Field of the Invention
[0001] The present invention relates generally to the neutralization of oxidizing agents
in a laundry solution, and more particularly to apparatus and a method for automatically
monitoring and precisely controlling the concentration of oxidizing and reducing agents
in the final rinse step of a laundry cycle.
Background of the Invention
[0002] The use of oxidizing agents such as destainers and bleaches for treating laundry
during a wash formula or cycle is commonplace today in both residential and commercial
laundering operations. The most commonly used strong bleaching agents are sodium hypochlorite
(chlorine bleach) and potassium permanganate. Chlorine bleach is more popular than
the other major type of bleach, hydrogen peroxide, because it costs significantly
less, is more effective at removal of certain types of stains, and is a better sanitizer.
[0003] A disadvantage of using destainers such as chlorine bleach is that fabric damage
can result if the bleach is overused or if the bleach is not thoroughly rinsed from
the fabric. Chlorine bleach is an example of an oxidizing agent that works by releasing
"free" oxygen which, in turn, reduces stains. If residual chlorine is allowed to remain
in the fabric as a result of the laundering cycle, the oxygen-producing agent of the
bleach will continue to attack the fabric's fibers which are converted into oxidized
cellulose known as oxycellulose. As a result, the fabric may develop holes or tears
in weakened areas. Because the tensile strength of the fabric decreases, the fabric's
wear life is shortened and the fabric tears more easily. The damage caused is irreversible.
Further, even a relatively small amount of residual chlorine, for example 1 to 2 parts
per million, is sufficient to cause fabric damage.
[0004] For the sake of simplification, the remainder of the discussion will address only
chlorine bleach oxidizing agents; however, it will be understood that the general
problems and principles discussed with regard to chlorine bleach oxidizing agents
apply equally well to other types of destainers and oxidizing agents and to their
respective neutralizing or reducing agents, when discussed.
[0005] The problem of chlorine removal or neutralization in a laundry cycle is less pronounced
in conventional tubtype or batch washing machines wherein the entire laundry tub is
filled and drained typically after each portion of a wash formula. The opportunity
for completely rinsing chlorine destainer additives from the laundry in such "conventional"
machines is fairly good. Further, such "conventional" washing machines typically employ
separate wash and bleaching cycles which enable the bleach to be added to relatively
low pH solutions, thereby enhancing relatively thorough rinsing of the chlorine from
the fabric during the rinse cycles. However, to the extent that the chlorine additives
are not entirely removed from or neutralized in such conventional washing systems,
the principles of this invention apply thereto.
[0006] For a more detailed description of the principles involved regarding oxidation agents
and their respective reducing/neutralizing agents, including a discussion of the meaning
of "bleach", "active chlorine" and "available chlorine" see White, George,
Handbook of Chlorination, 1972, pp. 189-190, which is herein incorporated by reference.
[0007] The problem of chlorine removal from the laundry and/or neutralization thereof is
significantly more pronounced in commercial washing applications in which normal bleaching
levels are typically significantly increased from the traditional level of 1 quart
of 1% bleach per 100 pounds of wash, in order to achieve effective stain removal.
The problem is further amplified in commercial applications wherein continuous batch
washers or tunnel washers are used. Tunnel washers are becoming increasingly popular
in industrial laundry applications, particularly for such applications as the processing
of hospital, hotel and other linen supply works, where large quantities of laundry
must be cleaned daily. In general, tunnel washers include a series of individual modules
or compartments each of which corresponds to a different step in the wash formula
or cycle. The textiles to be washed are automatically transported through a continuous
loading, washing, rinsing, conditioning and extracting process as they progress from
the input to the output of the tunnel washer. The tunnel washing technique significantly
reduces labor, since once the laundry is sorted into batches which are successively
loaded into the input hopper of the tunnel washer, they are not handled again until
they have been conditioned or dried. Utility costs associated with tunnel washers
are lower than conventional-type washing systems and processing time is significantly
reduced since there is no delay time for water filling of the machine or waiting time
for drying or extracting operations.
[0008] Tunnel washers are basically constructed in either double drum (modular) configuration
or single drum (monoshell) configuration. The modular washers have adjacent but separately
defined individual compartments each of which performs a different function. The laundry
batches progressively move through the compartments which form an inner cylinder of
the machine, and are successively transferred from module to module upon completion
of the process step therein by raising the laundry batches above the center line of
the washer and sliding them through a central connection between the modules. The
single drum tunnel washers typically use an Archimedes' screw principle which uses
a screw member that extends longitudinally through the drum for defining the various
steps of the wash formula and for moving the batches of laundry forward through the
drum. Typically each turn or segment of the spiral screw defines a laundry compartment,
and the transfer action is achieved when the cylinder or screw rotates through one
complete revolution, to move the textiles forward into the next compartment. Tunnel
washing apparatus is well known in the art, and a complete description of such apparatus
will not be defined herein. The foregoing merely serves as a brief introduction of
the advantages to be achieved by the use of tunnel washers in commercial laundering
applications, and as a prelude to the problems created by such washing systems in
the neutralization of excess oxidizing agents in laundry processed thereby.
[0009] Typically a tunnel washer apparatus requires approximately three times the amount
of bleach for effectively treating a batch of laundry, than does a washer of "conventional"
tub design. One reason for the excessive bleach requirement is that the bleach to
be effective, is typically added during the wash cycle in a tunnel washer, in which
the presence of detergents and alkalines significantly raise the pH levels of the
solutions in the washing chambers. Even if the bleach is added during a rinse cycle
in a tunnel washing system, a significant amount of bleach is required because of
the relatively low temperatures involved at that stage and the relatively high flow
rate of water in the rinse zone. Accordingly, since it is fairly impractical to thoroughly
remove excess chlorine from the laundry fabric in commercial washing apparatus such
as the tunnel washers, the industry has typically resorted to adding neutralizing
agents, typically at the final "rinse" stage of the laundry cycle for neutralizing
the excess chlorine. When chlorine bleaches are used, the neutralizing agent is typically
referred to as an antichlor product. A common antichlor is sodium thiosulfate.
[0010] It has been common in the commercial laundering industry to inject the neutralizing
agent into the final rinsing module or compartment of a tunnel washer which is typically
the next to the last processing step in the wash formula. The final cycle step is
typically used to recondition the laundry to add such conditioning chemicals as softeners,
sours and the like, that had been previously stripped from the laundry, back into
the textiles. Typically, the antichlor or neutralizing agent that is added to the
final rinse step for neutralizing excess chlorine in the fabric has been added on
a "timed-feed" basis. That is, a fixed, predetermined amount of antichlor has typically
been added to each batch of laundry at the final rinse cycle, regardless of the actual
amount of residual chlorine in the laundry requiring neutralization. The amount of
antichlor added to the rinse has on occasion been varied from cycle to cycle depending
upon the type of fabric within the rinse compartment, which may, for example, have
a history of retaining more or less chlorine. However, in general, the "timed-feed"
technique for adding antichlor neutralizer into the rinse container is a highly speculative
technique based on the best guess of the operator or manufacturer of the washing apparatus
as to how much neutralizer should be added.
[0011] In fact, the actual amount of oxidizing agent that requires neutralization in the
rinse compartment of a washer is highly variable. The residual chlorine level in the
rinse solution depends upon a plethora of variables such as on the amount of chlorine
added during the wash cycle, on the type of fabric, on the amount of soil present,
on the temperature, on the pH level, on the detergent and alkaline level, on how long
the laundry has been subjected to the destainer solution, on the amount of iron in
the water, and on the type of destainer/oxidizing agent solution that had been used.
Obviously, the presently practiced method of injecting a fixed amount of neutralizing/antichlor
agent on a timed-feed basis into the rinse solution, to neutralize the oxidizing agents
therein results in a poor solution to the problem. Injection of too little neutralizing
agent results in extensive irreversible damage to the fabric due to excess residual
chlorine in the fabric, as discussed above. On the other hand, injection of too much
antichlor into the solution, solves the destructive residual chlorine problems, but
is wasteful of the relatively expensive antichlor product, and creates undesirable
residual buildup of salts in the textile fabric which causes greying of the textile
when ironed, decreases the textile's wear life and results in a harsh feel to the
fabric unless further treated with a softener. With the use of timed-feed techniques
it is not uncommon to find residual salts left in the textile fabric that could be
higher than 20-30 parts per million.
[0012] From DE-A 29 20 492 there is known a method and apparatus for controlling the laundry
cycles in household washing machines. This prior art document does not disclose any
method for neutralizing an oxidizing agent in the laundry bath. The use of a bleach
is recited on page 10, line 12, page 11, line 9 and page 13, line 5 of the prior art
document, but there is not any disclosure as to the neutralization of such bleach.
The only neutralization agent disclosed in the document serves for neutralization
of the wash lye, not for reducing the bleach, within the first laundry cycle. Further
the document discloses only an on-off-control, in the adding step, but not a closed
loop control as tought in the present invention.
[0013] FR-A 80 04 638 is concerned with improving the washing quality in a laundry bath.
This prior art document discloses a measurement of the surface tension, the water
hardness and the electric conductivity of the laundry bath, but there is not any disclosure
as to neutralizing an oxidizing agent in the laundry bath.
[0014] The present invention addresses these problems associated with present-day techniques
for neutralizing excessive oxidation agent retention in laundered textiles, by providing
an automated method and apparatus for accurately neutralizing only that amount of
oxidizing agent actually present in the laundry solution during any given laundry
cycle and which prevents the overinjection of neutralizing or reducing agents into
the laundry cycle that can lead to fabric damage.
Summary of the Invention
[0015] The present invention provides an automated method and apparatus for neutralizing
excess oxidizing agents such as destainer chemical additives in a laundering solution
such as at the final rinse stage of a wash formula. The oxidation reduction potential
of the solution to be neutralized is constantly monitored in a closed loop system.
The amount of oxidizing agent is sensed and compared to a maximum acceptable threshold
amount. In response to the comparison a signal is provided to actuate the addition
of neutralizing agent. The process is terminated when the repeatedly sensed amount
of remaining oxidizing agent is less than said maximum acceptable threshold amount.
In a preferred application of the invention, the neutralization agent injection is
performed on a periodic pulsed basis with an interpulse duty cycle sufficiently long
to enable the last-injected measure of neutralizing agents to thoroughly disperse
and react in the solution, before injection of additional neutralizer agent is permitted.
Injection of neutralizer reduction agents into the solution is accurately controlled
such that once neutralization of the oxidizing agents present in the solution is achieved,
injection of additional neutralizing reduction agents is prevented, so as to maintain
the concentration of both reduction and oxidation agents in the solution preferably
to within approximately 1 part per million.
[0016] Accordingly, the invention effectively regulates the oxidation and reduction agents
so as to practically eliminate 100% of their residual remains in the fabric following
a treatment cycle. The present invention also reduces the cost of neutralization treatments
by eliminating overinjection of expensive reducing agents to the bath and extends
the fabric-wear life by reducing retained oxidation agents and salts therein.
[0017] According to one aspect of the invention, there is provided a method of automatically
neutralizing oxidation agents in a laundry bath, comprising:
(a) selecting a maximum acceptable threshold amount for said oxidizing agent in said
bath and producing a threshold signal indicative thereof;
(b) quantitatively sensing the amount of said oxidizing agent to be neutralized in
said bath and provinding a sensed signal in response thereto;
(c) comparing said sensed and said threshold signals and providing a comparison signal
in response thereto;
(d) adding a neutralizing agent of a type suitable for reducing said oxidizing agent
to said bath in response to said comparison signal;
(e) repeating steps (b), (c) and, if necessary, (d); and
(f) terminating said adding of the neutralizing agent when the repeatedly sensed amount
of remaining oxidizing agent in said bath is less than said maximum acceptable threshold
amount.
[0018] According to a further development of the invention, the neutralization process more
preferably terminates the neutralizer injection procedure when the amount of oxidizing
agent to be neutralized which remains in the bath is less than 2 parts per million
and even more preferably when it is less than 1 part per million, or most preferably
only after the neutralizing agent totally neutralizes the oxidizing agent in the bath.
According to a further aspect of the invention, the above injection process further
controls injection of the neutralizing agent into the bath so as to prevent undesirable
overinjection of the neutralizing agent above a level of 10 parts per million level
of excessive unreacted neutralizing agent and mote preferably still so, as to prevent
overinjection of the neutralizing agent above a 2 part per million level of excessive
unreacted neutralizing agent.
[0019] According to a preferred method of injection of the neutralizing agent into the bath,
such injection is performed on an intermittent periodic pulsed basis, by a pump which
is selectively and periodically energized in response to the real-time measured amount
of oxidizing agent present in the bath at any particular instant of time.
[0020] According to yet another aspect of the invention, there is provided a method of laundering
a textile including the steps of:
(a) placing the textile in the laundering bath;
(b) subjecting the textile to destainer including an oxidizing agent;
(c) rinsing substantially all of the oxidizing agent from the textile except for a
minute residual amount thereof;
(d) subjecting the textile to a neutralizing agent of a type suitable for reacting
with the residual oxidizing agent;
(e) causing the residual amount of the oxidizing agent to react with the neutralizing
agent until the amount of residual unneutralized oxidizing agent in the textile is
less than about 5 parts per million and more preferably less than about 1 part per
million; and
(f) preventing overexposure of the textile to the neutralizing agent such that retention
of the neutralizing agent by the textile is less than about 5 parts per million and
more preferably less than about 2 part per million.
[0021] According to yet another aspect of the invention, there is provided a textile laundered
according to the above-described laundering method.
[0022] According to the invention, there is provided apparatus for performing the above-described
methods of neutralizing oxidizing agents in a laundry bath. One such apparatus for
automatically neutralizing oxidizing agents in a laundry bath comprises:
(a) means for selecting a maximum acceptable threshold amount for said oxidizing agent
in said bath and for producing a threshold signal indicative thereof;
(b) means for repeatedly quantitatively sensing the amount of said oxidizing agent
to be neutralized in said bath and for providing a sensed signal in response thereto;
(c) means for comparing said sensed and said threshold signals and for providing a
comparison signal in response thereto;
(d) means for adding a neutralized agent of a type suitable for reducing said oxidizing
agent to said bath in response to said comparison signal; and
(e) means (40) for terminating said adding of the neutralizing agent when the repeatedly
sensed amount of remaining oxidizing agent in said bath (15) is less than said maximum
acceptable threshold amount.
[0023] According to a further aspect of the invention, there is provided such apparatus
as above-described, which also includes means for terminating the injection of neutralizing
agents into the bath before excessive unreacted neutralizing agent being introduced
into the bath exceeds 10 parts per million, and still more preferably before such
excessive unreacted neutralizing agent in the bath exceeds 5 parts per million and
most preferably before they exceed 1 part per million.
[0024] It will be understood that while the present invention as described with respect
to a particular type of washing apparatus (i.e. a tunnel washer), that the invention
is not limited to use with any particular type of laundry machine. While the practical
economics of constructing such apparatus that practice this invention primarily would
dictate that the invention be used in commercial laundering applications such as with
tunnel washers and large batch tub-type laundering applications, the principles of
the invention apply to all laundering applications wherein it is desired to minimize
the amount of oxidizing agents in the laundered textile and also to minimize the amount
of residual neutralizing agent introduced into the textile during the neutralization
process. Further, while the present invention will be described with respect to particular
types of circuits and individual components therein, the invention is not limited
to the use of such circuits or disclosed components thereof. Such circuits and components
have been described to merely illustrate one possible embodiment of a control network
that can be used to implement the principles of this invention.
[0025] These and various other advantages and features which characterize the invention
are pointed out with particularity in the claims annexed hereto and forming a part
hereof. However, for a better understanding of the invention, its advantages, and
objectives obtained by its use, reference should be had to the Drawing which forms
a further part hereof and to the accompanying descriptive matter, in which there is
illustrated and described a preferred embodiment of the invention.
Detailed Description of the Drawing
[0026] Referring to the Drawing, wherein like numerals represent like parts throughout the
several views:
Fig. 1 is a diagrammatic illustration of a continuous batch tunnel washing system,
illustrating the Automatic Neutralizer Control Circuit of this invention in relation
thereto;
Fig. 2 is a block diagram illustration of the functional blocks of the Automatic Neutralizer
Control Circuit disclosed in Fig. 1;
Fig. 3 is a schematic diagram of the Amplifier and Signal Conditioning functional
block of the diagram disclosed in Fig. 2; and
Fig. 4 is a schematic diagram of the Comparator, Set Point Adjustment and the Adjustable
Pulse Control functional blocks of the Automatic Neutralizer Control Circuit disclosed
in Fig. 2.
Detailed Description of the Preferred Embodiment
[0027] While the present invention can be used to neutralize the contents of a container
of any type of laundry machine, its preferred use is with commercial laundry machines,
and particularly with those typically referred to as batch washer systems and to continuous
batch washer systems referred to as "tunnel washers". The preferred embodiment of
the invention will be described with respect to its application with a tunnel washer
system. A diagrammatic illustration of a typical continuous batch tunnel washer system
is schematically illustrated in Fig. 1. Such tunnel washers are well known in the
art, and the details of construction thereof will not be set forth herein. Rather,
a brief functional description of a tunnel washing system should suffice to illustrate
how the present invention can be used to advantage therewith in commercial laundry
applications. Typical of such a washer system would be the double-shell tunnel washer
as, for example, manufactured by Pellerin Milner Corporation of Kenner, Louisiana,
under its Model CBW label.
[0028] Referring to Fig. 1, the tunnel washer, generally illustrated at 10, contains ten
separate laundry processing modules or containers, generally indicated at 11-20. Each
of the modules is associated with a portion of the complete laundering cycle. While
ten such modules and laundry functions are illustrated in Fig. 1, it will be .understood
that the number of steps in the laundering cycle and modules employed therefor can
widely vary, depending upon the particular laundering requirements of the equipment.
In the embodiment illustrated, the various modules and laundering functions are indicated
as: Flush (11), Break (12), Break (13), Suds (14), Flush (15), Bleach (16), Rinse
(17), Rinse (18), Rinse (19) and Conditioning (20). In the preferred embodiment, each
of the modules 11-20 is uniquely associated with performing its associated "function"
on a batch of laundry contained in that module. Each of the modules 11-20 is operatively
connected with one another, generally in longitudinal alignment such that a batch
of laundry can progressively move through the tunnel washer 10 during a complete laundering
cycle, from the first module 11 to the final module 20. Each module is sized to contain
a "batch" of laundry, generally illustrated at "L" in Fig. 1. The batches of laundry
are introduced into the input hopper 10A of the washer 10, and are withdrawn from
the exit end 10B of the washer, where the laundry is typically conveyed to extraction
and drying apparatus (not illustrated). Means (not illustrated) typically in the form
of a large auger which longitudinally extends from the input end 10A to the output
end 10B of the washer 10 simultaneously successively moves the batches of laundry
from module to adjacent module during the laundering cycle. The length of time that
a batch of laundry remains in any particular module varies depending upon the design
of the tunnel washer, and is typically from three to ten minutes depending on the
chemical additive formulas, and the type and amount of laundry being processed. The
various laundry processing steps performed within the modules 11-20 of the tunnel
washer are typically under microprocessor or computer control (not illustrated) which
provide for the proper addition and extraction of water and additives including such
things as detergent, bleach, softeners and the like as the batches of laundry automatically
progress through the tunnel washer. The primary control network also controls the
reuse of solutions, where appropriate, between adjacent modules and the reuse of recovered
water from, for example, extraction or drying processes. The primary control network
is also responsible for properly timing the movement of batches of laundry "L" between
modules at the completion of steps of the cycle and can typically be programmed to
distinguish between incompatible batches of laundry that have been successively loaded
into adjacent modules of the washer so that cross-contamination between such incompatible
batches of laundry is avoided (as for example, when "white" clothes follow "colored"
clothes). The primary control network also is responsible for determining the type
and quantity of chemicals that will be added to each module for the particular batch
of laundry being processed thereby, for determining whether the modules will be filled
rapidly or slowly, and for determining the mode of drainage of the respective modules.
[0029] Referring to Fig. 1, the various means for filling the respective module containers
of the washer 10 are schematically illustrated near the upper portions of the respective
modules by arrows with the following designations: "CA" meaning Chemical Augmentation;
"FF" meaning Fast Fill; and "SF" meaning Slow Fill. Draining of the module containers
is schematically illustrated by arrows exiting from the lower portions thereof with
the following designations: "FD" meaning Fast Drain; "SD" meaning Slow Drain; and
"TD" meaning Transfer Drain. Each of the modules which has a Transfer Drain outlet
includes a transfer conduit which flows back into the immediately preceding adjacent
module, providing an inlet thereto, designated in Fig. 1 as "TI" meaning Transfer
Inlet. Each of the "TI/TD" conduit arrangements has associated therewith a pair of
valves (generally designated at "V" in Fig. 1) operatively controlled by the laundry
machine primary control network (not illustrated) for directing solution counterflow
between adjacent modules, as dictated by the laundering requirements. The tunnel washer
10 of the embodiment illustrated also includes a pump "P" for pumping water from a
"Reuse Water Tank" 22 through, a filter 23 to a fill inlet (generally designated at
"F") leading into the input hopper 10A of the washer 10. Water recovered from various
operations such as extraction and drying stages may provide a source of input water
for the tank 22. A batch of laundry "L" is indicated in Fig. 1 as resting on a conveyor
24 adjacent the inlet hopper 10A, awaiting introduction to the tunnel washer 10. The
conveyor 24 is also under control of the primary control network of the washer 10.
[0030] It will be understood by those skilled in the art that the tunnel washer described
above is merely illustrative of one configuration of many possible variations of such
continuous batch washing systems currently found in the art and of others that fall
within the broad description of such systems.
[0031] The present invention provides an automated method and apparatus for removing excess
oxidizing agents such as destainer chemical additives from the laundry solution at
the final rinse stage or process of the laundering cycle, to thereby, remove excess
oxidizing agents from the laundry being processed at that stage. The present invention
not only automatically removes the excess oxidizing agents from the laundry but also
safeguards against the addition of excessive unreacted neutralizer chemicals, which
can also have a detrimental effect on the laundry as well as inflating the cost of
the neutralizing process. While the principles of this invention could be applied
to any of the processing steps in a washing cycle, they are most practically applied
at the "Final Rinse" stage in a laundering cycle, just prior to the "reconditioning"
of the laundry by the addition of such additives as starch, sours, etc. In the preferred
embodiment illustrated in Fig. 1, the neutralizer additives supplied to the Rinse
module 19 are provided through an inlet port designated as "NA" (meaning Neutralizer
Additive). The neutralizer additive is provided from an appropriate Neutralizer Supply
Source 26, and is transmitted to the "NA" input port by means of a pump 27. The pump
may be of any configuration well known in the art which is suitable when energized
to deliver a known quantity of pumped liquid to its outlet port per given period of
pumping time. In the preferred embodiment, the pump is a peristaltic type, as for
example manufactured by the assignee hereof, Ecolab Inc., under its DRYMASTER™ Model
P pump designation. The pump is controlled by an Automatic Neutralizer Control Circuit,
hereinafter described in more detail and generally illustrated at 30, which receives
input signals by means of a signal flow path 32 from a pair of sensor probes, positioned
within the Rinse module 19 and generally illustrated at 34 in Fig. 1. The control
signal from the Automatic Neutralizer Control Circuit 30 to the pump 27 is provided
by means of a signal flow path generally designated at 36.
[0032] For convenience, the present invention will be described with regard to its applicability
in neutralizing the oxidizing agent "chlorine", wherein the chlorine is neutralized
by an appropriate "antichlor" additive. It will be understood by those skilled in
the art that the invention is not limited to the use of chlorine and antichlor, or
to the use of any other particular components which may be described with regard to
the Automatic Neutralizer Control Circuit 30 or to the particular sensor probes 34
used herein. Those skilled in the art will readily perceive other components and circuits
that could equally well be employed within the spirit and broad scope of this invention.
[0033] Referring to Fig. 2, the Automatic Neutralizer Control Circuit 30 is illustrated
in functional block diagram form. As used herein, the terminology "signal flow path"
will be used to refer to that "course" traversed by signals between functional blocks
of a circuit. Such signal flow paths can in reality comprise one or a plurality of
actual conductors, connectors and the like. For the sake of continuity in notation,
where a plurality of conductors are illustrated in a schematic diagram as forming
a signal flow path, the conductors will bear the same reference numeral as the signal
flow path, wherein individual conductors thereof will be further designated by subdivisional
characters. Further, throughout the ensuing description of electrical components and
networks, it will be understood that while not specifically illustrated in the figures,
each of the electrical components is properly connected to appropriate supply and
ground and bias sources in order to properly operatively energize the respective circuits.
[0034] Referring to Fig. 2, the Automatic Neutralizer Control Circuit 30 is illustrated
as it would typically functionally appear when connected to neutralize oxidation agents
in solution 15 in a container such as a solution carrying laundry container 19ʹ as
it might appear during the "Rinse" portion of a laundry cycle. The sensor probe member
34 is operatively disposed within or in relation to the container 19ʹ so as to sense
the electrical characteristics of the oxidation agents within the solution 15 to be
neutralized. In the preferred embodiment, the sensor probe member 34-comprises a pair
of probes 34A and 34B as illustrated in Fig. 2. The probe 34A is, in the preferred
embodiment, a platinum electrode suitable for measuring the "oxidation reduction potential"
of the solution 15, and the probe 34B comprises a reference electrode. The oxidation
reduction potential electrode 34A (hereinafter simplified as the "O.R.P. Electrode"
determines the level of oxidizing agents present in the solution 15. In the preferred
embodiment, chlorine is the oxidizing agent. The structure and use of such electrodes
is well known in the art, and will not be detailed herein. It will be understood that
while a platinum O.R.P. Electrode is disclosed with respect to the preferred embodiment,
other appropriate probe materials of inert metals as well as other types of sensors
for determining the level of oxidizing agents present in the solution 15 could equally
well be employed.
[0035] The signal output from electrodes 34A and 34B are respectively transmitted by means
of signal flow paths 32A and 32B respectively to an Amplifier and Signal Conditioning
functional block 37. The reference electrode 34B is connected to and forms the reference
potential bus, hereinafter referred to throughout the drawing as 100. The signal output
from the Amplifier and Signal Conditioning functional block 37 is applied by means
of a signal flow path 38 to one signal input 40a of a Comparator network 40. The output
signal from the Amplifier and Signal Conditioning functional block 37 can also be
applied to an appropriate Display, generally illustrated at 39. A second input signal
is applied to a second input terminal 40b of the comparator 40 from a functional block
generally designated as a Set Point Adjustment block 42 by means of a signal flow
path 41. The output signal from the Comparator 40 is applied by means of a signal
flow path 43 to an Adjustable Pulse Control functional block 44. The signal output
from the Adjustable Pulse Control block 44 is carried by means of the signal flow
path 36 to energize the Pump 27. The Pump 27 is operative to pump neutralizing agent
(in the preferred embodiment "antichlor") from a source of such neutralizing agent
26 which is carried by means of the supply lines 28 and 29 to the Neutralizer Additive
(NA) inlet port to the container 19ʹ.
[0036] The Amplifier and Signal Conditioning functional block 37 is operative to receive
the sensed signal provided by the O.R.P. Electrode 34A and to provide a clean representation
thereof to the Comparator network 40. The Amplifier and Signal Conditioning functional
block 37 is illustrated in more detail in Fig. 3. Referring thereto, the Reference
Electrode 34B is illustrated as being operatively connected to the reference bus 100.
The sensed signal output from the O.R.P. Electrode 34A is carried by means of the
signal flow path 32A to the noninverting input terminal of an operational amplifier
37.1. The amplifier 37.1 is appropriately connected to positive and negative supply
potentials indicated by (+V) and (-V) respectively. While not indicated in the Drawing,
it will be understood that the positive and negative supply potentials (+V) and (-V)
respectively represent regulated voltage supply buses appropriately connected to an
appropriate supply power source. In the preferred embodiment, the supply potentials
(+V) and (-V) are (+12 volts) and (-12 volts) respectively.
[0037] The inverting input terminal of amplifier 37.1 is connected by means of a resistor
37.2 to the wiper arm of a variable resistor 37.3. The respective ends of variable
resistor 37.3 are connected between the positive and negative supply voltages (+V)
and (-V) respectively. A feedback resistor 37.4 is connected between the signal output
of amplifier 37.1 and its inverting input terminal.
[0038] The output terminal of amplifier 37.1 is directly connected to the noninverting input
terminal of a second operational amplifier 37.6. The amplifier 37.6 is properly operatively
connected to the positive and negative supplies (+V) and (-V) respectively, and has
its noninverting input terminal connected by means of a resistor 37.5 to the reference
bus 100. A variable resistor 37.7 is connected in series with a fixed resistor 37.8
in the feedback loop between the signal output terminal and the inverting input terminal
of amplifier 37.6. A feedback capacitor 37.9 is also connected in the feedback loop
of amplifier 37.6, in parallel with resistors 37.7 and 37.8. The output of amplifier
37.6 provides the signal output for the Amplifier and Signal Conditioning functional
block 37, and is directly connected to the signal flow path 38.
[0039] In the preferred embodiment, the amplifiers 37.1 and 37.6 are type TL 084 operational
amplifiers. As with all components described herein with respect to the description
of the preferred embodiment of the invention, it will be understood that the invention
is not to be construed as limited in any manner by the particular type of circuit
components herein described. Rather, such circuit components are merely typical of
particular circuit components that have been found to function satisfactorily in the
circuit configurations illustrated.
[0040] The amplifiers 37.1 and 37.6 function as unity gain amplifiers to condition and stabilize
the sensed signal (which can be in the low millivolt range) received from the O.R.P.
Electrode 34A. The variable resistor 37.3 "zeros out" imbalances in the sensor electrodes
34. Amplifier 37.6 provides a damping influence to the sensed signal with capacitor
37.9 acting to eliminate signal discrepancies which may appear in the sensed signal
as a result of turbulence, bubbles or the like in the solution 15. It should also
be noted that the signal flow paths leading from the sensor electrodes 34 to the Amplifier
and Signal Conditioning circuits 37 are shielded to eliminate extraneous noise and
interference signals.
[0041] Referring to Fig. 4, the signal output from the Amplifier and Signal Conditioning
circuit 37 is applied by means of the signal flow path 38 to the Comparator network
40. The signal flow path 38 is connected by means of a resistor 40.1 to the inverting
input terminal of an operational amplifier 40.2. The noninverting input terminal of
amplifier 40.2 is connected to the reference bus 100. A resistor 40.3 and a capacitor
40.4 are connected in parallel in the feedback loop between the signal output and
inverting input terminals of amplifier 40.2. The signal output and inverting input
terminals of 40.2 also form input terminals 40b1 and 40b2 for connection to receive
signals from the signal flow path 41 (see Fig. 2), which will be described in more
detail hereinafter. In the preferred embodiment, amplifier 40.2 is a type TL 082 operational
amplifier.
[0042] The output signal from amplifier 40.2 is directly applied to the inverting input
terminal of an operational amplifier 40.5. In the preferred embodiment, amplifier
40.5 is a type LM 311 open collector output comparator amplifier. The positive bias
terminal of amplifier 40.5 is connected to the reference bus 100, and its negative
bias terminal is connected to the negative bias supply (-V). The emitter of the output
transistor of amplifier 40.5 is also connected to the negative bias supply (-V). A
resistor 40.6 is connected between the signal output and the noninverting input terminals
of amplifier 40.5.
[0043] The noninverting input terminal of amplifier 40.5 is also connected to the inverting
input terminal of a second open collector output comparator amplifier 40.7 and provides
a third input terminal 40b3 for receiving signals from the signal flow path 41 from
the Set Point Adjustment functional block 42. In the preferred embodiment, amplifier
40.7 is also a type LM 311 operational amplifier, which has its positive bias terminal
connected to the reference bus 100 and its negative bias terminal and the emitter
of its output transistor connected to the negative bias supply (-V). The signal output
of amplifier 40.5 is connected by means of a resistor 40.8 to the noninverting input
terminal of amplifier 40.7. The noninverting input terminal of amplifier 40.7 is also
connected by means of a resistor 40.9 to the reference bus 100, and is connected by
means of a capacitor 40.10 to the negative bias supply potential (-V). The signal
output from amplifier 40.7 is directly applied to the signal flow path 43 for providing
an input reset signal to the Adjustable Pulse Control network 44, as hereinafter described
in more detail.
[0044] The Set Point Adjustment functional block 42 (see Figs. 2 and 4) comprises a plurality
of resistors and capacitors that can be adjusted (as hereinafter described) to vary
the various signals applied to amplifiers 40.2, 40.5 and 40.7 of the Comparator network
40. Referring to Fig. 4, a plurality of resistors 42.1-42.8 are switchably connected
in parallel by means of the conductors 41A and 41B with resistor 40.3 and capacitor
40.4 in the feedback loop of amplifier 40.2, to selectively vary the gain of amplifier
40.2. Each of the resistors 42.1-42.8 is respectively connected in series with a switch
42.11-42.18 which can be selectively opened or closed to connect the desired resistor(s)
in parallel in the feedback loop of amplifier 40.2. The switches 42.11-42.18 are,
in the preferred embodiment, comprise thumb-wheel switches operatively connected to
provide a binary coded two digit decimal number, wherein resistors 42.1-42.4 and their
accompanying switches 42.11-42.14 are associated with the "one's digit" of the number,
and wherein resistors 42.5-42.8 and their associated switches 42.15-42.18 are associated
with the "ten's digit" of the number. The binary coded decimal output designations
of the various resistor/switch pairs are indicated to the right of the respective
switches in Fig. 5. In the preferred embodiment, the resistor values for resistors
42.1-42.8 are as follows: R42.1 = 1 Megohm; R42.2 = 510 k ohm; R42.3 = 240 k ohm;
R42.4 = 120 k ohm; R42.5 = 62 k ohm; R42.6 = 30 k ohm; R42.7 = 15 k ohm; and R42.8
= 6.8 k ohm.
[0045] The second portion of the Set Point Adjustment network 42 comprises a resistor/capacitor
network that provides in the preferred embodiment, a fixed bias potential to the noninverting
input terminal of amplifier 40.5 by means of the conductor 41C through the input terminal
40b3. A capacitor 42.20 is connected in parallel with a resistor 42.21 between the
negative bias supply potential (-V) and the conductor 41C. A pair of resistors 42.22
and 42.23 are also connected in parallel between the reference bus 100 and the conductor
41C. In the preferred embodiment, as described in more detail hereinafter, the pair
of parallel circuits just described provides a constant 5 volt reference signal to
the noninverting input terminal of amplifier 40.5.
[0046] The signal output of Comparator 40, is carried by means of the signal flow path 43
to a "reset" input terminal of a Timer circuit 44.1 of the Adjustable Pulse Control
network 44. In the preferred embodiment, the Timer 44.1 is a type 555 timer having
its V
cc input terminal connected to the reference bus 100 and its reference or (GND) terminal
connected to the negative bias supply potential (-V). The timer also has a "threshold"
terminal designated as (THD), a "trigger" terminal designated as (TRIG) and a "discharge"
terminal designated as (DISCHG). The threshold (THD) and trigger (TRIG) input terminals
are commonly connected and are connected by means of a capacitor 44.2. to the negative
bias potential (-V). The (THD) and (TRIG) terminals are also connected by means of
a variable resistor 44.3 and a fixed resistor 44.4 to the reference bus 100. The movable
wiper of variable resistor 44.3 is connected to the discharge (DISCHG) terminal of
Timer 44.1, and is also connected by means of a diode 44.5 to the (THD) and (TRIG)
terminals.
[0047] The signal output of Timer 44.1 is connected by means of a resistor 44.6 to the base
of an npn transistor 44.7. The emitter of transistor 44.7 is directly connected to
the negative bias potential (-V) and its collector is connected to the cathode of
a light emitting diode 44.8. The anode of diode 44.8 is connected to the stationary
contact of a switch 44.9. The movable wiper of switch 44.9 moves between a pair of
contacts designated at (x1) and (x2) in Fig. 4. Contact (xl) of switch 44.9 is connected
by means of a resistor 44.10 to an unregulated power supply source, generally designated
at "PS" in Fig. 4, and it is also directly connected to a first input terminal of
a triac driver network 44.11. The second contact (x2) of switch 44.9 is connected
to a second input terminal of the driver network 44.11. In the preferred embodiment,
driver network 44.11 is a type MOC 3030 optically coupled triac driver network. When
the movable wiper of switch 44.9 is positioned in engagement with contact (x1), the
switch disables the optical coupler driver 44.11. When positioned with movable wiper
in engagement with contact (x2), the optical coupler is enabled for operation, upon
further conduction of transistor 44.7, as hereinafter described. Driver 44.11 has
a first output terminal connected by means of a resistor 44.12 to a first power terminal
of a triac 44.13, and closes an enabling supply path for Pump 27 by means of a conductor
36A of signal flow path 36. The second output terminal of the triac Driver 44.11 is
connected to the gate terminal of triac 44.13 and is also connected by means of a
resistor 44.14 to the second power terminal of triac 44.13, and to a second conductor
36B of the signal flow path 36 leading to the Pump 27. A capacitor 44.15 is connected
in series with a resistor 44.16 across the power terminals of triac 44.13 and between
the conductors 36A and 36B providing filtering of the triac generated signals.
[0048] The circuitry described above enables accurate, automatic neutralization of oxidizing
agents in a laundry bath, with practically zero residual neutralizing agent carryover
remaining in the bath after the neutralization process. As described above, the Amplifier
and Signal Conditioning Network 37 provides a clean sensed signal from the input probes
34 which accurately reflects the measured oxidation reduction potential levels of
the solution 15 and which accounts for perturbations within the solution caused by
turbulence, bubbles or the like.
[0049] For any given pH level of the measured solution 15, there exists a known correlation
between the measured oxidation reduction potential value and the actual amount of
oxidizing agent (i.e. chlorine in the preferred embodiment) in the solution, which
can be directly translated into parts per million (i.e. "ppm") units of the amount
of oxidizing agent in the bath. For example, at a given pH level of 10 for the bath
15, a 0.1 millivolt change in the measured oxidation reduction potential level at
the probes 34 may represent a change in the level of oxidizing agents in the bath
by 1 ppm. Using this correlation factor, a change in the measured oxidation reduction
potential level at the probes 34 of 0.5 millivolts would represent a change in the
level of oxidizing agents in the bath of 5 ppm. The measured oxidation reduction potential
as it correlates to parts per million of the oxidizing agents in the bath varies as
a function of the pH level of the bath. For example, in contrast to the above example
wherein a pH level of 10 was assumed for the bath 15, if the pH level of the bath
15 were to change to a different level such as to a pH of 9, there would be a corresponding
change in the measured oxidation reduction potential level at the probes 34 as well
as in the correlation factor of such measured oxidation reduction potential to the
actual level of oxidizing agents appearing in the bath. For example, at a bath pH
of 9, a 1.0 millivolt change in the measured oxidation reduction potential level at
the probes 34 might now represent a change in the level of oxidizing agents in the
bath by 1 ppm (in contrast to the 0.1 millivolt per 1 ppm example that existed for
a pH level of 10). A typical pH value for a laundry solution in a tunnel washer final
rinse stage is between 9 and 11. A typical level of excess chlorine appearing in such
bath before neutralization may be on the order of 10 to 50 parts per million.
[0050] The measured oxidation reduction potential values as correlated to the amount of
oxidizing agents (in ppm) in a bath for any given pH value can be empirically determined.
For the embodiment illustrated in the Drawing, the values of the components in the
Comparator 40 network and in the Set Point Adjustment 42 network have been selected
for use with a tunnel washer apparatus wherein the pH of the solution in the final
Rinse module in which the solution is being neutralized, is relatively constant from
batch to batch, at a pH level of approximately 9. Therefore, once the Set Point Adjustment
selections (as hereinafter described) are made for a desired percentage of neutralization
in a given system, such settings do not require change from day to day or from batch
to batch as the laundry machine performs successive laundering cycles. However, for
a system wherein the pH level of the solution which is being neutralized constantly
varies from one laundry cycle to the next, it would be desirable to include a pH monitoring
feature for continuously monitoring the pH of the solution 15 being neutralized and
for providing a real-time correlation adjustment to the Set Point Adjustment 42 network
as well as to the Comparator 40 network circuits which reflect the correlation changes
required by the changing pH values. Such real-time correlation function could be readily
performed by hardwired circuits or by microprocessor-controlled networks. For ease
of description herein, the following discussion will assume a constant pH value for
the solution 15 being neutralized.
[0051] Given the oxidation reduction potential value for the laundry bath at a "neutral"
contition, the gain of amplifier 40.2 can be selected by means of the thumbwheel switches
42.11-42.18 and their associated resistors 42.1-42.8 to provide the desired output
operating level from amplifier 40.2 that will be compared against the reference signal
applied to comparator amplifiers 40.5 and 40.7. The gain of amplififier 40.2 will
be set such that its output voltage at the "neutral" oxidation reduction potential
measurement of the bath, identically equals the reference voltage level applied to
conductor 41C. In a preferred application of the control network to neutralization
of oxidizing agents within the final Rinse module of a tunnel washer (as illustrated
in the Drawing), it has been determined that at an operating pH level of 9 (which
is typical for solution within the Rinse module), a measured oxidation reduction potential
of approximately 400 mv equals the desired zero parts per million of chlorine in the
bath 15. Therefore, referring to Fig. 4, the output signal from amplifier 40.2 should
equal the value of the reference signal applied by means of the conductor 41C to the
comparator amplifiers 40.5 and 40.7, at such zero ppm level. In the preferred embodiment,
a constant reference voltage level (appearing on conductor 41C) of 5 volts has been
selected as an optimum operating level for the comparator amplifiers 40.5 and 40.7.
Therefore, at an actual measured oxidation reduction potential level of 400 mv by
the probes 34, the signal output of amplifier 40.2 should also be 5 volts, by proper
selection of the nominal gain of the amplifier 40.2 with the resistor/switching network.
Any deviation from the measured "neutral" oxidation reduction potential value of 400
mv measured at the probes 34 represents an undesirable excess of chlorine in the solution,
or conversely an excess of antichlor in the solution.
[0052] The amplification level of the measured deviations from the neutral 400 mv level
are multiplied by the gain selection entered into the Set Point Adjustment 42 network
by means of the resistors 42.1-42.8 and their associated switches 42.11-42.18. For
simplicity in setting of the gain of amplifier 40.2, the resistor 42.1-42.8 values
have been selected such that their binary coded decimal representations set by switches
42.11-42.18 indicate a multiple of the "neutral" millivolt value of the oxidation
reduction potential measurement of the solution. For example a switch selection reading
of "01" would correspond to a "neutral" reading of 10 mv, a reading of "13" to a "neutral"
reading of 130 mv, etc.; wherein the output voltage from amplifier 40.2 at the respective
"neutral" gain settings would be 5 volts, to match the selected reference voltage
level of the preferred embodiment circuit configuraiton.
[0053] For the tunnel washing application described herein, it is known that a typical chlorine
content within the solution 15 which is to be neutralized at the final Rinse station
can typically vary from 10 to 50 parts per million. It is desirable to reduce such
residual chlorine content to as near zero ppm as possible, without introducing excessive
or residual antichlor to the solution which can be as undesirable as the chlorine
itself. The Automatic Neutralizer Control Circuit 30 operates in closed loop manner
to add antichlor to the rinse solution 15 in measured increments by operating the
Pump 27 on a pulsed basis, in response to the actual measured oxidation reduction
potential value by the probes 34. The determination as to whether antichlor injection
to the solution 15 is necessary, is made by the Comparator network 40.
[0054] Referring to Fig. 4, the comparator amplifier 40.5 continuously monitors the measured
oxidation reduction potential signal provided by amplifier 40.2 against the fixed
reference level on conductor 41C established by the reference potential circuit of
the Set Point Adjustment network 42. If the measured oxidation reduction potential
signal exceeds the fixed reference signal at the input to amplifier 40.5, an output
signal is provided by comparator amplifier 40.5 to the noninverting input of comparator
amplifier 40.7. Since the noninverting input of amplifier 40.7 is connected to the
RC network established by resistor 40.9 and capacitor 40.10, comparator amplifier
40.7 acts as a "delay" comparator which ensures that the signal received from amplifier
40.2 must exceed the fixed reference level on conductor 41C for at least a continuous
predetermined period of time before the comparator network 40 will provide a reset
signal to Timer 44.1. In the preferred embodiment, the "delay" function has been set
for a turn-on delay of 2 seconds and a turn-off delay of 0.1 seconds. The turn-on
delay is established by the charging time constant of capacitor 40.10. The turn-off
delay is provided by discharge of capacitor 40.10 through resistor 40.8 and the open
collector output terminal of amplifier 40.5 to the negative bias supply bus (-V).
Therefore, whenever the probes 34 measure a differential oxidation reduction potential
value differing from the "neutral" value for a continuous time period of 2 seconds,
the comparator network 40 provides a logical "high" reset signal to the "reset" input
terminal of Timer network 44.1.
[0055] Timer 44.1 is operative to establish a pulsed duty cycle for activating the Pump
27 so as to inject a predetermined amount of antichlor into the solution bath 15 on
each energized cycle of the Pump. In the preferred embodiment, the Timer 44.1 takes
approximately 20 seconds to charge following receipt of a reset signal from the comparator
40, and approximately 1 second to discharge before it can be reset again by the comparator
40. The capacitor 44.2 of Timer 44.1 is charged by the circuit path established from
the reference 100, through resistor 44.4, the left portion of resistor 44.3 (as viewed
in Fig. 4), and the diode 44.5. Once capacitor 44.2 is charged, the signal output
of Timer 44.1 switches to a logical "high", and its (DISCHG) terminal switches to
a logical "low" enabling capacitor 44.2 to discharge through the right portion of
resistor 44.3 and the (DISCHG) terminal. When the timer is triggered by the charged
capacitor 44.2, the "high" output signal from the output of Timer 44.1 drives transistor
44.7 into conduction, triggering triac driver 44.11 which enables triac 44.14 for
the duration of the enabling pulse from Timer 44.1. Following discharge of capacitor
44.2 and resumption of the output of Timer 44.1 to a logical "low" the pump is disabled
for the remainder of the time during which triac 44.13 is enabled. When enabled Pump
27 operates to inject a measured amount of antichlor additive to the solution bath
15. In the preferred embodiment, an injection of antichlor to the solution bath 15
during one pulsed interval of pump operation operates to reduce the measured oxidation
reduction potential by approximately 2-3 millivolts. For a bath having a Ph of 9,
wherein the "neutral" oxidation reduction potential value of the bath is approximately
400 mv, a change in 1.0 mv has been found to correlate to approximately a 1 ppm change
in the presence of unreduced oxidizing agents in the bath.
[0056] The above periodic injection process is continually repeated until the oxidation
reduction potential difference measured by the probes 34 from the desired "neutral"
level is insufficient to provide an adequate signal to activate comparators 40.5 and
40.7. Under such conditions, the Timer 44.1 will be disabled, as well as the output
drive circuitry for energizing the Pump 27. Experiments using the above described
Automatic Neutralizer Control Circuit 30 have demonstrated ability of the network
to repeatably neutralize excessive chlorine in the rinse solution to a level of less
than 1 ppm with less than 1 ppm of residual antichlor remaining in the bath 15 after
the neutralization process. This can be contrasted with prior art "timed feed" methods
of neutralization which would typically consider a residual amount of antichlor in
the bath of from 8 to 15 ppm to be very acceptable. It can be appreciated, therefore,
that the present invention provides an accurate method of controlling both the levels
of residual neutralization and oxidation agents remaing in a bath following a neutralization
process during execution of the normal laundry wash formula
[0057] While a particular embodiment of the invention has been described with respect to
its application with a continuous tunnel washing system for neutralizing the oxidation
agents in the final rinse portion thereof, it will be understood by those skilled
in the art that the invention is not limited to such application or to the particular
circuits disclosed and described herein. It will be appreciated by those skilled in
the art that other circuit configurations that embody the principles of this invention
and other applications therefor other than as described herein can be configured within
the spirit and intent of this invention. The circuit configurations described herein
were provided only as an example of one embodiment that incorporates and practices
the principles of the present invention. Other modifications and alterations not only
of the circuit configurations but also of the components therein and the application
of the overall control circuit to the controlled reduction of oxidation agents in
solution are well within the knowledge of those skilled in the art and are to be included
within the broad scope of the appended claims.
1. Method of automatically neutralizing an oxidizing agent in a laundry bath (15), comprising
the steps of:
(a) selecting a maximum acceptable threshold amount for said oxidizing agent in said
bath and producing a threshold signal indicative thereof;
(b) quantitatively sensing the amount of said oxidizing agent to be neutralized in
said bath and providing a sensed signal in response thereto;
(c) comparing said sensed and said threshold signals and providing a comparison signal
in response thereto;
(d) adding a neutralizing agent (26) of a type suitable for reducing said oxidizing
agent to said bath in response to said comparison signal;
(e) repeating steps (b), (c) and, if necessary, (d); and
(f) terminating said adding of the neutralizing agent when the repeatedly sensed amount
of remaining oxidizing agent in said bath (15) is less than said maximum acceptable
threshold amount.
2. Method according to Claim 1, wherein a maximum acceptable threshold amount of 5 ppm
is selected.
3. Method according to Claim 1, wherein a maximum acceptable threshold amount of 2 ppm
is selected.
4. Method according to Claim 1, wherein said terminating step is executed when said sensed
signal indicates that there remains no oxidizing agent to be neutralized in the bath.
5. Method according to one of the preceding claims, wherein the step of terminating said
adding further includes terminating said adding of said neutralizing agent to the
bath before the amount of excessive unreacted neutralizing agent in the bath exceeds
10 ppm.
6. Method according to Claim 5, wherein said adding step is terminated before said excessive
unreacted neutralizing agent in the bath exceeds 5 ppm.
7. Method according to Claim 6, wherein said adding of said neutralizing agent into the
bath is terminated when said sensed signal indicates that the amount of said oxidizing
agent to be neutralized remaining in the bath is less than 1 ppm and before said excessive
unreacted neutralizing agent in the bath exceeds 2 ppm.
8. Method according to one of the preceding claims, wherein the step of sensing the amount
of said oxidizing agent to be neutralized comprises the step of measuring the oxidation
reduction potential in said bath and subtracting therefrom a predetermined oxidation
reduction potential value of a like bath containing none of said oxidizing agent.
9. Method according to Claim 8, including the step of averaging the instantaneously measured
oxidation reduction potential signal over a period of time and providing said sensed
signal in response to said averaged signal.
10. Method according to one of the preceding claims, wherein said adding step comprises
energizing an injection pump (27) that is operatively connected to deliver said neutralizing
agent to said bath on an intermittent, periodic basis.
11. Method according to Claim 10, wherein the duty cycle of said period injection is less
than about 20%.
12. Method according to one of the preceding claims, wherein said bath solution has a
relatively constant pH.
13. Method according to Claim 8, wherein each of said injections reduces the measured
oxidation reduction potential of said bath by about 1 to 5 ppm.
14. Method according to one of the preceding claims, wherein said oxidizing agent comprises
active chlorine and wherein said neutralizing agent comprises an antichlor agent.
15. Apparatus for automatically neutralizing oxidizing agents in a laundry bath (15),
comprising:
(a) means (42) for selecting a maximum acceptable threshold amount for said oxidizing
agent in said bath and for producing a threshold signal indicative thereof;
(b) means (34A, 34B) for repeatedly quantitatively sensing the amount of said oxidizing
agent to be neutralized in said bath (15) and for providing a sensed signal in response
thereto;
(c) means (40) for comparing said sensed and said threshold signals and for providing
a comparison signal in response thereto;
(d) means (27) for adding a neutralizing agent of a type suitable for reducing said
oxidizing agent to said bath in response to said comparison signal; and
(e) means (40) for terminating said adding of the neutralizing agent when the repeatedly
sensed amount of remaining oxidizing agent in said bath (15) is less than said maximum
acceptable threshold amount.
16. Apparatus according to Claim 15, wherein said maximum acceptable threshold amount
is 5 ppm.
17. Apparatus according to Claim 15 or 16, wherein said means (40) for terminating said
adding of the neutralizing agent is operable to terminate said adding when excessive
unreacted neutralizing agent in the bath exceeds 10 ppm.
18. Apparatus according to one of Claims 15 to 17, wherein said means (40) for terminating
said adding of the neutralizing agent is operable to terminate the adding when said
sensed signal indicates that the amount of said oxidizing agent to be neutralized
remaining in the bath is less than about 1 ppm and before excessive unreacted neutralizing
agent in the bath exceeds about 5 ppm.
1. Verfahren zum automatischen Neutralisieren eines Oxidationsmittels in einem Wäschebad
(15), folgende Schritte umfassend:
(a) Wahl einer maximal akzeptablen Schwellwertmenge für das Oxidationsmittel in dem
Bad und Erzeugen eines Schwellwertsignals als Anzeige dafür;
(b) quantitatives Messen der Menge des zu neutralisierenden Oxidationsmittels in dem
Bad und Erstellen eines Meßsignals in Ansprache darauf;
(c) Vergleichen des Meß- und des Schwellwertsignals und Erstellen eines Vergleichssignals
in Ansprache darauf;
(d) Zugabe eines Neutralisationsmittels (26) einer zur Reduktion des Oxidationsmittels
in dem Bad geeigneten Art in Ansprache auf das Vergleichssignal;
(e) Wiederholen der Schritte (b), (c) und gegebenenfalls (d); und
(f) Unterbrechung der Zugabe des Neutralisationsmittels, wenn die wiederholt gemessene
Menge des verbleibenden Oxidationsmittels in dem Bad (15) weniger als die maximal
akzeptable Schwellwertmenge ist.
2. Verfahren gemäß Anspruch 1, worin eine maximal akzeptable Schwellwertmenge von 5 ppm
gewählt wird.
3. Verfahren gemäß Anspruch 1, worin eine maximal akzeptable Schwellwertmenge von 2 ppm
gewählt wird.
4. Verfahren gemäß Anspruch 1, worin der Unterbrechungsschritt erfolgt, wenn das Meßsignal
anzeigt, daß kein zu neutralisierendes Oxidationsmittel mehr in dem Bad übrig ist.
5. Verfahren gemäß einem der vorherstehenden Ansprüche, in dem der Unterbrechungsschritt
der Zugabe weiterhin die Unterbrechung der Neutralisationsmittel-Zugabe in das Bad
umfaßt, bevor die Menge des überschüssigen nicht-umgesetzten Neutralisationsmittels
in dem Bad 10 ppm übersteigt.
6. Verfahren gemäß Anspruch 5, worin der Zugabeschritt abgeschlossen ist, bevor das überschüssige
nichtumgesetzte Neutralisationsmittel in dem Bad 5 ppm übersteigt.
7. Verfahren gemäß Anspruch 6, worin die Zugabe des Neutralisationsmittels in das Bad
abgeschlossen ist, wenn das Meßsignal anzeigt, daß die in dem Bad übrigbleibende Menge
des zu neutralisierenden Oxidationsmittels weniger als 1 ppm ist, und bevor das überschüssige
nichtumgesetzte Neutralisationsmittel in dem Bad 2 ppm übersteigt.
8. Verfahren gemäß einem der voranstehenden Ansprüche, worin der Schritt der Messung
der neutralisierenden Oxidationsmittel-Menge den Schritt des Messens des Oxidationsmittel-Reduktionspotentials
in dem Bad und der Subtraktion eines vorbestimmten Oxidationsmittel-Reduktionspotentialwertes
eines Vergleichsbades, das kein derartiges Oxidationsmittel enthält, davon umfaßt.
9. Verfahren gemäß Anspruch 8, umfassend den Schritt der Mittelung des sofort gemessenen
Oxidationsmittel-Reduktionspotentialsignals über eine Zeitspanne und Erstellen des
Meßsignals in Ansprache auf das gemittelte Signal.
10. Verfahren gemäß einem der vorhergehenden Ansprüche, worin der Zugabeschritt die Aktivierung
einer Einspritzpumpe (27) umfaßt, welche maschinentechnisch derart angeschlossen ist,
daß sie das Neutralisationsmittel mit Unterbrechungen periodisch dem Bad zuführt.
11. Verfahren gemäß Anspruch 10, worin der Arbeitszyklus der periodischen Einspritzung
weniger als 20 % beträgt.
12. Verfahren gemäß einem der vorhergehenden Ansprüche, worin die Badlösung einen relativ
konstanten pH-Wert hat.
13. Verfahren gemäß Anspruch 8, worin jede der Einspritzungen das gemessene Oxidationsmittel-Reduktionspotential
des Bades um ca. 1 bis 5 ppm verringert.
14. Verfahren gemäß einem der vorhergehenden Ansprüche, in dem das Oxidationsmittel aktives
Chlor und das Neutralisationsmittel ein Antichlormittel umfaßt.
15. Vorrichtung zum automatischen Neutralisieren von Oxidationsmitteln in einem Wäschebad
(15), folgendes umfassend:
(a) eine Vorrichtung (42) zur Wahl einer maximal akzeptablen Schwellwertmenge für
das Oxidationsmittel in dem Bad und zur Erzeugung eines Schwellwertsignals als Anzeige
für diese;
(b) Vorrichtungen (34A, 34B) zum wiederholten quantitativen Messen der zu neutralisierenden
Oxidationsmittelmenge in dem Bad (15) und Erstellen eines Meßsignals in Ansprache
darauf;
(c) eine Vorrichtung (40) zum Vergleichen des Meß- und des Schwellwertsignals und
zum Erstellen eines Vergleichssignals in Ansprache darauf;
(d) eine Vorrichtung (27) zur Zugabe eines zur Reduktion des Oxidationsmittels in
dem Bad geeigneten Neutralisationsmittels in Ansprache auf das Vergleichssignal; und
(e) eine Vorrichtung (40) zur Unterbrechung der Zugabe des Neutralisationsmittels,
wenn die wiederholt gemessene Menge des verbleibenden Oxidationsmittels in dem Bad
(15) weniger als die maximal akzeptable Schwellwertmenge ist.
16. Vorrichtung gemäß Anspruch 15, worin die maximal akzeptable Schwellwertmenge 5 ppm
beträgt.
17. Vorrichtung gemäß Anspruch 15 oder 16, worin die Vorrichtung (40) zur Unterbrechung
der Zugabe des Neutralisationsmittels so betrieben werden kann, daß sie die Zugabe
unterbricht, wenn das überschüssige nicht-umgesetzte Neutralisationsmittel in dem
Bad 10 ppm übersteigt.
18. Vorrichtung gemäß einem der Ansprüche 15 bis 17, worin die Vorrichtung (40) zur Unterbrechung
der Zugabe des Neutralisationsmittels so betrieben werden kann, daß sie die Zugabe
unterbricht, wenn das Meßsignal anzeigt, daß die im Bad verbleibende Menge des zu
neutralisierenden Oxidationsmittels weniger als ca. 1 ppm beträgt und bevor überschüssiges
nicht-umgesetztes Neutralisationsmittel in dem Bad ca. 5 ppm übersteigt.
1. Procédé de neutralisation automatique d'un agent oxydant dans un bain de lavage (15),
comprenant les étapes consistant à :
(a) sélectionner une valeur seuil maximale acceptable et la quantité dudit agent oxydant
dans ledit bain et à produire un signal seuil indicatif de celle-ci ;
(b) détecter quantitativement la quantité dudit agent oxydant à neutraliser dans ledit
bain et à fournir un signal de détection en réponse à celui-ci ;
(c) comparer ledit signal seuil et ledit signal de détection et fournir un signal
de comparaison en réponse à ceux-ci;
(d) ajouter un agent neutralisant (26) de nature convenable pour réduire ledit agent
oxydant dans ledit bain en réponse audit signal de comparaison;
(e) répéter les étapes (b), (c), et, si nécessaire, (d) ; et
(f) terminer ladite addition d'agent neutralisant lorsque la quantité détectée de
façon répétée d'agent oxydant restant dans ledit bain (15) est inférieure à ladite
valeur maximale acceptable.
2. Procédé selon la revendication 1, caractérisé en ce qu'une valeur maximale acceptable
de 5 ppm est sélectionnée.
3. Procédé selon la revendication 1, caractérisé en ce qu'une valeur maximale acceptable
de 2 ppm est sélectionnée.
4. Procédé selon la revendication 1, caractérisé en ce que ladite étape terminale est
effectuée lorsque ledit signal de détection indique qu'il ne reste pas d'agent oxydant
à neutraliser dans le bain.
5. Procédé selon l'une des revendications précédentes caractérisé en ce que ladite étape
terminale d'addition comprend l'arrêt de ladite addition dudit agent neutralisant
dans le bain avant que l'excès d'agent neutralisant n'ayant pas réagi dans le bain
n'excède 10 ppm.
6. Procédé selon la revendication 5, caractérisé en ce que ladite étape d'addition est
arrêtée avant que ledit excès d'agent neutralisant n'ayant pas réagi dans le bain
n'excède 5 ppm.
7. Procédé selon la revendication 6, caractérisé en ce que ladite addition dudit agent
neutralisant dans le bain est arrêtée lorsque le signal de détection indique que la
quantité dudit agent oxydant à neutraliser restant dans le bain est inférieur à 1
ppm et avant que l'excès d'agent neutralisant n'ayant pas réagi dans le bain n'excède
2 ppm.
8. Procédé selon l'une des revendications précédentes, caractérisé en ce que l'étape
de détection de la quantité dudit agent oxydant à neutraliser comprend une étape consistant
à mesurer le potentiel d'oxydo-réduction dans ledit bain et à en soustraire une valeur
prédéterminée de potentiel d'oxydo-réduction d'un bain identique ne contenant pas
ledit agent oxydant.
9. Procédé selon la revendication 8, incluant une étape consistant à établir la moyenne
du signal de potentiel d'oxydo réduction instantané mesuré sur une période de temps
donnée et à fournir ledit signal de détection en réponse audit signal moyen.
10. Procédé selon l'une des revendications précédentes, caratérisé en ce que ladite étape
d'addition comprend l'excitation d'une pompe d'injection (27) connectée de façon opérationnelle
afin de délivrer ledit agent neutralisant dans ledit bain par intermittence, périodiquement.
11. Procédé selon la revendication 10, caractérisé en ce que le cycle opératoire de ladite
période d'injection est inférieur à environ 20 %.
12. Procédé selon l'une des revendications précédentes, caractérisée en ce que la solution
dans ledit bain présente un pH relativement constant.
13. Méthode selon la revendication 8, caractérisée en ce que chacune desdites injections
réduit le potentiel d'oxydo-réduction mesuré dudit bain d'environ 1 à 5 ppm.
14. Procédé selon l'une des revendications précédentes, caractérisé en ce que ledit agent
oxydant comprend du chlore actif et en ce que ledit agent neutralisant comprend un
agent anti-chlore.
15. Dispositif pour neutraliser des agents oxydants dans un bain de lavage (15), présentant
:
(a) des moyens (42) pour sélectionner une valeur seuil maximale acceptable de la quantité
dudit agent oxydant dans ledit bain et pour produire un signal seuil indicatif de
celui-ci ;
(b) des moyens (34A, 34B) pour détecter de façon répétée la quantité dudit agent oxydant
à neutraliser dans ledit bain (15) et pour fournir un signal de détection en réponse
à celui-ci ;
(c) des moyens (40) pour comparer ledit signal de détection et ledit signal seuil
et pour fournir un signal de comparaison en réponse à ceux-ci;
(d) des moyens (27) pour ajouter un agent neutralisant d'un type convenable pour réduire
ledit agent oxydant dans ledit bain en réponse audit signal de comparaison; et
(e) des moyens (40) pour arrêter ladite addition d'agent neutralisant lorsque la quantité
détectée de façon répétée d'agent oxydant restant dans ledit bain (15) est inférieure
à ladite valeur seuil maximale acceptable.
16. Dispositif selon la revendication 15, caractérisé en ce que ladite valeur seuil maximale
acceptable est de 5 ppm.
17. Dispositif selon la revendication 15 ou 16, caractérisé en ce que lesdits moyens (40)
pour arrêter ladite addition d'agent neutralisant sont mis en oeuvre pour arrêter
ladite addition lorsque l'excès d'agent neutralisant n'ayant pas réagi dans le bain
dépasse 10 ppm.
18. Dispositif selon l'une des revendications 15 à 17, caractérisé en ce que lesdits moyens
(40) pour arrêter ladite addition d'agent neutralisant sont mis en oeuvre pour arrêter
l'addition lorsque ledit signal de détection indique que la quantité dudit agent oxydant
à neutraliser restant dans le bain est inférieure à environ 1 ppm et avant que l'excès
d'agent neutralisant n'ayant pas réagi dans le bain ne dépasse environ 5 ppm.