U.S. patent number 3,775,053 [Application Number 05/198,111] was granted by the patent office on 1973-11-27 for continuous solvent recovery process.
Invention is credited to Dorothea R. Wisdom.
United States Patent |
3,775,053 |
Wisdom |
November 27, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
CONTINUOUS SOLVENT RECOVERY PROCESS
Abstract
A continuous process of recovering dirty non-flammable solvent
after discharge from a remote applicator moving over a fabric being
cleaned. Immediate vacuum extraction of the dirty solvent from the
applicator with purification effected by boiling and condensation,
condensate recirculated to applicator. Portable apparatus adapted
for in-situ use includes an applicator to spray the solvent under
pressure, vacuum pump structure for suction extraction and to
provide some of the pressure which is augmented by a liquid pump,
electric or combustible gas means to boil dirty extracted solvent,
condensa to distil pure solvent introduced into a supply tank for
recirculation through the applicator.
Inventors: |
Wisdom; Dorothea R. (Torrance,
CA) |
Family
ID: |
22732022 |
Appl.
No.: |
05/198,111 |
Filed: |
November 12, 1971 |
Current U.S.
Class: |
8/142; 15/302;
15/320; 15/322; 68/18C; 34/469 |
Current CPC
Class: |
A47L
11/34 (20130101); D06F 43/081 (20130101); A47L
11/4022 (20130101); D06F 43/002 (20130101) |
Current International
Class: |
A47L
11/00 (20060101); A47L 11/34 (20060101); D06F
43/00 (20060101); D06F 43/08 (20060101); D06l
001/10 () |
Field of
Search: |
;8/142 ;68/18C
;15/3L,320,322 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Weinblatt; Mayer
Claims
What I claim is:
1. A continuous process of recovering cleaned non-inflammable dry
cleaning solvent from soil laden solvent, the solvent being used in
a remote applicator for cleaning drapes, upholstery, rugs and like
fabric having an outer surface, the applicator receiving clean
solvent and returning soil laden solvent, there being relative
motion between the applicator and the surface being cleaned, the
process including steps of:
a. discharging clean solvent liquid under pressure from the
applicator as a spray directed to impinge an incremental strip of
the outer surface of the fabric, the solvent extracting soil from
the fabric to form soil laden solvent,
b. substantially immediately thereafter exposing the incremental
strip to a vacuum to withdraw the soil laden solvent from the
fabric, the solvent being substantially liquid as it is
withdrawn,
c. vaporizing the withdrawn soil laden solvent liquid into a soil
free solvent gas to separate the soil from the solvent,
d. condensing the soil free solvent gas into liquid remote from the
separated soil so as to obtain soil free solvent liquid,
e. collecting the recovered solvent liquid,
f. returning the recovered solvent liquid back to the applicator
for recycling through the steps above.
2. A continuous process as claimed in claim 1 in which vaporization
of the solvent is effected by heating.
3. A continuous process as claimed in claim 1 in which the exposure
of the incremental strip to vacuum is effected by a vacuum produced
in a confined space defined in part by the incremental strip.
4. A continuous process as claimed in claim 1 in which the
discharge of solvent onto the incremental strip is effected from
within a confined spray space defined in part by the incremental
strip.
5. A continuous process as claimed in claim 1 in which the solvent
has a relatively low boiling point and a relatively low latent
heat.
6. A continuous process as claimed in claim 1 in which the
condensation of the soil free solvent gas into liquid is effected
by heat exchange between ambient air and the gas.
7. A continuous process as claimed in claim 1 in which the
condensation of the soil free solvent gas into liquid is effected
by heat exchange between a relatively colder liquid and the
gas.
8. A continuous process as claimed in claim 1 in which the
condensation of the soil free solvent gas into liquid is effected
by heat exchange between evaporation of a second liquid and the
soil free gas.
9. A continuous process as claimed in claim 2 in which the heating
takes place under a pressure less than atmospheric.
Description
FIELD OF THE INVENTION
The invention relates to a continuous process of recovering soil
laden solvent as it is being used with a remote applicator for
cleaning drapes, upholstery, rugs, and like fabrics, with the
solvent being purified and recycled to the applicator. The
invention also provides apparatus expressing the process.
BACKGROUND OF THE INVENTION AND PRIOR ART
The present invention is particularly, but not exclusively,
directed to cleaning of drapes, rugs and carpets, upholstery, and
like fabric, whilst the same are in place. That is to say for
example light and, particularly, heavy drapes can be cleaned by the
instant process without taking them down, and are dry in a few
hours.
Fluorocarbon solvents are commonly used for such cleaning purposes,
and are expensive; consequently they are often reclaimed and
regenerated. A classical method of regenerating solvents is by
boiling and subsequent distillation, with or without filtering.
U.S. Pat. No. 3,177,126 issued to Charreau in 1965 teaches process
and apparatus for purifying solvents by evaporation at a
temperature substantially below boiling point in an atmosphere
swept by a hot inert gas. A mixture of gas and vapors is cooled and
the solvent recovered in a liquid state. This is a process adapted
to operate continuously, the regenerated solvent being returned to
a cleaning machine and reused. This ingenious process is well
adapted for use with a stationary cleaning machine such as is
commonly used in a dry cleaning establishment.
U.S. Pat. No. 2,924,557 of which De Furia is the inventor, is
directed to a closed filter and distillation system particularly
well adapted for use with a solvent having noxious fumes, the
apparatus being directly connected to existing systems of a dry
cleaning plant.
A process capable of expression in portable apparatus which can be
taken, for instance, to the home of a customer for cleaning drapes
and upholstery in-situ without taking down the drapes, and without
removing the upholstery fabric, which apparatus is also capable of
cleaning rugs and carpets and, at the same time of effecting a
continuous withdrawal and cleaning of soil laden solvent with
recycling for continuous use, is not known to the present
inventor.
OUTLINE OF THE INVENTION
In the contemplated uses the solvent is sprayed upon the fabric.
While, in one expression of the invention, the spray is confined in
an applicator, this is not a closed circuit since at least some of
the sprayed solvent escapes into the atmosphere. Consequently, and
because of heat later applied effects change of state, use of a
nonflammable solvent is required, and it is in a practical sence
required that the solvent have little or no odor or, at least, have
an odor which quickly disappears.
Broadly the method withdraws soil laden solvent from the fabric as
it is being cleaned, the withdrawn solvent being then in a liquid
state with the soil in solution. A first change of state is
effected changing the liquid solvent to a gas. In the first change
of state the soil in solution does not pass over, and means are
provided for collecting, and for disposing of, the soil. A second
change of state follows wherein the gas, now without material soil
content, is changed to clean liquid solvent. The clean solvent is
collected and introduced into a tank for recirculation and
spraying. This completes a continuous cycle.
An embodiment of the apparatus includes vacuum means for
withdrawing the soil laden solvent from an applicator used to clean
the fabric, means to effect the first change of state by adding
heat to change the liquid to gas, means to effect the second change
of state condensing the gas to clean solvent, the clean solvent
then being introduced into a solvent tank supplying clean solvent
under pressure to be sprayed on the fabric by the applicator.
A detail description following related to drawings, exemplifies
apparatus by means of which the process is accomplished, the detail
description also sets forth further particulars of the process. The
invention can be expressed in process and in apparatus other than
particularly described below.
DESCRIPTION OF THE DRAWINGS
FIG. 1 shows means effecting recovery of soil laden solvent and
removal of the soil therefrom by a continuous process according to
the invention, recovery and removal being concurrent with cleaning,
the means aforesaid being shown in side elevation with parts broken
away to show interior construction, and an applicator being shown
in perspective.
FIG. 1-A is an alternative means for extracting heat to change
state of the solvent from gas to liquid, being an elevation of an
air cooled condenser.
FIG. 1-B is a further alternative means for extracting heat, being
an evaporation condenser with parts broken away to show interior
construction.
FIG. 2 is an alternative means for changing state of the solvent
from liquid to gas, heat being supplied by an electrical heating
element, the said means being shown in vertical section with some
parts not sectioned.
FIG. 3 is a change of state means alternative to FIG. 2, heat being
supplied by a combustible gas.
FIG. 4 is a top plan of an intake pipe of the FIG. 3 means.
FIG. 5 is a perspective detail of the applicator.
FIG. 6 is a side elevation of the applicator viewed from 6--6 FIG.
5, with parts broken away to show interior construction.
Preferred embodiment, means
description of fig. 1
apparatus means designated generally 10, has a solvent recovery
tank 11 having a vacuum gauge 11.1, and a solvent tank 12 having a
liquid gauge 12.1, a pressure gauge 12.2, and a pressure relief
valve 12.3. The tanks are secured to a frame 13 having wheels 14
for movement on a floor 15.
A vacuum pump 16 is secured to lower members of the frame 13, and
an intake pipe 17 extends vertically upwards through the tank 11 as
shown. The pipe 17 has an upper open bell mount 18 spaced below a
top wall 19 of the tank. A solvent recovery intake pipe 21 extends
inwards through a side wall of the tank, the intake having a
downturned inner discharge end 22.
The vacuum pump 16 has a discharge pipe 23 leading from a discharge
port of the pump to an inlet port 24 of a condenser 25. A check
valve 23.1 of the discharge pipe permits flow only in a direction
shown by an arrow 23.2. The condenser has a helical coil 25.1, and
a discharge pipe 25.2 extends centrally downwards within the
solvent tank 12 as shown, with the condenser being disposed
centrally above the solvent tank.
A solvent outlet pipe 26 leads downwards from an outlet port 27 of
the tank 12 to an inlet port of a liquid pump 28 a discharge line
29. A pressure gauge 29.1 is provided in the discharge line 29 as
shown, an outer end of the line being adapted for securing a
flexible hose 31 thereto. The flexible hose 31 extends to a fluid
inlet connection 32 of a remote applicator 33. The applicator shown
is a known two chamber hand tool, later described. A fluid outlet,
or vacuum, connection 34 of the applicator is adapted for securing
a second flexible hose 35 thereto, the hose 35 being of a
relatively large diameter extending to the recovery intake line 21
aforesaid, and being attached to an outer end thereof.
An electric motor 36 is secured to lower members of the frame 13 as
shown, and is operatively connected by drive means 37 and 38
adapted to drive, respectively, the liquid pump 28 and the vacuum
pump 16. A male receptacle 39 is provided on an end member of the
frame, with a three conductor cable 41 extending from the motor to
the receptacle.
A bottom wall of the recovery tank 11 is designated 42, closely
spaced heating elements severally 43 being provided as shown spaced
above the tank bottom wall 42. A second male receptacle 39.1 and a
second three conductor cable 41.1 supply the heating elements,
switches 39.2 and 39.3 are provided to control the motor and the
heating elements respectively.
Mechanical operation
mechanical operation of the apparatus 10 is as follows.
A solvent 44 is introduced into the solvent tank 12 through a
filler spout 45 having a removable pressure cap 46. The solvent has
particular properties exemplified later herein. With power lines
(not shown) plugged into each of the receptacles 39 and 39.1, when
the switches 39.2, 39.3 are on the motor drives the liquid pump 28
and the vacuum pump 16, and the heating elements 43 are
energized.
Flow of fluid is indicated by unreferenced arrows. The solvent from
the tank 12 passes down the line 26 and is driven by the liquid
pump 28 outwards through the discharge line 29 as shown by the
arrows, and enters the applicator 33. The discharge line 23 of the
vacuum pump 16 is connected to the condenser, consequently there is
a pressure urging the fluid out of the tank through the line 26
aforesaid, which pressure augments that of the liquid pump 28 -- so
that pressure at the applicator is the sum of these less line
drop.
The fluid outlet connection 34 of the applicator 33 is connected by
the flexible hose 35, which is a suction line, to the recovery tank
11. FIG. 1 shows a hanging fabric 47, for instance a heavy drape,
being cleaned in position. The applicator is moved downward by hand
in a direction shown by an arrow 33.1, while being held against the
fabric. Solvent under pressure discharges from the applicator as a
spray impinging directly against the fabric 47 being cleaned as
indicated by arrows 48, seen in FIG. 6 only. Because of suction
from the vacuum pump 16, the solvent impinging the fabric 47 is in
major part withdrawn to pass outwards of the fluid outlet
connection 34 and, at this stage, the solvent is dirty being laden
with soil in solution extracted from the fabric. The soil laden
solution now passes through the hose 35 and discharges from the
inner end 22 of the pipe 21 in liquid form, as small droplets, or
as a mist, discharging on the heating elements 43 and changes state
from liquid to gas. Suction from the vacuum pump 16 maintains
pressure within the tank 11 somewhat below atmospheric, thus
depressing boiling point of the liquid solvent. This results in
less energy required to vaporize the liquid and facilitates
condensation back to liquid. The elements 43 are means to supply
heat to the withdrawn solvent changing its state from liquid to
gas, a first change of state. With this change of state, the soil
in solution with the solvent is in part deposited on the tank
bottom wall 42 as indicated at 49, with some adhering to the
heating elements 43 as a crust. At least one cleanout port 51 is
provided, opening into the tank side wall above the base in a
position convenient for insertion of a cleaning tool to remove the
deposited soil 49, and to clean the crust off the heating elements
43.
In the change state from liquid to gas, the soil does not pass over
but is deposited as above. A proportion of the gas, depending upon
conditions, may change state back to liquid. The liquid being of
soil free gas is, as it forms, clean or free of soil. The solvent
which has changed its state from liquid to gas, together with any
liquid produced as above, are drawn upwards and enter the bell
mouth 18 of the vacuum pump intake pipe 17, being drawn downward to
and pass through the pump 16.
This gas and any liquid droplets or mist are now driven by the pump
to pass as shown by the directional arrows upwards through the
discharge pipe 23 and enter the condenser 25 through its inlet port
24, passing through the condenser coil 25.1. Liquid condensate
discharges at 25.2, as shown; as recovered liquid. The recovered
liquid, which as explained is soil free or substantially so, will
thus be added to the unused solvent 44 in the tank. The condenser
is a means to extract heat from the solvent gas, adapted to effect
a second change of state viz from gas to liquid, the tank being a
collecting means for the recovered or cleaned solvent.
Flurocarbon solvents which are non-flammable and are suitably
odorless are well known being used in the trade for cleaning of
this general kind. For instance an intermediate grade of
trichlorotriflouroethane is suitable for use in the instant process
and apparatus, or a mixture of such solvents can be used. These
solvents are characterized by relatively low boiling points and
latent heats, 118.degree. and 63 BTU/lb being the boiling point and
latent heat at atmospheric pressure of a particular
trichlorotrifluouroethene suitable for use herein, namely ISOTRON T
produced by Pennusalt Cehmicals Corp. of Philadelphia. Solvents and
mixtures of solvents required for optimun cleaning in particular
cleaning operations are well known in the trade and, therefore, are
not further discussed in that aspect herein.
Alternative means for effecting the first change of state
description of fig. 2
in FIG. 2 an alternative recovery tank 52 has a cylindrical side
wall 53 through which a recovery pipe 54 extends, the pipe having a
capped inner end 54.1. An outer end of the recovery pipe is adapted
for attachment of the flexible hose 35, FIG. 1. The pipe 54 has
perforations 55 adapted to discharge solvent as shown at 56 to
impinge a saucer like member 57 supported above a heating element
58 on forked brackets 59. The heating element 58 shown is a common
Calrod unit of suitable wattage.
An electrical conduit pipe 61 containing a conductor cable is
secured in a bracket 62 of the member 57, an outer end of the
conduit having a male receptacle 63 as the receptacles 39 and 39.1
FIG. 1.
The soil laden solvent from the applicator enters the flexible hose
35, passes to discharge through the perforations 55 of the recovery
intake pipe 54, and impinges the shallow saucer 57 heated by the
heating element 58. Thus upon impingement the dirty solvent changes
state from liquid to gas, with the soil being deposited in the
saucer 57. An inspection plate 64 is secured over a clean out port
65 of the side wall 53 by bolts 66. The conduit 61 has an outer end
secured in the plate 64, thus by removing the bolts 66, the heating
elements, saucer, and conduit, can quickly be removed together as a
unit. The bracket 62 is also forked so that the saucer 57 is
readily removable, either for cleaning or for replacement with a
clean saucer. The soil in the dirty solvent entering the flexible
hose 35 collects in the saucer 57 as explained, and the solvent in
the form of a gas passes downwards through an intake 67 to the pump
16 as before. Note that the boiling point of the exemplified
solvent is under 120.degree. F.
DESCRIPTION OF FIGS. 3 AND 4
In FIG. 3 tank 69 has a cylindrical side wall 71 and a concave
upwards saucerlike base 72. An intake pipe 73 with an open upper
bell mouth 74 (similar to the intake pipe 17 FIG. 1) leads to the
vacuum pump 16 FIG. 1. The base 72 is spaced upwards from the frame
13 FIG. 1 by legs 75 to provide space for a burner 76 supported by
the said frame. The legs are secured to the frame 13 and to the
base 72. The burner 76 is adapted for attachment of a gas supply
line 77, providing propane or other combustible gas. Discharge of
the dirty solvent is as before, and the action of the FIG. 3 boiler
is as described with reference to FIG. 2. A cleanout port 78, as
the cleanout port 51 FIG. 1, is provided for cleaning of the soil
accumulated in the concave bottom wall of the tank.
The recovery intake pipe 54 can have a generally circular shape as
seen in FIG. 3. In FIG. 2 the intake pipe 54, which is there shown
as a straight perforated pipe, can be an intake pipe as 54.1 FIG.
4. A straight pipe 54 FIG. 2 can be used in the FIG. 3 alternative
with a suitable positioning with reference to the pump intake pipe
73 to avoid interference therewith.
MOTOR AND PUMPS
The motor 36 FIG. 1 draws not over 15 amps, so that it can be
connected to one ordinary household circuit and, as later will be
explained, an applicator can require further power. Thus three
circuits might be required. Where these are not conveniently
available, suitable connection is made to the distribution box. In
the three conductor cables referred to above, the third conductor
is a ground, wiring of the apparatus is according to code
requirement, and is well grounded to the frame 13.
The vacuum pump 16 FIG. 1 is a positive feed blower as used in
positive extraction systems. 1 to 1 1/4 HP is adequate. The liquid
pump can be an impeller type, 1/4 HP will suffice an
automative-type water circulation liquid pump. being suitable. In
some circumstances the fluid pump can be dispensed with. Obvious
by-pass means (not shown) can be provided to isolate the pump in
these circumstances.
HEAT EXTRACTIONS MEANS EFFECTING THE SECOND CHANGE OF STATE
The condenser 25 FIG. 1 is shown with an outer jacket 81 having an
intake 82 and an outlet 83. A cold water supply hose (not shown)
can be attached to the inlet 82, with a waste hose (not shown)
attached to the outlet 83, the hose leading to a sink drain.
Cooling of the condenser coil can thus be effected.
Under some conditions, the jacket 82 can be dispensed with, leaving
the coil 25.1 exposed to ambient air. Where this provides
insufficient cooling, a common electric fan 85 FIG. 1-A is used to
cause a current of air 86 to flow over the coil 25.1 for
cooling.
FIG. 1-B shows a condenser 91 having a coil 92 with an outer
lagging 93 of absorbent material, and means 94 for moistening the
lagging. Evaporation of the moisture results in cooling -- so that
the coil 92 connected as before described -- is also cooled
extracting heat from the gas so as to condense it. Evaporation
cooling as above is, as is well known, particularly effective in
conditions of high ambient temperature and low humidity. Fan
cooling means as FIG. 1-A can be included to increase
evaporization.
THE HAND APPLICATOR
DESCRIPTION OF FIGS. 5 AND 6
The applicator 33 has fluid inlet and vacuum connections 32 and 34
aforesaid, and includes a transversely extending elongated head
portion 96 having a hollow interior enclosed by front and rear
walls 96.1 and 96.2 respectively, opposite end walls 98, and a top
wall 100. The head has an open flat bottom provided with a large
mouth 101. A baffle 102 is disposed within the mouth 101 extending
transversely between the end walls 98, so as to partition the
interior of the head into two chambers, a front vacuum chamber 104
and a rear spray chamber 106. A lower edge surface of the baffle
102 can have spaced notches 103 to minimize the gripping power of
the vacuum when end walls of the mouth 101 are in contact with
upholstery or other fabric.
At least one spray nozzle 108 is mounted in the rear wall 96.2
within the spray chamber so as to direct a liquid spray uniformly
outwardly of the mouth 101. The spray nozzle 108 has a coupling 110
at an exterior face of the rear wall 96, to which coupling one end
of a short length of flexible tubing 112 is attached. An opposite
end of the tubing 112 is coupled to an outlet end of a shutoff
valve 114 mounted on an upper portion of the head 96. A lever 115
is provided so that the valve can be controlled by hand.
The applicator above is a hand tool as described in US Pat. No.
3,562,844, issued 16 Feb. 1971 in which the present inventor is
named as co-inventor. This is adapted for use on drapes and
upholstery being processed according to the present invention.
In FIG. 6 the applicator is shown with end walls of the mouth in
contact with an outer surface 47.1 of a fabric 47.2 having as here
illustrated, a nap 47.3. The fabric is shown in section, with
exaggerated depth. The hand tool is moved in a direction shown by
an arrow 117, the solvent spray from the nozzle 108 passing as
shown by the arrows 48 passing through the nap 47.3 and over the
surface 47.1 to the vacuum chamber 104. In so doing the solvent
picks up soil from the fabric. It is seen that there is an
incremental strip 47.4 of fabric being sprayed, and a contiguous
incremental strip 47.5 being subjected to vacuum. The applicator
thus provides a confined vacuum space defined by the vacuum chamber
104 and the incremental strip 47.5, and a confined spray space
defined by the spray chamber 106 and the strip 47.4
A rug or carpet, or floor, tool (not shown) differs from the hand
applicator 33 in size, and in obvious provision of handle means to
move it along the rug or carpet. Because of the increased size, a
plurality of spray nozzles is provided.
DESCRIPTION OF THE CONTINUOUS PROCESS
From the description of mechanical operation it is seen that the
process therein expressed includes steps as follows.
The soil laden solvent is withdrawn from the fabric. The solvent as
continuously withdrawn is in a liquid state although, having been
discharged as a spray, it will be mainly small droplets with the
soil being contained in the droplets.
The state of the solvent so withdrawn is then changed to gas. This
is accomplished by adding heat, effected by the heating element 43,
FIG. 1, or by one of the means illustrated in FIGS. 2 and 3, or for
instance by electronic means not shown.
It is now required to change the state of the soil free gas to
liquid solvent. This is effected by extracting heat in a condenser
according to FIG. 1, 1-A, 1-B, or by suitable heat exchange
means.
The first change of state above requires heat to be added according
to the latent heat of the solvent -- while the second change of
state requires heat to be extracted in the like amount. The
particular means used to effect the addition and extraction of heat
are not relevant to the method.
Finally, the recovered cleaned solvent is collected. In the FIG. 1
apparatus it is introduced into the solvent supply tank 12
recirculated and reused -- to have its soil removed as before. Thus
there is a cycle in which the solvent is sprayed on the fabric,
picks up soil, is removed, loses the soil in the first change of
state, the second change of state results in clean solvent -- and
the cycle repeats.
With the FIG. 1 apparatus, pressure of discharge of the solvent
through the nozzle 108 FIG. 2 is (when the pump is not by-passed)
limited as aforesaid to somewhat less than pump plus vacuum
pressure.
With this limited pressure, in order that the spray do its work
rather than escape in material quantity and be dissipated in the
open air, it is confined in a spray space defined by the spray
chamber FIG. 6 and the incremental strip being sprayed. The vacuum
too is confined in a vacuum space defined by the vacuum chamber
FIG. 6 and the contiguous incremental strip. With relative motion
of the applicator to the carpet as shown by an arrow 117 FIG. 6 the
incremental strip after being sprayed is exposed to the vacuum. The
exposure commences immediately and, the incremental strip having a
finite width in the direction of travel exposure of the incremental
strip to vacuum is substantially immediate -- which term is used
herein to describe the action above.
An applicator or head according to U.S. Pat. No. 3,436,787 or U.S.
Pat. No. 3,439,374, both of which is issued to the present
inventor, can be used upon rugs and carpets. As well as differing
from the hand applicator in size, both heads have additional
heating means. The first patent above has a heated head, and in the
second lips of the nozzle are also heated. Each requires additional
electric power.
These heads do not confine the jet as in the applicator 33, but
they provide means to increase the pressure of discharge. With the
increased pressure confinement is not necessary. However, a lower
limit of pressure for effective spray operation of the above heads
is about 20 psi, and 30 to 40 psi is ordinarily used. This is
higher than that required for satisfactory operation of the hand
applicator 33 -- which in some circumstances can work without a
pump at all. Hence when either patented head is used with the FIG.
1 apparatus, the liquid pump 28 is capable of delivering 30 or 40
psi, This indicates a positive displacement pump such as e.g. a
Roote pump or a piston pump.
It will be observed that, while spraying and exposure to vacuum
occur simultaneously in time, as seen by the incremental strip
there are two discrete actions, first exposure to the spray then
substantially immediately thereafter exposure to the vacuum. Using
the process as most of the solvent sprayed is readily recovered
both with the hand applicator 33 and with either heated head
above.
The process can also be expressed in an apparatus (not shown)
wherein the fabric is caused to move with respect to a stationary
applicator. This part of the process is expressed in any apparatus
providing relative motion between applicator and fabric, whether
the applicator moves as in the described apparatus, or whether the
carpet moves as in apparatus for use in a fixed position, e.g. a
cleaning plant.
With the hand applicator 33, or using a heated head according to
either patent above in lieu of the illustrated applicator, the
process is restricted to use with a non-flammable solvent. While
the process is operative with a solvent regardless of whether, or
what, odor it have, for practical reasons the process is used with
an odorless or nearly odorless non-toxic solvent, or at the lowest
with a solvent having an odor which disappears rapidly after the
fabric has been cleaned.
* * * * *