WO2011035759A1 - Method for examining the reactivity of an electronic sensor with a comparison medium as part of a test routine - Google Patents

Abstract

The invention relates to a method for examining the reactivity of an electrical and/or electronic sensor for gaseous and/or liquid media, in particular of a measuring electrode for determining chemical or physical variables, after the sensor surface has been sooted or covered by the process medium (surrounding medium) or components contained therein, the sooting or covering impairing the response behavior of the sensor relative to the medium to be measured, wherein in the examination, the sensor is exposed to a comparison medium as part of a test routine and a comparison sensor value is detected, and for this purpose the sensor is switched over from a process mode to the test routine and the comparison medium is fed to the sensor, and wherein series of sensor values are detected relative to the comparison medium and stored, and the series of sensor values relative to the comparison medium detected and stored successively at intervals are compared with each other, and a statement about the state of the sensor is derived and/or evaluated therefrom based on the change and development over time of series of sensor values relative to the comparison medium recorded at different times.

Description

 DESCRIPTION

 METHOD FOR VERIFYING THE REAGABILITY OF AN ELECTRONIC SENSOR WITH A CLEANING MEDIUM IN THE CONTEXT OF A TESTROUTINE

The invention relates to a method for checking the reactivity of an electrical and / or electronic sensor for gaseous and / or liquid media, in particular a measuring electrode for determining chemical or physical quantities, according to a sooting of the sensor with respect to the medium to be measured sooting or occupancy of the Sensor surface through the process medium (surrounding medium) or components contained therein, wherein the sensor is subjected to the review as part of a test routine with a comparison medium and a comparison sensor value is detected and to the sensor is switched from a process mode in the test routine and thereby the comparison medium for Sensor is guided and wherein based on the comparison medium sensor value series are detected and stored and with time interval sequentially detected and stored sensor value series related to the comparison medium miteinan are compared and derived therefrom a statement about the state of the sensor from the change and time evolution of recorded at different times sensor value series based on the comparison medium and / or evaluated.

Such a method is evident from the patent DE 102 60 046 B4. In this case, it is disadvantageous that the method as a whole is time-consuming, since between the measuring mode and the test routine, a purge process which purifies the sensor and which is time-consuming in terms of time is used.

The invention has the object of providing a method for checking the reactivity of an electrical and electronic sensor having the features of the preamble of claim 1 such that the entire process can be performed within a shorter time and precise information about the nature and degree of Pollution of the sensor can be obtained. It is another object of the invention to optimize the cleaning of the sensor automatically and the amount of cleaning medium required for cleaning the sensor over a period of time comprising several cleaning phases or to keep it as low as possible. This object is solved by the features of claim 1. Advantageous developments of the invention will become apparent from the dependent claims 2-30.

As the core of the invention, it is considered that the sensor surface as a comparison medium

CONFIRMATION COPY a cleaning medium having a pH <7 is supplied, which acts over a continuous exposure period of at least 30 seconds, in particular 2 minutes on the sensor to replace the Versotterung and / or occupancy and a statement about the detachment process of Versotterung / occupancy of the detected Sensor value series derived and / or evaluated. During exposure of the sensor surface to the cleaning medium, the sensor is active and decreases in chemical and / or physical quantities. The measured values determined in this way during the exposure of the sensor to the cleaning medium are used to derive or evaluate statements about the stripping process of the adsorption / occupation. For example, in the case of a pH value measurement via the sensor, it can be ascertained that, over the course of time of the measured values, in a pH value-time diagram, a faster, slower or no adjustment to a reference value is achieved. Since the cleaning medium has a pH <7, this is suitable for ensuring an active (chemically conditioned) cleaning of the sensor. Due to the fact that during the active cleaning process of the sensor by means of the cleaning medium, a measurement is simultaneously carried out on the manner of the detachment process or the cleaning of the sensor, a faster check of the reactivity of the electrical and / or electronic sensor is achieved. In particular, the data collected during cleaning can be used to determine an optimized (prolonged, shortened, consistent) exposure time of the cleaning medium for a subsequent cleaning operation.

In an advantageous embodiment, during the exposure period of the cleaning medium, an intermediate measurement series is carried out for determining a series of intermediate measurements on the sensor, the series of intermediate measurements being compared with previous measured series of intermediate reference measurements and / or preset series of intermediate reference measurements, failing the series of intermediate measurement reference values the cleaning medium acting on the sensor is exchanged or mixed with a fresh cleaning medium. Because a comparison of the detected cleaning fluid values at the sensor with preceding cleaning processes and / or preset intermediate reference measured values takes place within the cleaning process, a defect and / or an increased contamination (which falsifies the measured values of the sensor) can be detected at an early stage. It is advantageous if the intermediate measurement series is carried out after at least a quarter of the action period of the cleaning liquid. In particular, it is advantageous if the intermediate measuring row is then executed when at least half of the exposure period has elapsed. The fact that at least a quarter and / or the at least half of Einwirkzeitraumes wait, a statement about the cleaning effect of the cleaning medium can be made.

If, for example, an exchange of the cleaning medium described above has been carried out, it is advantageous if, after elapse of at least one quarter of the exposure period of the exchanged cleaning medium, a further intermediate measurement takes place in order to be able to make a statement as to whether and how strong the "new" cleaning medium is a cleaning In particular, if the measured values before and after replacement of the cleaning medium are identical, it can be concluded that the sensor is defective or can not be cleaned by the cleaning liquid.

A further advantageous measure is to place the derivation and / or evaluation of the detected sensor values of the detachment process of at least one series of sensor measurements at the end of the exposure period, wherein if the reference value is not reached, the exposure period is extended to a time-extended exposure period. By extending the exposure period, the cleaning fluid is given more time to remove the contaminants on the surface of the sensor. By storing the data records within the electronic control system, it is advantageously possible to store and / or further process a large number of measurement series values, in particular all measurement series and intermediate measurement series values for the purpose of long-term value recording and archiving. This is particularly desirable with regard to statutory provisions on the control, logging and ensuring of individual procedures. For example, can be traced by a precise, automated and reliable archiving of the process and in particular the series of measurements of the sensors used whether the process was operated at certain times in the target range. A further advantageous measure is when the data and measured value series of the electronic control system are either procured on a commercial PC and / or an export of the data in any file format, for example as an Excel spreadsheet is possible. This at least largely complete recording of the values tapped on the sensor can be used in particular also for purposes of quality management and / or controlling. For example, an internal query of the sensor values for any time in the past can be performed. Furthermore, a data record is stored in an electronic control system if the target value is not reached after the original exposure period and / or after the extension of the exposure period. This data record contains information such as a time stamp (time of measurement) as well as information about the measured values and the difference to the missed target values. For example, a sensor measurement is carried out at the end of the first and / or extended exposure period, wherein the non-achievement of the desired value is stored in an electronic control system and an indication is issued in the form of a maintenance message. Such a maintenance message signals to the operator of the process device that the sensor must be serviced (mechanically cleaned and / or manually cleaned) or replaced.

A further advantageous method step is, before exchanging the process medium with the cleaning medium or after exchanging the cleaning medium with the process medium, at least in the area of the sensor, to subject it to a flushing medium in the course of a flushing step. The flushing medium can be, for example, water and is used to free the sensor of easily soluble residues of the process medium, so that the cleaning medium fed to the flushing medium is merely confronted with the "persistent" residues of the process medium on the sensor For this purpose, bacterial detergents can also be used as dishwashing or ZIP cleaning methods.

The flushing medium is to apply to the sensor a time-variably adjustable, predefined period of time. This allows, for example, to increase the exposure period of the flushing medium to the sensor when changing the viscosity of the process medium within the process. Also, information from the previous cleaning phases can be used to adjust the flushing period.

Another basic idea according to the invention lies in the fact that the exposure period of the cleaning medium is evaluated over several passes (cleaning phases) and at least the duration of the following active period of the cleaning medium is determined on the basis of these evaluations. This determined duration of the following exposure time interval can be regarded as a first prognosis, since during the cleaning period, in turn, measurements take place which adapt the current and / or subsequent exposure period according to need and progress of the cleaning.

It is also advantageous if, over a plurality of passes, a repetition frequency of the repetition frequency derived automatically from preceding sensor value data Cleaning procedure determined and carried out automatically. The derivative can contain different conditions and / or logic sequences, eg, if the setpoint values are reached later while the cleaning liquid acts on the sensor, it is concluded that the next cleaning cycle is to be carried out after a shorter waiting time. Again, a fuzzy logic method can be used.

Another essential idea of the invention is to determine by comparisons of the preceding series of measurements how long the sensor will be in the desired range (tolerance range) and when the next (mechanical) cleaning and / or maintenance is to be expected. Based on the cleaning progress of the individual cleaning phases can be derived when a purely automated cleaning according to the above-described cleaning phase can not achieve sufficient cleaning of the sensor. At the latest at this time, the sensor would have to be cleaned by other means, for example manually by an operator in a mechanical manner. Such a prognosis can be carried out in the manner of a fuzzy logic method.

Basically, when it is spoken of a comparison of values or value ranges, the consideration of a predefined tolerance range applies. Since, in particular, in production-integrated process processes, the composition of the end products certain fluctuations are granted, it is advantageous if the process-accompanying control measurements on the sensor also take into account tolerance ranges within which the desired process product is achievable.

A second sensor arranged parallel to the first can prove to be expedient. This makes it possible to detect the process medium via a parallel to the first sensor second sensor in the manner of a by-pass control while applying a first sensor with the cleaning medium. This makes it possible to continue the production process continuously despite the fact that a cleaning phase is being carried out on a first sensor, since the process medium to be controlled can be controlled via the second sensor operating parallel to the first one. Moreover, in a method which provides a second sensor arranged parallel to the first one, in periods where no cleaning phases are carried out, the process medium can be simultaneously detected via the first and the second sensor. Thus, a redundant measurement of the process medium is achieved, which on the one hand in the event of failure of a sensor allows early detection of this fact and / or allows the generation of pairs of values a more accurate evaluation, for example, can be formed by the value pair at any time a value on the arithmetic mean , Advantageously, the two sensors can be automatically subjected to a cleaning process alternately with a time offset. When the cleaning process of the one sensor is completed, the cleaning process of the parallel-acting sensor is not immediately started, but a time buffer is waited until the cleaning process starts for the second sensor. Due to this time buffer, the second sensor is initially ready for a short time if faults occur in the first sensor reintroduced into the process.

The sensors used in the process can be used, for example, to analyze the pH, the redox reaction, the temperature, the sodium content and / or the conductivity of the process medium. Other sensors for detecting further chemical and / or physical variables are also included in the concept of the invention.

If the cleaning liquid is applied, the measured value is recorded within an interval of <15 s. This interval can also take place, for example, in an interval <2 s or even smaller intervals. The smaller the interval, the more memory and computing resources must be available to archive and evaluate the correspondingly larger amount of data. In principle, it is advantageous if the cleaning liquid has a lower pH than the process medium. For example, the pH of the cleaning fluid is lower by 3 or more than the pH of the process medium.

The pH of the cleaning liquid is, for example, at a pH of <3, in particular at a pH of 0.5, in particular at a pH of approximately 0. The lower the pH of the cleaning liquid, the better On the one hand, the cleaning effect of the cleaning fluid and, on the other hand (if the sensor is used for pH analysis), a low pH value tends to result in a greater distance from the pH of the process medium. A "relatively large" distance (difference) of the pH value of the cleaning fluid and the process medium is therefore desirable, as this results in a larger span to be measured and thus the sensor can pass a greater distance between the actual and the desired value.

After maintenance work on the process device or the sensor and / or during startup of the process device, it is necessary to calibrate the sensors. This can advantageously be done by the sensor (s) being automatically charged with at least one calibration medium. For this purpose, several reservoirs of different calibration media are arranged within the device, the be supplied sequentially to the sensor to be calibrated. Subsequently, a supply of the cleaning medium to determine the current cleaning medium-specific reference value. This process step lacks a manual measurement of the cleaning medium. Between the change from a first to a further calibration medium, it is advantageous if the sensor is subjected to a flushing medium. In addition to the sensor, the space surrounding the sensor can also be "rinsed out" so that there are as few residues as possible of the preceding calibration medium and there is a risk of falsification of the further subsequently fed calibration medium Further, it is advantageous for the operator of the process device after its maintenance You can choose whether the measured value currently measured during calibration should be used as a further reference for the following calibration processes.

Since a cleaning medium is used as the comparison medium, it is necessary that, after a change or refilling of the cleaning medium, this "new" cleaning medium is again measured for reference value determination on the sensor in the course of a startup and / or maintenance procedure lead to distortions of the statements, if these are based on an "old" reference value. It is thus advantageous, if not absolutely necessary, for a corresponding new reference value to be determined manually or automatically within the framework of a startup and / or maintenance routine for the respective new cleaning medium. In particular, an automatic calibration of the sensors is advantageous here. Even when changing or mechanically cleaning the sensor, manual or automatic determination of a current reference value for the cleaning fluid is an advantage or mandatory for valid values.

In a further development of the invention, it is provided that in the case of failure to reach a desired value, the system starts an emergency program. This emergency program includes, for example, an automatic message in the form of an SMS, e-mail or the like to a predefined recipient. The receiver may either be a higher-level computer or control unit in the hierarchy or the operator of the device. Furthermore, the start of the emergency program can be linked to the condition that the emergency program does not start until an exchange or mixing of the cleaning medium with a fresh cleaning medium has previously taken place on the sensor. Also, the emergency program may be granted a certain relevance assessment with appropriate response, for example, in the emergency program, a comparison of the measured values with an emergency tolerance value interval is performed and if the measured values within the Emergency tolerance interval are a maintenance message and / or if the measured values are outside the emergency tolerance interval an alarm message sent to a predefined recipient. In the context of the invention, it is possible to make statements about the state of the sensor from the time profile of individual sensor values purely related to the cleaning medium. If, in this context, the term of individual sensor values is referred to purely, this applies in each case to individual rows of sensor values which are recorded, for example, within a few seconds or minutes on the day.

By generating measurement series during the cleaning phase, the system determines how difficult it has been / how difficult it is to remove the sensor from the coating (cleaning information). The system uses the cleaning information to optimize the process parameters (cleaning interval, exposure time, etc.) and regulates the process parameters in such a way that the measured measurement targets of the process medium can be met with the least possible cleaning time and cleaning medium.

It is furthermore essential to the invention that after a change of a sensor, after mechanical cleaning of a sensor, after the replacement of the electronics of a sensor and / or after replacement or a change of the cleaning medium, an automatic reference value determination for the cleaning medium takes place. These described events can also be referred to as maintenance and / or commissioning. By one of the changes enumerated above, the measured values determined are significantly influenced, so that it is necessary for the system to determine new reference values. This is done according to the invention automatically by the targeted supply of at least two calibration media and subsequent to the application of the calibrated sensor with the cleaning medium for determining the "new" reference value for the cleaning medium.

The cleaning medium may be, for example, a cleaning concentrate.

The process is based on the acquisition and comparison of measurement series. This means that all currently measured values required for the method are recorded and stored or stored continuously, eg, every second or even less (millisecond clock), together with the associated time; in the flow chart, these are briefly designated with a series of measurements. The continuously recorded series of measurements are the basis for calculating the optimal and effective cleaning time. Thus, the cleaning time as well as the repetitive cycle of the cleaning process can be determined by the system in a predictive and self-learning manner.

If required, all required valves can be provided with feedback (open / closed), these are then waited for after setting and resetting (monitored).

The invention is explained in more detail with reference to embodiments in the drawing figures. These show

Fig. La-d is a schematic flow diagram representation of the invention

 Comparative method with cleaning medium; Fig. 2a-c is a schematic block diagram of the automatic determination of the

 Comparison value as commissioning / maintenance procedure;

Fig. 3 is a schematic representation of the device of the method. In drawing figure la, a flowchart is shown, which speaks essentially for itself. After starting the comparison procedure, it is checked whether a redundant measurement is available. The redundant measurement is understood to mean that the device of the method is designed so that at least two sensors are arranged working parallel to each other and thus the possibility during the cleaning process of the one sensor to run the continuous measurement of the process medium on the other sensor , The second sensor is checked via its measured values and if this does not seem plausible, the procedure continues as if there were no redundant measurement. If there is no redundant measurement, the next step is to check the active control activity. This means that it is checked whether the control parameters (valves which regulate the process medium by supplying appropriate media) are active. If an active control is currently taking place, it is either waited until this control activity is ended or the control activity is interrupted. As soon as there is no regulation activity, a HOLD value is used for the process process at least during the time of the cleaning phase of the sensor. This HOLD value can either be a predefined value or the last measured process value is set as the HOLD output value.

As shown continuously in Figure lb, the inlet valve in front of the measuring device (the Sensor) closed, so that the sensor is separated from the process medium. Before the supply of the cleaning medium to the sensor optionally a rinsing process can be initiated, this would open a purge valve, fed to the sensor flushing medium and waited for a set purge time and finally the purge valve are closed. If the cleaning medium is supplied to the sensor by opening the corresponding valve, a configured purging time of the cleaning medium is awaited, while the cleaning medium can exert its cleaning effect on the sensor. The valve behind the sensor is closed and the recording of the series of measurements, which are tapped on the sensor on the sensor during the exposure phase of the cleaning medium, is started. Based on the previously determined series of measurements, the optimum residence time / exposure time for the cleaning medium is determined in a forward-looking manner via the constant comparison. For example, it can be seen from the preceding series of measurements that the cleaning process proceeds faster than originally thought, so that the optimum exposure time has a reduction compared with the originally intended exposure time. This allows the process process to be accelerated overall since the overall time of the cleaning process is reduced.

Reference is made to drawing Figure lc, which continues the process that after half of the optimal pre-calculated residence time / exposure time, a comparison of the current series of measurements with previous series of measurements is performed to predict whether the measured value is likely to reach the comparison value. If the comparison value is considered "unavailable" (and thus the cleaning effect of the cleaning medium does not appear sufficient to clean the sensor within the original exposure time in such a way that the target value can be reached), the cleaning medium applied to the sensor is replaced by a "fresh" Cleaning medium replaced or mixed. Once the remaining (original) exposure time has been waited for, a comparison value is interrogated again and, if the target value has not been reached, the exposure time is extended to another predefined extended (possibly maximum exposure time). If the desired comparison value does not exist even after such a defined exposure time, an emergency program is activated. If the comparison value is reached, a rinse can be carried out according to the example described above. Subsequently, the cleaning medium is exchanged again with the process medium and carried out a kind of control measurement of the test medium. If this control measurement is negative, an automatic extension of the waiting time for the HOLD release is switched. If the measured value of the process medium is not the desired one even after the lapse of a further waiting time, an emergency program is again activated.

The last section of the method is explained in drawing figure ld, with the query begins if an activation of an emergency program has taken place. If an activation has taken place, an emergency response will be used - if the value is outside the emergency tolerance - to issue an alarm signal indicating necessary maintenance or, if the value is within the emergency tolerance, a message recommending maintenance and, if applicable, the Possibility to add the signal specified in the system off-set (difference value) added to the measured value to signal. The latter would mean an adjustment of the evaluation electronics / electrics. If no emergency program has been activated, the next step inquire whether there is a redundant measurement - if not - the HOLD value is reset, the measured value is output and a release of the measurement is controlled in the process. If a redundant measurement took place, the last cleaned measurement for control / regulation tasks is released. The redundant measurement is thus decoupled from the process and the comparisons in the cleaning procedure for redundant measurements are released. Finally, with such a method, a prediction of the times for the next comparison method due to the deviation from the comparison medium (the cleaning medium) can be self-learning determined (fuzzy logic).

The flowchart shown in the drawing figures 2a - 2c comprises an automatic determination of the comparison value as commissioning / maintenance procedure for the existing comparison method for the monitoring of sensors. After the start command to initiate the start-up procedure, the inlet valve in front of the sensor is closed, thus disconnecting the sensor process medium. After an optional durchfuhrbaren rinsing process, the sensor is used new or without contamination. The new or cleaned sensor is then automatically calibrated using at least two calibration media (in the case of a pH sensor using buffer solutions). After the calibration process is complete and the sensor has been calibrated, the valve for supplying the cleaning medium is opened and the medium is supplied to the sensor. The purging time of the cleaning medium configured in the system is waited for and then the valve behind the sensor is closed. Subsequently, the measurement series is recorded for the duration of the exposure / residence time. On the basis of previous series of measurements, the optimal residence time of the sensor in the cleaning medium (exposure time) is determined in advance and waited until the comparative value to be determined has tendentially stabilized in its value behavior.

According to drawing Figure 2c, the method with the measurement and storage of the comparison value (measured value I) is continued together with the optimally calculated residence time. If necessary, a follow-up inspection is carried out, which is an adjustable Repeat the rinsing process includes, if this should be active, a purge valve is opened, the set purge time is waited, the purge valve is closed, the cleaning medium supplied and the valve in turn closed. If the follow-up check is not activated, the valve for the inlet of the cleaning medium is briefly opened and closed again. The further procedure is followed by waiting for the previously determined dwell time and recording a further comparison value (measured value II). The difference between the measured values I and II is determined and displayed if necessary. It is next queried whether the current measured value is to be taken over as comparison value; if this is not provided, a manual input of the comparison value and the maximum permissible measuring tolerance can be used to prompt for it, which is then stored. Alternatively, the comparison value of the difference measurement can be stored as comparison value for the following processes. After a release has been made for the measurement, the valves for cleaning media and flushing media are closed, the valve for the supply of the process medium is opened again and the entire process continues. Based on the determined measurement series, a forward-looking calculation of the time of the next comparison process can be performed.

With reference to Figure 3, an apparatus for performing the method is shown, wherein the device is essentially a first container 1, in which the medium to be measured (process medium) is located, a second container 2 for receiving a cleaning medium, e.g. a cleaning concentrate, a third container 3 for receiving a flushing medium, a fourth container 4 for receiving a first calibration solution (buffer solution A) and a fifth container 5 for receiving a further calibration medium (buffer solution B). Furthermore, a closure container 6 is arranged to accommodate no longer used in the process media. The cleaning medium, the flushing medium, the first or second calibration medium can optionally be supplied to the container 1 and / or the sensor 11 to be measured via the valves 7-10. Via the valve 12, the medium passed by the sensor 11 is optionally supplied to the container 1 or the drainage container 6.

If the system is driven in process mode, the medium contained in the container 1 via the line 13 and a change-over valve 15 via a line 16 to a flow fitting 17 is supplied via the pump 13. With the introduction of the test routine, the valve 15 is closed, the valve 7 is opened and cleaning medium of the flow fitting 17 and thus supplied to the sensor 11. If desired, flushing medium is previously supplied from the container 3 to the circulating valve 15 and thus to the sensor 11 via the control of the valve 8.

The vent valve 18 allows an exchange of the voltage applied to the sensor 11 For example, in this way the flushing medium applied to the sensor 11 can be derived by opening the venting valve 18 by gravity out of the sensor area (circulation manifold 17) The cleaning medium can then be fed into the cleaning medium whose properties change barely or not measurably due to the small residues, so that a replacement of the medium can be achieved without "consuming" new medium for execution purposes. This is further supported by the fact that near the sensor 11, a drain valve 19 is arranged so that the old medium can be discharged into the drain tank 6 on a short way and only under the action of gravity and eg the atmospheric pressure (opening of the vent valve 18).

This evacuation method is further illustrated in the flowcharts of drawing figures 1b, 1c, 2b and 2c.

LIST OF REFERENCE NUMBERS

1 container

 2 containers

 3 containers

 4 containers

 5 containers

 6 drainage tank

 7 valve v. 2

 8 valve v. 3

 9 valve v. 4

 10 valve v. 5

 11 sensor

 12 valve

 13 pump

 14 line

 15 changeover valve

 16 line

 17 flow fitting

 18 breather valve

 19 drain valve

Claims

1. A method for the reactivity of an electrical and / or electronic sensor for gaseous and / or liquid media, in particular a measuring electrode for determining chemical or physical quantities, according to a the response of the sensor with respect to the medium to be measured affecting sooting or occupancy the sensor surface by the process medium (surrounding medium) or components contained therein, wherein the sensor is subjected to the review as part of a test routine with a comparison medium and a comparison sensor value is detected and to the sensor is switched from a process mode in the test routine and thereby the comparison medium is guided to the sensor and wherein  relative to the comparison medium sensor value series are recorded and stored and  the series of sensor values successively recorded and stored in relation to the comparison medium are compared with one another and from this a statement about the state of the sensor is derived from the change and temporal development of sensor value series recorded at different points in time relative to the comparison medium and / or evaluated in that a cleaning medium with a pH value <7 is supplied to the sensor surface as the comparison medium, which acts on the sensor for detachment and / or occupancy over a continuous action period of at least 30 seconds and a statement about the detachment process of the plot / occupancy derived and / or evaluated the detected sensor value series. 2. The method according to claim 1, characterized in that the cleaning medium acts on the sensor over a continuous exposure period of at least 2 minutes. 3. The method according to claim 1 or 2, characterized in that during the exposure period of the cleaning medium an intermediate measurement series is carried out for determining a series of intermediate measurements on the sensor, the series of intermediate measurements being compared with previous measured series of intermediate reference measurements and / or preset series of intermediate reference measurements, wherein if the series of intermediate measurement reference values is missed the cleaning medium acting on the sensor is exchanged or mixed with a fresh cleaning medium. 4. The method according to claim 3, characterized in that the intermediate measurement series is carried out when at least a quarter of the exposure period has elapsed. 5. The method according to claim 4, characterized in that the intermediate measurement series is carried out when at least half of the exposure period has elapsed. 6. The method according to any one of claims 3-5, characterized in that after replacement of the cleaning medium and the elapse of at least a quarter of the Einwirkzeitraumes another intermediate measurement is performed. 7. The method according to any one of the preceding claims, characterized in that the derivation and / or evaluation of the detected sensor values of the detachment process comprises at least one sensor measurement at the end of the Einwirkzeitraumes, wherein at If the reference value of the exposure period is not reached, the reaction time is extended to a time-extended exposure period. 8. The method according to claim 7, characterized in that at least one record is stored in an electronic control system, if the desired value is not reached after the original exposure period and / or after the extension of the exposure period. 9. The method according to any one of the preceding claims, characterized in that at the end of the first and / or extended Einwirkzeitraumes a sensor measurement is performed, wherein the non-achievement of the target value is stored in an electronic control system and an indication is issued in the form of a maintenance message. 10. The method according to any one of the preceding claims, characterized in that prior to the exchange of the process medium with the cleaning medium or after replacement of the cleaning medium with the process medium at least in the region of the sensor of this is applied in a rinsing step with a flushing medium. 11. The method according to claim 10, characterized in that the flushing medium acts on the sensor a time variable adjustable, predefined period. 12. The method according to claim 10 or 11, characterized in that Water is used as flushing medium. 13. The method according to any one of the preceding claims, characterized in that over a plurality of passages of the Einwirkzeitraum the cleaning medium is evaluated and based on these evaluations at least the duration of the following exposure period of the cleaning medium is determined. 14. The method according to any one of the preceding claims, characterized in that over several passes across a automatically derived from previous sensor value data repetition frequency of the cleaning method is determined and carried out automatically. 15. The method according to any one of the preceding claims, characterized in that it is determined by comparing the previous series of measurements, how long the sensor will be in the desired range (tolerance range) and when the next (mechanical) cleaning and / or maintenance is expected. 16. The method according to claim 15, characterized in that the prognosis is carried out in the manner of a fuzzy logic method. 17. The method according to any one of claims 3-16, characterized in that the comparison of a first row with a further series of sensor values the Includes a predefined tolerance range. 18. The method according to any one of the preceding claims, characterized in that during the application of a first sensor with the cleaning medium, the process medium is detected via a second sensor operating in parallel to the first sensor in the manner of a by-pass control. A method according to claim 18, characterized in that the at least two sensors automatically alternately with a time offset one Cleaning process to be subjected. 20. The method according to claim 18 or 19, characterized in that the detection via the second sensor during the cleaning of the first sensor enables a continuous measured value acquisition during the entire process. 21. The method according to claims 18 - 20, characterized in that the sensors perform a simultaneous measurement of the process medium in the manner of a redundant system, when applied to sensors of the process medium. 22. The method according to any one of the preceding claims, characterized in that the sensor for analyzing the pH, the redox reaction, the temperature, the sodium content and / or the conductivity of the process medium is used. 23. The method according to any one of the preceding claims, characterized in that when applying the cleaning liquid, a measured value in an interval <15 s, in particular in an interval <2 s. 24. The method according to any one of the preceding claims, characterized in that the cleaning liquid has a lower pH than the process medium. 25. The method according to any one of the preceding claims, characterized in that the cleaning liquid has a pH <3, in particular a pH <0.5, in particular a pH value «0. 26. The method according to any one of the preceding claims, characterized in that the sensor (s) for calibration are automatically acted upon by at least one calibration medium. 27. The method according to claim 26, characterized in that between the change from a first to another calibration medium of the sensor is subjected to a flushing medium. 28. The method according to claim 26 or 27, characterized in that the calibration is carried out for commissioning or after a maintenance of the process device. 29. The method according to claim 28, characterized in that the operator of the process device can choose after the maintenance of whether the currently measured during the calibration measured value is to be used as a further reference for the following Kalibierprozesse. 30. The method according to any one of the preceding claims, characterized in that in case of failure to reach a desired value, the system starts an emergency program. 31. The method according to claim 30, characterized in that the emergency program transmits an automatic message in the form of an SMS, e-mail or the like to a predefined recipient. 32. The method of claim 30 or 31, characterized in that the emergency program starts when previously an exchange or mixing of the cleaning medium with a fresh cleaning medium has taken place on the sensor. 33. Method according to claim 30, characterized in that in the emergency program a comparison of the measured values with an emergency tolerance value interval and if the readings are within the emergency tolerance interval, a maintenance message and / or if the readings are outside the emergency tolerance interval, an alarm message is issued. 34. The method according to any one of the preceding claims, characterized in that after a change of a sensor, after mechanical cleaning of a sensor, after the replacement of the electronics of a sensor and / or after replacement or a Changing the cleaning medium an automatic reference value determination for the cleaning medium takes place.