JPH01254853A - Electrode for measuring conductivity - Google Patents

Abstract

PURPOSE:To enable conductivity measurement without receiving any influences from the resistance which is produced in the liquid outside an outer cylinder and variable by additionally providing an electrode for compensation to a four- terminal four-electrode electrode for conductivity measurement on the outside of the electrode array in the axial direction. CONSTITUTION:An electrode 1 for current detection, insulating cylinder 19, electrode 2 for voltage detection, insulating cylinder 18, electrode 3 for voltage detection, insulating cylinder 17, electrode 4 for current detection, insulating cylinder 16, and electrode 5 for compensation are arrayed in the described order. Then, by fixing one end of a short circuit electrode 22, the other end of which is screwed into the electrode 1 for current detection, to the electrode 5 for compensation with a metallic washer 21 and nut, an electrode rod is formed. The electrode 5 for compensation is screwed into the base section 10 of the electrode rod and each electrode is connected to a current and voltage detecting means through each electrode cable 11. Therefore, even if a considerable large bubble extracting hole is formed in the outer cylinder of the cell, this electrode rod can be made free from the influences of outside resistances.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a conductivity measuring electrode for measuring the conductivity of industrial water, sewage, etc. This invention relates to electrodes for rate measurement.

(Prior Art) As an electrode for measuring the conductivity of a liquid, a four-electrode conductivity measurement electrode using a four-terminal resistance measurement method is known.

FIG. 6 is a circuit diagram for explaining the principle of the four-terminal resistance measurement method.

A current I is applied to the resistor to be measured through current terminals C1 and C2.
is flowing, voltage terminal 1)1. Measure the voltage ■ occurring between p2.

The resistor thus constructed is called a four-terminal resistor (four-terminal resistor).
rminal resistor).

(2) and (2) are electrodes for current detection, and (2) and (2) are electrodes for voltage detection.

When the resistance of the voltmeter is high and the current flowing here is very small, no voltage is generated here even if there are resistances Rp+ and RP2 in the lead wires, so the voltage across R is equal to . Also, even if there is resistance in the circuit passing through the current terminal, the current passing through R is measured as I by an ammeter. Therefore R
R=V/I except for the shadow 1 of the resistor in all circuits except
A low value of resistance R can be obtained as follows.

Although the resistance R of liquid is not necessarily small,
Since the contact resistance between the electrode and the liquid is also large, a four-terminal resistance measurement method can be used.

FIG. 4 is a diagram showing a conventional 4-terminal, 4-electrode conductivity measuring electrode that is used by being put into an industrial water tank or the like.

Partially cut away to show internal structure.

FIG. 5 is an equivalent circuit diagram for explaining the operation of the conventional four-terminal, four-electrode conductivity measuring T4 shown in FIG.

The base 30, the electrodes 1 to 2, and the electrode rod formed from the insulating cylinders 36, 37, and 38 are integrally provided.

An outer cylinder 32 is coupled to a threaded portion 30a provided on the base 30.

As described above, when this electrode is put into a tank or the like filled with a liquid to be measured, the liquid to be measured fills the cylindrical space between the outer cylinder 32 and the electrode rod.

2 and 3 are electrodes for current detection, to which the current I from the AC #IS is connected via the current detection means A.

(2) and (2) are electrodes for voltage detection, and the voltage drop between them is detected by the voltage detection means (2), and the resistance or conductivity of the liquid is measured according to the above-mentioned principle.

RsL Rs2+ Rs3. Rs4 is the contact resistance formed on the surface of each electrode (1) to (2).

R12 is the resistance value of the liquid in the outer cylinder 32 between the electrode ■ and 0 (excluding the contact resistance value, the same applies hereinafter), R23 is the resistance value of the liquid in the outer cylinder 32 between the electrode ■ and 0, R34
is the resistance value of the liquid in the outer cylinder 32 between the electrodes ① and 0.

To calculate the conductivity, the indicated values of the voltage detecting means (1) and the current detecting means 11fiA described above and a cell constant determined by the geometric shapes of the electrode and the outer cylinder are used.

(Problem to be Solved by the Invention) The outer cylinder 32 of the electrode described above has air bubble holes 33a to 33d, 3.
4a to 4d are provided, and the structure is such that air bubbles, etc. generated or invaded inside the cylinder can escape without adhering to the periphery of the electrode.

However, due to the presence of the bubble vent holes 33a-d, 34a-d, a fifth resistance RL4 is generated between the electrodes 1 and 0, as shown in FIG.

This resistance R14 changes depending on the position where the outer cylinder 32 is placed. It also changes when the electric field within the tank container fluctuates, and the cell constant is affected by the outside world.

An object of the present invention is to provide an electrode for measuring conductivity that enables measurement without being influenced by the variable resistance generated in the liquid outside the outer cylinder.

(Means for Solving the Problems) In order to achieve the above object, the electrode for measuring conductivity according to the present invention has a current measurement method for measuring the conductivity of a liquid in an outer cylinder having a bubble removal hole and forming a cell space. In a 4-terminal, 4-electrode conductivity measurement electrode in which an electrode bar is arranged in which a pair of terminals for power and voltage measurement are arranged in the axial direction, there is further provided an electrode on the outside of the axial arrangement of the electrode group. A fifth electrode is provided, and this fifth electrode is connected to a current electrode located at a more distant position in the electrode group.

(Example) The present invention will be described in more detail below with reference to the drawings and the like.

FIG. 1 is a sectional view showing an embodiment of a 4-terminal, 5-electrode conductivity measuring electrode according to the present invention.

Electrode for current detection■, insulating tube 19, electrode for voltage detection■
, an insulating cylinder 18, a voltage detection electrode (2), an insulating cylinder 17, a current detection electrode (2), an insulating cylinder 16, and a compensation electrode (fifth electrode) (5) are arranged in this order.

Then, the other end of the shorting metal rod 22, whose tip is connected to the current detection electrode ■ with a screw, is fixed to the compensation electrode (fifth electrode) ■ with a fully bent washer 21 and a nut. form.

Further, the short-circuiting metal rod 22 short-circuits the electrodes (1) and (2) inside the electrode rod.

For compensation? The electrodes 1 and 2 are screwed to the base 10, and each electrode is connected to a cable 11 as shown in FIG. 2 and connected to voltage and current detection means.

Cell outer cylinder 12 with bubble vent holes 13a-d, 14a-d
is threadedly coupled to the compensation electrode (2).

Note that the base 11 and the inside of the electrode rod are filled with resin.

FIG. 2 is an equivalent circuit diagram for explaining the operation of the 4-terminal, 5-electrode conductivity measuring electrode shown in FIG. 1 according to the present invention.

Rsla + Rslb are the contact resistances formed between the electrode for current detection and the liquid (for ease of understanding, they are shown separately for each branch formed in the external liquid. Below The same shall apply.)

Rs2a and Rs2b are contact resistances formed between the voltage detection electrode ■ and the liquid, respectively, and R53a+R
s3b is a contact resistance formed between the voltage detection electrode (2) and the liquid.

R54a and R54b are contact resistances formed between the current detection electrode ■ and the liquid, respectively, and R55a+R
s5b is the contact resistance formed between the compensation electrode (2) and the liquid.

R12 is the resistance value of the liquid in the outer cylinder 32 between the electrode ■ and 0 (excluding the contact resistance value, the same applies hereinafter); R23 is the resistance value of the liquid in the outer cylinder 32 between the electrode ■ and 0; R34 is the resistance value of the liquid in the outer cylinder 32 between the electrode ■ and 0, R45
is the resistance value of the liquid in the outer cylinder 32 between the electrodes ① and 0.

In this embodiment as well, air vent holes 13a-d, 14 are provided in the cell outer cylinder 12 as in the conventional example shown in FIGS. 4 and 5.
Although electrodes a-d are formed, R5 is formed between electrode ■ and electrode 0.
5a, R15, and R51b are formed.

Similar to the conventional example described above, R15 changes depending on the position, such as when the electrode is placed near the wall of the tank or at the center.

It also changes when the electric field inside the tank container outside the cell outer cylinder 12 changes.

However, both ends of this resistor R15 are Rs5a and R
Since it is short-circuited by the short-circuit metal rod 22 via slb,
This variation in resistor R15 has no effect on the detected values of the voltage and current detection means.

In addition, R s5b and R formed inside the cell outer cylinder
A circuit of 45°Rs4a will be connected in parallel between terminals ■ and 0.

This resistance component is not influenced by the external world as described above, and is only a factor in determining the cell constant and is not an unstable factor.

Various modifications can be made to the embodiments described in detail above within the scope of the present invention.

FIG. 3 is a diagram showing the electrode rod of the electrode of the above-mentioned example in approximately the actual size.

The electrode positions are DI, D2. D3. D4. It is indicated by D5.

In the embodiment described above, the electrode is the DI as indicated by I.

D2, D3, D4. D5 is made to correspond to ■, ■2■, ■, and ■ in this order.

This array is ■ [■, ■, ■, ■, ■], ■ [■.

■, ■, ■, ■], ■ [■, ■, ■, ■, ■] can also be made to correspond.

(Effects of the Invention) As explained in detail above, the electrode for measuring conductivity according to the present invention is suitable for current measurement and voltage measurement for measuring the conductivity of a liquid in an outer cylinder having bubbles and pores and forming a cell space. In the 4-terminal, 4-electrode conductivity measurement electrode in which electrode rods each having a pair of measurement terminals arranged in the axial direction are arranged, a fifth electrode is further provided outside the axial arrangement of the electrode group. is provided, and this fifth electrode is connected to a current electrode located at a more distant position in the electrode group.

Thereby, even if a bubble removal hole of considerable size is formed in the cell outer cylinder, it can be prevented from being affected by resistance formed outside.

Therefore, the unstable factors of the electrode for measuring conductivity according to the present invention are almost eliminated, and it can be widely used in the field of measuring industrial water and controlling using the measurement results.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a 4-terminal, 5-electrode conductivity measuring electrode according to the present invention. FIG. 2 is an equivalent circuit diagram for explaining the operation of the 4-terminal, 5-electrode conductivity measuring electrode shown in FIG. 1 according to the present invention. FIG. 3 is a schematic diagram showing a modification of the electrode arrangement. Figure 4 is a cross-sectional view showing an example of a conventional 4-terminal, 4-electrode conductivity measuring electrode. Figure 5 is an operation of the conventional 4-terminal, 4-electrode conductivity measuring electrode shown in Figure 3. FIG. 2 is an equivalent circuit diagram for explaining. FIG. 6 is a circuit diagram for explaining the principle of the four-terminal resistance measurement method. ■, ■... Electrode for current detection ■, ■... Electrode for voltage detection ■... Compensation electrode (fifth electrode) 10... Base 11... Cable 12... Cell outer cylinder 13.14...bubble vent hole 16.1? , 18.19...Insulating cylinder 20...Nand 21...Metal washer 22...Short circuit full bending 30...Base 31...Cable 32...Cell outer cylinder 33.34...・Bubble vent hole patent applicant Nikoku Kikai Kogyo Co., Ltd. Representative Patent Attorney Hisashi Inoro Figure 3 Figure 4 Figure 5 Figure 6 Procedural Amendment 1, Indication of Case 1985 Patent No. 83373 2. Name of the invention Conductivity 411 Regular electrode 3. Person making the amendment Relationship to the case Patent expert 4. Agent 7. Contents of the amendment (1) Page 7, line 8 to 10 of the specification. Line [cJ￥g
... [1 ■ Information and Procedure NejIT Right and Wrong 1 Office June 17, 1963] I%11163 Patent Application No. 83373 2, Name of Invention Electrical Conductivity All Constant JTJ Electrode 3, Amendment Relationship with the case of the person who issued the patent 4, agent

Claims (1)

[Claims] Four terminals 4 in which electrode rods each having a pair of terminals for current measurement and voltage measurement for measuring the conductivity of the liquid are arranged in the axial direction in an outer cylinder having a bubble vent hole and forming a cell space. In the electrode for measuring the conductivity of an electrode, a fifth electrode is further provided outside the axial arrangement of the electrode group, and this fifth electrode is connected to a current electrode located at a more distant position in the electrode group. An electrode for measuring conductivity, characterized in that it is configured as follows.