U.S. patent number 3,557,817 [Application Number 04/821,873] was granted by the patent office on 1971-01-26 for control for mixing fluids of different specific gravity.
Invention is credited to Edwin H. Royse.
United States Patent |
3,557,817 |
Royse |
January 26, 1971 |
CONTROL FOR MIXING FLUIDS OF DIFFERENT SPECIFIC GRAVITY
Abstract
A hydrometer-actuated control for mixing dampening fluid
comprising water and other chemical ingredients mixed with alcohol
to be applied to the plate of a lithographic printing press. The
control device comprises a mixing chamber, in which alcohol and
dampening fluid are mixed, adapted to remove air bubbles therefrom;
a test chamber having a hydrometer freely floating in a sample
solution drawn from the mixing chamber; and an electrical conductor
on the hydrometer which moves with the hydrometer relative to the
surface of the sample solution to actuate a relay to open and close
a solenoid operated valve to regulate flow of alcohol to the mixing
chamber.
Inventors: |
Royse; Edwin H. (Dallas,
TX) |
Family
ID: |
25234498 |
Appl.
No.: |
04/821,873 |
Filed: |
May 5, 1969 |
Current U.S.
Class: |
137/91; 73/453;
101/148; 101/487 |
Current CPC
Class: |
B41F
33/0054 (20130101); Y10T 137/2504 (20150401) |
Current International
Class: |
B41F
33/00 (20060101); B41l 025/00 () |
Field of
Search: |
;73/314,451,453
;137/88,91,392,399 ;340/244A,244C |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Dea; William F.
Assistant Examiner: Zobkiw; David J.
Claims
I claim:
1. In apparatus for regulating the specific gravity of a solution
of first and second liquids comprising: a control chamber; means
for admitting a solution of first and second liquids into the
control chamber; electrically actuated means for injecting the
first liquid into the solution for mixing therewith; a receptacle
in the control chamber; an electrically conductive liquid in the
receptacle; electrical insulation means separating the receptacle
from the chamber; a hydrometer freely floating in the solution in
the control chamber; a first electrode submerged in the solution in
the chamber; a second electrode submerged in the liquid in the
receptacle; an electrical circuit connected between the electrodes;
a source of electricity in the circuit; switch means for connecting
the circuit to the electrically actuated means; and an electrical
conductor mounted on the hydrometer, said conductor having ends
arranged to contact the solution in the control chamber and the
liquid in the receptacle respectively, the hydrometer being movable
upwardly in the solution in response to increase in the specific
gravity thereof to cause one of the ends to break contact with the
liquid in which it is disposed to thereby actuate the switch
means.
2. The combination called for in claim 1 wherein the means for
admitting a solution of first and second liquids into the control
chamber includes a mixing chamber with means therein to mix the
first and second liquids before admitting the solution into the
control chamber.
3. The combination called for in claim 1 wherein the means for
admitting a solution of first and second liquids into the control
chamber includes means for eliminating air bubbles therefrom.
4. The combination called for in claim 1 wherein the electrical
conductor mounted on the hydrometer comprises a conductor having
one end submerged in the liquid in the receptacle and having the
other end secured to the hydrometer and arranged to contact the
solution in the control chamber as the hydrometer moves vertically
relative thereto.
5. The combination called for in claim 1 wherein the means for
admitting a solution of the first and second liquids into the
control chamber includes a circulating system for a lithographic
offset press dampening device; and means for directing liquid from
the circulating system through the control chamber and back into
the circulating system.
6. The combination called for in claim 1 wherein the switch means
connecting the electrical circuit to the electrically actuated
means for injecting first liquid into the solution includes current
responsive switching means constructed and arranged to connect the
electrically actuated means for injecting first fluid into the
solution to a source of electricity when the electrical conductor
on the hydrometer disengages the solution in the control
chamber.
7. The combination called for in claim 1 wherein the switch means
for connecting the electrical circuit to the electrically actuated
means for injecting a first liquid into the solution includes
current responsive means constructed and arranged to disconnect the
electrically actuated means for injecting first liquid into the
solution from a source of electricity when the electrical conductor
engages the solution in the control chamber.
8. In a control device for regulating the specific gravity of a
liquid solution comprising, a mixing chamber; a control chamber; an
inlet to the mixing chamber for admitting liquid solution thereto;
an outlet to the mixing chamber for discharging liquid solution
therefrom; means in the mixing chamber for agitating the solution
as it passes from the inlet to the outlet; a passage between the
mixing chamber and the control chamber; a control chamber outlet
passage communicating with the inside of the control chamber above
the first named passage; an insulated receptacle in the control
chamber, said receptacle having an open upper end disposed above
the control chamber outlet passage; electrically conductive liquid
in the receptacle; an electrode in the receptacle; an electrode in
the control chamber; a freely floating hydrometer in the control
chamber; an electrical conductor mounted on the hydrometer
constructed and arranged to engage both the solution in the control
chamber and the liquid in the receptacle as the specific gravity of
the solution decreases to a predetermined value; electrically
actuated means for injecting a liquid having a different specific
gravity from that of the solution in the control chamber into the
mixing chamber; and electrical actuating means operably connected
between the electrodes and the electrically actuated means to cause
the said liquid to be injected into the solution when the conductor
on the hydrometer moves out of contact with the surface of the
solution in the control chamber as the specific gravity of the
solution changes.
9. The combination called for in claim 8 wherein the means in the
mixing chamber for agitating the solution includes an overflow tube
having an open upper end and a lower end communicating with the
outlet.
10. The combination called for in claim 9 wherein the mixing
chamber has a curved inner wall and the inlet is positioned to
cause fluid to flow into the mixing chamber substantially tangent
to the curvature of the wall thereof.
11. In apparatus for maintaining the density of a solution of at
least two liquids at a predetermined value comprising: a chamber; a
solution of liquids in the chamber; electric current responsive
means for adding a liquid to the solution; a first electrode
submerged in the solution in the chamber; a receptacle; electricity
conductible liquid in the receptacle; a second electrode submerged
in the conductible liquid in the receptacle; means connected to the
electrodes for energizing the current responsive means when an
electrical circuit is completed between the first and second
electrodes; a hydrometer freely floating in the solution; and a
conductor having at least two free ends mounted on the hydrometer,
one of the free ends being submerged in the conductible liquid and
the other free end being positioned to move vertically with the
hydrometer relative to the surface of the solution and contact or
move out of contact with the solution depending upon the vertical
position of the hydrometer in the solution.
12. The combination called for in claim 11 with the addition of
means to vary the vertical relationship between at least one end of
the conductor on the hydrometer and the hydrometer.
13. In a device for automatically controlling the specific gravity
of a solution of a multiplicity of liquids; a housing including a
mixing chamber and a control chamber; means for circulating the
solution through the mixing chamber; means for admitting a portion
of the solution to the control chamber; a free floating hydrometer
in the solution in the control chamber; an electrically insulated
liquid receptacle mounted on the wall of the control chamber having
an open end extending above the level of the solution therein; an
electrical conductive liquid in the receptacle; means for
controlling the level of the liquid in the mixing chamber; means
for controlling the level of the liquid in the control chamber; an
electric conductor secured to the hydrometer having free ends
extending into the solution in the control chamber and the liquid
in the receptacle respectively, the free end in the solution being
arranged to move out of or into contact with the solution as the
hydrometer rises or falls in the solution; an electrode in the
solution in the control chamber; an electrode in the liquid in the
receptacle; an electric circuit attached between the electrodes;
means for admitting a liquid of a different specific gravity from
that of the solution into the mixing chamber, said means including
a container for said liquid; a conduit between the container and
the mixing chamber, and an electrically actuated valve in the
conduit; and electrically actuated switch means in the electric
circuit operably connected to the valve to control the opening and
closing of said valve responsive to the closing or opening of the
circuit by downward and upward movement of the hydrometer in the
solution in the control chamber.
14. The combination called for in claim 13 wherein the means for
circulating the solution through the mixing chamber includes, a
conduit; a venturi in the conduit, and the conduit between the
container and the mixing chamber communicates with the outlet to
the venturi whereby fluid is drawn from the container into the
mixing chamber by the drop in pressure in the venturi.
15. The combination called for in claim 14 wherein the container is
located below the level of the solution in the mixing chamber.
16. In a device for automatically controlling the specific gravity
of a solution of a plurality of fluids, at least one of which is a
volatile fluid, comprising a solution container; a quantity of
solution in the container; a free floating hydrometer in the
solution; an insulated liquid receptacle in the container having an
open upper end above the solution; an electrically conductive
liquid in the receptacle; an electrical conductor carried by the
hydrometer having contacts contacting the solution and the liquid,
at least one of which is arranged to move out of contact with the
liquid or solution in which it is disposed in response to the
predetermined rise of the hydrometer in the solution; and means to
admit additional volatile fluid to the container including a
conduit for said fluid, a solenoid valve controlling flow through
the conduit, and an electric circuit in which the solenoid valve is
disposed, which electric circuit is also in series with the
contacts so that the circuit is opened or closed depending upon
whether the contact in the solution container is out or in contact
with the solution.
17. In a device for controlling the specific gravity of a solution
of first and second liquids, comprising: a mixing chamber; means
for admitting the solution into the mixing chamber; actuated means
for admitting first liquid into the mixing chamber to be mixed with
the solution; means in the mixing chamber for agitating the
solution and the said first liquid; means for removing bubbles of
gas from the solution; means for determining the specific gravity
of the solution mixed with the said first liquid; actuating means
operably connected between the actuated means for admitting first
liquid and the means for determining the specific gravity of the
solution, said actuating means being constructed and arranged to
maintain the specific gravity of the liquid within predetermined
limits.
18. The combination called for in claim 17 wherein the actuated
means comprises electric current operated valve means; and the
actuating means comprises a hydrometer floating in the solution,
switching means actuated by the hydrometer, and an electrical
circuit between the switching means and the valve means.
19. In a device for automatically controlling the specific gravity
of a solution of a plurality of liquid ingredients, the combination
comprising a container for the solution; current responsive means
for adding at least one of the liquid ingredients to the solution;
an insulated receptacle adjacent to the container; conductive
liquid in the receptacle; a first electrode submerged in the liquid
in the receptacle; a hydrometer freely floating in the solution in
the container; a conductor having at least two free ends secured to
the hydrometer; one of the free ends being submerged in the liquid
in the receptacle and the other end being movable into and out of
contact with the solution in response to movement of the
hydrometer; a second electrode secured relative to the container
such that an electrical circuit is completed between the conductor
and the second electrode when the specific gravity of the solution
changes to a predetermined value; and means electrically connected
to the first and second electrodes and the current responsive means
for adding at least one of the liquid ingredients to cause the
liquid ingredient to be added when an electrical circuit is broken
between the second electrode and the conductor.
Description
BACKGROUND OF THE INVENTION
In a dampening device for transferring dampening fluid to the plate
of a lithographic offset printing press, a pan roller is rotated
through dampening fluid in a pan and a film of fluid on a pan
roller is transferred to the printing plate.
U.S. Pat. No. 3,259,062 to Harold P. Dahlgren teaches that a water
soluble, volatile, organic liquid, such as a volatile alcohol mixed
with water is a very effective dampening fluid for use in
lithographic printing. However, the volatile fluid, exposed to the
atmosphere, evaporates readily and the optimum ratio of alcohol to
water is difficult to maintain in the system.
U.S. Pat. No. 3,352,317 to Harold P. Dahlgren on "Dampening Fluid
Cooling And Circulating Apparatus For Lithographic Offset Press
Dampening Device" teaches that when a new batch of volatile fluid
is added to the fountain of a dampening system to be circulated
through the pan, the fluid does not readily mix with the dampening
fluid therein. The added dampening fluid changes the proportions of
the ingredients of the dampening fluid, which changes the chemistry
thereof, and will therefore affect the quality of the printing
produced by the press until such dampening fluid has become
thoroughly mixed, which usually requires a considerable length of
time. The said patent also points out that the temperature of the
dampening fluid should be maintained below 75.degree. to prevent
emulsification of the dampening fluid with the ink and to reduce
oxidation of the plate which is contacted by the dampening
fluid.
The objects of the devices disclosed in the before-mentioned
patents were to provide an improved dampening fluid with storage
and circulation system which diffuses and mixes the dampening fluid
and to maintain the temperature of the dampening fluid at a
predetermined optimum value. The method and apparatus described
therein is a significant improvement over the prior art. However,
the devices did not include means for automatically regulating the
specific gravity of the dampening fluid to compensate for
ingredients of the fluid which are depleted and for evaporation of
volatile fluid from the dampening fluid as the fluid was circulated
through the system. The device may also be employed to replace any
fluid which is depleted or consumed in use.
No simple device heretofore developed had the capability of
automatically injecting desired amounts of volatile fluid into the
dampening fluid for accurately maintaining the specific gravity of
the dampening fluid within reasonable limits.
Specific gravity regulating apparatus heretofore developed have
attempted to use a hydrometer floating in liquid to actuate devices
for controlling specific gravity of the liquid. However, these
devices have provided an imperfect solution to the problem because
attempts have been made to employ force exerted by the hydrometer
to close contacts in electrical circuits through various mechanical
arrangements.
No hydrometer actuated control device heretofore developed has
employed a freely floating hydrometer to automatically control the
specific gravity of the liquid in which it is floating.
A hydrometer is a very sensitive instrument, the accuracy of which
is materially affected by application of external forces
thereto.
High flow rate of fluid through a chamber or receptacle in which
the hydrometer is floating affects the depth to which the
instrument sinks in the liquid.
Air bubbles in the liquid being tested also adversely affect the
accuracy of a hydrometer.
Another major difficulty encountered heretofore has resulted from
the fact that the sample solution being tested was drawn from a
relatively large reservoir and fluid was injected directly into the
large reservoir of fluid. In such devices, an excessive amount of
fluid is injected into the reservoir before a control system,
sampling the reservoir solution, detects a change therein,
particularly in situations where the fluid being injected and the
fluid in the reservoir do not mix readily.
SUMMARY OF THE INVENTION
I have developed a device for controlling the specific gravity of
dampening fluid or other liquids which employs a freely floating
hydrometer. Air bubbles are removed from a sample of the liquid and
low velocity flow is maintained during testing to provide maximum
accuracy.
A primary object of the invention is to provide a control for
mixing dampening fluid which uses a hydrometer for controlling the
specific gravity of the fluid wherein no appreciable external force
is exerted upon the hydrometer.
Another object of the invention is to provide a control for mixing
dampening fluid in which fluid injected into fluid circulating from
a reservoir is thoroughly mixed in a mixing chamber and a sample of
the resulting solution is immediately tested thereby eliminating
the possibility that excessive amounts of fluid will be injected
into the reservoir solution.
A still further object of the invention is to provide a control for
mixing dampening fluid particularly adapted for use in combination
with a dampening fluid cooling and circulating apparatus for
lithographic offset press dampening devices.
A still further object of the invention is to provide a control for
mixing dampening fluid incorporating a venturi in a fluid
circulating system for drawing a second fluid into the fluid
normally circulated through the system.
A still further object of the invention is to provide a control for
mixing dampening fluid having a high degree of accuracy, which is
adjustable and inexpensive to construct and use, making the use
thereof economically feasible.
Other and further objects of the invention will become apparent
upon referring to the specification and drawings annexed
hereto.
DESCRIPTION OF THE DRAWINGS
Drawings of the preferred embodiment of the invention are provided
so that the invention may be better and more fully understood, in
which:
FIG. 1 is a diagrammatic view of the invention illustrating the
cooperative relationship between the control device and dampening
fluid cooling and circulating apparatus;
FIG. II is a top plan view of the invention with parts broken away
to more clearly illustrate details of construction;
FIG. III is a cross-sectional view taken along lines III-III of
FIG. II;
FIG. IV is a cross-sectional view taken along lines IV-IV of FIG.
III;
FIG. V is a perspective view of the back of the control device with
parts broken away to more clearly illustrate details of
construction;
FIG. VI is a cross-sectional view taken along lines VI-VI of FIG.
III;
FIG. VII is a cross-sectional view taken along lines VII-VII of
FIG. III; and
FIG. VIII is a diagrammatic view of a modified form of the
invention.
Numeral references are employed to indicate the various parts shown
in the drawings and like numerals indicate like parts throughout
the various FIGS. of the drawings.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to FIG. I of the drawings, the numeral 1 generally
designates the body of the control device having a tubular mixing
chamber 2 and a tubular control or test chamber 4 connected by a
passage 6.
One end of conduit 10 is connected to a circulating system 8
through which electrically conductive fluid circulates as will be
hereinafter more fully explained and the other end of conduit 10 is
connected to a venturi 12. A conduit 14, connected through normally
closed valve 16 and conduit 15, communicates with fluid supply
source 18 such that when valve 16 is opened fluid is drawn from
supply source 18 through conduit 14 by the partial vacuum at the
throat of venturi 12.
The outlet of venturi 12 communicates with inlet 20 of mixing
chamber 2.
An overflow tube 22 in mixing chamber 2 has its lower end connected
through outlet 24 to a conduit 26 which returns fluid to the
reservoir 101 of circulating system 8.
A test chamber outlet passage 30 communicates with the inside of
test chamber 4 at a position slightly below the elevation of the
upper end of overflow tube 22 in mixing chamber 2. Crossover
passage 6 between mixing chamber 2 and test chamber 4 is of smaller
diameter than test chamber outlet passage 30 to maintain the fluid
level in test chamber 4 at a substantially constant elevation.
From the foregoing it should be readily apparent that a portion of
the fluid flowing through circulating system 8 passes through
conduit 10, venturi 12 and inlet 20 into mixing chamber 2. A major
part of the fluid entering mixing chamber 2 flows downwardly
through overflow tube 22, outlet 24 and conduit 26 into the
reservoir 101 of circulating system 8.
A sample of the fluid in mixing chamber 2 passes through passage 6
into test chamber 4, and through test chamber outlet 30 to be
returned to the circulating system 8.
A conventional hydrometer 40 is disposed within test chamber 4 and
floats in a sample solution 5 contained therein. The hydrometer is
a well-known device for measuring the density or specific gravity
of liquids. It consists of a long slender glass float weighted at
the lower end and has a graduated scale on the slender neck portion
such that the specific gravity of the liquid is indicated by the
depth to which the instrument sinks therein.
An isolated solution receptacle 42 is disposed within the test
chamber 4 and has isolated solution 44 contained therein. The wall
43 of isolated solution receptacle 42 is made of electrical
insulator material and is electrically insulated from the sample
solution in test chamber 4.
A conductor 46 is secured about the stem 40a of hydrometer 40 and
opposite ends thereof extend into test chamber 4 and insulated
receptacle 42 in position to contact the liquid therein.
An electrode 50, extending through the wall of test chamber 4, is
submerged in sample solution 5 contained therein and electrode 52,
extending through the wall of test chamber 4 into receptacle 42, is
submerged in the isolated solution 44 contained therein. Electrode
50 is connected through line 54 to a current responsive switching
device, such as the coil 56 of a single pole double throw relay 58.
The other end of coil 56 of relay 58 is connected through line 60
to one side of the secondary winding 62 of a transformer 64.
Electrode 52 in isolated solution receptacle 42 is connected
through line 66 to the secondary winding 62 of transformer 64.
The primary side 68 of transformer 64 is connected through lines 70
and 72 to the electrical lines 74 and 76, respectively, which are
connectable to a conventional source of electricity.
From the foregoing it should be readily apparent that when
hydrometer 40 sinks into sample solution 5 in test chamber 4,
causing the end 47 of conductor 46 to engage the sample solution,
an electrical circuit is completed from electrode 50 through the
sample solution 5 in test chamber 4, through conductor 46, isolated
solution 44, electrode 52, line 66, secondary winding 62, line 60,
coil 56, line 54 to electrode 50. Therefore, when the end 47 of
conductor 46 on hydrometer 40 engages the surface of the sample
solution 5 in test chamber 4, coil 56 of relay 58 is energized.
Line 74, connectable to an external power supply (not shown), has a
switch 78 therein. When switch 78 is closed electrical current is
delivered through lines 70 and 72 to primary winding 68 of
transformer 64.
Line 74 is connected to electro-magnetically actuated switch 56a of
relay 58 in series with switch 78.
Relay 58 is of conventional design and in the particular embodiment
of the invention illustrated in the drawing the fluid in fluid
supply source 18 is alcohol having a specific gravity lower than
that of the fluid which flows through circulating system 8.
Movable pole 56a of relay 58 is spring biased to the closed
position so that alcohol will flow from fluid supply source 18 when
the specific gravity of the fluid flowing through circulating
system increases, causing hydrometer 40 to move upwardly,
disengaging the end 47 of contact 46 from the surface of the sample
solution 5 in test chamber 4. When a sufficient quantity of alcohol
has been added hydrometer 40 will settle in the sample solution,
causing end 47 of contact 46 to engage sample solution 5,
completing a circuit, energizing coil 56 of relay 58, thereby
opening switch 56a to stop the flow of alcohol.
Lines 74' and 76 are connected to solenoid device 80 which is
operably connected in conventional manner to valve 16.
It should be appreciated that when switch 78 in line 74 is closed
and switch 56a of relay 58 is closed a circuit is completed through
solenoid device 80 to line 76 to open valve 16. When valve 16 is
opened fluid is drawn from container 18 through line 14 into
venturi 12 to be mixed with the fluid flowing through circulating
system 8 in line 10.
A pilot light 82 is connected to lines 74' and 76 through lines 83
and 84, respectively, in parallel with solenoid 80. Pilot light 82
is illuminated when solenoid 80 is energized, thereby indicating
that valve 16 is open and that fluid is flowing from supply source
18.
Referring to FIG. V of the drawing, the body 1 of the control
device is preferably cast or molded as an integral unit, having
mixing chamber 2, test chamber 4, passage 6, venturi 12, inlet
passage 20, outlet passage 24, and test chamber outlet passage 30
formed in the body 1 of the control device by positioning suitable
cores within a mold to be filled with molten material such as
polyester resin.
While it is not absolutely necessary that the body 1 of the control
device be cast as an integral unit having passageways formed
therein, it is desirable to do so for several reasons. It should
also be noted that while it is not absolutely necessary that the
body 1 be constructed of material which is an electrical insulator,
such construction offers several material advantages.
Casting body 1 as an integral unit minimizes leakage of fluid which
is circulated therethrough and reduces construction costs resulting
from savings in material and labor. It is also desirable that the
walls of mixing chamber 2 and control chamber 4 be transparent,
allowing visual inspection of the operation of the device.
Construction of the body 1 of a material which is a good electrical
insulator assures that electrical current cannot flow from
electrode 50 in mixing chamber 4 to electrode 52 in isolated
solution receptacle 42 except through conductor 46 when the end 47
thereof is in contact with the sample solution in test chamber 4. A
short circuit between electrode 50 and electrode 52 makes the
device inoperable. If the body 1 of the control device is
constructed of a material which is a conductor of electricity
insulation 43 must be provided as illustrated in FIG. III.
It is desirable that passage 6 connecting mixing chamber 2 and test
chamber 4 have a smaller cross-sectional area than overflow tube 22
and test chamber outlet passage 30.
As best illustrated in FIG. VII, fluid entering the control device
through conduit 10 circulates through inlet 20 into mixing chamber
2. The end 20a of inlet passage 20 is substantially tangentially
disposed relative to the inner surface of tubular mixing chamber 2
which imparts a churning, agitating motion to the fluid therein to
thoroughly mix the fluids from conduits 10 and 14. Centrifugal
force of the swirling liquid causes air bubbles to be moved toward
the center of the chamber allowing them to move upwardly through
the liquid about tube 22 away from passage 6.
Fluid which passes through passage 6 is thoroughly mixed and is
free of air bubbles. The flow rate of liquid through passage 6 is
small relative to the flow rate of liquid through inlet 20. The
majority of the liquid entering mixing chamber 2, through inlet 20,
is discharged through overflow tube 22. For example, diverting 15
percent of the fluid which enters mixing chamber 2 into test
chamber 4 through passage 6 will normally provide adequate solution
for sampling without causing excessive turbulence to disturb the
free floating condition of hydrometer 40.
The percentage of fluid to be diverted through passage 6 into test
chamber 4 may vary depending upon the flow rate of fluid through
circulating system 8 and the quantity of fluid passing through
conduit 10. A primary consideration governing the flow through the
test chamber is to maintain forces of the fluid on the hydrometer
resulting from motion of the sample of fluid within desired
limits.
It is desirable that control chamber outlet passage 30 be larger
than passage 6 to assure that the surface of the sample solution in
control chamber 5 be maintained substantially constant. A tubular
restrictor 41 extends upwardly from the bottom of control chamber 4
to disperse the jet of liquid flowing into the control chamber to
minimize the force exerted by the liquid on hydrometer 40.
Conductor 46, best illustrated in FIG. III, may be constructed of
any suitable material which is a good conductor of electricity.
However, to minimize interference with the freely floating
condition of hydrometer 40 it is desirable that conductor 46 be
very lightweight. In the particular embodiment of the invention
illustrated in the drawing, conductor 46 is a very thin wire. The
ends 47 and 47a of conductor 46 are substantially vertical and of
substantially uniform cross section to minimize interference with
vertical movement of the hydrometer.
It is desirable that conductor 46 be constructed of material which
is highly resistant to chemical action. A conductor plated with
noble metals, such as gold, exhibits the desired qualities.
The weight of conductor 46 must be taken into consideration when
hydrometer 40 is calibrated because hydrometer 40 will sink deeper
into the liquid with the conductor attached thereto than it would
if the conductor were not attached. For example, to maintain the
specific gravity of the solution in test chamber 4 at .970 the end
47 of conductor 46 must be set at .968 if the weight of the
conductor varies the hydrometer reading .002.
It should be readily appreciated that no power is required to open
and close the circuit between the solution 5 in test chamber 4 and
the end 47 of the conductor 46. As hydrometer 40 moves upwardly as
the specific gravity of the fluid increases, the end 47 of the
conductor moves upwardly relative to the surface of the liquid
until the end of the thin wire is withdrawn therefrom, breaking the
electrical circuit, thus deenergizing coil 56 of relay 58, causing
switch 56a to be closed, thereby opening valve 16 allowing alcohol
to be drawn through venturi 12 into the solution, reducing the
specific gravity thereof. The effect of surface tension of the
liquid on the wire is negligible.
It should be readily apparent to a person having ordinary skill in
the art that if it is desired to maintain the specific gravity of
the sample solution in test chamber 4 above a desired FIG., the
control device hereinbefore described may be utilized with minor
modification. A liquid having a specific gravity greater than that
of the fluid flowing through the circulating system 8 may be placed
in fluid supply source 18. The only other change required of the
system is to cause switch 56a of relay 58 to close as the end 47 of
conductor wire 46 engages the sample solution in test chamber 4 by
spring biasing the switch 56a open. This may be accomplished by
connecting line 74' to the normally open contact 56d instead of the
normally closed contact 56c of relay 58. Such modification would be
within the skill of a person having ordinary skill in the art and
further description thereof is not deemed necessary.
As hereinbefore pointed out the above described control system is
particularly adaptable for use as a control device for
automatically maintaining a desired specific gravity of dampening
fluid used in lithographic printing. The relationship of the
control device to the circulating and refrigeration system of a
lithographic printing press is illustrated in FIG. I of the
drawing.
A dampening fluid tank or reservoir 101 is provided, having heat
insulation 102 in the walls thereof. A quantity of dampening fluid
103 may be conventional type of dampening fluid, which usually
consists of a mixture of chemical ingredients in water, or it may
be water and other chemical ingredients mixed with alcohol, as it
is used with the dampening device disclosed in U.S. Pat. No.
3,168,037 to Harold P. Dahlgren. The level of the dampening fluid
103 is maintained above the impeller 104 of the pump 105. The
impeller 104 is rotated through a shaft 106a by an electric motor
106 mounted on the top of the reservoir 101. The impeller 104 picks
up dampening fluid from the container 101 through the intake
opening 105a in the lower wall of the pump housing.
The dampening fluid is forced through the discharge line 107 and is
passed through a refrigerator unit 108 which has the usual
compressor, condenser, receiver, filter and dryer, expansion valve
and evaporator coils therein. Discharge line 107 is connected to a
pipe 109 which passes adjacent to the evaporator coils of the
refrigeration unit, and as the dampening fluid passes therethrough,
it is cooled. The temperature of the refrigeration unit may be
maintained by a suitable thermostat control (not shown).
A portion of the refrigerated dampening fluid is passed from the
pipe 109 through a hand operated valve 111 and a supply line 110 to
the dispenser pipe 118 which is disposed in the dampening fluid pan
or fountain 115.
A branch line 112 communicates with the upper part of the reservoir
101 through a discharge nipple 114.
A return hose 126 is attached to the outlet drain nipple 125
through which dampening fluid may return from the pan 115 to the
reservoir 101. The hose 126 communicates with a drain back pipe 128
in the reservoir 101 through a suitable nipple 127 passing through
the upper wall of the reservoir 101. The drain back pipe 128 is
connected in communication with a T-fitting 129.
A restrictor nozzle 130 is connected between an outlet from the
discharge conduit 107 and the T-fitting 129. A venturi 132 is
connected to an outlet of the T-fitting 129 opposite the restrictor
nozzle 130. A venturi discharge line 133 is connected to the
opposite end of the venturi 132 and terminates at the bottom of the
reservoir 101.
Dampening fluid circulating through supply line 110 into pan 115 is
exposed to the atmosphere and the alcohol evaporates therefrom,
changing the chemical composition of the dampening fluid, which
results in a reduction of the quality of printing.
A T-fitting 10a is positioned in supply line 110 or branch line 112
for directing a portion of the fluid flowing therethrough through
conduit 10 to the control device as hereinbefore explained.
Outlet conduit 26, which communicates with overflow tube 22 in
mixing chamber 2 of the control device, extends through a suitable
nipple 27 passing through the upper wall of the reservoir 101.
In multicolor printing a separate dampening fluid circulating
system is normally used for the dampening system of each printing
station. Therefore a conventional electrical outlet socket 79 is
connected through lines 79a and 79b to lines 76 and 74 to
facilitate connecting a series of control devices to a single
source of electricity. Lines 74 and 76 of a second control device
(not shown) may be connected to outlet 79 of the first control
device.
The operation and function of the device hereinbefore described is
as follows:
A portion of the dampening fluid 103 flowing through circulating
system 8 is diverted through conduit 10 into mixing chamber 2 in
the body 1 of the control device. A portion of the dampening fluid
flows into control chamber 4 through passage 6 and the specific
gravity of the dampening fluid is automatically tested by
hydrometer 40 having a conductor 46 on the upper end thereof.
If alcohol has evaporated from the dampening fluid causing the
specific gravity of the dampening fluid to be too high, the end 47
of conductor 46 will be disposed above the surface of the sample
solution 5 of dampening fluid in test chamber 4 causing the
electrical circuit to be broken, thus deenergizing relay 58 causing
switch 56a to close thereby opening valve 16, allowing dampening
fluid to flow from fluid supply source 18 as the result of the
vacuum lift created at the throat of venturi 12.
Alcohol is thus automatically added to the system as required and
is thoroughly mixed with fluid already in the system before being
tested and released into the system.
Although this device has been disclosed primarily for automatically
mixing alcohol with dampening fluid for use in lithographic
printing it will be understood that it is useable for mixing any
two fluids of different specific gravity.
In certain applications it may be desirable to control specific
gravity of a solution which is not a good conductor of electricity.
If the solution in control chamber 4 is nonconductive a circuit
will not be completed between electrodes 50 and 52 when conductor
46 engages the solution therein. The embodiment of the invention
illustrated in FIG. VIII of the drawing is a modified form for
controlling the specific gravity of a nonconductive solution.
Control chamber 4' is identical to control chamber 4 hereinbefore
described except that electrode 50' is submerged in an electrically
conductive liquid 5', which is separated from the solution in
control chamber 4' by a container 5a constructed of a suitable
material which is not electrically conductive. The surface of
liquid 5' is maintained at the same level as the surface of the
solution in control chamber 4' by balancing the weight of container
5a and liquid 5' with buoyant force exerted thereon by liquid in
the control chamber. If the surface of the solution in control
chamber 4' is maintained at a constant level container 5a may be
secured to the wall of the control chamber in the same manner as
isolated solution receptacle 42'.
From the foregoing it should be readily apparent that when line 66'
is connected to transformer 64 and line 54' is connected to relay
58 as hereinbefore described with respect to the embodiment of the
invention illustrated in FIG. I of the drawing, that a circuit is
completed from contact 52' through conductive liquid 44', conductor
46', conductive liquid 5', contact 50', conductor 54' to the
transformer 64 and relay 56 as the end 47' of conductor 46' engages
the surface of liquid 5' in container 5a. The operation of the
remainder of the system hereinbefore described with respect to the
first embodiment remains unchanged.
From the foregoing it should be readily apparent that I have
developed a device for controlling the specific gravity of a
solution of two or more fluids having different specific gravities
readily adaptable to systems in which it is desirable to maintain a
constant specific gravity of a solution circulated therethrough in
which one of the fluids is depleted from the solution.
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