DE8914571U1 - Device for (continuous) electrolyte supply and reference electrode system - Google Patents

Description

'!.PETEROTTEPATENTANVALT _{<# #} ,- D-7250 Leonberg

Representative at the European Patent Office / European*'Patent Wtotne? ','·'l'' Tiroler Straße

22Sl/ot/wi 20.11.1989

Firm a Conducts Society for Mfrü- and Regeltechnik mbH & Co., Dieselstr. 24, 7.0X6 Gerungen

Device for (continuous) electrolyte supply and reference electrode system

State of the art

The invention is based on a device for (continuous) electrolyte supply to a reference electrode according to the preamble of claim 1.

Reference systems in analytical chemistry, i.e. reference electrodes that provide a constant reference potential, especially for pH and redox measurements, are known (DE-OS 32 03 406, DE-OS 32 03 407, DE-OS 34 11 800 and finally European patent application 0299372 A2), also in the form of so-called electrolyte bridge systems with two

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diaphragms connected in series or in the form

% emsr for example suitable for pH measurement

jL·. rod measuring chain (pH combination electrode), in which the pH

sensitive electrode and the reference electrode are housed together in a glass tube.

The known reference electrodes use diffusion junctions in a variety of forms, for example as a ceramic diaphragm, platinum diaphragm, Teflon diaphragm, but also very small holes made in the side wall of the glass tube, whereby the reference electrode electrolyte used can be a KCl or KNO ₃ solution in liquid form or a gel of suitable consistency and then consists for example of agar-agar, polyacrylic material or PVC. Such a gel acts as a molecular sieve in which KCl ions are usually embedded.

J Reference electrodes normally contain a half-

:· Cells made of silver/silver chloride, which are dissolved in a solution

constant chloride ion concentration. This solution is then connected to the measuring medium via the diaphragm provided.

■■■ Such reference systems are generally problematic

the fact that these are not potential-constant due to the possibility of contamination from the outside, which cannot be ruled out, whereby diffusion in both directions occurs through the diaphragm, which forms a gate for the reference electrolyte to the mephitic medium.

! can be caused by concentrations below

differences or pressure differences between the reference*

til · &igr; t t Kl *

»·

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Electrolytes and the measuring medium. The diaphragm may also become blocked by crystallization or clogging with other media. Finally, poisoning of the reference electrolyte and the discharge system by the measuring medium cannot be ruled out.

In the opposite direction, a loss of reference electrolyte or changes in the concentration of the electrolyte due to so-called leaching can occur.

Further problems that may arise in the area of a reference system are listed in detail in EP 0299372 A2 mentioned above, so that there is no need to go into them further here.

^One very frequently used possibility for a number of problems arising in the area of the reference electrolyte and its diaphragm is to provide a reference system with a flowing electrolyte, whereby liquid reference electrolyte is fed into the chamber containing the electrolyte via a suitable inlet fitting under specially generated pressure or only by the static water column pressure. The electrolyte then develops a general flow towards and through the diaphragm, so that very small amounts of reference electrolyte continuously enter the heating medium, but on the other hand the reference system is maintained in perfect condition and the diaphragm is cleaned and rinsed from the inside so that poisoning cannot occur. If

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In this context, a bridge electrolyte system, the inner electrolyte can also be a gel, which is connected via a first inner diaphragm to another outer chamber, which then dips into the measuring medium via an outer diaphragm. It is then the liquid electrolyte in the outer chamber which emerges as flowing electrolyte via the outer diaphragm and flows past the inner diaphragm, which is set higher for example. This results in a number of advantages, but on the other hand the supply of the flowing electrolyte is particularly complicated, since it has previously been necessary to connect the space containing the flowing reference electrolyte via an outward-facing branch, i.e. in a single-rod measuring chain, for example, a glass tube angled upwards and a hose connection connected to it, to a vessel containing the reference electrolyte KCl or KNO ₃ . The electrolyte then flows through this hose and inlet fitting connection into the electrolyte chamber at such a pressure that any possible counterpressure of the measuring medium is overcome.

However, since it is relatively often necessary to remove the reference system - in the case of a combination measuring chain, especially the measuring electrode - from the holders for cleaning, maintenance purposes or to calibrate and replace the electrodes, the hose supplying the reference electrolyte had to be removed, the vessel emptied and the liquid electrolyte supply completely

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be prevented, whereby a drop of tile also in the area of the Elaletredanlegpfoc ivnA daiP.it dSSSSIi

Destruction was often unavoidable.

In any case, to change the electrode, you first have to release the pressure in the reference electrolyte, then empty the KCl container, empty the hose, pull off the hose, vent the system, then you can carefully remove the electrode, with the reference electrolyte dripping everywhere, and you have to repeat these steps in reverse order when reinserting it and vent the system.

The invention is therefore based on the task of remedying this situation and enabling an electrode change with a "flowing reference electrode", even when designed in the form of a combination electrode, without having to worry about the flowing reference electrolyte and its interruption, even if it is under considerable pressure.

advantages of the invention

The invention solves this problem with the characteristic

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the features of the main claim and has the advantage that, with a corresponding redesign of the possible uses of the electrode part in the holder, the carriage or an external bearing tube, the electrolyte supply is automatically monitored and interrupted and reopened during the usual manual change (removal and insertion of the electrode part in the bearing tube), whereby the electrolyte supply is routed from the outside to the inside and therefore no disruptive hose connections need to be connected to connecting glass tubes on the outside. This not only reduces the possible risk of breakage, but also the overall effort involved in such measuring systems in analytical chemistry that work with a refillable rinsing electrolyte, both in terms of maintenance and operating effort and in terms of the complexity of the structural design.

Above all, the invention increases the accuracy of the measuring system, as it is always ensured that no faults occur due to human error during maintenance or reconnection, ^r i which may not be noticed until much later

and in continuous processes

ff can lead to considerable damage.

Another decisive advantage of the present invention is that the otherwise practically unavoidable mixing of the liquid rinsing _electrolyte for the reference electrode is completely eliminated, the

;· yes not only by connecting and disconnecting the hose

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20.11.1989 .;».:,. - .7.H..

connections, but also because, for example after maintenance or replacement of the electrode part, this must also be vented, especially since the otherwise necessary frequent disconnection of a hose connection does not contribute to its tightness.

The invention can be applied to any type of reference electrode, preferably in conjunction with single-rod measuring chains, in which an electrode insert in the form of an electrode part comprising an inner support tube must be inserted into an outer support tube or a receiving carriage standardized for certain application purposes, which in turn is then mounted via flange connections in the area of the measuring medium, immersed in it.

The invention is therefore particularly suitable for electrode holders which connect a suitable measuring electrode, for example a pH electrode, with a measuring medium, for example in the form of a flow-through fitting, attachment fitting or immersion fitting.

The measures listed in the subclaims enable advantageous further developments and improvements to the invention. Particularly advantageous is the implementation of the manual removal and insertion movement of the electrode part into the bearing sleeve by means of an internal bayonet lock, so that the electrode part can be securely snapped into the sealed insertion position by a single rotational movement of considerably less than one revolution, in contrast to the manipulations previously required to remove the electrode part.

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by means of a large number of turns into the bearing tube.,

The fastening bayonet is also insensitive to the accumulation of dirt or other disturbances, unlike threads , it does not tend to "seize" when actuated and, in addition, provides a noticeable relative lifting movement which ensures that the seals enclosing the bayonet locking area move into their sealing positions.

In this case, it is also particularly advantageous to form a "valve area" resulting from the insertion movement of the electrode part into its bearing tube, which always opens when the electrode part is inserted, thereby creating corresponding communicating passages, and closes when the electrode part is removed.

In a further advantageous embodiment, the present invention does not, as one might assume, use the lifting movement when inserting the electrode part into the bearing tube to actuate the valve, but rather the rotary movement resulting from the bayonet actuation, since this is the only way to maintain the dimensions specified in this way, even with carrier carriages subject to strict standardization in the field of analytical chemistry (the usual diameter of such a standardized carrier carriage in numerical size, which does not restrict the invention, is only 45 mm) and still achieve a

* t · · suffered

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to guarantee perfect function and tightness for the "flowing electrolyte*".

Finally, a further advantageous embodiment of the present invention consists in dividing the deployment movement into gradations, for example by means of a corresponding additional step in the bayonet connection area, so that a
The first insertion movement initially introduces the electrode part into the bearing tube so far that, when the valve is already opened, the flow and chamber areas of the reference electrode can be vented by the reference electrode, which is then already flowing and which also noticeably penetrates outwards, so that the maintenance person can determine this, until the electrode part is completely inserted into the bearing tube with a further insertion end turn and a lower end seal also closes. This then gives the maintenance person the certainty that everything is put together in perfect operating function.

drawing

Embodiments of the invention are shown in the drawing and are explained in more detail in the following description. They show: Fig. 1 shows a schematic cross-section of the complete assembly of a measuring system with an outer bearing tube and the electrode part held by it including the valve mechanism;

ti ti · « IMl If

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20.11.1989 -&Igr;&Ogr;&Igr; Fig. 2 compared to the embodiment of Fig. 1

f: smaller in a day?- Idrauf sees the valve-

ß| rotating sleeve;

Fig. 3 a possible embodiment of the electrode part with bridge electrolyte for the reference electrode system and
Fig. 4 another possible embodiment of the

Electrode part with flowing reference electrolyte and lower annular gap diaphragm.

Description of the embodiments

The basic idea of the present invention is to automate a reference electrode system with flowing electrolyte supply in such a way that the further electrolyte supply is automatically shut off and the supply is opened when the electrode part is removed from its holder or reinserted into it.

A valve system is used to block or open the inflow, which reacts to the removal or insertion movement of the electrode part, more precisely to the rotary movement required when inserting the electrode part, which is based on a bayonet lock movement.

" Before going into the invention in detail,

It is pointed out that for calibration purposes the flajonett lock connection between the electrodes

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part and the outer bearing tube that accommodates it is already described in the utility model 6 89 09 902.8, which is not part of the state of the art and whose priority is claimed here, so that the basic principle of the bayonet connection is only discussed here to the extent that is necessary for understanding the present invention.

In the illustration in Fig. 1, an outer Lagair tube accommodating an electrode part is designated with 10; the electrode part or electrode insert designated with 11 in the drawing in Fig. 1 is shown continuously unhatched from top to bottom for a better understanding of the invention and consists itself of an outer, stepped housing 11a with at least two annular grooves 12a, 12b and 12c, each of which accommodates ring seals 13a, 13b, 13c, usually O-rings.

In the simplest case, the electrode part insert can only contain a conventional reference electrode system, provided that a flowing electrolyte supply is provided for this; in the preferred embodiment shown, this involves the implementation of an electrode part in the manner of a single-rod measuring chain, optionally also supplemented by an additional temperature sensor, whereby the measuring electrode part 14 with the glass membrane 14a can be arranged on the inside of the electrode insert 11, while, as indicated by the dashed lines, the electrolyte chamber 15 for the reference system is located around the measuring electrode on the outside.

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system, with a diaphragm indicated at 16.

What is important is that the entire measuring system shown and its reference electrode system are a design in which for the reasons already mentioned above, a pressure-dependent reference electrolyte refill is provided (liquid electrolyte).

To stay with the electrode part for now, we will now look at the representations in Figures 3 and , whereby Figure 3 shows a schematic and partial representation of a reference electrode system 17 with a bridge electrolyte. The inner measuring electrode 14' is surrounded by a first (ring-shaped) reference electrolyte chamber 15' with silver/silver chloride discharge at 17. The reference electrolyte contained in the inner electrolyte chamber 15' can preferably be in gel form, with a first inner diaphragm 18, which forms a transition to an outer electrolyte chamber 19, which is then filled with the refillable rinsing electrolyte, for example KCl, which is liquid in this case and flows through in the direction of the arrow, with a lower ring-shaped outer diaphragm 20, from which the outer electrolyte then passes into the heating medium, albeit in comparatively very small quantities (indirect reference system).

Such an electrode system is then accommodated, just like the electrode system without bridge electrolyte according to Fig. 4, in a suitable housing as indicated by 11 in Fig. 1, whereby in the

"■"■■■/

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Design of the electrode system of Fig. 4 (direct reference system - the electrode of the reference systems is immediately flowed through with KCl) the reference electrode ring chamber 15" holding the liquid reference electrolyte is drawn down to the sensitive glass membrane 14a" of the measuring electrode 14" and forms a so-called ring diaphragm 21 at the transition point. These are therefore two further possible embodiments of the electrode part, whereby the chamber holding the liquid refillable reference electrolyte is connected via corresponding internal bores and passages in the housing 11a of the electrode part to a corresponding inlet opening in the storage tube via a valve mechanism, which will be discussed further below. Furthermore, a measuring method with a raised reference electrode can be mentioned.

The electrode insert 11 is fastened in the bearing tube 10 by means of a threaded connection, in any case in the simplest case this can be done in the manner usual in the state of the art, so that the electrode insert is inserted into the bearing tube from below in Fig. 1 and then screwed tight. The invention uses this screwing movement in its simultaneous rotary and axial displacement to open the valve mechanism mentioned above when removing it and to close it again when inserting it, whereby the flow of liquid rinsing electrolyte for the reference system is opened or interrupted.

In the preferred embodiment, the "screw connection ^11" is designed in the form of an internal and therefore non-contaminating bayonet system 22, consisting of at least one, preferably two

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Guide pins 23a, 23b, which engage in corresponding guide sliding grooves 24 (only one is visible on the housing 11a of the electrode insert). The basic mechanism can be seen without further ado from the illustration in Fig. 1 ; if the electrode pin 11 is rotated in the direction of the arrow Δ/β in the α-direction for removal, then the interaction of the guide pins 23a, 23b with the guide tracks 24 finally pushes the electrode insert downwards and frees it from the bearing tube.

The guide track(s) 24 have a first, horizontally extending section 24a and an obliquely rising section 24b adjoining this at a predetermined angle of rotation, for reasons related to the simultaneous activation of the valve mechanism. In any case, the obliquely rising section 24b of each guide track 24 ensures that the ring seals 13a, 13b and 13c, which naturally also cause a certain clamping effect, are released from their associated seats by the rotational movement and therefore with the corresponding reduction, so that the electrode insert can be easily pulled downwards and removed.

In order to simplify the structures that accommodate the valve mechanism, an additional tube insert 25 is inserted into the outer bearing tube 10, although its shape and functions can also be taken over by a correspondingly machined bearing tube itself. The tube insert 25 or the bearing tube

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in any case has an inflow channel 26 for the (flushing) electrolyte to be supplied, whereby the inflow channel can be designed as a deep hole in the tube insert 25, which merges into a cross hole 27. This cross hole is already part of the valve mechanism, which comprises a stepped rotating sleeve 28 accommodated in the tube insert via several seals.

The transverse opening of the deep hole forming the supply channel 26 can also be produced by machining the pipe insert 25 internally to a bore diameter such that the deep hole is thereby cut.

The transverse bore continuing the flow channel 26

27 in the rotary sleeve 28 preferably opens into an annular channel 29 in the housing 11a of the electrode insert 11, so that at each rotational position of the rotary sleeve

28 the electrolyte flow can take place via the ring channel 29 through corresponding inner channels, not shown in detail, into the reference electrolyte chamber of the measuring system(s) containing the (external) electrolyte.

This electrolyte flow is noticeably interrupted when the rotating sleeve 28 is rotated so far that its through-hole 27 can no longer communicate with the opening of the supply channel 26, whereby appropriate sealing means are still provided, which in the preferred embodiment example can consist of an eleventh ring seal, preferably an o-ring 30.

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- 16 -

which is inserted into the passage channel 27 in the outer wall of the rotary sleeve 28 - see also the illustration in Fig. 2, from which it can also be seen that a comparable seal can also be achieved by a ring seal 30* running very tightly around the entire outer body of the rotary sleeve 28.

The rotating sleeve 28 is sealed to the outside and inside by a number of additional ring seals in the form of O-rings 32a, 32b, 32c.

In order to make the valve mechanism provided by the rotary sleeve respond, it is therefore necessary to rotate the rotary sleeve 28 at least by a predetermined angle so that its through-hole 27 is either aligned with the electrolyte supply channel 26 or is turned away from it, whereby the further electrolyte supply is then sealed via the seals 32a, 32b and 32c, while the ring seal 30 reliably prevents any possible leakage of electrolyte located in the ring gap in the area of the through-hole 27.

According to an essential feature of the present invention, this required rotary movement for opening and closing the valve mechanism is synchronized with and dependent on the rotary/lifting movement mentioned above, caused by an external manual intervention and controlled in the sequence by the first fastening bayonet system when removing or inserting the electrode parts.

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For this purpose, the rotary sleeve 28 has at least one driving pin 33 which engages in a suitably designed guide 34 which is machined into the outer wall of the electrode holder body. This can of course also be the other way round, as is the case with the bayonet lock system - the guide pins can therefore each be arranged on the housing of the electrode holder, while the guide tracks are inner ring tracks on the bearing tube 10 or the rotary sleeve 28.

In the embodiment shown, the guide rail 34 is designed in such a way that it comprises a vertical groove area 34a in which the guide pin 33 is located in the fully inserted position according to Fig. 1, and a partial area 34b with a horizontal course adjoining this in a right-angled transition. In the latter case, there does not need to be any upper limit, as can also be seen from the illustration in Fig. 2.

The following basic function then results. If the electrode insert 12 is manually rotated in the direction of the arrow Δ from the position shown in Fig. 1, in which the electrode insert 11 is completely inserted into the bearing tube that accommodates it, all seals are perfectly sealed and the flow opening for the electrolyte between the channel 26 and the cross hole 27 is open, then the driver pin 33 of the rotating part 28 strikes the right-hand groove wall 35 of the func-

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rungsfculissensbscbMtts a'la and the rotating sleeve 28

&iacgr; is carried along. This causes the passage

bore 27 moves out of alignment with the channel opening and the valve thus formed closes.

It is advantageous to leave the electrode insert in its fully inserted and therefore completely sealed position until the valve is completely closed, so that this process takes place over the angle of rotation during which the guide pin 23a of the bayonet system 22 is in the horizontal region 24a of the bayonet track.

Therefore, the guide pin 23a preferably only enters the oblique course 24b of the bayonet track when the valve is completely closed, whereby the electrode insert 11 is simultaneously pulled downwards with further rotation, i.e. carries out an axial movement, which means that the driver pin 33 of the rotary sleeve gradually comes free from the axial part groove 34a of the guide rail, whereby the rotary sleeve 28 is rotated by further angular amounts until the driver pin has completely exited the axial area of the guide rail and is, for example, at the point marked 33' in Fig. 1 or at another point further to the right. lying position. In any case, this area represents

. 34b the guide rail for the valve actuation

. Kind of freewheel and since the backdrop is open at the top

is, the electrode insert can be removed after the seals 13a, 13b and 13c have been released.

remove downwards.

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The reinsertion of the electrode part after the desired maintenance, cleaning or replacement is self-explanatory as a kinematic reversal of the process just described; the relative positions are necessarily aligned with one another by the previous removal process so that when the guide pins 23 in the bayonet area reach the guide track(s), the driver pins 33 are also in the correct position so that they can be caught again by the slotted guide by the subsequent lifting/rotating movement and the opening in the valve area occurs when the guide pins 23a slide further in the horizontal area 24a of the guide track as they continue to rotate.

A further preferred embodiment of the present invention is that the guide track can be designed in two stages in the bayonet area, as shown in dashed lines at 24*. The process is basically similar; however, it is modified in that when inserting, by appropriately adjusting the relative position to one another, the valve opens when, starting from the starting position of the guide track 24' shown in Fig. 1 with C, it first transitions into a horizontal guide area.

Since the entire electrode insert is not yet in its final position at this point in time, the lower ring seal 13c is not yet sealed, while the other seals can already achieve their respective sealing properties by moving them accordingly.

«&bull;&bull;&bull;let » » · I · V I ·· · &diams;

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have taken up their sealing seats and, as mentioned, the electrolyte supply is already taking place when the electrode insert is first rotated further to the end point of the first horizontal path, which is marked C. Therefore, the guide track section C-C', in which the electrode insert does not perform any axial movement, corresponds to the valve opening and the electrolyte that is now already flowing fills the electrolyte chamber and also vents it, since a vent opening is provided at a suitable point, for example at 36 in the reference electrolyte chamber. The reference electrolyte that is flowing in then finally exits again through this vent opening and also partially flows downwards, since the lower seal 13.' is still open, so that the operator can observe this and then, in an advantageous way, also immediately determine that everything is OK, the valve is open and the electrolyte chamber is vented. The operator then rotates the electrode part further so that the guide pin 23a overcomes the next incline of the guideway, pulls the electrode insert completely into the bearing tube with effective seal at 13c and the system as a whole is then transferred to the final working position.

All features presented in the description, the following claims and the drawing can be essential to the invention both individually and in any combination with one another.

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Claims (1)

. !&rdquor;&igr;&diams; 2?,91/ot/mu
15.02.1990 Conducta Society for Measurement and Control Technology iiiijH s Cü. , Protection claims . Device for (continuous) electrolyte supply to a reference electrode in analytical chemistry, for pH value determination, redox measurement and the like, whereby there is either a direct connection to the measuring medium via an (external) diaphragm or an indirect connection via a bridge electrolyte and the liquid electrolyte supplied to the reference electrode passes through this at least one diaphragm into the measuring medium for rinsing, cleaning and the like, characterized in that an electrode insert (11) is arranged in an external bearing tube (10) and is inserted and held in place via a threaded connection, and between the bearing tube and the electrode insert there is a valve mechanism (26, 27, 28) which is positively controlled by the threaded connection. 2. Device according to claim 1, characterized in that the removable electrode insert (11), which closes the inner valve mechanism (26, 27, 28) by its removal movement and opens the valve mechanism again by its insertion movement, is held in a sealed manner in the outer bearing tube (10). /2 > > > &igr; Il > ' Flit > I I I I I I I ·■ it· &bull; ■ I I I I Il I » 2291/ot/mu 15.02.1990 - 2 - 3. Device according to claim 1 or 2, characterized in that between the electrode insert (11) and the bearing tube (10) there is arranged a threaded connection which actuates the valve mechanism (26, 27, 28) during relative rotational movement, that the threaded connection simultaneously enables the execution of an axial movement. j &eegr; j _j ti it *? ^t.iii &lgr;. &igr; J_n _aj_ _ &igr; ___ J__ ucii ciciyany uuei riKiioui cniiian. uiiu uau iux l. ciiiici ucu Inflow of reference electrolyte via communicating transverse bores (26, 27) forming a valve area is connected to a drive clutch (33, 34, 35) activated by the relative rotation between the bearing tube (10) and the electrode insert (11). 4. Device according to one of claims 1 to 3, characterized in that the threaded connection is formed by a bayonet lock (22).vjclches after engagement of guide pins (23a) in associated guide tracks (24) the electrode insert a combined stroke/ 5. Device according to claim 4, characterized in that the valve region for interrupting the electrolyte flow when the electrode insert is removed and for opening it when it is reinserted is designed like a rotary ^valve and is angularly synchronized with the stroke/rotation movement generated by the bayonet lock system (22). &ngr;-. Device according to one of claims 1 to 5, characterized in that a rotary sleeve (28) is provided in the valve area, which has a passage (26) to the housing (11a) via a transverse bore (37). /3 2291/ot/mü 15.02.1990 of the electrode insert (11) opens or closes depending on the rotation position. 7. Device according to one of claims 1 to 6, characterized in that the forced guidance by the bayonet lock (22) comprises a partial area in which an exclusive rotary movement takes place. 8. Device according to one of claims 1 to 7, characterized in that the forced control of the combined stroke/rotation movement of the electrode insert (11) comprises at least two
Height-running horizontal pure rotary movement areas, with a lower seal on the electrode insert
is open to allow ventilation and
Electrolyte flow control. 9. Device according to one of claims 1 to 8, characterized in that the rotary sleeve (28) in its &bull;&bull;&bull;ft»· · · · f 2291/ot/wi 20.11.1989 - 4 - respective rotational position is controlled by a Kv.I issen guide (34), the relative angular orientation of which is related to the relative angular orientation of the bayonet lock guide track(s) (24). 10. Device according to one of claims 1-9, characterized in that for the synchronous control of the rotary sleeve (28) in the valve area and the bayonet lock (22) for inserting and fixing the electrode insert (11) respective driver pins (33) on the rotating sleeve (28) or guide pins (34) on the inner wall of the bearing tube (10) and sliding track guides (34, 34a, 34b, 35; 24, 24a, 24b, 24') are arranged in a predetermined angular orientation on the outer housing wall of the electrode insert or vice versa. 11. Device according to one of claims 1-10, characterized in that the cross bore (27) of the rotary sleeve (28), which opens or closes the inflow via a deep hole (26) as an electrolyte supply channel in the bearing tube (10) or in a tube insert (25) inserted therein, opens into an outer annular channel (29) on the housing (Ha) of the electrode insert (11), from which the rinsing electrolyte flows into the reference electrolyte chamber and that the rotary sleeve (28) of the valve area is sealed inwards and outwards by seals (32a, 32b, 32c). 12. Device according to claim 11, characterized in 2291/ot/wi 20.11.1989 - 5 - net, that a ring seal (30) is inserted into the wall surrounding the through hole (27) in the rotating sleeve (28). 13. Device according to one of claims 1-12, characterized in that the outer ring seals (13a, 13b, 13c) of the electrode insert (11) are arranged offset from one another in such a way that, with different stroke positions of the electrode insert (11), certain upper seals (13a, 13b) come to the seat earlier than lower seals (13c) relative to the bearing tube (10). 14. Device according to one of claims 1-13, characterized in that the guide track(s) (2Λ) of the bayonet lock system (22) is (are) designed in a stepped manner such that inclined guide sections (24b) for carrying out combined lifting/rotating movements of the electrode insert (11) alternate with horizontal guides (24a) for carrying out pure rotary movements at least twice and that the rotary lock mechanism of the valve sleeve (28) is so coordinated with the forced entrainment by the movement sequence of the bayonet lock system (22) that when the first horizontal rotary plateau of the bayonet lock guide track is reached, the electrolyte inflow is already open with the lower ring seal (13c) still open for the electrode insert (11) in such a way that the reference system is rinsed with noticeable overflow and the rinsing electrolyte escapes via the lower open ring seal (13c).