JP3451145B2 - Pressurized composite electrode - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite electrode used for measuring pH, ion concentration and the like in fermentation industry, chemical industry, etc. The present invention relates to a composite electrode.

[0002]

2. Description of the Related Art Conventionally, a composite electrode in which a reference electrode and a measurement electrode are integrated is frequently used for measuring pH, ion concentration and the like. Especially in the fermentation and chemical industries, when measuring a process liquid with pressure, if the process liquid flows backward from the liquid junction of the reference electrode into the reference electrode, the concentration of the internal liquid changes and the Clogs occur.
In order to solve such a problem, various attempts as described below have been made.

That is, the first method is, as shown in FIG. 5, a measuring electrode 2 provided with a sensitive film 2a, and this measuring electrode 2
In a composite electrode having a reference electrode 6 arranged concentrically in an annular shape with respect to the reference electrode 6, a compressed air supply source including a pump 201 and a valve 202 is connected to a tank 200 for replenishing the internal liquid to a separate reference electrode 6. Then, compressed air is supplied to bring the inside of the tank 200 to a predetermined pressure to pressurize the liquid inside the reference electrode to a predetermined pressure. The pressurization of the liquid inside the comparison electrode prevents the process liquid from flowing back into the comparison electrode 6 via the liquid junction 26.

The second method is shown in FIG. According to this method, the electrode holder 203 holding the composite electrode has an airtight structure, and the electrode holder 203 and the upper space portion of the comparison electrode 6 are communicated with each other. The electrode holder 203 is used for the check valve 20.
4 is connected to a compressed air supply source including a valve 202 and a pump 201, and the upper part of the internal liquid is maintained at a predetermined pressure. A third method for preventing the process liquid from flowing back into the reference electrode through the liquid junction portion 26 is described in Japanese Patent Publication No. 6-35950 and in FIG. 7 attached to the present application. Method. That is, according to this method, the upper portion of the reference electrode 6 formed in an annular shape around the measurement electrode 2 is sealed, and the gas supply pipe 205 is attached to a part thereof. The gas supply pipe 205 is connected to a compressed air supply source composed of a valve 202 and a pump 201 at the time of manufacturing the electrode, and compressed air having a predetermined pressure is supplied into the reference electrode annular chamber. After that, the gas supply pipe 205 is hermetically sealed.
The compressed air source is removed. As a result, the inside of the reference electrode annular chamber, that is, the upper portion of the internal liquid is maintained at a predetermined pressure, and the backflow of the process liquid into the reference electrode through the liquid junction portion 26 during use is prevented.

[0005]

However, the above first and second methods have a relatively high pressure, that is,
It is used in a process of 1.5 Kg / cm ² (absolute pressure) or more with the atmospheric pressure of 1 Kg / cm ² , but the airtight internal liquid tank 200 and the electrode holder 203 are used to hold compressed air. is necessary. In addition, when using it, a compressed air supply source etc. is required, and further piping between the electrode and the compressed air supply source is indispensable, which not only raises the price of the electrode but also causes problems in operability and handleability of the electrode. There is.

Further, the third method requires a compressed air supply source and a compressed air supply piping device at the time of manufacturing the electrode.
Further, the gas supply pipe 205 provided in the reference electrode 6 is a platinum capillary tube, which is not only expensive, but also a skilled special work that enables glass work to attach the gas supply pipe 205 to the reference electrode forming wall made of glass. Need someone. Thus, the electrode according to this method is not only high in manufacturing cost but also has a problem in productivity.

Therefore, the object of the present invention is that the manufacturing cost is low and the productivity is low because there is no need for a compressed air supply source, a compressed air supply piping device, etc. at the time of manufacturing the electrode, and no special skilled worker is required. Of course, it is to provide a high-performance pressurized composite electrode.

[0008] Another object of the present invention is to provide a high-performance pressure-type composite electrode which can adjust the internal pressure of the reference electrode as desired and has a low manufacturing cost, good productivity, and high performance. is there.

[0009]

The above object can be achieved by the pressure type composite electrode according to the present invention. In summary, the present invention has an inner cylinder that constitutes a measurement electrode provided with a sensitive film, and an outer cylinder that constitutes a reference electrode concentrically arranged with respect to the inner cylinder. A composite electrode having an internal liquid in an annular chamber defined by the outer cylinder and having a liquid junction at a lower end of the annular chamber, wherein an annular packing having the internal electrode attached is provided. This is a pressurizing type composite electrode that is press-fitted inward from the upper open end of the annular chamber to compress and pressurize the air in the annular chamber above the internal liquid.

Preferably, the packing is filled with an adhesive to fix the packing in its position. According to another method, a packing press-fitting adjusting means is further provided on the outer cylinder,
By moving a pressing member that is movable downward with respect to the outer cylinder provided in the packing press-fitting adjustment means, the annular packing having the internal electrodes attached thereto is moved from the upper open end of the annular chamber. Pressing inward to a predetermined position to compress the air in the annular chamber above the internal liquid, and further moving the pressing member downward as necessary so that the air in the annular chamber can be pressurized. You can

In the present invention, the packing is made of an electrically insulating material having rubber elasticity, and preferably the electrically insulating material is nitrile rubber (NBR), chloroprene rubber (CR), ethylene propylene rubber (EPM). , Silicone rubber (Si), or fluororubber (FPM). Further, the liquid junction can be made of water-absorbing porous polyethylene, porous polyester, or porous acrylic, and in particular, porous ceramics having a water absorption of 5 to 15% are preferable.

Further, the internal liquid used is an aqueous solution or a gel liquid, and the gel liquid is a potassium chloride solution gelled with hydroxyethyl cellulose, carboxymethyl cellulose or acrylamide polymer.

[0013]

EXAMPLES The pressure type composite electrode according to the present invention will be described in more detail with reference to Examples.

Example 1 Referring to FIG. 1 (A), an example of a pressure type composite electrode 1 according to the present invention is shown. In the present embodiment, the pressure-type composite electrode 1 is a glass electrode, and an inner cylinder 4 constituting the measurement electrode 2 having a sensitive film 2 a and a comparison arranged concentrically with the inner cylinder 4. The outer cylinder 8 that constitutes the electrode 6 is included.

In order to form the measuring electrode 2, a buffer solution 12 is contained in an internal chamber 10 defined by the inner cylinder 4, and an electrode 14 is arranged therein. The electrode 14 has an internal chamber 1
A lead wire 18 extending through the plug 16 that closes the top of the 0 is connected. Also, to form the comparison electrode 6,
An internal liquid (reference electrolytic solution) 22 is contained in an annular chamber 20 defined by the inner cylinder 4 and the outer cylinder 8 and an internal electrode 24 is arranged. A liquid junction 26 is provided at the lower end of the annular chamber 20.

According to the invention, the internal electrode 24 is mounted on an annular packing 28 fitted and inserted in the annular chamber 20. The lead wire 30 connected to the internal electrode 24 penetrates the packing 28 and is taken out to the outside. At this time, it is preferable that the internal electrode 24 does not penetrate the packing 28 and is inserted to about half the thickness of the packing 28 so that only the lead wire 30 penetrates the packing 28. This is to prevent the internal electrode 24 from penetrating the packing 28 and protruding upward when the packing 28 is pushed into the annular chamber 20, as described later.

To further explain, according to the present invention, the annular packing 28 to which the internal electrode 24 is attached is shown in FIG.
As shown in FIG. 3, the internal electrode 24 is located at the lower open end of the reference electrode annular chamber 20 so that the internal electrode 24 is located below, and then the upper opening of the reference electrode annular chamber 20 is opened, as shown in FIG. 3B. Press down from the end using the cylindrical press fitting member 100. By press-fitting the packing 28 downward from the upper end of the annular chamber, the air in the annular chamber 20 above the internal liquid 22 is compressed and pressurized.

Now, let us consider the length with which the packing 28 is press-fitted. Now, when the packing 28 is press-fitted into the annular chamber 20, the amount of air dissolved in the internal liquid 22 is extremely small. Therefore, ignoring this, the following equation (1)
Holds. If the pressure before press-fitting is P ₁ , the volume is V _1, and the pressure after press-fitting is P ₂ and the volume is V ₂ , then from Boyle's law, P ₁ V ₁ = P ₂ V ₂ (1) In FIG. 3, the cross-sectional area of the packing 28 is S, the distance between the packing 28 before press-fitting and the internal liquid level is L ₁ , the distance between the packing 28 after press-fitting and the internal liquid level is L _2, and before the press-fitting. Assuming that the pressure is P ₁ = 1 Kg / cm ² (atmospheric pressure), the above formula (1) becomes P ₂ = V ₁ / V ₂ = SL ₁ / SL ₂ = L ₁ / L ₂ (2).

Therefore, it is understood that the pressure in the annular chamber 20 can be easily set to a desired pressure by changing the ratio of L ₁ and L ₂ .

The packing 28 press-fitted into the annular chamber 20 to a predetermined position in this way is short-term due to the frictional force between the packing 28 and the wall surfaces of the inner cylinder 4 and the outer cylinder 8 forming the annular chamber. For example, in about 30 minutes, the compressed air in the annular chamber 20 does not push back upward. But 3
When left for a long time of 0 minutes or more, it is conceivable that the frictional force between the packing 28 and the wall surface is reduced due to the moisture adhering to the inner surface of the outer cylinder 8 and the material is pushed back. Therefore, FIG.
As shown in (B), it is also possible to fill the upper surface portion of the packing 28 with the adhesive 32 and fix the packing 28 at that position to prevent the packing 28 from being pushed back upward.
Further, as shown in FIG. 2, one or a plurality of other packings 28 'may be added on the packing 28 to be used in two steps or in a plurality of steps. Depending on,
It is also possible to fill the upper portion of the packing 28 'with the adhesive 32.

The packing 28 (28 ') may be made of any electrically insulating material having rubber elasticity, and examples thereof include nitrile rubber (NBR), chloroprene rubber (CR) and ethylene propylene. Rubber (E
PM), silicone rubber (Si), fluororubber (FP)
M) etc. Although the packing 28 may be designed in various sizes, if the outer diameter of the inner cylinder 4 and the inner diameter of the outer cylinder 8 are 5 mm and 10 mm, respectively, the packing 28
The inner diameter of (28 ') is 4.5 mm, the outer diameter is 10.3 mm,
Good results could be obtained by setting the thickness to 5 to 20 mm.

However, in particular, when a material having a high gas permeability such as silicone rubber is used as the material of the packing 28 (28 '), the adhesive 32 is used as shown in FIGS. 1 (B) and 2. Filling is preferable, and in this case also, as the filling adhesive, a material having low gas permeability, for example, an epoxy resin adhesive is preferable. Experimental results of the present inventors, silicone adhesive, the gas permeability is large, for example, decreased to 2Kg / cm ² (absolute pressure) in air 3 days of 4 Kg / cm ² (absolute pressure) I found out. On the other hand, the epoxy resin-based adhesive did not substantially decrease in pressure even after 3 days.

In the present invention, the internal liquid 22 for the reference electrode 6 housed in the annular chamber 20 may be an aqueous solution or a gel-like liquid, but the gel-like liquid has a smaller pressure reduction rate in the annular chamber. Examples of the gel-like liquid include potassium chloride solution gelled with hydroxyethyl cellulose, carboxymethyl cellulose or acrylamide polymer.

The liquid junction 26 can be made of any material having a high resistance to pressure and a high water absorption. For example, water-absorbing porous polyethylene, porous polyester, porous acrylic or the like may be used. In particular, porous ceramics having a water absorption of 5 to 15% should be repeatedly exposed to high temperature steam of 120 to 130 ° C. for sterilization when the electrode of the present invention is used in the fermentation industry. Therefore, it is particularly effective. In the specification of the present application, the water absorption rate is the ratio (V ₀ / of the volume (V ₀ ) of the communication hole to the total volume (V) of the liquid junction portion.
V) is meant.

Example 2 In the pressure type composite electrode 1 shown in FIG. 1, the outer diameter of the inner cylinder 4 made of glass and the inner diameter of the outer cylinder 8 are 5 mm and 10 mm, respectively, and the inner diameter of the packing 28 made of silicone rubber is 4.5
mm, the outer diameter was 10.3 mm, and the thickness was 15 mm.

The liquid junction 26 has an outer diameter of 1 mm and a length of 2
A porous ceramic having a water absorption rate of 10% finished to mm was used, and a potassium chloride solution gelled with hydroxyethyl cellulose was used as the internal liquid 22.

The packing 28 was press-fitted into the annular chamber 20 using the press-fitting member 100 (FIG. 3 (B)). The press-fitting operation was extremely easy. The distance L ₁ between the packing 28 and the internal liquid surface before press fitting is 4 cm, and the distance L ₂ between the packing 28 and the internal liquid surface after press fitting is 1 cm.
The pressure inside 0 was 4 kg / cm ² (absolute pressure).

In this embodiment, the packing 28 is filled with the epoxy adhesive 32. This adhesive 32 is 30
Hardened within minutes.

Pressurized composite electrode 1 produced in this way
, The pressure in the annular chamber 20 was kept at 1.5 Kg / cm ² (absolute pressure) or more even after one year passed at room temperature.

Embodiment 3 FIG. 4 shows another embodiment of the present invention. The pressure-type composite electrode 1 of this embodiment has the same overall structure as the pressure-type composite electrode 1 of the embodiment shown in FIG. 1 described above, except that the packing 28 is not fixed with the adhesive 32. The difference is that the amount of press-fitting of the packing 28 can be adjusted as necessary. Therefore, members having the same functions and configurations as those of the pressure type composite electrode of the previous embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The pressure type composite electrode 1 of this embodiment has a packing press-fitting adjusting means 40. Packing press-fitting adjustment means 4
0 is a male screw member 42 fixed to the outer peripheral portion of the outer cylinder 8,
The male screw member 42 and a sleeve-shaped pressing member 46 in which a female screw portion 44 to be screwed is formed.

The pressing member 46 is formed with an annular shoulder portion 48 at a substantially central portion of its inner circumference, and the press-fitting member 100 can be pressed downward by the shoulder portion 48. Press-fitting member 100
Can be made of any material such as plastic or metal. The diameter of the central opening 48a of the annular shoulder portion 48 is made slightly larger than the outer diameter of the inner cylinder 4. Even when the pressing member 46 is moved downward, the annular shoulder 4
This is because 8 does not collide with the inner cylinder 4 of the electrode.

In the present embodiment shown in FIG. 4, a terminal member 50 is arranged above the pressing member 46, and the lower end portion of the terminal member 50 is attached to the upper portion of the inner cylinder 4. Although the seal member 52 and the like can be arranged between the pressing member 46 and the terminal member 50, the pressing member 46 is not the terminal member 50.
It is rotatable with respect to. The lead wires 18 and 30 connected to the electrodes 14 and 24 of the measurement electrode 2 and the reference electrode 6, respectively, are connected to the terminal member 50.

In the above structure, when the pressing member 46 is rotated in the predetermined direction, the pressing member 46 moves downward and urges the press-fitting member 100 downward. As a result, the press-fitting member 100 pushes the packing 28 into the annular chamber 20,
The inside of the reference electrode is pressurized. In this embodiment, the press-fitting member 1
00 is not removed from the electrodes and packing 28
Are constantly pressed by the pressing member 46 via the press-fitting member 100.

If the pressure inside the reference electrode drops after a certain period of time, or if it is desired to pressurize the inside of the reference electrode further, the pressing member 46 is further rotated to move the packing 28 into the annular chamber 20. Can be press-fitted to increase pressure.

In the case of this embodiment, since the packing 28 is movable, the filling of the adhesive 32 is not performed. Therefore, the packing 28 is made of fluororubber having a smaller gas permeability. Is preferred.

In the above embodiment, the pressing member 46 is the outer cylinder 8
However, the present invention is not limited to this, and the pressing member 46 may be attached so as to be movable downward with respect to the outer cylinder 8, and other modes for those skilled in the art. Would be variously conceived within the scope of the invention.

[0038]

As described above, according to the pressure type composite electrode of the present invention, in the composite electrode provided with the reference electrode around the measurement electrode, the annular packing having the internal electrode is attached to the upper part of the annular chamber of the reference electrode. Since it is configured to press inward from the open end and to compress and pressurize the air in the annular chamber above the internal liquid, there is no need for a compressed air supply source and a compressed air supply piping device when manufacturing the electrode, Further, it does not require special skilled workers, has low manufacturing cost, good productivity, and high performance. Further, according to another aspect of the present invention, it is possible to obtain an effect that the pressure in the annular chamber of the reference electrode can be arbitrarily adjusted as desired.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of a pressure type composite electrode according to the present invention.

FIG. 2 is a cross-sectional view of another embodiment of the pressure type composite electrode according to the present invention.

FIG. 3 is a cross-sectional view illustrating a procedure for producing a pressure-type composite electrode according to the present invention.

FIG. 4 is a cross-sectional view of another embodiment of the pressure type composite electrode according to the present invention.

FIG. 5 is a cross-sectional view of a conventional pressure-type composite electrode.

FIG. 6 is a sectional view of a conventional pressure-type composite electrode.

FIG. 7 is a cross-sectional view of a conventional pressure-type composite electrode.

[Explanation of symbols]

1 Pressurized composite electrode 2 measuring electrodes 4 inner cylinder 6 Reference electrode 8 outer cylinder 20 ring room 22 Internal liquid 24 internal electrodes 26 Liquid junction 28 (28 ') packing 30 internal electrode lead wire 32 adhesive 40 packing press-fitting adjustment means 46 Pressing member

Claims (9)

(57) [Claims] 1. An inner cylinder forming a measuring electrode provided with a sensitive film, and an outer cylinder forming a reference electrode concentrically arranged with respect to the inner cylinder. The inner cylinder and the outer cylinder. Is a composite electrode having an internal liquid in an annular chamber defined by and a liquid junction at the lower end of the annular chamber, the annular packing having the internal electrode attached to the annular chamber. A pressure-type composite electrode in which the air in the annular chamber above the internal liquid is compressed and pressurized by being pressed inward from the upper open end. 2. The pressure-type composite electrode according to claim 1, wherein an adhesive is filled on the packing, and the packing is fixed at that position. 3. A packing press-fitting adjusting means attached to the outer cylinder, wherein the packing press-fitting adjusting means comprises:
A pressing member that is movable downward with respect to the outer cylinder is provided, and by moving the pressing member downward,
The annular packing with the internal electrodes attached is pressed inward from the upper open end of the annular chamber to a predetermined position to compress the air in the annular chamber above the internal liquid, and if necessary, lower the pressing member. 2. The pressurizing type composite electrode according to claim 1, wherein the pressurizing type composite electrode is capable of moving to, and pressurizing the air in the annular chamber. 4. The pressure type composite electrode according to claim 1, wherein the packing is made of an electrically insulating material having rubber elasticity. 5. The nitrile rubber (N
BR), chloroprene rubber (CR), ethylene propylene rubber (EPM), silicone rubber (Si), or fluororubber (FPM). 6. The pressure-type composite electrode according to claim 1, wherein the liquid junction is water-absorbing porous polyethylene, porous polyester, or porous acrylic. 7. The pressure-type composite electrode according to claim 1, wherein the liquid junction is a porous ceramic having a water absorption of 5 to 15%. 8. The pressure-type composite electrode according to claim 1, wherein the internal liquid is an aqueous solution or a gel liquid. 9. The pressure-type composite electrode according to claim 8, wherein the gel-like liquid is a potassium chloride solution gelled with hydroxyethyl cellulose, carboxymethyl cellulose, or acrylamide polymer.