JPS63283700A - Apparatus and method for neutralizing oxidizing agent in washing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates generally to the neutralization of oxidizing agents in laundry solutions, and more particularly to reducing the concentration of oxidizing and reducing agents during the final rinse of a laundry cycle. The present invention relates to apparatus and methods for automatic monitoring and precise control.

BACKGROUND OF THE INVENTION The use of oxidizing agents, such as bleaching agents and bleaching agents, to handle laundry during laundry procedures or cycles is commonplace today in domestic and commercial laundry operations. The most commonly used strong bleaches are sodium hypochlorite (chlorine bleach) and potassium permanganate.

Chlorine bleach is more common than many other types of bleach, and hydrogen peroxide is even more effective at removing some colorants and is a better cleaning agent because its cost is low enough. .

[Problem to be Solved by the Invention] The disadvantage of using bleaching agents such as chlorine bleach is that if the bleach is abused or if the bleach is not thoroughly rinsed from the fabric, it can cause damage to the fabric. It means that it occurs. Chlorine bleach is an example of an oxidizing agent that acts to reduce colorants by liberating "free" oxygen. If residual chlorine remains in the fabric as a result of a wash cycle, the oxygen generators in bleach continue to damage the fabric's fibers by converting it to oxidized cellulose, known as oxycellulose. As a result, this fabric becomes punctured or tears at weak points. Since the tension in the fabric is reduced, the service life of the fabric is shortened (and the fabric tears more easily). The damage caused is irreparable. even enough to damage the fabric.

For brevity, the following discussion only addresses chlorine bleach oxidizers, but the general issues and principles discussed regarding chlorine bleach oxidizers are equally applicable to other types of decolorizers and oxidizers as well. It will be understood that each of them is supplied equally with the neutralizing or reducing agent.

The problem of chlorination and neutralization in the wash cycle is less evident in conventional tub-type or batch washers, where the entire wash tub is typically filled and drained after each portion of the wash cycle. The chances of thoroughly rinsing the chlorine bleaching additive from the laundry in such "traditional" equipment are good enough. Furthermore, such "traditional" washing machines typically use separate wash and bleach cycles in which bleach is added to a relatively low pH solution, thereby eliminating relatively complete removal of chlorine from the fabric during the rinse cycle. Enhances rinsing effect. However, to the extent that chlorine additives are not completely removed or neutralized in such conventional laundry systems, the principles of the present invention are also provided therewith.

For a more detailed explanation of this principle, including consideration of oxidizing agents and their respective reducing/neutralizing agents, see the literature, including a discussion of the meaning of "bleaching,""activechlorine" and "available chlorine." White, George, Handboo
k of' Chlorinatlon, 1972.
pp, LH-190) is hereby incorporated by reference.

The problem of chlorine removal from laundry and/or its neutralization is that normal bleaching levels typically range from a normal level of 1/4 of 1% per 100 loads of laundry for effective colorant removal. This is even more evident in commercial laundry applications, which are on the rise. This problem is further magnified in commercial applications where continuous batch or tunnel washers are used. Tunnel washers are increasingly common in industrial washing machine applications, especially for applications such as processing hospitals, hotels, and other linen supply workplaces where large quantities of laundry must be washed daily. Generally, tunnel washing machines include a series of individual modules or compartments that correspond to different stages in the wash type or cycle. The fabrics to be laundered are automatically transported through successive water filling, washing, rinsing, conditioning and dewatering processes 6 as they progress from the input to the output of the tunnel washing machine.

Tunnel washing technology significantly reduces labor because once the laundry is sorted into batches that are successively loaded into the input hopper of the tunnel washing machine, they are not handled again until they have been conditioned or dried.

The practical costs associated with tunnel washers are lower than conventional laundry systems, and process time is significantly reduced as there is no delay time for filling the machine with water or waiting time for drying or spin operations.

Tunnel washing machines are basically constructed in either double drum (modular) or single drum (monoshell) format. Modular washing machines have adjacent but separately defined individual compartment portions that perform different functions.

This batch of laundry moves progressively through the compartments that form the internal cylinder of the machine, rinsing the batch of laundry on the centerline of the washer and sliding them through the central connection between the modules. are continuously transferred from module to module upon completion of the processing steps.

Single-drum tunnel washing machines typically employ the Archimedean screw principle, which uses a threaded member extending lengthwise through the drum to move a batch of laundry forward through the drum, defining the various stages of washing. use Typically each turn or segment of the helical screw defines a laundry compartment, and the transfer action accomplishes moving the laundry from one compartment to the next as the cylinder or screw makes one complete revolution. Tunnel washing devices are well known in the art and a complete description of such devices will not be provided here. The following is provided merely as a brief introduction to the advantages achieved by the use of tunnel washers in commercial laundry applications, as well as the problems encountered by such laundry systems in neutralizing excessive oxidants in the laundry treated thereby. This is given as a prelude to.

Typically, tunnel washers require approximately three times the amount of bleach to efficiently handle a load of laundry than a conventional tub design washer. The reason for the need for excessive bleach is that effective bleach is typically added during the wash cycle in a tunnel washer, and the presence of detergent and alkali does not sufficiently raise the pH level of the solution in the laundry room. It is to rise. Even if this bleach is added during the rinse cycle in a tunnel laundry system,
A sufficient amount of bleach is required due to the relatively low temperature involved at that stage and the relatively high water flow rate in the rinse zone. Therefore, it is quite impractical to completely remove excess chlorine from laundry in commercial laundry equipment such as tunnel washers, so this industry typically uses wash cycles to neutralize excess chlorine. Neutralizing agents are typically added during the final "rinsing" step.

When chlorine bleach is used, the neutralizer is commonly referred to as the dechlorinator product. Common dechlorinating agents are thiosulfates.

In the commercial laundry industry, it has been common to inject neutralizing agents into the final rinse module or compartment of a tunnel washer, which typically follows the cleaning process of the laundry type. This final cycle step is typically used to recondition the laundry to add back to the fabric conditioning chemicals such as fabric softeners and sours that were previously removed from the laundry. Typically, dechlorinators or neutralizing agents added to the final rinse step to neutralize excess chlorine in the fabric were added on a "timed feed" basis. That is, a fixed, predetermined amount of dechlorinator is typically added to each load of laundry during the final rinse cycle, regardless of the actual amount of residual chlorine in the load requiring neutralization. Ta. The amount of dechlorinator added to the rinse sometimes varied from cycle to cycle depending on the type of fabric in the rinse compartment, for example, which had a history of maintaining more or less chlorine. However, in general, the "timed feed" technique for adding dechlorinating neutralizer to the rinse container is the laundry equipment operator's or manufacturer's best guess as to how much neutralizer should be added. It is a highly uncertain technology based on

In fact, the actual amount of oxidizing agent that requires neutralization in the rinse compartment of a washing machine varies widely. The residual chlorine level in the rinse solution is determined by the amount of chlorine added during the wash cycle, the type of fabric, the amount of soil, temperature, pH level, detergent and alkaline levels, and how long the laundry is soaked in the bleach solution. , the amount of ions in the water, and the type of decolorizer/oxidizer solution used. clearly,
Currently practiced methods, such as injecting a fixed amount of neutralizing/dechlorinating agent into the rinse solution on a timely feed basis, do not significantly solve the problem as they neutralize the oxidizing agent therein. Injecting too little neutralizer will result in extensive irreparable damage to the fabric due to excessive residual chlorine in the fabric, as discussed above. On the other hand, injecting too much into the solution solves the problem of harmful residual chlorine, but it is a wasteful and relatively expensive dechlorination product, and the unwanted buildup of salts in the fabric darkens the fabric when ironed. This results in increased residue, reduces the life of the fabric, and gives the fabric a rough feel if not further treated with a fabric softener. Through the use of timed feed techniques, it is not uncommon to find residual salts remaining in fabrics in excess of 20 to 30 ppm.

The present invention provides an automatic method and apparatus for precisely neutralizing only the total oxidants actually present in the wash solution during any given wash cycle, thereby remaining in the fabric being washed. Addressing these problems associated with today's technology for neutralizing excessive oxidizing agents, it also prevents over-injection of neutralizing and reducing agents into the wash cycle, which can lead to fabric damage.

SUMMARY OF THE INVENTION The present invention provides an automated method and means for neutralizing excess oxidizing agents, such as bleaching chemical additives, in wash solutions during the final rinse step of a wash system. provide. The redox potential of the neutralized solution is constantly monitored in a closed loop system. The monitored redox potential signal is compared to a signal representative of the desired neutralization level of the solution and, depending on the compared signal, n1 is compared until the determined redox potential signal indicates neutralization of the oxidant in the solution. Allows neutralizing agent to be injected into the solution. In a preferred application of the invention, the neutralizer injection is to allow for a final injection measurement of the neutralizer that is completely dispersed and reactivated in solution before additional neutralizer injections are allowed. It is implemented on a periodic pulse basis with a duty cycle of sufficiently long pulse intervals. Injection of a neutralizing reducing agent into the solution preferably increases the concentration of reducing and oxidizing agents in the solution once neutralization of the oxidizing agent present in the solution is achieved.
The injection of additional neutralizing reductant is precisely controlled to be prevented so as to maintain ppm.

Thus, the present invention effectively adjusts the oxidizing and reducing agents to virtually remove 100% of their residue in the fabric following the treatment cycle. The present invention also reduces the cost of the neutralization process by eliminating the overfilling of expensive reducing agents into the bath and extends the useful life of the fabric by reducing residual oxidizing agents and salts therein.

According to one aspect of the invention: (a) determining the amount of neutralized oxidizing agent present in the washing tub at a particular moment and providing a detection signal accordingly; and (b) reducing the oxidizing agent. (c) injecting a measured amount of neutralizing agent of a type that can be injected into the bath in response to a detection signal; A method is provided for neutralizing an oxidizing agent in a laundry tub, comprising terminating the injection of neutralizing agent into the tub when:

According to a further development of the invention, the neutralization treatment is further carried out when the amount of neutralized oxidizing agent remaining in the bath is less than or equal to 29I)I, more preferably less than or equal to 1 ppm, or most preferably Only after the neutralizer has comprehensively neutralized the oxidant in the bath is the neutralizer injection process terminated. According to yet another aspect of the invention, the injection process further prevents undesirable over-injection of neutralizing agent above a level of 20 ppm of unreactivated neutralizing agent, more preferably 1 ppm of unreacted neutralizing agent. The injection of neutralizing agent into the tank is controlled to prevent over-injection above the level of . In accordance with the preferred method of injection of neutralizing agent into the bath, such injection is selectively and periodically activated depending on the real-time measured amount of oxidizing agent present in the bath at a particular moment; is implemented on the basis of intermittent periodic pulses.

According to another aspect of the invention, (a) detecting the amount of oxidizing agent to be neutralized in the washing tub;
responsively providing a signal indicative of the amount of oxidant in the bath; (b) selecting a maximum allowable threshold level for the oxidant in the bath and generating a threshold signal indicative thereof; comparing the signal with a threshold signal and generating a comparison signal accordingly; (d) depending on the comparison signal, injecting into the bath a neutralizing agent of a suitable type to reduce the oxide If; ) a method for automatically neutralizing oxidant in a selected tank, comprising terminating the addition of neutralizing agent to the tank when the unneutralized oxidant remaining in the tank is below a maximum allowable threshold level; is provided.

In accordance with yet another aspect of the invention, (a) placing the fabric in a selective tank; (b) immersing the fabric in a bleaching agent containing an oxidizing agent; (d) soaking the fabric in a neutralizing agent of a suitable type to react with the residual oxidizing agent; <e> the amount of remaining unneutralized oxidizing agent in the fabric is determined; Approximately no more than about 5 ppm, more preferably 1 ppm
(f) react with the remaining amount of oxidizing agent by the neutralizing agent until the amount of neutralizing agent is less than or equal to about 5 ppm, preferably less than about 1 ppm; A method of laundering textiles is provided which includes the step of preventing over-exposure of the textiles.

According to yet another aspect of the invention, there is provided a fabric laundered according to the laundering method described above.

According to yet another aspect of the invention, there is provided an apparatus for carrying out the above-described method for neutralizing oxidizing agents in a laundry tub. Such a device for automatically neutralizing oxidizing agents in a washing tub comprises: (a) determining the amount of neutralized oxidizing agent present in the washing tub at a particular moment and detecting it accordingly; (b) means for providing a signal that is
(c) means connected and operative to receive the detected signal for injecting a measured amount of neutralizing agent of a type capable of reducing the oxidizing agent into the bath in response to the detected signal; Injecting neutralizing agent into the tank when the detected signal indicates that the amount of neutralized oxidant remaining in the tank is about 20 ppm or less, preferably about 5 ppm or less, most preferably 1 ppm or less. and means connected and operative to receive the detected signal for terminating.

According to yet another aspect of the present invention, an apparatus as described above is provided, which also provides for the introduction of an excess of non-reduced neutralizer into the cypress, more preferably in the bath, before more than 20 ppm of neutralizing agent is introduced into the cypress. A means is included for terminating the injection of neutralizing agent into the bath before excess non-reducing neutralizing agent exceeds 5 ppm, and most preferably before they exceed 1 ppm.

According to yet another aspect of the invention: (a) for detecting the amount of neutralized oxidant present in the bath and correspondingly providing a detected signal indicative of the amount of oxidant in the bath; (b) means for establishing and generating a threshold signal indicative of a maximum allowable threshold level for an oxidant in the layer; and (c) comparing the detected signal and the threshold signal and responding accordingly. (d) comparison means connected and operative to receive the detected signal and the threshold signal for generating a comparison signal; (d) for injecting a neutralizing agent into the bath in response to the comparison signal;
means connected and operative to receive the comparison signal and connected to a source of neutralizing agent of a type suitable for reducing the oxidizing agent; (e) any unneutralized material remaining in the bath; and a control means connected and operative to the injection means for terminating the addition of neutralizing agent to the tub when the oxidizing agent is below a maximum allowable threshold level established therefor. A device is provided for neutralizing the agent.

The invention relates to a particular type of washing machine (i.e. tunnel washing machine).
Although described with respect to a washing machine, it will be understood that the invention is not limited to use with any particular type of washing machine. The practical economy of constructing such an apparatus embodying the invention demonstrates that the invention may be used in commercial laundry applications such as tunnel washers and high-volume laundry applications, while also demonstrating the principles of the invention. is suitable for all laundry applications where it is desirable to minimize the amount of oxidizing agent in the fabric being laundered and to minimize the amount of residual neutralizing agent introduced into the fabric during the neutralization process. do. Furthermore, although the invention is described with respect to particular types of circuits and individual components thereof, the invention is not limited to the use of such circuits or the disclosed components thereof. Such circuits and components are described merely to illustrate one possible embodiment of control circuitry that may be used to implement the principles of the present invention.

These and various other advantages and features which characterize the invention are pointed out with particularity in the claims annexed to and forming a part hereof. However, for a better understanding of the invention, its advantages and the objects to be obtained by its use, reference should be made to the drawings and accompanying description which form a further part of this, in which preferred embodiments of the invention are shown. Examples are explained.

EXAMPLE Although the present invention can be used to neutralize the contents of the container of any type of washing machine, its preferred use is in commercial washing machines, particularly those typically referred to as batch washing machine systems. and those associated with continuous batch washing machine systems called "tunnel washers." A preferred embodiment of the invention will be described with respect to its application with a tunnel washer system. A typical continuous batch tunnel washer system is shown schematically in FIG. Such tunnel washing machines are well known in the art and the details of their construction are not described here. Rather, a simple functional description of a tunnel laundry system should be sufficient to explain how the present invention can be used with its attendant advantages in commercial laundry applications. A typical such washer system is a dual shell tunnel washer, such as the model C8M label manufactured by Pellerin Mllner of Kenner, Louisiana.

Referring to FIG. 1, a tunnel washer, generally designated IO, includes ten separate laundry processing modules or containers, designated 11-20. Each module is associated with a portion of the total wash cycle. Although ten such modules and wash functions are shown in Figure 1, the number of wash cycles and steps in the modules used can vary widely depending on the specific washing requirements of the equipment. One thing should be understood. In the illustrated embodiment, the various modules and washing functions are flush 11. Dehydration (break
) 12, Dehydration (break) 13, Soapy water (5u
ds) 14. Flush 15. Bleach (b
leach) 1B, rinse 17.
18.19, and conditioning
ionlng) 20. In the preferred embodiment, each of the modules 11-20 has a unique association with performing its associated "function" on the laundry batches (badges) contained in that module. Each of the modules 11-20 is operatively connected to the other - such that the laundry load is moved sequentially through the tunnel washer IO throughout the wash cycle, i.e. from the first module 11 to the last module 20. They are aligned and connected vertically. Each module is sized to contain a load of laundry designated as "L" in FIG. The laundry mass is introduced into the input popper 10a of the washing machine IO and is collected from the washing machine outlet 10b, where the laundry is typically conveyed to extraction and drying equipment (not shown). Means (not shown), typically in the form of a large spiral extending vertically from the input end 10a to the output end 10b' of the washing machine 10, simultaneously transport laundry from one module to an adjacent module during a wash cycle. Continuously move the blocks. - The length of time that the bulk laundry remains in a particular module varies depending on the tunnel washer design and typically depends on the chemical addition method and the type and amount of laundry being processed. It takes 3 to 10 minutes.

The various laundry process steps carried out in modules 11-20 of the tunnel washing machine are controlled by a microprocessor or computer provided for proper injection and extraction of water and additives including detergents, bleaches, fabric softeners, etc. A load of laundry (not shown) is automatically passed through a tunnel washer. The first control circuitry also controls the reuse of solutions therein between adjacent modules and the reuse of water recovered, for example from extraction or drying processes. The first control circuitry is also used to properly time the movement of the laundry "L" mass between the modules at the completion of the cycle, typically for arms of laundry of different quality. programming the discrimination between arms of different quality laundry that are successively fed into adjacent modules of the washing machine to avoid mixing between them (e.g. when a “white” fabric follows a “colored” fabric) be done. The first control circuitry is also configured to determine whether the modules are filled quickly or slowly, and to determine the mode of drainage of each module, for the particular load of laundry to be processed thereby. used to determine the type and nature of chemicals added to each module.

Referring to FIG. 1, the various means for filling each module container of washing machine 10 are schematically illustrated near the top of each module by arrows associated with the following symbols: 'CA' indicates chemical additives; 'FF' indicates fast fill; 'SF' indicates slow fill. Drainage of the module container is schematically indicated by an arrow extending from its bottom with the following symbols: 'FD
” indicates rapid draining. “SD” indicates slow draining. “TD” indicates moving draining. Each module with a moving drain outlet includes a moving conduit that flows back into the immediately preceding adjacent module. , "T" which shows the moving entrance in Figure 1
with an entrance to it designated “I”. “Tl/TD
"Each of the conduit devices includes a pair of valves whose operation is controlled by washer first control circuitry (not shown) to direct solution backflow between adjacent modules as dictated by wash requirements." (indicated by "V" in FIG. 1).The tunnel washer 10 of the described embodiment also has a "reuse water tank" 22 that connects the washer 10 to the washer 10.
The input hopper 10a includes a pump "P" for pumping through a filter 23 to a filling inlet (designated "F").

Water recovered from various operations such as extraction and drying stages provides an input water source for tank 22. −
A lump of laundry "L" is shown in FIG.
It is shown as awaiting introduction to 0. Conveyor 24 is also under control of the first control circuitry of washing machine 10.

It will be appreciated by those skilled in the art that the tunnel washer described above is merely illustrative of the many possible variant forms of such continuous batch washing systems found today in the art and elsewhere with a broad description of such systems. It will be understood.

The present invention provides a method for removing excess oxidizing agents, such as detergent chemical additives, from laundry solutions during the final rinse step or process of a wash cycle, and thereby from the laundry being processed at that step. Provides an automated method and apparatus for removing.

The present invention not only automatically removes excess oxidizing agents from the laundry, but also protects against the addition of excessive neutralizing chemicals, which also increases the cost of the neutralization process. It also has a negative effect on the laundry. Although the principles of the present invention are adapted to any process step in the wash cycle, they may be applied immediately prior to reconditioning of the laundry by the addition of additives such as glue, sours, etc. during the wash cycle. It is most practically adapted for the "final rinse" stage. In the preferred embodiment illustrated in FIG. 1, the neutralizing additive fed to the rinse module 19 is fed through an inlet designated as "NA" (indicating neutralizing additive). Neutralizing additive is supplied from a suitable neutralizing agent source 26 and pumped by pump 27 to “NA”
Sent to Inputro. The pump may be of any shape well known in the art which is suitable when energized to expel a known amount of liquid pumped to its outlet per given pumping time. It's fine to use one. In a preferred embodiment, the pump is, for example, manufactured by Ecolab, the same applicant (of the periStaltlc type, such as the DRYMASTER Model P pump). This pump is controlled by an automatic neutralizer control circuit, described in more detail below and generally designated at 30, and receives an input signal by a signal path 32 located in the rinse module 19 and designated at 34 in FIG. received from a pair of sensor probes. Control signals from the automatic neutralizer control circuit 30 to the pump 27 are provided by a signal path indicated at 36.

For convenience, the invention will be described in terms of its applicability in neutralizing the oxidizing agent "chlorine", where the chlorine is neutralized by a suitable "dechlorinator" additive. The present invention is not limited to the use of chlorine and dechlorinators, or to the use of automatic neutralizer control circuit 30 or other specific components described with respect to the particular detection probe 34 used herein. It will be understood by those skilled in the art that there are no limitations. Those skilled in the art will readily recognize other components and circuits that may equally be used within the scope of the invention.

Referring to FIG. 2, automatic neutralizer control circuit 30 is illustrated in a functional block diagram. As used herein, the term "signal path" is used to refer to the "course" traversed by a signal between functional blocks of a circuit. Such a signal path actually consists of one or more actual including conductors, connectors, etc. Due to the continuity of the symbols, several conductors are illustrated in the schematic diagrams when forming a signal path, and the conductors bear the same reference numerals as the signal path, and their individual Further, in the following description of electrical components and circuitry, although not specifically illustrated in the figures, each of the electrical components properly operatively energizes each circuit. It will be appreciated that the circuit must be properly connected to the appropriate power and ground and bias supplies.

Referring to FIG. 2, an automatic neutralizer control circuit 30 is configured to neutralize oxidizers in the solution 15 of a container, such as the solution-carrying laundry container 19', as it appears during the "rinse" portion of the wash cycle. The sensor probe member 34 is described as it typically appears functionally when connected.
It is mounted and operative with respect to the container 19' to detect the electrical properties of the oxidizing agent in the solution 15 to be neutralized.

In a preferred embodiment, sensor probe member 34 includes a pair of probes 34A and 3 as illustrated in FIG.
Contains 4B. Probe 34A is, in the preferred embodiment, a platinum electrode suitable for measuring the "redox potential" of solution 15, and probe 34B constitutes a reference electrode. Redox potential electrode 34A (hereinafter referred to as “O, R, P,
The electrode (abbreviated as "electrode") determines the level of oxidizing agent present in solution 15. In the preferred embodiment, chlorine is the oxidizing agent. The construction and use of such electrodes are well known in the art. are provided and will not be explained in detail here.

Although platinum O, R, P electrodes are disclosed with respect to the preferred embodiment, other suitable inert metals as well as other types of sensors for determining the level of oxidizing agent present in solution 15 may be used. Probe materials are equally used.

Signal output from electrodes 34A and 34B is carried out through signal flow path 32.
A and 32B respectively to amplifier and signal conditioning functional block 37. The reference electrode 34B is as follows:
It is connected to a reference potential bus, referred to in the drawings as 00, to form a reference potential. The signal output from amplifier and signal conditioning functional block 37 is provided by signal path 38 to one signal input 40a of comparator circuitry 40. The output signal from the amplifier and signal conditioning functional block 37 is generally 39
to an appropriate display device as indicated by . A second input signal is provided by a signal path 41 from a functional block shown as a setpoint adjustment block 42 to a second input terminal 40b of the comparator 40. The output signal from comparator 40 is provided by signal path 43 to adjustable pulse control function block 44 . The signal output from adjustable pulse control block 44 is carried by signal path 36 to energize pump 27. Pump 27 supplies neutralizing additive (
NA) Pumping neutralizing agent ("dechlorinating agent" in the preferred embodiment) from such a source 26 of neutralizing agent delivered to the inlet.

Amplifier and signal conditioning functional block 37 includes 0, R, P,
The detection signal provided by electrode 34A is received and provides a clear indication to comparator circuitry 40. Amplifier and signal conditioning functional block 37 is shown in more detail in FIG. With reference thereto, reference electrode 84B is described as being operatively connected to reference potential bus 100.

The detection signal output from the 0, R, P electrode 34A is transmitted by the signal path 32A to the non-inverting input terminal of the operational amplifier 37.1. Amplifier 37.1 has voltages of (+V) and (-
V) to the positive and negative supply potentials indicated by V). Although not shown in the drawings, it is understood that the positive and negative supply potentials (+■) and (-V) each represent a regulated voltage supply bus suitably connected to a suitable supply voltage source, respectively. right. In the preferred embodiment, the supply potentials (10 volts) and (-■) are (+12 volts) and (
-12 volts).

The inverting input terminal of amplifier 37.1 is connected by resistor 37.2 to the wiper arm of variable resistor 37.3.

Each end of variable resistor 37.3 is connected between 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.

The output terminal of the amplifier 37.1 is connected to the second operational amplifier 37.6.
connected directly to the non-inverting input terminal of the Amplifier 37.
6 is operatively connected to the positive and negative supply voltages (+V) and (-V), respectively, and has a non-inverting input terminal connected to the reference potential bus 100 by a resistor 37.5. The variable resistor 37.7 is connected in series with a fixed resistor 37.8 in the feed pack loop between the signal output terminal and the inverting input terminal of the amplifier 37.6. A feedback capacitor 37.9 is also connected in parallel with resistors 37.7 and 37.8 in the feedback loop of amplifier 37.6. The output of amplifier 37.6 is the amplifier and signal conditioning functional block 37 signal output and is connected directly to signal flow path 38.

In the preferred embodiment, amplifiers 37.1 and 37.
6 is a TL 084 type operational amplifier. With all the components described herein with respect to the description of embodiments of the invention, it is not intended that the invention be limited in any way by the particular types of circuit components described herein. It will be understood that it is not. Rather, such circuit components are merely typical and specific circuit components found to function satisfactorily in the circuit configurations described.

Amplifiers 37.1 and 37.6 function as unity gain amplifiers that condition and stabilize the detection signal (in the low millivolt range) received from O, R, P, electrode 34A.

Variable resistor 37.3 zeros out any imbalance in sensor electrode 34. Amplifier 37.8 is configured to eliminate signal discrepancies appearing in the sensed signal as a result of agitation, bubbles, etc. in solution 15. A damping effect is provided to the detection signal by the capacitor 37.9, which operates in a similar manner.It is also noted that the signal flow path leading from the sensor electrode 34 to the amplifier and signal conditioning circuit 37 is shielded to remove external noise and interference signals. It should be.

Referring to FIG. 4, the signal output from amplifier and signal conditioning circuit 37 is routed by signal path 38 to comparator circuitry 40.
supplied to Signal path 38 is connected by resistor 40.1 to the inverting input terminal of operational amplifier 40.2. A non-inverting input terminal of amplifier 40.2 is connected to reference potential bus 100. A resistor 40.3 and a capacitor 40.4 are connected in parallel in a feedback loop between the signal output and the inverting input terminal of the amplifier 40.2. Amplifier 40.
The two signal output and inverting input terminals also form input terminals 40b1 and 40b2 for connection to receive signals from signal flow path 41, which will be described in more detail below. In the preferred embodiment, amplifier 40.2 is TL
It is a 082 type operational amplifier.

The output signal from amplifier 40.2 is fed directly to the inverting input terminal of operational amplifier 40.5. In the preferred embodiment, amplifier 40.5 is an LM 311 oven collector output comparison amplifier. The positive bias terminal of amplifier 40.5 is connected to reference potential bus 100 and its negative bias terminal is connected to a negative bias supply potential (-V). The emitter of the output transistor of amplifier 40.5 is also connected to a negative bias supply potential (-■). Resistor 4
0.6 is connected between the signal output of amplifier 40.5 and the non-inverting input terminal.

The non-inverting input terminal of the amplifier 40.5 is also connected to the inverting input terminal of a second oven collector output comparator amplifier 40.7 for receiving the signal from the signal flow path 41 from the setpoint adjustment function block 42. Third input terminal 4
It is equipped with 0b3. In the preferred embodiment, the amplifier 40.7 is also an LM 311 type operational amplifier, which has its positive bias terminal connected to the reference potential bus 100 and its output transistor connected to the negative bias supply potential (-V). has a negative bias terminal and an emitter. The signal output of amplifier 40.5 is connected by a resistor 40.8 to the non-inverting input terminal of amplifier 40.7. The non-inverting input terminal of amplifier 40.7 is also connected to reference potential bus 100 by resistor 40.9 and capacitor 40.
．． Connected by LO to a negative bias supply potential (-V). The signal output from amplifier 40.7 is provided directly to signal path 43 for providing an input reset signal to adjustable control circuitry 44, as described in more detail below.

The setpoint adjustment function block 42 (see FIGS. 2 and 4) is connected to the amplifier 40.2° 40 of the comparator network 40.
．． 5 and 40.7 (as explained below). Referring to FIG. 4, a plurality of resistors 42.1-42.8 connect resistor 40 in the feedback loop of amplifier 40.2 by conductors 41A and 41B to selectively vary the gain of amplifier 40.2. .3 and 40.4 capacitors are switchably connected in parallel. Each of the resistors 42.1-42.8 is in series with a switch 42.11-42.18 that can be selectively opened or closed to connect the desired resistors in parallel in the feedback loop of the amplifier 40.2. are connected to each. Switches 42.11-42.18, in the preferred embodiment, include thumb-wheel switches operatively connected to provide a two-digit decimal value coded in binary; 42.1-42.4 and their associated switches 42.11-42.14 are associated with the first digit of the number, resistors 42.5-42.8 and their associated switches 42.15- 42.18 is the number “1”
The binary code for the various resistor/switch pairs is shown to the right of each switch in FIG. 4. In the preferred embodiment, resistor 4
The resistance values for 2.1-42.8 are R42,1-1 megohm, R42,2-510 kohm, R42,3
-240k ohm, R42, 4-120k ohm,
R42,5-62 kohm, R42,8-30 kohm, R42,7-15 kohm, and R42,8
-6.8 kilohms.

A second portion of setpoint adjustment circuitry 42 applies a fixed bias potential to input terminal 4 in the preferred embodiment.
Amplifier 40.5 by conductor 41c via 0b3
includes a resistor/capacitor network feeding the non-inverting input terminal of the circuit. Capacitor 42.20 is connected to resistor 42.21 between the negative bias supply potential (-■) and conductor 41c.
are connected in parallel. A pair of resistors 42.22 and 4
2.23 also includes the reference potential bus 100 and the conductor 41c.
connected in parallel between In a preferred embodiment,
As will be explained in more detail below, the described pair of parallel circuits provides a constant 5 volt reference signal to the non-inverting input terminal of amplifier 40.5.

The signal output of the comparator 40 is transmitted by a signal path 43 to a "reset" input terminal of a timer circuit 44.1 of an adjustable pulse control network 44. In the preferred embodiment, timer 44.1 has its VCC input terminal connected to reference potential bus 100 and its reference or (GND) terminal connected to a negative bias supply potential (-V). It is a 555 type timer.

This timer also has a "threshold" terminal designated as (THD), a "trigger" terminal designated as (TRIG),
and CDl5CHG). Threshold (THD) and trigger (TRIG)
The input terminals are connected in common and connected to a negative bias potential (-■) by a capacitor 44.2. (THD)
and (TRIG) terminals are also connected to reference potential bus 100 by variable resistor 44.3 and fixed resistor 44.4. The movable wiper of variable resistor 44.3 is connected to the discharge (DISCHG) terminal of timer 44.1 and is also connected to (THD) and (TR) by diode 44.5.
IG) terminal.

The signal output of timer 44.1 is connected to n by resistor 44.6.
pn ) connected to the base of transistor 44.7.

The emitter of transistor 44.7 is at a negative bias potential (
-■), the collector of which is connected to the cathode of a light-emitting diode 44.8. Diode 44.
The anode of 8 is connected to the stationary contact of switch 44.9. The movable wiper of switch 44.9 moves between a pair of contacts designated (xl) and (xl) in FIG. Contact (xl) of switch 44.9 is resistor 4
4.10 to an unregulated power source, generally designated 'PS' in FIG. 4, and directly to the first input terminal of a triac (trlac) drive network 44.11. The second contact (xl) of 44.9 is connected to the second input terminal of the drive network 44.11.In the preferred embodiment, the drive network 4
4. The IL is a MOC3030 type optically coupled to the triac drive circuitry. When the movable wiper of the switch 44.9 is in the position where it contacts the contact (xl), the switch disables the optical coupling drive network 44.11. When the movable wiper is positioned in contact with the contact (xl), optical coupling is enabled for operation based on a further state of transistor 44.7, as explained below. The drive network 44.11 connects the first of the triacs 44.13 by means of a resistor 44.12.
, which closes the enable supply path for pump 27 by conductor 38A of signal path 36.

The second output terminal of the triac drive network 44.11 is connected to the gate terminal of the triac 44.13 and is also connected by a resistor 44.14 to the gate terminal of the triac 44.13.
a signal flow path 3 leading to the second power terminal of the pump 27 and to the pump 27;
6 to the second conductor 36B. A capacitor 44.15 is connected between the power terminals of the triac 44.13, and a resistor 44.1 is connected between the conductors 36A and 3[iB].
8 and filters the triac generated signal.

The circuit described above allows accurate automatic neutralization of the oxidizing agent in the washing tub with virtually zero residual neutralizing agent remaining in the tub after the neutralization process. As mentioned above, the amplifier and signal conditioning circuitry 37 provides an input probe 34 that accurately reflects the measured redox potential level of the solution 15 and takes into account perturbations in the solution caused by agitation, bubbles, etc. Provides a clean detection signal from

For any given pH level of the solution 15 measured, the known correlation between the measured redox potential value and the actual amount of oxidizing agent (i.e., chlorine in the preferred embodiment) in the solution. is present, which can be directly converted into units of parts per million (or "ppa+,") of the amount of oxidant in the bath. For example, a given pH for tank 15
At level IO, a 0.1 millivolt change in the redox potential level measured by probe 34 represents a change in the level of oxidant in the bath at 1 ppm. Using this correlation factor, a change in the redox potential level measured with the 0.5 millivolt probe 34 represents a change in the 5 ppm oxidant level in the bath. p of the oxidant in the tank
The measured redox potential when correlated to p in the bath
Varies as a function of H level. For example, pH level 1
In contrast to the above example where 0 was assumed for tank 15, if the pH level of tank 15 were changed to a different level, such as pH 9, the correlation factor of such measured redox potential would be similar to There is a corresponding change in the redox potential level measured by probe 34 to the actual level of oxidant present in the bath. For example, at a bath pH of 9, a 1.0 millivolt change in the redox potential level determined by probe 34 represents a change in the level of oxidant in the bath by 1 ppm (for a pH level of 10, 1 (as opposed to the 0.1 millivolt per ppm example). Typical pH values for the wash solution in the final rinse stage of a tunnel washer are between 9 and 11. Typical levels of excess chlorine found in such baths prior to neutralization are 10 to 50 ppm+.

m of oxidant in the bath for any given pH value (
The measured redox potential values correlated with ppm) are determined experimentally. For the embodiment illustrated in the figures, the values of the components in comparator circuitry 4G and setpoint adjustment circuitry 42 are compared from batch to batch such that the pH of the solution in the final rinse module is such that the solution is neutralized. It was selected for use with tunnel washing equipment where the pH level is approximately 9 at a constant pH level. Therefore, setpoint adjustment selections are made (as explained below) for the desired percentage of neutralization in a given system, and such settings are used to ensure that the washer is No need for day-to-day or batch-to-batch changes when running cycles. However, for systems where the pl (level) of the solution to be neutralized (15) is constantly changing from one selection cycle to the next, it is necessary to It is desirable to include a pH monitoring feature to provide real-time correlation adjustments to the comparator circuitry 40 circuitry and setpoint adjustment circuitry 42 to reflect the correlation changes required by the value. The interrelated functions can be easily implemented by hard-wired circuitry or by microprocessor-controlled circuitry. To facilitate this explanation, the following description assumes that a constant pH value for solution 15 is neutralized. Assume that

Given a redox potential value for a tub in the "neutralized" state, the gain of amplifier 40.2 is controlled by the thumbwheel switches 42.11-42.18 and their associated resistors 42.1- Comparator amplifier 40.5 by 42.8
and 40.7 are selected to provide the desired output operating level from amplifier 40.2 which is compared against a reference signal provided to amplifier 40.2 and 40.7. The gain of amplifier 40.2 is such that its output voltage in the "neutralization" redox potential measurement of the bath is
is set equal to the reference voltage level supplied to c. In a preferred application of the control circuitry to the neutralization of oxidants in the final rinse module of a tunnel washer (as illustrated in the figure), at an operating pH level of 9 (which is typical for solutions in the rinse module) It was determined that the measured redox potential of approximately 400 mv was equal to the desired zero ppm in bath 15.

Therefore, referring to FIG. 4, the output signal from amplifier 40.2 is reduced to such zero pp
11 level should be equal to the reference signal value supplied to comparator amplifiers 40.5 and 40.7. In the preferred embodiment, a constant reference voltage level of 5 volts (appearing on conductor 41c) is connected to comparator amplifiers 40.5 and 40.5.
was chosen as the optimal operating level for 7. Therefore,
At a redox potential level of 400 mv actually measured by probe 34, the signal output of amplifier 40.2 should be 5 volts by appropriate selection of the normal gain of amplifier 40.2 by the resistor/switching network. Any deviation from the measured "neutralization" redox potential value of 400 mv determined n1 at probe 34 represents an undesirable excess of chlorine in the solution, or conversely, an excess of dechlorinator in the solution.

The amplification level of n1 determined deviation from the 400 mV level of neutralization is the gain selection input to the setpoint adjustment network 42 by resistors 42.1-42.8 and their associated switches 42.11-42.18. Multiplied by For simplicity in setting the gain of amplifier 40.2, the values of resistors 42.1-42.8 are similar to those of switch 42.1.
Their binary code decimal representation set according to 1-42.18 was chosen to represent the redox potential of the solution multiple times the constant "neutralization" millivolt value. For example “01”
The selected reading corresponds to the “neutralization” reading of 10 mv, the reading “13” corresponds to the “neutralization” reading of 130 mv, and so on. The output voltage from amplifier 40.2 at each "neutralizing" gain setting is here 5 volts to match the selected reference voltage level of the preferred embodiment circuit configuration.

For the tunnel laundry application described herein, typical chlorine content in the solution 15 that is neutralized in the final rinse condition can typically vary between 10 and 50 ppm. It is desirable to reduce such residual chlorine content to as close to zero ppl as possible without injecting undesirable excessive or residual dechlorinators into the solution as well as chlorine. Automatic Neutralizer Control Circuit 30 adds the dechlorinating agent in a closed loop manner to the adverse rinsing solution 5 determined by operating the pump 27 on a pulsed basis, depending on the redox potential value actually measured by the probe 34. The decision as to whether injection of dechlorination agent into solution 15 is necessary is made by comparator circuitry 40.

Referring to FIG. 4, comparator amplifier 40.5 connects the measured voltage supplied by amplifier 40.2 to a fixed reference level on conductor 41c established by the reference potential circuit of setpoint adjustment circuitry 42. Continuously monitor the redox potential signal. If the measured redox potential signal exceeds the reference signal fixed at the input to the amplifier 40.5, the output signal is output to the comparator amplifier 40.5.
is applied to the non-inverting input of comparator amplifier 40.7.

The non-inverting input of the amplifier 40.7 is connected to an RC network established by a resistor 40.9 and a capacitor 40.10, the comparator amplifier 40.7 ensuring that the signal received from the amplifier 40.2 is It operates as a "delay" comparator such that a fixed reference value on conductor 41c must be exceeded for at least a consecutive predetermined time before network 40 provides a reset signal to timer 44.1. . In the preferred embodiment, the "delay" function is 2
It was set for a turn-on delay of seconds and a turn-off delay of 0.1 seconds. The turn-on delay is capacitor 40.
Established by a charging time constant of 10. The turn-off delay is determined by resistor 40.8 and the negative bias supply bus (-■)
is provided by the discharge of capacitor 40.10 through the open collector output terminal of amplifier 40.5. Therefore, if the probe 34 measures a redox potential value different from the "neutralization" value during a continuous period of 2 seconds, the comparator circuitry 40 outputs a logically "high" reset signal to the "neutralization" value of the timer circuitry 44.1. Supplied to the “Reset” input terminal.

Timer 44.1 operates to establish a duty cycle of pulses to energize pump 27 to inject a predetermined amount of dechlorination agent into the solution bath on each energized cycle of the pump. . In the preferred embodiment, timer 44.1 takes approximately 20 seconds to charge following reception of the reset signal from comparator 4o and approximately 1 second to discharge before it is reset again by comparator 40. It takes. The capacitor 44.2 of the timer 44,1 is connected to the circuit established from the reference potential bus 100 by the resistor 44.4, the left part of the resistor 44.3 (seen in FIG. 4), and the diode 44.5. charged by.

When capacitor 44.2 is charged, timer 44.1
The signal output of switches to a logic “high level” and its (
DISCHG) terminal is connected to the right part of resistor 44.3 and (
capacitor 44.2 via the D I S CHlG) terminal.
Switch to a logical ``low level'' to discharge.

“High level” from the output of timer 44.1 when the timer is triggered by charged capacitor 44.2
The output signal causes transistor 44.7 to conduct and triggers triac drive circuitry 44.11 which enables triac 44.14 during the enable pulse from timer 44.1. Following discharge of capacitor 44.2 and restoration of the output of timer 44.1 to a logical "low" level, the pump is stopped for the remainder of the time triac 44.13 is enabled. When enabled, pump 27 operates to inject a measured amount of dechlorination additive into solution bath 15. In a preferred embodiment, injection of dechlorinator into bath 15 during one pulsed period of pump operation operates to reduce the measured redox potential by approximately 2-3 millivolts. For a bath with a pH of 9, the "neutralizing" redox potential value of the bath is approximately 400 mv, and a 1.0 mv change is approximately 1p in the presence of unreduced oxidant in the bath.
It was found that there is a correlation with the change in pm.

The periodic injection process described above ensures that the redox potential difference with the desired "neutralization" level measured by probe 34 provides an appropriate signal to energize comparators 40.5 and 40.7. is repeated continuously until it is insufficient. Under such conditions, the timer 4461
is disabled along with the output drive circuit for energizing. Experiments using the automatic neutralizer control circuit 30 described above have shown that excess chlorine in the rinse solution is reduced to 1 ppm by less than 1 ppm of residual dechlorinating agent remaining in the tank 15 after neutralization.
The ability of the network to repeatedly neutralize to the following levels was demonstrated. This contrasts with the prior art "temporal feed" method of neutralization, which typically considers a residual amount of dechlorinator in the vessel of between 8 and 1591) liters, which is very suitable. It is therefore appreciated that the present invention provides an accurate method of controlling both the levels of residual neutralizing agent and oxidizing agent remaining in the bath following the neutralization process during normal laundry washing formats. Ru.

Although particular embodiments of the present invention have been described with respect to its application with a continuous tunnel washing system to neutralize oxidizers in its final rinse section, the present invention is applicable to such applications or to the specific embodiments disclosed and described herein. It will be understood by those skilled in the art that the present invention is not limited to this circuit. It will be apparent to those skilled in the art that other circuit configurations implementing the invention and other applications thereof other than those described herein may be formed within the scope of the invention. The circuit configuration described herein is merely illustrative as one embodiment incorporating and practicing the principles of the present invention. Other modifications and selections of circuit configurations as well as components herein, adaptation of the entire control circuit to the controlled reduction of the oxidizing agent in solution are known to those skilled in the art and are within the scope of the claims. It is.

[Brief explanation of drawings]

Reference is now made to the drawings, where like numbers represent similar parts in the several figures. FIG. 1 is an illustration of a continuous batch tunnel washing system, showing the automatic neutralizer control circuit of the present invention in connection therewith. FIG. 2 is a block diagram of the functional blocks of the automatic neutralizer control circuit shown in FIG. FIG. 3 is a schematic diagram of the amplifier and signal conditioning functional blocks identified in FIG. FIG. 4 is a functional block diagram of the comparator, set point adjustment and adjustable pulse control of the automatic neutralizer control circuit identified in FIG. 10...Washing machine, 11.15...Running water, 12.13
... Dehydration, 14... Soapy water, 16... Bleaching, 19
... Rinse, 19'... Container, 20... Conditioning, 22... Reusable water tank, 2B...
- Neutralizing agent source, 27... Pump, 28. 29... Supply line, 30... Automatic neutralizing agent control circuit, 34... Detection probe, 37... Signal adjustment function block, 38.
43...Signal flow path, 100...Reference bus.

Claims (41)

[Claims] (1) (a) determining the amount of neutralized oxidant present in a washing tub at a particular time and providing a detected signal accordingly; (c) said detected signal indicates that the amount of neutralizing agent remaining in the bath is injected into the vessel in response to said detected signal; A method for neutralizing an oxidizing agent in a washing tub, the method comprising: terminating the injection of the neutralizing agent into the tub when the amount is 5 ppm or less. (2) When the detected signal indicates that the amount of the oxidizing agent to be neutralized remaining in the tank is 2 ppm or less, the injection of the neutralizing agent into the tank is terminated. The method according to claim 1. 3. terminating the injection of the neutralizing agent into the tank when the detected signal indicates that there is no oxidizing agent in the tank to be neutralized. the method of. (4) A claim characterized in that the step of terminating the injection includes terminating the injection of the neutralizing agent into the tank before an excessive amount of the unreduced neutralizing agent in the tank exceeds 10 ppm. The method described in Section 1. 5. The method of claim 4, wherein the injection step is terminated before excess unreduced neutralizing agent in the bath exceeds 5 ppm. (6) When the detected signal indicates that the amount of neutralized oxidizing agent remaining in the bath is less than 1 ppm, the excess unreduced neutralizing agent in the bath is less than 2 ppm. 6. The method of claim 5, wherein the injection of the neutralizing agent into the tank is terminated before the neutralizing agent is exceeded. (7) The step of determining the amount of said oxidizing agent to be neutralized includes measuring the redox potential in said bath and calculating therefrom a predetermined redox potential value in a similar bath that does not contain said oxidizing agent. 2. The method of claim 1, further comprising the step of subtracting. 8. The method of claim 7, further comprising the step of: (8) averaging the instantaneous redox potential signals measured over a period of time. 9. The step of injecting includes intermittent periodic energization of an infusion pump connected and operative to discharge the neutralizing agent into the reservoir. Method. (10) The duty cycle of the periodic injection is 20%
10. The method according to claim 9, characterized in that: 11. The method of claim 1, wherein the bath solution has a relatively constant pH. 12. The method of claim 7, wherein each of said injections reduces the measured redox potential of said bath by about 1 to 5 ppm. (13) The method according to claim 1, wherein the oxidizing agent includes active chlorine and the neutralizing agent includes a dechlorinating agent. (14) (a) detecting the amount of the oxidizing agent to be neutralized in the tank, and reacting thereto to supply a detection signal indicating the amount of the oxidizing agent in the tank; (b) in the tank; (c) comparing the detection signal and the threshold signal and generating a comparison signal accordingly; (d) injecting a neutralizing agent of a suitable type into said vessel to reduce said oxidizing agent in response to said comparison signal; A method of automatically neutralizing an oxidizing agent in a laundry tub comprising the step of terminating the addition of neutralizing agent to the tub when the neutralizing agent is below a possible threshold level. 15. The maximum allowable threshold level of oxidant in the bath is approximately 5 ppm or less.
Method described. 16. The method of claim 15, wherein the maximum allowable threshold level of the oxidant in the bath is 2 ppm or less. (17) The accumulation of unreacted amount of the neutralizing agent in the tank is 10
15. The method of claim 14, further comprising the step of terminating the addition of the neutralizing agent to the tank before the amount exceeds ppm. 18. The method of claim 17, wherein the addition of the neutralizing agent to the tank is terminated before the accumulation of unreacted amounts of the neutralizing agent in the tank exceeds about 2 ppm. . (19) laundry in said tub such that the amount of residual oxidant remaining in said laundry after treatment is proportionately less than or equal to said maximum allowable threshold level for said oxidant in said tub; 15. The method according to claim 14, comprising the steps of: (20) The method according to claim 14, wherein the step of adding the neutralizing agent is carried out intermittently. (21) The intermittent addition of the neutralizing agent is carried out in periodic pulses, and the time intervals of successive additions of the neutralizing agent to the bath are such that the neutralizing agent is neutralized before additional neutralizing agent is added to the bath. 21. A method according to claim 20, characterized in that the oxidizing agent and previously added neutralizing agent are present long enough for complete reaction. (22) The method according to claim 14, wherein the oxidizing agent includes active chlorine, and the neutralizing agent includes a dechlorination agent. (23) (a) placing the fabric in a washing tub; (b) immersing the fabric in a bleaching agent containing an oxidizing agent; and (c) removing substantially all of the oxidizing agent from the fabric except for trace amounts. (d) soaking the fabric in a neutralizing agent of a suitable type to react with the oxidizing agent; and (e) reducing the amount of remaining unneutralized oxidizing agent in the fabric to about 5 ppm or less. (f) preventing over-soaking of the fabric in the neutralizing agent such that the neutralizing agent is retained by the fabric at 10 ppm or less; A method for washing textiles, comprising the step of: (24) The neutralizing agent maintained by the fabric is about 5 ppm.
24. A method according to claim 23, characterized in that: (25) The neutralizing agent maintained by the fabric is about 2 ppm.
24. A method according to claim 23, characterized in that: 26. The method of claim 23, wherein the step of soaking the fabric in the neutralizing agent occurs during a final rinsing step of a laundering type. (27) The method according to claim 23, wherein the oxidizing agent includes active chlorine and the neutralizing agent includes a dechlorination agent. (28) A fabric washed according to the method according to claim 23. (29) A fabric washed according to the method according to claim 24. (30) A fabric washed according to the method according to claim 25. (31) (a) means for determining the amount of neutralized oxidizing agent present in a washing tub at a particular moment and providing a detected signal accordingly; and (b) said oxidizing agent. (c) means connected and operative to receive said detection signal for injecting into the vessel in response to said detection signal a measured amount of neutralizing agent of a type capable of reducing said detection signal; is connected and operative to receive the detection signal to terminate injection of the neutralizing agent into the tank when the amount of the oxidizing agent to be neutralized remaining in the tank is less than 5 ppm. A device for automatically neutralizing an oxidizing agent in a washing tub, characterized in that it includes means for automatically neutralizing an oxidizing agent in a washing tub. (32) The amount of the neutralizing agent that has not been excessively reduced in the tank is 10
32. The apparatus of claim 31, including means connected and operative to receive the detection signal to terminate injection of the neutralizing agent into the bath before ppm is exceeded. (33) the means for terminating the injection of the neutralizing agent into the tank, wherein the detection signal indicates that the amount of the oxidizing agent to be neutralized remaining in the tank is 1 ppm or less; 33. The apparatus of claim 32, wherein the injection is terminated before excess unreduced neutralizing agent in the bath exceeds 5 ppm. (34) (a) means for detecting the amount of neutralized oxidizing agent present in the washing tub and outputting a detected signal indicative of the amount of oxidizing agent in the tub; (b) said tub. (c) comparing the detected signal and the threshold signal;
comparison means connected to receive said detected signal and said threshold signal for generating a comparison signal responsive thereto; (d) injecting said neutralizing agent into said bath in response to said comparison signal; (e) means connected to a source of neutralizing agent of a type suitable for receiving said comparison signal and reducing said oxidizing agent; control means connected to and operative in said injection means to terminate the addition of said neutralizing agent to said tub when said oxidizing agent is below said maximum permissible threshold level; equipment for neutralizing oxidizing agents. 35. The apparatus of claim 34, wherein said injection means intermittently adds said neutralizing agent to said tank. (36) said injection means determines that the time interval between successive additions of neutralizing agent to said tank is such that the previously added neutralizing agent is injected into said oxidizing agent before additional neutralizing agent is injected into said tank; 36. The apparatus of claim 35, including means for adding said neutralizing agent to said bath in periodic pulses long enough for complete reaction. 37. The apparatus of claim 34, wherein said threshold level determining means includes selection means that allows an operator to selectively vary an acceptable threshold level for said oxidant in said bath. (38) (a) detection means operable with respect to the solution to detect the redox potential of the solution and provide a detection output signal indicative of the amount of unneutralized oxidant in the solution; (b) means for establishing a threshold signal corresponding to a desired neutralization level of the oxidizing agent in the solution; (c) for comparing the detection signal and the threshold signal;
and a first state connected to the detection means and the threshold value determining means for supplying an output control signal accordingly, wherein the control signal is greater than a predetermined deviation between the detection signal and the threshold value signal; (d) a comparison means having a second state when the detection signal and the threshold signal are within the predetermined deviation; means connected to receive a signal, the means for generating the periodic energizing signal upon receipt of the control signal in the first state of the energizing signal generating means; (e) means for generating the periodic energizing signal; connected to receive the activation signal and connected to a source of neutralizing agent suitable for reducing the oxidizing agent to release the neutralizing agent into the wash solution in response to the activation signal; pumping means configured, said pumping means being capable of releasing a measured amount of said neutralizing agent into said solution upon receipt of said energization signal; can prevent the neutralizing agent from leaching into the solution until the oxidizing agent therein is reduced to about 2 ppm or less. pumping means for periodically adding neutralizing agent to the solution until the agent exceeds about 10 ppm above the amount required to completely neutralize the oxidizing agent. Device for automatically neutralizing oxidizing agents in solutions. (39) comprising: (a) a rinsing chamber suitable for containing a bath solution for rinsing the fabric; and (b) an automatic neutralization device according to claim 31 connected to the rinsing chamber. type of washing machine suitable for washing textiles. (40) (a) a rinsing chamber suitable for containing a bath solution for rinsing the fabric; and (b) an automatic neutralization device according to claim 34 operatively connected to the rinsing chamber. type of washing machine suitable for washing textiles. (41) (a) a rinsing chamber suitable for containing a bath solution for rinsing the fabric; and (b) an automatic neutralization device according to claim 38 operatively connected to the rinsing chamber. type of washing machine suitable for washing textiles.