Note: Descriptions are shown in the official language in which they were submitted.
1~ 77730
BACKGROUND OF THE INVEI~TION
With the advent of OP~C, and the high cost and short
supply of hydrocarbons,'alternatives for existing vapor de-
greasing solvents has intensified.
The'ordinary vapor degreasing solvents are normally
chlorinated hydrocarbon ones, which meet the'criteria of having
no flash point and possessing good contaminant solvency and
reusability through reclamation processes.
The prior art has utilized, as the basic vapor degreas- '
ing solvent p~rchlorethylene or 1, 1, 1 trichloroethane or
trichlorethylene for use in the ubiquitous vapor degreasing
machine and operation. These s'o~lvents are ordinarily used
in co~junction with a stabilizer which will extend the use-
ful life of the vapor degreasing solvent.
In the vapor degreasing process, a non-flammable sol-
vent is boiled to produce a vapor zone,' the heigh~ of whi,ch
is controlled by condensing coils, Cold work is introduc d
into the vapor, causes vapor condensation thereon, and the
contaminant carried on the cold work, usually oil, grease or
flux, is flushed off by the liquid solvent condensate. The
` contaminant, along with the condensate, is returned to the
boiling sump of the vapor degreasing machine. This con-
densate or distillate, then is revaporized to repeat the
cycle of cleansing through condensation.
The work piece which is ~ be cleansed is held in
the vapor zone until the temperature thereof reaches the
vapor temperature within the vapor zone, at which time con-
' densation stops. Vapor flushing is usually followed by pure
distillate spray and/or liquid immersionO The cool pure
distillate reduces ~le temperature of the metal surface below
the vapor temperature producing a second vapor aondensation.
~1~7'~30
When the work piece again reaches vapor temperature, it is
withdrawn from the vapor zone, clean and dry.
The vapor degreasing solvent is used at its boiling
point in order to produce the vapor zone necessary for vapor
condensation and resultant cleaning.
Where perchlorethylene or 1, 1, 1 trichloroethane or
trichlorethylene either alone or in conjunction with certain
stabilizers to prolong the life thereof are utilized, serious
drawbacks occur.
That is, during the degreasing operations, the degreas-
ing solvent is adversely affecte~ by the increasing amounts
of contaminan~s finding their way into the boiling sump in
that the ~oiling temperature of the solvent in the sump
increases as the amount of contaminant increases. To com-
pensate for this added contamination, solvent manufacturers
add acid inhibitors or stabilizers in an effort to extend
its vapor degreasing life.
When the temperature in the boiling sump of the vapor
degreasing device reaches and exceeds a designated temperature
range, normally signifying extensive contamination, depletion
of the stabilizers is nearly complete and additional usage of
the solvent is not recommended because of acidic breakdown and
failure. For pe~chlorethylene this range is about 256-258F
whereas for 1, 1, 1 trichloroethane this range is about 172-
174F; whereas for trichlorethylene it is 195-198F.
Vapor degreasing handbooks recommend that vapor degreasers
be shut down and the degreasing operation terminated to allow
clean-out of the boiling sump once the boiling sump temperatures
reach about 256F for perchlorethylene, 172F for 1,1,1 tric~oro-
ethane and 195F for trichlorethylene. The general criteria,
measur-~ in other terms for solvent rejuvenation, are when the
boil sump specific gravity is between 1.21 and 1 44 or has an
-- 2 --
~77~730
acid acceptance ~alue of about 0.02 - 0.06, or wherein the
pH value is between about 5~5 - 6Ø
In order to extend the life of the~solvent by as much
as 50%, and to reduce the boiling sump temperature,' even
with contamination present, and to provide a satisfactory
vapor degreasing solvent of lower overall cost, it has been
found that the addition of triehlorethylene to,perchlorethylene
or m~thylene chloride to 1, 1, 1 trichloroethane, or trichlor-
ethylene in an amount to reduce the initial boiling temperature
of the resultant blend to about 240F, 110F to 190F
respectively ~for the resultant blends, achieves' definite
attributes, while alleviating many of the detriments found
in prior art uses and methods of vapor degreasing using
other solvents alone or with stabilizers to extend its use-
ful life.
In the United States, environment protection regulations,
(~PA) dictate that a degreasing solvent may not contain more
than 20% by volume of trichlorethylene. Thus, a solvent
blend in accordance with this invention of about 20-10 volu~me
percont of tr:iehlorethylene and 80-90 volume percent methylene
chloride is efficacious and better than trichlorethylene alone
or methylene ehloride alone.
In the'conventional vapor degreasing process, there
ideally exists about a 45-50F temperature differential between
the temperature of the inlet cooling water and the temperature
of the degreasing vapors~ Thus, where refrigerated or cooler
temperatures are made'available, a solvent blend of the in-
vention using higher methylene chloride proportions may be
utilized. In suchcases a preferred percentage of methylene
chloride in the blends of the invention will be abou~ 70-90
volume percen~ disregarding environmental regulatio~s.
~177'730
The lower boiling point of the resultant blends of the
invention not only extends solvent life, but also lowers
energy or heating requirements since the boiling point tem-
peratures of the vapor degreasing solvents of the invention
are lowered.
OBJECTS AND SUr~ARY OF THE INVENTION
-
According to one aspect of the present invention there is
provided a method of vapor degreasing by contacting a contaminated
article with the vapors of a solvent consisting essentially
of trichloroethylene, the improvement which comprises, (a) adding
a sufficient amount of methylene chloride to the solvent to
reduce the initial boiling point of the resultant solvent blend
to about 120F, (b) continuing vapor degreasing operations with the
solvent blend of step (a) at reflux temperatures until the acid
acceptance value of the contaminated solvent blend is within
the range of about 0.01 to 0.06.
According to a further aspect of the present invention there
is provided a method of vapor degreasing by contacting a contaminated
article with vapors of solvent consisting essentially of
perchloroethylene, the improvement which comprises, (a) adding
a sufficient amount of trichloroethylene to the solvent to reduce
the initial boiling point of the resultant solvent blend to about
240F., and (b) conducting vapor degreasing opera~ions with the
solvent blend of step (a) at reflux temperatures and removing
contaminants with said solvent until the temperatures of the
contaminated solvent blend reaches about 256F.
1~7~730
DESCRIPTION OF TilE BEST EMBODIMENTS CONTEMPLATED
In the conventional vapor degreasing apparatus, a boiling
chamber of sump contains a heating element thereby forming a
boiling zone. Positioned above the boiling zone is a vapor
condensation zone wherein condensing coils and cooling J acket
may be employed to condense vapors therein. In operation on
a straight vapor cycle, the work piece to be cleaned is
]owered into the vapor zone and is washed by solvent vapors
which condense on the work piece surface. The resulting
condensate flows from the surface of the work piece together
with the contaminants and drips back into the boiling solvent
contained in the boiling chamber or boiling sump.
When the work piece temperature reaches that of the vapors
in the vapor zone, condensation and cleaning action ceases.
In some instances, vapor losses ofEthe solvent contained in
the boiling chamber or boiling sump are maintained at the
operational level by addition of solvent, and by the continuous
return of the condensate from the work piece being cleaned,
which, of course, will also take with it into the boiling
sump or boiling chamber, contaminants comprising oil, grease
and the like.
In this type of vapor degreasing apparatus, which is of
the ~onventional type, vapor degreasing may continue until such
time as adversely high temperatures resul-t in the boiling sump
11~7~3(~
or boiling zone. This is for the reason that, while the
initial boiling point of the boiling sump or boiling zOnQ
may be that of the degreasing solvent being used, vapor
degreasing action may only continue until such time as the
contaminants in the boiling sump or boiling zone raise the
temperature to certain points depending on solvent mixtures
and as will be seen hereinafter, at which time breakdown
and failure of the solvent may result. When this occurs,
the vapor degreasing operation must be shut down, and the
boiling sump cleaned out, and the vapor degreasing solvent
replaced or subjected to a reclamation process, in order
to remove the contaminants therefrom.
~ necessary property or a vapor degreasing solvent
is its ability to be reclaimed, that is, to be subjected to
a process that separates the solvent from the solvent-
contaminant mixture so that the solvent may be used again.
That process which is used throughout the vapor degreasing
industry is distillation. The solvent blends of the invention
may be reclaimed, or distilled for re-use.
In the normal course of vapor degreaser operation, the
solvent condensate is returned to the boiling solvent-
contaminant mixture in the boil sump. A vapor degreaser is
commonly design~d by the vapor degreaser manufacturer to also
function as a solvent recovery still. To functiDn as a sol-
vent recovery still, design~ted valves are opened and/or
closed to cause the solvent condensate to be directed to sol-
vent storage tanks or to drum storage instead of being returned
to the boil sump . The solven'c is thus separated from the
solvent-contaminant mixture and, following removal of the
residual contaminant from the boil sump of the vapor degreaser,
the solvent may be transferred back into the vapoF degreaser
~or re-use.
- 6
1177~30
A second and less frequently used procedure for the dis-
tillation of vapor degreasing solvents is the use of a sepa-
rate still.
Conventionally, a simple one-plate still, such as
commonly found and as those of ordinary skill in the vapor
degreasing art are familiar, will do a satisfactory job of
reclaiming chlorinated solvents. Such units may be operated
on a batch basis or can be coupled directly to the degreaser
and operated continuously. With the latter arrangement,con-
taminated solvent is pump~d directly to the still from thedegreaser. Solvent leveI in the still is maintained by an
automatic level control which actuates a solvant transfer
pump. This affords maximum cleaning efficiency in the de-
greaser while minimizing shut-down time to clean the unit and
1~ refill with fresh solvent. Many solvent recovery stills use
live steam injectinn to maximize efficiency.
Thus,by usual and conventional distillation, the solvent
blends of the invention are recovered for reuse in the
practice of the invention.
Where trichlorethylene alone or with stabilizers is
utilized, its boiling point is approximately 188F., and its
use in a vapor degreasing operation wherein the boiling sump
approached 250F. would be contraindicated because of its
well-known tendency for thermal decomposition or pyrolysls at
this temperature.
However, contrary to what the prior art would indicated,
and in accordance with this ~nvention, a solvent blend com-
prising perchlorethylene and trichlorethylene in an amount
sufficient to reduce the initial boiling point of the resultant
solvent blend to about 240F., has been found to satisfactorily
extend the useful life of a vapor degreasing solvent in a vapor
degreasing operation, subject to the contaminatinn referred
- 7 -
~177730
to hereinabove. ~ttendant energy savings result because of
th~se lower temperature requirements.
Thus, it is has been found by the addition of trichlo~-
ethylene in about the range of about 0~1 volume percent to
50.0 volume percent to perchlorethylene, a blended solvent
is obtained which has a lower initial boiling point than
perchlorethylene alone, and wherein the resultant solvent
blend is capable of operating at temperatures substantially
higher than those that would normally be predicted for
trichlorethylene alone without pyrolysis. The preferred range
for ~he solvent blend in order to increase useful life there-
of is 81 volume percent for perchlorethylene and 19 volume
percent for trichlorethylene.
The solvent blend comprising the perchlorethylene and
trichlorethylene provides a constant boiling point solvent
exhibiting stable operating characteristics in a vapor de-
gr0aser. The theory which would appear to explain the lack of
fractionati~n of the two disparate solvents, making up the
solvent blend of the invention, would appear to be as a re-
sult of Raoult's Law.
By addition of methylene chloride in about the range of
about 0~1 volume percent to 90.0 volume percent to 1, 1,1
trichloroethane or trichlorethylen~, a blonded solvent is
obtained which has a lower initial boiling point than 1, 1, 1
trichloroethane or trichlorethylenealone. The solvent blend
comprising the 1, 1, L trichloroethane and methylene chloride
or trichlorethylene and methylene chioride provides a constant
boiling point solvent exhibiting stable operating characteristics
in a vapor degreaser. The theory which would appear to ex-
plain the lack of fractionation of the two disparate solvents,making up the solvent blends of the invention, would appear
to be as a result of Raoult's Law.
- 8 -
~7~730
In accordance with Raoult's Law, groups of similar sol-
vents are classified in specific classes andin accordance with
theory, a solvent blend of two or more components of the same
' class of solvents will operate in a sta~e of total reflux
(applied to vapor degreasing where the blend is boiled, vapors
condensed, and condensate returned to boiling sump) and
equilibrium will result wherein the temperatures and compo-
sitions of both the vapor phase and the boiling liquid phase
are constant.
In order-to comply with the criteria of the application
of Raoult's Law, in the operation of the instant invention,
minor losses of vapor and condensate in the vapor degreasing
operation are'replaced through daily solvent make-up with
solvent comprising the solvent blends of perchlorethylene
and trichlorethylene or 1, 1, 1 trichloroethane and ~ethylene
chloride or trichlorethylene and methylene chloride.
In order to ascertain the functionability of the applica-
tion of the'theory behind the solvent blends as being appli_.
cable to the practice of the inventian, a commercially
available grade of perchlorethylene, on one hand and 1, 1, 1
trichloroeth~ne on the other was re~luxed with different
volumes of oil until acid breakdown of the solvent occurred.
The length of time which it took for the solvents to reach
the breakdown point was recorded in each instance. Thereafter,
a solvent blend of perchlorethylene and trichlorethylene and
1, 1, 1 trichloroethane and methylene chloride, in accordance
with the volume percentages set forth herein, was similarly
tested under the same conditions.
It was found that the perchlorethylene-trichlorethylene
or 1, 1, 1 trichloroethane-methylene chloride solvent blend
had an extended life and the initial boiling point of the
solvent blend was lower than that of perchlorethyiene or 1, 1,
1 trichloroethane alone. In conducting the tests, a neutral
_ g
11'7773()
mineral oil is used in varying amounts to provide different
boiling temperatures in the boiling zone or boiling sump
to determine acid deterioration of the solvent. Esch of
the solvents and solvent/oil blends was boiled at total re-
flux for a number of days. That is, 500 milliliter flasks
were connected to condensing columns measuring 400 millimeters
in jacket length. These were, in turn, connected to water
sources by 3/8 inch tubing to continuously cool the columns.
For maintained heating, the flasks and solvent solutions
were placed on a 1~ inch square hotplate.
During the test periods and at selected intervals, each ,
of the samples was tested for acidic deterioration by determin-
ing its acid acc~ptance value in accordance with A.S.T.M.
procedure D-2942. In this test method, a known amount of
standard hydrochlorination reagent is used and ~ acid
acceptance value is calculated following titration with 0.1 N
NaOII. The acid acceptance valua of virgin vapor degreasing
grade l, 1, ~ trichloroethane is in the range of 0.10 to 0.20%.
The acid acceptance determinations use 10 and 25 millimeter
volumetric pipettes to transfer the solutions into 400
millimeter beakers. The pH of the solution during the tests
was checked further using a digital pH meter in conjunction
with a stirring rod and magnetic stirrer in order to obtain
a homogeneous mixture.
Solvent manufacturers usually recommend that perchlor-
ethylene or 1, 1, 1 trichloroethane be cleaned out from the
vapor d~greaser when the acid acceptance value drops to the
range of about 0.02 to 0.06% for the first named solvent
blend and 0.03 to 0.065' for the latter which correIates with
oil contaminatiDn of about 25% to 30~. in the tests, the
solvents were refluxed beyond the recommended clean out values
to total acidic decomposition to determine maximum life of
the solvent. ~-
-- 10 --
,
1~77730
,
These tests are tabulated in the following Table I and
IA :
TABLE I
Sample
Oil, % Boil ~ours of Refluxing
Volume Temp. Before Acidic Failure
Run 1
Perchlorethylene 0 250F 2088*
Blend, perc./tri. 0 240F 2088*
Run 2
Perchlorethylene 25% 258F 1560
Blend, perc./tri. 25~ 247F 1920
Run 3
Perchlorethylene 40% 260F 432
Blend, perc./tri. 40~ 252F 696
Run 4
~ . ~
Perchlorethylene 50~ 264F 192
Blend, perc./tri. 50% 254F &24
*Test discontinued at this time . Acid acceptance
values of the two samples showed no significant
difference and were both in the 0.01 to 0.02% range.
1 77~73()
TABL~ IA
Sample
Oil, ~ Boil Hours of refluxing
Run 1 Volume Temp. before acidic ~ailure
1, 1, 1 trichloroethane 165F 3288*
Blend, 1, 1, 1 trich-
loroethane/methylene 0 138F 3288*
chloride
Run 2
1, 1, 1 trichloroethane 25% 172F 1704
Blend, 1, 1, 1 trich-
loroethane/methylene
chloride 25% 143F 2208
Run 3
1, 1, 1 ~richloroethane 50% 182F 528
Blend, 1, 1, 1 trich-
loroethane/methylene
chloride 50% 150F 864
* Test discontinued at this time. Acid acceptance
valu~s of the two samples showed no significant
difflerence and were both in the 0.06 to 0.07%
which is the safe operating range recommended by
solvlent manufacturers.
~' From the foregoing tables, it will be noted that the
addition of trichlorethylene to pe~chlorethylene or
methylene chloride to 1, 1, 1 trichlo~ethane without ~il
contaminant does nothing more than lower the initial boiling
temperature as compared to perchlorethylene or 1, 1, 1
trichloroethane alone. However, upon the addition of oil
and the like contaminants as would be found in the con-
ventional vapor degreasing environment, the addition of
trichlorethylene or methylene chloride not only has an effect
on the initial boiling point or temperature of th,e solvent.
but also upon its useful life.
- 12 -
1~7~;'30
That is, the addition of trichlorethylene or methylene
chloride, as, for example, in test 2, in each of tables 1 and lA
extended the useful life of the solvent by as much as 23.1% and 30%
respectively before acidic breakdown. As contamination grew, solvent
life was extended 40-64% as compared to perchlorethylene or 1, 1, 1
trichlorethane alone.
In order to further prove the applicability of the solvent
blend in vapor degreasing operations, another series of runs was
conducted, utilizing commercially available vapor degreasing solvents,
namely, perchlorethylene 1, 1, 1 trichloroethane and the solvent
blends of the invention. Each of the solvents was boiled at total
reflux in the presence of the types of contaminants usually found in
typical industrial vapor degreasing applications including measured
amounts of aluminum and iron metal fines with heavy duty machine oilO
At spaced intervals, each of the solvents was tested for acidic
deterioration similar to that testing procedure as set forth for the
runs tabulated in Table I and Table IA.
The results of the test runs are tabulated in Table II and
Table IIA hereinafter following, wherein the first six runs and the
first three runs of Tables II and IIA respectively employed
commercially available perchlorethylene and 1, 1, 1 trichloroethane,
whereas the seventh run ~Table II) fourth run (Table IIA) employed the
perchlorethylene-trichlorethylene and 1, 1, 1
trichloroethane-methylene chloride blends respectively.
As noted in Tables II and IIA, a commercially available
industrial solvent specifically designated for vapor degreasing, was
compared to the solvent blends of the invention and this data is shown
in the following Tables II and IIA:
;~',
.~ 1.7'7730
O X
~ X o ~`
z , a~ O r~ ~
~ IY ~ ~ X _~
~ ~ 80o80Xx~o b
o 8 8
In X X
. X X
d' o. X 'O X O ,1 ~ ,1
g o o o o o
, g
d~ X
o X U- ~ ~ ~r !` 0
~r o X _l _l ,~
og~ o o o o o o
U~l X rC ~ ~ _
t~
I I I I I I a~
E~ O ~ O s O ~ O ~ O ~ O
Z
FL1
U ~ O ~ C) ~ U
~1 ~ h.C
o ~ O ~ O
u~ P. a~ m ~ o ~ ~ ,~
1:: ~ S ~0 S
~ ~ $ ~ ~
-- 14 --
1~77~730
TABLE IIA
Manufacturing 25% 40% 50%
Source _ Oil O-l Oil
Run 1
Vulcan `4at'1s Co. Inc 888 648 96
Run 2
PPG Corp. 888 816 192
Run 3
Dow Chemical Co. 840 504 144
Run 4
.,
1, 1, 1 trichloroethane/
methylene chloride blend 1608 1056 1008
The foregoing TABLE II illustrates that, as with
increasing oil contamination by volume the perchlorethylene
solvent becomes less effective and it was found that Run 7,
comprising the blended solvent, had an extended useful life
over the perchlorethylene solvent alone as used in Runs 1 -
, 6 inclusive.
Table IIA illustrates the longevity of the 1, 1, 1trichloroethane-methylene chloride solvent blend of the in-
vention in terms of both hoursof effective use under various
levels of oil contamination.
Another series of tests were conducted using acid
acceptance values (ASTM Procedure D~2942) to determine solvent
longevity using conventional degreasing solvents alone and
the solvent blends of the invention. This date is tabulated
in Tables III and IIIA following:
1177~73(~
,~
C
., ' '"
o ~ o . o . o . . .
H H 'r X X . X . O O
~ ~ OX ~ X ~ X '7N ~1
~ P~ O ~o oX O X X o -I '~
O ~ O~. . .. .
~ o X. o o o o o
X NIr) I~ U') ~ ~
E~ 0~ ~D X o o o o _~ ~
'.,~ 3cn o o o o o o
.~ o ul ~ o _l ~r
X l ~
~1 N1~ ~11~ ~D C
C)~ O ~JO Q~
1~ F ~::~: C ~ ~:: ,~ C) _~
E.l. C) C~C) ~Dal o ~( ~1 .,1
U~ _l ~ ~ _l_~ ~ V ~ O
W :>~1 ~::- >1:~ ~ ~ (11
E`~ .c: ~: .C. ~:: .C U E~
E~ ~ 0 0 ~ ~Q) h q~ :~
: ~ ~ h ~ ~1~ ~ O _1
O O O O O O ~ O
:> ~1 ~1_~rl ~ ~ ~ 1
~: ~ ~ ~ ~.C
O U ~ U U U U ~ C
Vl ~1 ~ h h ~ h U C) .q
O ~~Q~ O O ~ ~
~1 P~. ;1~ P~ ~ P. P. a~ ~
. ~ ~ ~ ~ In~D 1` U)
- 16 -
~L~'77730
TABLE IIIA
-
~IOURS OF OPERATION
SOLVENT OR
SOLVENT BLEND 400 800 1200 1600
_
SOLVENT with 25% OIL (Vol.) PLUS WATER, ALUMINUM AND IR~N
Perchlor~thylene xxxl32hr
Perc~Tri, Blend xxxxxx28~hr
1,1,1 Trichloreoethane xxxxxxxxxxxxxxxxxx864hr-
Trichlorethylene xxxxxxxxxxxxxxxxxxx984hr.
1,1,1 Trichloroethane~
Methylene Chloride blend. Xxxxxxxxxxxxxxxxx~xxxxxxxxxxxxxxl6o8hr.
(35% Methylene Chloride)
SOLVENT with 40% OIL (Vol.) PLUS WATER, ALU~5INUM AND FIRNOWES
Perchlorethylene xx100 hr.(est.)
Perc/Tri. Blend xxxx216hr.
1,1,1 Trichloroethane xxxxxxxxxxxxx656hr.
Trichlorethylene xxxxxxxxxxxxxxxx816hr.
1,1,l/Trichloroethane/ xxxxxxxxxxxxxxxxxxxxxl056hr.
Methylene Chloride blend
(35% Methylene Chloride)
SOLVENT with 50% OIL (Vol.) PLUS WATER, ~LUMINUM ~D IRON
FINES
_ . .
Perchlorethylene xx72hr.
Perc/Tri.Blend xxxl44hr.
1,1,1 Trichloroethane xxxl36hr.
Trichlorethylene xxxxxxxxxxx552hr.
l,l,l/Trichloroethane/ xxxxxxxxxxxxxxxxxxxxl 008hr.
Methylene Chlorid~ blend.
(35% Methylene Chloride)
- 17 -
773()
To demonstrate the efficacy of the trichlorethylene and
methylene chloride solvent, a series of tests were conducted
directed to a solvent's acid acceptance value parameter. As
is known, the acid acceptance value of a vapor degreasing
solvent may be determinative and used to ascertain contamination
levels of the solvent thereby indicating need to replace and/
or replenish the solvent.
A plurality of solvent samples were prepared having
varying proportions of the methylene chloride component of the
10 trichlorethylene-methylene chloride solvent blend. To each
of the samples 50 volume percent of oil was added as a con-
taminant. Each sample was placed in a flask and subjected
to boiling point temperatures for a number of hours and their
acid acceptance level readinys taken. Acid acceptance values
15 were in accordance with ASTM procedure D-2942.
The data obtained from the foregoing tests are summarized
in the following table IV:
-- 18 --
~17~730
T~BLE IV
Acid
SOL~7ENT Accept~
+ 50 oil No 24 48 72 96 120 144 168
Run ~ MC Initial l~rs hrs hrs hrs hrs hrs hrs
1 10.1229- -.1229 .1229-.1083 .1083 .0g91 .0991 .ogi8
2. 20.1331 .1331 .1331 .1130 .1130 .1038 .1038 .0963
3. 30- .1366 .1366 .1366 .1141 1141 .1104 .1104 .1010
4. 40.1341 .1341 .1341 o1152 .1152 .1152 .1152 .1133
5 50.1354 .1354 .1354 .1259-.1259 .125g .1259 .iI63
6 60.1349 .1349 .1349 .1175 .1175 .1272 .1272 .1175
7 70.1421 .1421 .1421 .1284 .1284 .1264 .1264 .1187
8 80.1317 .1317 .1317 .1337 .1337 .1297 .1297 .1199
.
9 90.1429 .1429 .1429 .1370 .1370 .1311 .1311 .1211
10 0.1315 .1315 .0858 .0858 .0675 .Q675 .0675 .0274
_
11 MC +
50~ Oil.1555 .1555 .1435 .1434 .1414 .1414 .1414 .1394
solvent ~ Trichlorethylene
MC = methylene Chloride
-- 19 --
.
~17~;~730
TABLE IV Cont~d
192 216 240 264 288 312 336 360
hrs hrs hrs hrs hrs hrs hrs hrs
1. cont'd .0918 .0711 .0711 .0587 .0587 .0587 .0275 .0128
2. cont'd .0963 .0945 .0945 ,0908 .0908 .0908 .0871 .0871
3. cont'd .1010 .0992 .0992 .0973 .0973 .0973 .0954 .0954
4. cont'd .1133 .1114 .1114 .1096 .1096 .1096 .1077 .1077
5. cont'd .1163 .1114 .1114 .1125 .1125 .1125 .1106 .1106
6. cont'd .1175 .1156 .1156 .1137 .1137 .1137 .1117 .1117
7. cont'd .1187 .1168 .1168 .1148-.1148 .1148-.1128 .1128
8. cont'd .1199 .0924 .0924 .0609 (DISCONTINUED DUE TO EQUIP.
FAILURE)
cont'd .1211 .1188 .1188 .1169 .1169 .1169 .1149 .1149
.
lO.cont'd .0237 acid~
_
ll.cont'd .1394 .1394 .1252 .1252 .1252 .1212 .1212 .1212
solvent = Trichlorethylene
MC = methylene chloride
- l9a -
7';'30
TABLE IV ~ont'd
384 408 432 456 480 504 520 552
hrs hrs hrs hrs hrs hrs hrs hrs
. cont'd acid~
2. cont'd .0871 .0648 .0502 .0502 acid---
3. cont'd .0954 ~0823 .0823 .0823 .0748 .0748 .0748 .0542
4. cont'd .1077 .1058 .1058 .1058 .1039 .1039 .1039 .0888
5. cont'd .1106 .1087 .1087 .1087 .1049 .1049 .1049 .0953
6. cont'd .1117 .1098 .1098 .1098 .1059 .1059 .1059 .0983
7. cont'd .1128 .1109 .1109 .1103 .1070 .1070 .1070 .0973
8. cont'd DISCONTINUED DUE TO EQUIPMENT FAILURE
9. cont'd .1149 .1129 .1129 .1129 .1089 .1089 .1089 .1030
.
10.cont'd ------
ll.cont'd .1192 .1192 .1192 .0202 ~cid---
-
Solvent -= trichlorethylene
MC - methylene chloride
- l9b-
1177'i'30
TABL~ IV Cont'd
576 600 624 645 672 696 720 744 768
hrs hrs hrs hrs hrs hrs hrs hrs hrs
.
1. cont'd
2. cont'd
3. cont'd 0542 .0542 .028i .0281 .0281 Acid~
4. cont'd .0888 .0388 .0737 .0737 .0737 Acid
5. cont'd .0953 .0953 .0805 .0805 .0805 .0095 Acid
6. cont',d .0983 .0983 .0809 .0809 .0~09 .1193 Acid
7. cont~d .0973 .0973 .08~7 .0817 .0817 .a4Qg .0233 ACid
8. cont'd (Acld---
Estimated)
9. cont'd .rO30 .10~0 .0991 .0991 .0991 .0594 .0416.099ACid
lO.cont'd
ll.cont'd
_
solvent = trichloret~ylene
MC = methylene Chloride
-- l9C_
1~7773V
From Table IV, the synergism of the solvent combinations
of the inventi~n become clear. For example, where
trichlorethylene alone has a useful life of abou-t 216 hours
and methylene chloride alone. a useful life of about 480
hours, a blend of the two within certain parameters extends
. the useful life many more hours to a maximum for some blends of
about 744 hours.
Thus, for a solvent blend, as dictated by EPA standards
of 20 volume percent trichlorethylene and 80 volume percent
methylene chloride, the useful life of the solvent under con-
ventional degreasing conditions would be about 744 hours,
extrapolating between runs 7 and 9 of Table IV.
Where cooling is available in the degreasing system
and where it is desired to reduce energy input to the de-
greaser, more methylene chloride may be used and initialboiling point temperatures and sump end operating temperatures
determined in accordance with Table V following:
- 20 -
~l~177~73()
TABLE V
INITIAL B.P. OF Solvent
SOLVENT VAPOR TEMPF SUMP TEMP F Blend APPROX. of
-
Tri ~
10~ MC 173 195 175
20% MC 160 183 163
Tri +
30% MC 152 173 153
.
Tri +
40% MC 141 168 148
-
Tri +
50~ MC 132 161 141
Tri + 127 153 133
70% MC 119 145 125
Tri +
80% MC 115 139 119
Tri +
90% MC 108 134 114
TRI 184 209 189
MC 106 124 104
Tri = Trichlorethylene
MC = Methylene Chloride
- 21 -
li7773()
~ nother series of tests is conducted similar to those
described with respect to Tables IA, IIA andIIIA utilizing the
solvent blends of trichlorethylene amd methylene chloride and
similar results obtainéd to illustrate the efficacy of the
solvent blends of the invention.
Thus, there has been disclosed a unique method of carry-
ing out vapor degreasing operations utilizing a solvent blend
that has an extended useful life and lower initial boiling
point. The resultant solvent blends by reason of lower boi`ling
points require less energy and are more economical than the
usual degreasing solvent alone in that lower heat requirements
makes for increased fuel efficiency.
While the solvent blends of the invention have been dis-
closed as comprising about 0.1 volume percent to 90.0 volume
percent trichlorethylene or methylene chloride, those of
ordinary skill in the vapor degreasing art will readily appreci-
ate that a solvent blend in accordance with the invention may
be selectively formulated to be used most effectively as dis-
, closed hereinbefore. Because of unique operational characteris-
tics of solvent blends, the perferred solvents for use in the
' selected degreasing method of the invention will be dictated
by governmental regulations and the type of vapor degreasing
operation being conducted.
While I have described particular embodiments of my
invention for purposes of illustration, it is understood that
other modifications and variations will occur to those skilled
in the art, and the invention accordingly is not to be taken
as limited except by the scope of the appended claims.Those
of ordinary skill will recognize that the solvent blend of the
invention is more economical because gallon for gallon more
work product can be vapor degreased than with the unblended
vapor ~aegreasing solvents alone.
- 22 -
