RU2549249C1 - Reference electrode for deep research - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: electrode comprises a body (1) in the form of a cylinder attached via a seal (2) to a tail (3). Inside the body (1) via a seal (4) of a mobile contact there is a container (5) made in the form of a sleeve with a flange. In the cavity of the container (5) there is a potential-forming element, which consists of a silver wire (6) and a paste AgCl/KC1 (7) that covers it. The wire (6) with the seal stretches via an axial hole made in the bottom of the container (5). The container (5) is closed with a cover (8), where there is an axial hole (9), into which a filter is installed. A bellows (10) filled with KC1 (11) solution is installed onto the container (5). By its other side the bellows (10) is tightly fixed on the bushing of a salt bridge, which is made dismountable and comprises a wide part - a flange (12) with the axial hole, and a narrow part - a rod (13) with an axial through capillary hole (14), which is screwed via a seal (15) into the axial hole of the flange (12). On the outer generatrix of the flange (12), perpendicularly to its axial line, there are pins installed (16). The entire structure is installed into a sleeve (17), made with an axial hole in the bottom - for a rod (13), by longitudinal slots on its generatrix - for pins (16), and thread on its outer surface. On the bottom of the sleeve (17) there is a spring (18) that supports the end of the flange (12). The slot (21) is installed into the axial hole of the tail (3) via the seal (22). The lead of the wire (6) is soldered to the lead of a tight slot (21) by a conductor (23) in insulation. The cavity of the body (1) formed by the end of the container (5) and the end of the tail (3) is filled with an electroinsulating liquid (24).

EFFECT: increased reliability of electrode operation and improvement of its operational properties.

1 cl, 1 dwg

Description

The invention relates to techniques for measuring the hydrochemical parameters of aqueous media in oceanographic, hydrographic and environmental studies and can be used in various technological processes associated with controlling the concentration (activity) of dissolved ions.

In operational hydrochemical studies, potentiometric methods are widely used to implement electrochemical measurement systems that effectively automate the work of scientists, in contrast to direct chemical analysis methods, especially with the advent of ion-selective electrodes. However, each industry of application has its own specifics, which means its own implementation technology, its own difficulties. A measuring electrode is only a component of an electrochemical system, another component of which is a reference electrode, in relation to which the information potential or current of the measuring electrode is measured. Experience shows [1] that almost 75% of difficulties when working with measuring electrodes are associated with problems of reference electrodes.

A laboratory reference electrode is known [2], widely produced by the industry and having a rather stable potential, of the order of + 0.203V, regardless of the composition of the medium under study. The electrode has a glass case filled with KCl solution, gradually flowing out of the case through the key into the test medium. Inside the case there is a silver chloride electrode made in the form of a spiral of silver wire placed in a paste of AgCl and KCl. This is a potential-forming element that is sealed on both sides in a glass case. Seals are made of rubber. A silver wire comes out through one of the seals to connect to the measuring circuit, and in the other seal an axial hole is made for the silver chloride electrode to communicate with the KCl solution in the electrode body. A filter is located in the axial bore to hold the AgCl / KCl paste between the seals.

Due to the fact that the potential-forming silver wire does not have a special fastening, in deep-sea measurements there is a high probability that the liquid in the body, under the influence of deep pressure, will start to flow out along the silver wire towards the measuring circuit, which leads to electrode failure . This is a disadvantage of the analogue.

The known reference electrode [3], developed and manufactured at the Special Design and Technology Bureau of the applicant, Marine Hydrophysical Institute of the NAS of Ukraine. (In the documentation of SKTB MGI NAS of Ukraine, this device is listed under the decimal number RT 5.519.022 - Electrode EV-022). The device is very well proven in operation and is still used.

The device is a silver chloride flow type electrode. The electrode contains a cylindrical body made of plexiglass. A container is installed in the body cavity through a radial seal. A potential-forming element is located inside the container. It is made in the form of a spiral of silver wire and AgCl / KCl paste, enveloping this wire.

The container is closed by a lid with a seal, which has an axial hole filled with a filter. A rubber bellows filled with a KC1 potassium chloride solution is hermetically fixed to one end at the body, and this solution communicates with the AgCl / KCl paste paste through the lid opening. The filter is necessary to prevent AgCl / KCl paste from entering the container into the bellows with KC1 solution.

The other end of the rubber bellows is hermetically fixed to the wide end of the sleeve, the narrow end of which is made in the form of a capillary with a through axial hole in which the glass thread is tightly mounted. The sleeve is a salt bridge between the KO solution in the bellows and the external environment.

Pins are installed along the outer generatrix of the wide end of the sleeve perpendicular to the axial line of the sleeve.

The whole structure is placed in a glass, which has an axial hole in the bottom, longitudinal slots for the pins and thread on the outer surface. The glass is mounted on the housing so that during operation the capillary of the salt bridge communicates through the axial hole in the bottom of the glass with the external environment.

Between the bottom of the cup and the wide end of the sleeve is a spring, through the axial hole of which a capillary is passed. The spring supports the sleeve away from the bottom of the cup, thereby creating excessive pressure inside the bellows. A nut is screwed onto the thread of the cup, interacting with the pins when fixing the position of the bellows in the idle state.

A shank made in the form of a flange with a through axial hole in which the connector is mounted is hermetically connected to the housing. Using the insulated wire, the central conductor of the connector is soldered: to the silver wire (spiral) on the outside of the container. Through the connector, the electrode is connected to the measuring circuit of the device.

In idle mode, a cap is put on the capillary. A threaded filling hole is made on the side surface of the housing, into which a plug is installed.

To fill the electrode with electrolyte, instead of a cork, a funnel is installed, and the nut is turned away towards the body until it stops. In this case, the bellows is completely compressed under the action of the spring. Then, the required amount of KCl is poured into the funnel, and by rotating the nut, with emphasis on the pins, the salt bridge is moved toward the bottom of the glass. The spring is compressed, and the bellows is stretched.

This reference electrode for the combination of essential features most closely matches the claimed technical solution, therefore, adopted as a prototype.

Similar essential features of the prototype and the claimed invention are: a cylindrical body made with an axial cavity, into which a cylindrical container is installed through the radial seal, made with an axial cavity, which is sealed with a lid and filled with AgCl / KCl paste, in which the silver wire is located, output which with a seal is passed through an axial hole made in the container, is electrically isolated and connected to the terminal of the connector installed in the through axial hole a wick, which is hermetically fixed to the body, a bellows filled with KCl solution communicating with the container cavity through an opening made in the lid, a salt bridge in the form of a cylindrical sleeve with an axial capillary hole, at one end of which a bellows is hermetically fixed, the sleeve is placed in a glass that fixed on the outer side of the housing, in the transverse plane of the sleeve from the side of its outer generatrix, radial holes are made in which the pins are installed, longitudinal slots for the pins and axle are made in the glass e hole in the bottom, into which the other end of the sleeve is omitted so that the capillary aperture communicates with the external environment, at the bottom of cup mounted propping spring sleeve, on the outer cup forming a locking nut is installed in the axial opening of the lid a filter.

Together with the undoubted advantages of the prototype has technological disadvantages, namely.

In case of unsuccessful termination of the silver wire (which may not occur immediately) due to the fact that adhesion over the entire surface of the wire is difficult to verify, during operation under the influence of external pressure, the electrolyte begins to leak through the wire through the container. In depth measurements, this is observed as spasmodic changes in the information signal of the meter. This effect is especially convincing when the reference electrode serves several measuring channels - then spasmodic changes in the signal appear simultaneously in several measuring signals. Direct technological methods for improving the reliability of sealing the silver wire make the bottom of the container thicker, but the problem is not completely eliminated - the silver wire remains loaded. Since the container communicates directly with the electronics through the thread of the connector, if the container is destroyed, for example, when struck at a depth, water will enter the meter with electronics, to which the reference electrode is connected.

The air remaining between the container walls and the electrode body after assembly can get inside the bellows with KCl solution, block the channels and damage the electrode - this is the warning given in the documentation for it. To avoid this, after each filling of the electrode with electrolyte, it must be evacuated, for which it is necessary to remove the electrode from the meter, use a vacuum pump. Of course, in the conditions of the expedition this is sometimes impossible.

The salt bridge can be blocked due to the appearance of air bubbles in the capillary or biological ingredients (microorganisms) in the non-working volume of the electrolyte - in the places where the container and the body are connected. In these cases, it is necessary to either replace the electrode with a new one and re-calibrate the measuring channel, or disassemble the electrode and boil the capillary, as indicated in the instructions for use of the electrode.

The basis of the invention is the task of creating a reference electrode for deep-sea research, a set of essential features of which provide new technical properties:

- equalization of static pressure inside and outside the container, which leads to the unloading of the silver wire and eliminates the need for technologically sophisticated special wire sealing;

- a significant reduction in the inoperative volume of the KC1 solution due to the exclusion of the cavity formed by the container-case conjugation;

- the ability to quickly replace a failed capillary;

- ensuring the reliable operation of the measuring device (the probe into which the electrode is installed) when the container with the potential-forming element is destroyed, for example, when struck at a depth of an object (which is difficult to visualize and provided by the operator), by imparting a connector through which the electrode is connected to electronic measuring circuit of the device, hermetic properties.

These new properties are especially evident in difficult expeditionary conditions and determine the achievement of the technical result of the invention — improving the reliability of the electrode and improving its performance.

The problem is solved in that in the claimed reference electrode for deep-sea research, containing a cylindrical body made with an axial cavity, into which a cylindrical container is installed through the radial seal, filled with an axial cavity, which is sealed with a lid and filled with AgCl / KCl paste, in which is a silver wire, the output of which with a seal is passed through an axial hole made in the container, is electrically isolated and connected to the output of the connector installed in a through axial hole of the shank, which is hermetically fixed to the body, a bellows filled with KCl solution communicating with the container cavity through an opening made in the lid, a salt bridge in the form of a cylindrical sleeve with an axial capillary hole, at one end of which a bellows is sealed, the sleeve is placed in a glass, which is fixed on the outer side of the housing, in the transverse plane of the sleeve from the side of its outer generatrix - made radial holes in which the pins are installed; in the glass there are longitudinal slots for pins and an axial hole in the bottom, into which the other end of the sleeve is passed so that the capillary hole is in communication with the external environment, a spring supporting the sleeve is installed on the bottom of the glass, a fixing nut is installed on the glass’s outer generatrix, and a cover axial hole is installed a filter, new is that the other end of the bellows is hermetically fixed to the other end of the container, the body cavity has a space filled with an electrically insulating liquid, which is limited on one side s - the end of the container installed in the cavity through the seal of the movable contact, and on the other hand, the end of the shank, which is installed in the cavity through the seal and in the hole of which the connector is installed through the seal, the terminal of the connector is immersed in an electrically insulating liquid and connected to the terminal located in the electrically insulating liquid wire, while the sleeve is made collapsible in the form of a flange with a through axial hole, in which a rod with an axial capillary hole is installed with a seal.

The invention is illustrated using the drawing, which shows a General view of the reference electrode, in section.

The housing 1 is a hollow cylinder, screwed through the seal 2 to the shank 3. Inside the housing 1 through the movable radial seal 4 is installed a container 5, made in the form of a glass with a flange. In the cavity of the container 5 there is a potential-forming element, which consists of silver wire 6 and AgCl / KCl 7 paste enveloping it. The container 5 can be made of any electrical insulating material, preferably opaque, so as not to illuminate AgCl - for example, from colored organic glass, as in prototype.

The silver wire 6 with a seal is brought out through an axial hole made in the bottom of the container 5 — through an adhesive material, for example, glue, or through a rubber stopper, as in the laboratory electrode EVL-SHZ. one.

The container 5 is closed by a lid 8, in which an axial hole 9 is made in which a filter is installed (not indicated by the position). From the side of the lid 8, a bellows 10 filled with a KCl solution 11 is hermetically installed on the container 5 (on its flange).

The other side of the bellows 10 is hermetically mounted on the sleeve of the salt bridge, which is also made of electrical insulating material, for example, plexiglass.

The sleeve is collapsible and has a wide part - a flange 12 with an axial hole, and a narrow part - a rod 13 with an axial through capillary hole 14, which is screwed through the seal 15 into the hole of the flange 12. The main link of the salt bridge is a capillary hole 14, designed for slow flow KCl solution in the external environment.

To stretch the bellows 10 perpendicular to the axial line of the flange 12, pins 16 are installed on its outer generatrix.

The specified design is installed in the glass 17, made with an axial hole in the bottom - under the rod 13, with longitudinal slots on its generatrix - for the pins 16, and a thread on its outer surface. The glass 17 is mounted on the housing 1 so that the rod 13 extends beyond the hole in the bottom of the glass, and the capillary hole 14 is constantly in communication with the external environment.

At the bottom of the cup 17, a spring 18 supporting the end face of the flange 12 is installed, which serves to create excess pressure in the bellows 10.

The glass 17 performs two functions - a protective fence for the bellows 10 and the link that controls the compression and extension of the bellows, for which a nut 19 is thrown on the glass 17, interacting with the pins 16.

So that in idle mode the capillary hole 14 does not dry out, a protective cap 20 is put on the rod 13.

The shank 3 is made in the form of a flange made of titanium or stainless steel with a through axial hole. For electrical connection of the electrode to the electronic measuring circuit of the probe and its sealing from liquids contained in the electrode, a connector 21 is installed through the seal 22 in the axial hole of the shank 3.

The output of the silver wire 6 is soldered to the output of the pressure seal 21 by the conductor 23 in isolation.

To equalize the pressures inside the container 5, from the side of the solution KC1, located in the bellows 10, and from the output side of the silver wire 6, located outside the container 5, the body cavity formed by the end of the container and the end of the shank is filled with an electrically insulating liquid 24, for example, oil.

The device operates as follows.

Unlike the prototype, the proposed device is filled not through a screwed-off plug, but through a screwed-out capillary (rod) 13.

Then, the pins 16 are released by unscrewing the union nut 19. Under the influence of the spring 18, the bellows 10 is compressed, forcing the electrolyte 11 to flow out through the capillary hole 14 into the external environment. In this process, unlike the prototype, the interface between the container 5 and the housing 1 is not involved, which eliminates the ingress of random air bubbles from this zone into the KCl 11 working solution with which the bellows 10 is filled.

If an air bubble remains in the oil-filled cavity 24 formed by the end of the container 5 and the end of the shank 3, then when the electrode is immersed to a depth, the increasing pressure of the external environment will cause the container 3 to work in the axial hole of the housing 1 as a piston, compressing the air bubble and equalizing the pressure on the silver wire 6 from both ends.

USED SOURCES:

1. Kamman K. Work with ion-selective electrodes / Per. with it., ed. doc Chem. sciences O.M. Petrukhina - M.: Mir, 1980.

2. Passport for EVL-1M3.1.

3. Rabinovich M.E., Vnukov Yu.L. Methods of measuring hydrochemical parameters and their application in the probing complexes of the Moscow State Institute of Science NAS of Ukraine / Preprint of the Moscow State Institute of Science NAS of Ukraine - Sevastopol .: SO ECOSI - Hydrophysics, 1995, 76 sec.

Claims (1)

Comparison electrode for deep-sea research, comprising a cylindrical body (1) made with an axial cavity into which a cylindrical container (5) is installed through a radial seal (4), made with an axial cavity, which is sealed with a lid (8) and filled with AgCl paste / KCl (7), in which there is a silver wire (6), the output of which is sealed with a seal through the axial hole made in the container (5), is electrically isolated (23) and connected to the output of the connector (21) installed in the through axial hole of the tail a closure (3), which is hermetically fixed (2) on the housing (1), a bellows (10) filled with a solution of KC1 (11) communicating with the cavity of the container (5) through an opening (9) made in the lid (8), saline a bridge in the form of a cylindrical sleeve with an axial capillary hole (14), at one end of which a bellows (10) is hermetically fixed, the sleeve is placed in a glass (17), which is fixed on the outside of the housing (1), in the transverse plane of the sleeve from the side of its outer radial holes are made into the generatrix, in which the pins (16) are installed, in the glass (17) are made longitudinal slots for the pins (16) and an axial hole in the bottom, into which the other end of the sleeve is passed so that the capillary hole (14) is in communication with the external environment, a spring (18) supporting the sleeve is installed on the bottom of the cup (17), and on the outside of the cup (17) a fixing nut (19) is installed, a filter is installed in the axial hole of the cover (8), characterized in that the other end of the bellows (10) is hermetically attached to the other end of the container (5), the cavity of the housing (1) is filled with an electrically insulating liquid ( 24) space that is limited to one on the other hand, with the end of the container (5) installed in the cavity through the seal (4) of the movable contact, and on the other hand, with the end of the shank (3), which is installed in the cavity through the seal and in the hole of which the connector (21) is installed through the seal (22) ), the output of the connector (21) is immersed in an electrically insulating fluid (24) and connected to the wire lead (6) located in the electrically insulating fluid (24), while the sleeve is collapsible in the form of a flange (12) with a through axial hole in which with a seal installed rod (13) with axial capillary a borehole (14).

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