capacity. One way
to determine the maximum capacity a carbon adsorber can hold is to
check the carbon adsorber exhaust with a colorimetric detector
tube. Once the exhaust reads over 100 parts per million of PCE on
the colorimetric detector tube, the carbon adsorber is considered
saturated. The saturated carbon adsorber should then be completely
desorbed by steam desorption for one hour. The amount of PCE
returned from this desorption will be the maximum quantity of PCE
that the carbon adsorber can hold. (See reference 2 and Attachment
B on operating and maintaining carbon adsorbers.)
In addition to the monitoring requirements of the NESHAP, all
lint filters and screens associated with carbon adsorbers should be
cleaned on a weekly basis. All gaskets and duct work associated
with the carbon adsorber should also be included in a weekly leak
detection and repair program.
11
-------
A carbon adsorber's maximum holding capacity can diminish
substantially over time depending on how the carbon .is used. It is
recommended that owners consider replacing or reactivating the
activated carbon every 5 years, as performance may degrade to the
point where the carbon adsorber will allow PCE to "break through"
in the carbon adsorber exhaust past the 100 ppm limit before the
next desorption. The recommended 5 year interval for replacing or
reactivating the activated carbon may be more or less frequent
depending on the type of use the activated carbon sees. (See
reference 1.)
4.0 OTHER COMMON CAUSES OF FCE LIQUID AND VAPOR LOSS
There are many potential causes of PCE liquid and vapor loss
that could occur at a dry cleaning facility. (See reference 2.)
Most of these causes were discussed in the previous sections on
machine and control device operation and maintenance. Other
significant causes of PCE losses may be:
(1) Leaking exhaust damper;
(2) Improper cooling water or drying temperature;
(3) Insufficient drying time;
(4) Over or under loading of machine; and
Even though item (l) above, the leaking exhaust damper, was
discussed under Section 2.1. above, it can not be overemphasized
the need to check that the exhaust damper is not leaking. It is a
well known fact that this exhaust damper has been a major source of
PCE losses. Unfortunately, these exhaust dampers are usually
located in difficult to get to areas of the dry cleaning plant,
such as in the back of the dry-to-dry machine or dryer which is
often placed against a wall, thus making repairs burdensome.
Nevertheless, it is very important to repair the exhaust damper, if
it is found to be leaking.
If the cooling water or refrigerant temperature is not kept
cool enough, the condenser coils cannot cool the air stream enough
and drying takes longer. One indication of this problem is if
clothes have a PCE odor after the end of typical drying cycle.
12
-------
This can be a problem in summer months at dry cleaning facilities
in warmer climates using water cooled condenser coils and using
water cooling towers. Some potential solutions to this are: to
increase drying time, to use a water chiller, or to use a city
water supply during these times.
Drying temperature is important for the same reasons as proper
cooling temperature. If the temperature is not hot enough, clothes
will not be dry when the cycle is completed. Care should be taken
to maintain adequate steam pressure to keep the drying temperature
between 14QQF and 15QQF.
The length of the drying cycle should be adjusted to ensure
that garments are completely dry when it is finished. In addition
to the two reasons mentioned in the previous paragraphs, the proper
cycle length may vary according to the amount of air flow through
the machine. To ensure the maximum amount of air flow in the__
machine, keep the steam and condenser coils and lint bags clean.
Finally, to ensure that clothes are completely dry and
machines recover the maximum amount of PCE, it is recommended that
machines be under loaded by at least 5 pounds, but not by more than
25 percent of the machine's capacity. (See reference 2.)
Otherwise, the normal PCE losses due to running the machine will
outweigh the PCE savings gained by slight under loading.
13
-------
5.0 REFERENCES
1. National Task Force on the Reduction of Solvent Emissions from
Dry Cleaning Facilities, Environmental Code of Practice for
the Reduction of Solvent Emissions from Dry Cleaning
Facilities. Draft Document prepared for the Canadian Council
of Ministers of the Environment. April 1992.
2. Neighborhood Cleaners Association (NCA), Keep It Clean;
Guidelines to Reduce or Eliminate Perchloroethylene Releases
to the Air. Soil and Water.
3. International Fabricare Institute (IFI), "An Equipment
Handbook," Focus on Drycleaning. vol. 8, No. 3, July 1984.
4. Multimatic Incorporated, Owner's Manual. February, 1994.
5. Michigan Department of Public Health (MDOH), Division of
Occupational Health, Drycleaning Section, Class IV
Establishment Rule P.A. 368 of 1978.
14
-------
ATTACHMENT A
(See reference 3.)
15
-------
ATTACHMENT B
(See reference 2.)
16 16
-------
ATTACHMENT A
(See reference 3.)
-------
Constant Pressure Filters
Constant pressure filters are only used in powder filtration
systems. The pump must run continually to keep the powder
adhered to the filter. The type of constant pressure filters
presently in use are rigid tube filters.
The diatomite filter powder is lightweight, organic, and
composed of fossil shells. The powder forms clusters, which
remain porous and allow PCE to flow through while trapping soil
particles. The powder built up on the tube should be cleaned off
and fresh powder reapplied to the tube when the PCE flow rate
decreases to 1 gallon per minute for each pound of rated load
capacity to enter the wheel. This will vary depending on the
amount of clothes cleaned, the size of your filter, and the size
of your pump.
Excessive Filter Pressure
Excessive filter pressure is a common problem. The causes
of excessive pressure include the accumulation of muck in the
filter to a point above the manifold, which reduces the filtering
area, PCE in poor condition, nonvolatile residue which causes
slime to deposit on the filter plate if the filter is drained and
not refilled, damp filter powder, and improper precoating or
insufficient precoat.
All powder should be kept in a dry place to avoid absorbing
moisture. Determine the correct amount of filtering powder for
your filter by using either the filtering area. For example, l
and 1/2 pounds per 10 square feet of filtering area for precoat
and at least 1/2 pound per 100 pounds of clothes to provide a
sufficient amount of powder in the PCE to maintain the filter
coating.
Rigid tube filters need at least 4 1/2 pounds of powder per
1,000 gallons per hour rated flow, or 30 square feet of filtering
area for a good precoat.
Loss of Precoat
Some common causes for loss of precoat are back pressure,
air in the filters, and obstructions or air leaks in the inlet
line to the pump that result in uneven settling of the filter
powder. Slipping pump belts or badly worn tubes could also be
reasons for the loss of precoat.
A-l
-------
Regenerative Filters
Regenerative filters are the most widely used-powder
filters. They consist of flexible tubes that are constructed of
braided metal wire, metal helical springs, or braided knit
fibers. Two and one-half pounds of powder per 10 square feet of
area are used to precoat regenerative filters since no body feed
is needed. Regenerative filters do not require body feed as
constant pressure filters do since the precoat is bumped off
after each load and is reapplied to the tube before the next
load.
The chief advantage of regenerative filters is that they do
not require as much filter area as constant pressure filters.
Only 60 square feet is needed for a 100 pound washer using a
regenerative filter, compared to 150 square feet for a constant
pressure filter.
The braided wire tubes in regenerative filters can become
crimped during the bumping operation, leaving holes in the tubes
which result in leakage. Damaged tubes allow powder and carbon
to pass through the filter and muddy the PCE. Correct this by
repairing or replacing damaged tubes.
When you see carbon or powder in the load, or your filter
isn't working well, inspect the filter for holes. Replace the
filter if you discover holes.
Tubes can also become clogged. If the PCE flow is not
continuous, air may enter the filter and the precoat may be
dislodged, allowing soil, powder, or carbon to enter the washer
and cause high redeposition. There must not be any interruption
of PCE flow after precoating and while PCE is flowing into the
washer. Always be sure the tubes are seated properly. You may
be able to correct this condition by backwashing. If not, remove
the tubes and clean them with trisodium phosphate.
A-2
-------
Liquid Leakage
Look for the brown residue of PCE soluble nonvolatiles on
the under side of fittings as a sign of leakage in pipe fittings,
welds, elastomers, and plastic hose connections. Loose pipe
connections are generally caused by wear, normal expansion and
contraction created by temperature, and vibration of equipment.
Check connections, unions, and couplings as soon as they start to
leak. When required, replace the packing on the valves.
Loss from pipe fittings can be considerable. PCE dripping
at the rate of one drop per second means losing a gallon of PCE
in an eight hour work day. Routine checkups with a halide leak
detector can detect vapor losses before they become leaks.
Cartridge Filters
Cartridge filters require less maintenance than regenerative
or constant pressure filters because you don't have to worry
about precoating or body feed. The filters come in a range of
sizes, and use various filtering media. Because cartridges are
changed routinely, manufacturers' information for cartridges is
always readily available and should always be used.
Standard Cartridge
Standard-sized (7 3/4 in. diameter and 14 1/4 in. high)
cartridges are made using various media for filtering. Carbon-
core cartridges remove both insoluble soil and color. They have
a normal lifespan of approximately 1,000 pounds per cartridge,
depending on the type of work being processed and the amount of
soil, moisture, and lint it contains. All-carbon cartridges
primarily remove color.
Adsorptive Cartridges
Adsorptive cartridges, 13 1/2 in. diameter and 18 in. high,
contain more activated clay and carbon. A later development cut
the height of these cartridges in half (9 inches) which makes
them easier to handle.
Adsorptive cartridges are designed to remove insoluble soil
and nonvolatile residue along with the color. Most full-sized
adsorptive cartridges are built to process 2,000 pounds before
being replaced. (Half-sized cartridges or "splits" are made to
process 1,000 pounds before being replaced.) Don't exceed this
recommendation because the cartridges ability to remove
nonvolatile residue may be exhausted before a pressure rise
indicates its capacity for insoluble soil has been reached.
A-3
-------
Changing Cartridges
Change cartridges either by pounds cleaned or by pressure
increase as recommended by the manufacturer and according to
manufacturer's instructions. Change cartridges that are to be
changed at a specific pressure (or pressure increase over the
original) according to instructions. Never let the pressure
exceed 40 pounds per square inch. Exceeding this pressure may
force soil through the filter and rupture it. If PCE starts to
become too dark or streaks and swales appear, change cartridges
or increase your distillation rate. Otherwise, change cartridges
according to the manufacturer's instructions.
Make sure gaskets or felt washers used between the
cartridges are seated properly. Damaged gaskets or ones used too
long can allow soil to leak out. Some all-carbon cartridges take
a different sized gasket than other cartridges made by the same
manufacturer. Read the manufacturer's instructions carefully.
Replace gaskets frequently.
Excess moisture or poorly dispersed moisture in the filter
will cause a rapid increase in pressure. The same result may
occur when some water repellents or fabric finishes are removed
from fabric by the PCE and carried over into the filter.
A new set of cartridges will often leak insoluble soil
and/or carbon until several loads have been cleaned. Run only
dark loads until this leakage stops.
Inspect new cartridges for physical damage before installing
them. They are rarely damaged, but the few minutes it takes to
inspect them is worth it.
A-4
-------
ATTACHMENT B
(See reference 2.)
-------
Operating and Maintaining Carbon Adsorber
Operator maintenance is all important with carbon
adsorption. If a carbon adsorber is in poor repair or not
desorbed frequently enough, it can be a useless piece of
equipment.
The lint screen must be cleaned regularly or it will clog
and block the air flow that must exhaust from the vented dry-to-
dry machine or dryer.
Be sure that the damper that restricts steam from entering
the adsorber does not leak. If it does, the carbon bed will
become wet and not adsorb PCE vapor.
You should restrict desorption (steam stripping) to a
maximum of 60 minutes, whether or not PCE is still returning. It
is extremely important to dry out the adsorber for at least 15
minutes after desorbing. If water remains in the carbon bed, it
cannot adsorb PCE.
After an undetermined period, the carbon bed may become
coated (contaminated) with petroleum distillates or other
products that may enter the air stream. It will then adsorb
reduced quantities of PCE. At that time, you may want to try an
extended (all day) steam stripping at the highest possible steam
pressure. If that does not burn off the contamination, the
carbon bed may have to be replaced.
Most important, the carbon adsorber must be desorbed as
frequently as necessary, often daily. If you don't desorb on
schedule, escaping PCE will pass through the adsorber into the
outside air or if you have no stack leading to the outside air,
into your plant.
You determine how often to desorb by how often the adsorber
fills up, not by the loads or poundage cleaned. The frequency is
directly related to your personal method of dry cleaning and the
condition of your reclaiming equipment. An adsorber's capacity
of PCE is determined by the pounds of carbon it contains.
Typical adsorber capacities are 2 gallons, 4 gallons or 6
gallons.
B-l
-------
To establish a desorption schedule, begin by desorbing
(stripping) every day. If your capacity is 4 gallons and every
day produces less than 2 gallons but at least 1/2, strip every
second day. If the stripout produces more than 2 gallons, strip
every day. If the stripout produces 4 gallons every day, you
must strip twice daily or better still, determine why so much PCE
is getting to the adsorber and remedy the problem. If you get
back no more than one gallon daily, strip the carbon adsorber
every third day.
Use simple arithmetic to determine the proper schedule for
your carbon adsorber. Remember to base your calculations on the
PCE capacity of your own adsorber.
B-2
-------
TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing)
REPORT NO. 2.
EPA-4531R-94-073
. TITLE AND SUBTITLE
terchloroethylene Dry Cleaning Facilities-General
Recommended Operating and Maintenance Practices for
Dry Cleaning Equipment (Only for Use When
vlanufacturers' Information Is Completely Unavailable)
'. AUTHOR(S)
1. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
2. SPONSORING AGENCY NAME AND ADDRESS
Director
Office of Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
October 1994
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
1 1 . CONTRACT/GRANT NO .
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/200/04
5. SUPPLEMENTARY NOTES
6. ABSTRACT
On September 22, 1993, the United States Environmental Protection Agency (EPA) finalized the
lational emission standards for hazardous air pollutants (NESHAP) for perchloroethylene dry cleaners
;58 FR 49354). Included in the NESHAP were requirements that owners or operators of dry cleaning
nachines and control devices follow their manufacturers' instructions for the proper operation and
naintenance of machines and control devices. The EPA realizes that some dry cleaners may no longer
lave equipment manuals for older dry cleaning machines and control devices. The purpose of this
nanual is to outline general recommended operating and maintenance practices for such owners or
Dperators concerning proper operation and maintenance of their dry cleaning machines and emission
control devices.
7. KEY WORDS AND DOCUMENT ANALYSIS
i. DESCRIPTORS
Air pollution
Dry cleaning
Drycleaning
Perchloroethylene
Maintenance
Manual
8. DISTRIBUTION STATEMENT
Release Unlimited
b. IDENTIFIERS/OPEN ENDED TERMS
Air pollution control
19. SECURITY CLASS (Report)
Unclassified
20. SECURITY CLASS (Page)
Unclassified
c. COSATI Field/Group
21. NO. OF PAGES
22. PRICE
'A Form 2220-1 (Rev. 4-77) PREVIOUS EDITION IS OBSOLETE
------- |