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FEATURES:
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35
Minute Cycle Time
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Cool
Operating Temperature/ no heat setting of stains
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Rotating
Basket With Speed Control for Cleaning Versatility
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Adjustable
Load Size
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Simple
One Button Operation
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Patented
Compressor Driven Process
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Stainless
Steel Construction
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Dual
Viewport
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Precision
Safety Door Mechanism
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Vacuum
Insulated Vessel for Maximum Thermal Efficiency
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55
Pound Cleaning Capacity
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20
cubic foot Drum
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TECHNICAL COMPARISON
A. Background -
CO2
Liquid Carbon
Dioxide appears to be an almost ideal solvent. It is non-toxic,
non-flammable, non-corrosive, chemically stable, inexpensive, and
available in large quantities. Carbon dioxide's major sources are
petroleum refineries, alcohol fermentation, and fertilizer
manufacturers, where it is produced as a by-product. As such, CO2 will
not contribute to the so-called "greenhouse effect" since it
will be recycled. In other words, no new CO2 will be generated for dry
cleaning applications.
B. Chemical and
Physical Properties
The suitability of
CO2 as a dry cleaning solvent can be determined by comparing its
physical and chemical properties against those of currently used
solvents (see Table 1). The properties typically compared are:
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Kauri butanol value (Kb). This measures the cleaning power of
the solvent. The higher the Kb, the more aggressive the solvent.
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Density. This property is more important for conventional
processes in which "solvent drop" is used to impart the
necessary mechanical action for cleaning..
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Viscosity. This measures a solvent's ability to flow. The lower
the viscosity, the easier the solvent can "flow" within
fibers of a fabric.
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Surface Tension. This is a measure of the ability to wet a
fabric. The lower the surface tension, the easier it is to wet a
fabric.
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Solubility in water. Generally, the more soluble a solvent is in
water, the easier to remove water-soluble stains.
TABLE 1 - Solvent Comparison Chart top
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PROPERTY
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PCE
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VALCLENE
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1,1,1 TCA
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PETROLEUM
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WATER
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CO2
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Solvent
Power(Kb)
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90
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31
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124
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27-45
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Petroleum Like
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Density(g/ml)
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1.6
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1.6
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1.3
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0.78
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1.00
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0.9-0.6*
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Surface
Tension(Dynes/cm)
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32.3
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18
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25.6
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27.6
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72
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5
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Flash
Point(°F)
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none
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none
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none
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140-149
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none
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none
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Solubility
of Water in Solvent
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0.01
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0.009
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0.05
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0.01
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N/A
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0.1
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Viscosity(cp)
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0.54
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0.7
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0.9
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1.2
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0.89
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0.07
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Exposure(TLV)
(ppm)
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100(50)(25)
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1,000
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200
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200
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5,000
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*Densities in range
of 7°-30°F
1. Kauri Butanol
Value (Kb)
Perchloroethylene
(perc or PCE) has a Kb of 90. This is probably the upper limit of
solvent strength that can be used in a practical manner for dry
cleaning. Even so, it is sufficiently aggressive that items such as
sequins and many types of trim cannot be cleaned in it. It also tends
to remove dyes. A dry cleaner therefore should not clean one part of a
two-part garment since the colors may not match after cleaning. Some
attempts were made to using 1,1,1 trichloroehane (TCA) as a dry cleaning solvent
a number of years ago but were abandoned because of its aggressiveness.
Petroleum
(hydrocarbon) solvent has a Kb in the 27-45 range. It is a much milder
solvent, gentler than perc towards dyes and plastics and therefore a
preferred solvent for cleaning more sensitive items such as leathers
and plastic trimming. Because it is milder, it is however not as
effective as perc in removing some types of stains such as inks and
dirty motor oil. Hydrocarbon solvents would probably be ideal solvents
if it were not for their flammability, difficulty in drying, and
susceptibility to odors.
Valclene(R)
(Freon(R) 113) has all of the desirable properties of hydrocarbons
without its drawbacks. It has a Kb of 31, is not susceptible to
bacterial action and its resulting odors, dries easily, and is
non-toxic. It would probably be the solvent of choice today if it were
not for its adverse effect on the ozone.
CO2 is similar to
hydrocarbon in its solvent strength, is odorless, easy drying,
non-toxic, environmentally friendly, and is the second most abundant
solvent after water. It therefore is an obvious candidate as a cleaning
solvent.
2. Density
A high density is
important in the conventional dry cleaning process because the
combination of weight and drop height imparts the mechanical action
needed to remove insoluble soil. By contrast, in the CO2 Cleaning
Process the action of fluid jets is used to dislodge the insoluble
soil. Density is therefore not as significant in this cleaning process.
3. Surface Tension
The wetting
property of a solvent is one of the prime factors in the removal of
particulate soil. The wetting property of a fluid is measured by its
surface tension. The lower the surface tension, the better the wetting.
Water, with a surface tension of 72 dynes/cm, is a poor wetter. Without
the addition of a detergent to lower the surface tension of water, it
would not be an effective cleaner. Perc with a surface tension of 32
dynes/cm, petroleum with a surface tension of 27 dynes/cm., and
Valclene(R) with 18 dynes/cm, all require the addition of a surfactant
for good cleaning. CO2 has a surface tension of only 5 dynes /cm., and
therefore is an extremely effective wetting agent. If it were not for
the need to solubilize water, and suspend particulate soil, CO2 would
probably not need a detergent.
4. Viscosity
The viscosity is a
measure of the ability of a liquid to flow. The lower the viscosity,
the more fluid it is. A low viscosity reinforces the beneficial effects
of a low surface tension. A viscous liquid such as molasses will take a
long time to wet a fiber. The viscosity of CO2 (0.07cp) is 14.5 times
lower than that of water (0.9 cp.), 6 times lower than perc (0.54cp.),
and 17 times lower than petroleum (1.2 cp.). As a result, it has the
ability to quickly wet a fiber and hence facilitate the removal of
particulate soil.
5. Solubility of
Water
The solubility of
water in CO2 is 0.1%. This is ten times higher than its solubility in
both perc and petroleum. This however is still not sufficient for the
removal of water-soluble soil. The addition of a detergent is need for
this purpose.
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