JPH0754849Y2 - Composite electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a composite electrode for measuring water quality such as pH by combining a measurement electrode and a reference electrode.
The present invention relates to a composite electrode preferably used for measuring the water quality in a place where a pressure difference occurs between the inside and outside of an electrode such as the ocean and a river.

[Conventional technology]

Conventionally, an inner support is disposed along the axial direction in the hollow portion of the outer cylinder, and a measurement electrode such as a glass electrode or an ion selective electrode is attached to the sample water at the tip of the inner support. In addition, the inner electrode of the reference electrode is placed between the outer cylinder and the support to enclose the reference electrode internal liquid, and the reference electrode internal liquid is continuously discharged from the liquid junction into the sample water. There is known a composite electrode for measuring water quality such as pH and various other ion concentrations in a standing state.

In the above-mentioned composite electrode, the pressure from the sample water always acts on the liquid junction, and there is a problem in the internal liquid outflow from the liquid junction especially when the pressure is high.

To solve this problem, when only the tip detector is immersed in the sample water for measurement, the internal solution replenishment hole is normally opened and the internal solution is allowed to diffuse into the sample water by the gravity of the internal solution column. However, if the sample water pressure is high,
Measures such as pressurizing with instrument air are taken.

However, when the whole electrode is thrown into the sample water for measurement in the ocean, river, etc., the above measures cannot be taken. Therefore, the structure shown in FIG. 4 has been conventionally used.

That is, in the composite electrode of FIG. 4, a is a tubular inner support, b is a glass electrode film provided at the tip of the inner support a, c is a glass electrode inner electrode disposed in the electrode film b, and d is Liquid inside the glass electrode, e is an outer tube provided around the support a, and f is an elastic body for pressure compensation fixed by fixing bands g and h between the tip of the outer tube e and the tip of the support a. A tube, i is an inner electrode of the reference electrode arranged between the support a and the tube f, j is a liquid inside the reference electrode, k is a liquid junction portion made of a porous body provided at the lower end of the outer tube e, l Is a cap, m
Indicates a lead wire. In this device, the inner support a and the outer tube e are each formed of a rigid body such as glass, and the liquid junction k is fixed to the outer tube e by welding or the like. Further, when injecting the reference electrode internal liquid j,
First, the internal liquid j is injected from between the lower end of the tube f and the support tube a, and then the lower end of the tube f is fixed to the support tube a with a fixing band h.

When the composite electrode of FIG. 4 is submerged in the ocean or the like, the pressure compensation elastic tube f expands and contracts to balance the pressure inside and outside the electrode in accordance with the water depth, and from the liquid junction k to the comparison electrode internal liquid j. Is to flow out of the electrode due to diffusion.

[Problems to be solved by the device]

However, the composite electrode shown in FIG. 4 has the following drawbacks. That is, in general, the liquid junction of the electrode needs to be located as close as possible to the lower end of the electrode because of the use of the calibration liquid, but the electrode of FIG. Since the elastic tube f is connected to the lower end of e, the surface area of the elastic tube f is necessarily small due to the positional relationship of the liquid junction. Therefore, the compensation range of the pressure by the tube f is narrow, and the pressure is not sufficiently compensated at some measurement points, which may cause inconvenience in measurement.

Inner support a and outer tube e supporting the elastic tube f
Since it is formed of a rigid body, a large stress is applied to the elastic tube f due to a rapid pressure change or the flow rate of the sample water, and the elastic tube f is easily damaged.

When measuring the water quality of sample water flowing in a river, a boundary film is formed near the surface of the electrode device, and the sample water in this part becomes a laminar flow state, so the outer surface of the measurement electrode is easily contaminated by the components in the sample water. , Inconvenience may occur in measurement.

Since the structure is such that the internal liquid j of the reference electrode cannot be replenished,
Even if the internal liquid j is exhausted or the sample water flows into the internal liquid j through the liquid junction k and is contaminated, the internal liquid j cannot be replenished or replaced. Therefore, the life of the electrode is limited.

Since the liquid junction k is sealed in the outer tube e by welding or the like, the liquid junction k cannot be replaced even if the liquid junction k becomes dirty and clogged.

Furthermore, an electrode that is pressurized with instrument air requires instrument air equipment, and an electrode that seals the internal liquid relies only on the diffusion of the internal liquid from the liquid junction, so that the sample water Each has the disadvantage that there is an influx of.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a composite electrode that solves the above-mentioned problems, particularly the problems (1) to (3).

[Means for Solving the Problems]

According to the present invention, in order to achieve the above object, an inner support is disposed in the hollow portion of an outer cylinder along the axial direction, and a measurement electrode is provided at the tip of the inner support and a detection end of the measurement electrode contacts sample water. In addition, the inner electrode of the reference electrode is placed between the outer cylinder and the support to enclose the reference electrode internal liquid, and the reference electrode internal liquid is continuously discharged from the liquid junction into the sample water. In a composite electrode for measuring water quality in the above state, there is provided a composite electrode in which a peripheral wall portion of the outer cylinder is formed of a thin elastic body and an inner support is formed of an elastic body.

In this case, silicone rubber, viton rubber, chloroprene rubber, nitrile rubber or the like can be preferably used as the material of the elastic body forming the peripheral wall portion of the outer cylinder and the internal support.

Also, the thickness of the peripheral wall of the outer cylinder is 0.3 to 0.6 mm, and the length is 100 to 1
It is preferably about 50 mm.

[Action]

In the composite electrode of the present invention, since the entire peripheral wall of the outer cylinder is formed of a thin elastic body, the surface area of the elastic body is large, and therefore the pressure balance should be ensured even when the pressure difference between the inside and outside of the electrode is large. You can In addition, since the peripheral wall of the outer cylinder and the inner support are both made of elastic material, the entire electrode section has flexibility, and therefore the outer cylinder and the inner cylinder are protected against the flow of sample water and sudden pressure changes. The support is flexible. Therefore, it is difficult to apply strong stress to the peripheral wall of the outer cylinder,
The outer peripheral wall is not easily damaged. Further, since the peripheral wall portion of the outer cylinder and the inner support are elastic bodies, the outer cylinder and the inner support constantly vibrate in the flow of the sample water. Therefore, even if a boundary film is formed on the outer surface of the measurement electrode, this boundary film is not stable, and the surface of the measurement electrode is unlikely to be soiled.

Next, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples.

〔Example〕

1 to 3 show a pH measuring composite electrode according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a substantially cylindrical outer cylinder made of silicone rubber. The outer cylinder 1 has a structure in which a thick wall portion 1b is integrally connected to the lower end of a thin peripheral wall portion 1a. The peripheral wall portion 1a of the outer cylinder 1
The lower part of the cylindrical holder 2 is inserted into the upper end opening of the outer holder 1 so that the outer cylinder 1 is held by the holder 2. A liquid junction insertion hole 3 is formed in the thick portion 1b along the axial direction, and a cylindrical liquid junction 4 made of a porous body is detachably inserted into the insertion hole 3.

In the figure, reference numeral 4 denotes a substantially columnar internal support made of silicone rubber, and the upper part of the support 5 is inserted into the hollow portion of the holder 2 and held by the holder 2.
The lower portion is liquid-tightly inserted into the hollow portion of the thick portion 1b of the outer cylinder 1, whereby the support 5 is arranged in the outer cylinder 1. An electrode insertion hole 6 and a protective tube insertion hole 7 are formed in the lower portion of the support body 5, and the glass electrode film 8 is formed in these insertion holes 6 and 7.
Also, the temperature compensating element protection tube 9 is inserted in a liquid-tight manner with its tip portion protruding, and at the upper part of the support body 5, a lead wire which communicates with the insertion holes 6 and 7 and reaches the upper end surface. The insertion holes 10 and 11 are formed, and the lead wires 12 and 13 of the electrode film 8 and the protective tube 9 are inserted into the insertion holes 10 and 11, respectively.

Further, in the figure, 14 is the reference electrode inner electrode attached to the outer surface of the inner support 5, 15 is the reference electrode inner liquid injected into the space between the outer tube 1 and the inner support 5, and 16 is the outer tube. An internal liquid replenishing port formed in the holder 2, 17 is a plug of this replenishing port, and 18 is an outer cylinder 1.
A ring-shaped protective cylinder detachably attached to the tip of the
19 is a holding stand, 20 is a tightening screw, 21 is a washer, 22 is a packing, and 23 is a lead wire.

Since the method of using the composite electrode of the present embodiment is the same as the conventional pH measuring electrode, its description is omitted, but the electrode of the present embodiment is not only used when submerged in the sample water, but also only at the tip detection part. Even when dipped in sample water, it can be suitably used without requiring equipment such as instrumentation air.

When the electrode of the present example is used for measuring a portion where a pressure difference is generated between the inside and outside of the electrode, this electrode is a large electrode because the entire peripheral wall portion of the outer cylinder is formed of a thin elastic body having elasticity. In addition to being able to compensate for the pressure difference between the inside and outside, the internal support is also made of an elastic material, so the electrode part flexibly responds to the flow of sample water and sudden pressure changes, and the peripheral wall of the outer cylinder Since strong local stress is unlikely to be applied to the outer cylinder, the outer cylinder is less likely to be damaged. Moreover, since both the outer cylinder and the inner support are elastic bodies, the detection end constantly vibrates when measuring the water quality of the flowing sample water, and the measurement electrode surface is less likely to be contaminated due to the boundary film.

Also, in this electrode, the outer cylinder holder is provided with an internal liquid replenishment port so that the internal liquid can be replenished and exchanged. Even if the internal liquid is contaminated by flowing back from the internal liquid, the internal liquid can be easily replaced.

Furthermore, since the liquid junction is detachably attached, the liquid junction can be replaced even if the liquid junction is clogged due to dirt or the like.

Although the glass electrode for pH measurement was used as the measuring electrode in the above-mentioned examples, various ion electrodes and the like may be used. Further, the peripheral wall portion of the outer cylinder may be formed in a bellows shape or the like, and other configurations may be variously changed without departing from the scope of the present invention.

[Effect of device]

As described above, the composite electrode of the present invention has the following effects a to c.

a. Since the surface area of the pressure compensating elastic body (outer cylinder peripheral wall portion) is large, the pressure compensating range is wide, and therefore the water quality of the sample water at various points can be stably measured.

b. Since the pressure compensating elastic body is less likely to be stressed, the elastic body is less likely to be damaged.

c. Since the outer cylinder and the internal support constantly vibrate in the flow of sample water, dirt does not easily adhere to the surface of the measurement electrode, and accurate measurement can be performed.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a sectional view, FIG. 2 is a front view, FIG. 3 is a bottom view, and FIG. 4 is a conventional pH measuring composite electrode. It is sectional drawing which shows an example. 1 ... Outer cylinder, 1a ... Peripheral wall 5 ... Internal support, 8 ... Glass electrode film 14 ... Reference electrode inner pole, 15 ... Reference electrode internal liquid

Claims (1)

[Scope of utility model registration request] 1. An inner support is disposed in the hollow portion of an outer cylinder along the axial direction, and a measuring electrode is attached to the tip of the inner support so that the detection end of the inner support contacts the sample water. The inner electrode of the reference electrode is placed between the outer cylinder and the support to enclose the reference electrode internal liquid, and the water quality is measured while the reference electrode internal liquid is continuously discharged from the liquid junction to the sample water. In the composite electrode for carrying out the above, the outer wall of the outer cylinder is formed of a thin elastic body, and the inner support is formed of an elastic body.