JPH09288083A - Calibration method of residual chlorine meter and residual chlorine meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly accurate measurement by a method wherein a current value is stored when a reference liquid with zero chlorine flows into a container and the current value stored is added to the current value obtained to correspond to the zero chlorine when a zero calibration is performed with the inside of the container empty. SOLUTION: A reference liquid S1 such as dechlorinated solution flows into a container 4, a fixed voltage Va is applied to a detection electrode 5 and a counter electrode 6, stirring up the liquid. A current value ib during the application of the voltage is measured by an ammeter 8 to be stored into a memory 18. In the zero calibration, the fixed voltage Va is applied to the electrode 5 and the counter electrode 6 in an open state of input with the inside of the container 4 being empty and a current value ic during the application of the voltage is measured by the ammeter 8. An arithmetic device 19 adds up the current values ib and ic and the concentration of chlorine is shown on a display device 9 corresponding to the added current value ib+ic. A calibration is performed by adjusting the device 9 to display the zero of the concentration of residual chlorine. Current value id is obtained using a solution S2 to be inspected with the known concentration thereof to perform a span calibration. This enables highly accurate zero calibration simply.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for calibrating a residual chlorine meter and a residual chlorine meter.

[0002]

2. Description of the Related Art As a conventional residual chlorine meter, there is one using a polarographic method as shown in FIG.

In the residual chlorine meter 1, a detection electrode (gold electrode) 5 is provided at the bottom in a sealed container 4 having an inlet 2 for the test liquid S formed at the lower part and a discharge port 3 formed at the upper part. A counter electrode (silver / silver chloride electrode) 6 is disposed in a state of being inserted into the upper part of the container 4 from the side, and a voltage is applied to the outside of the closed container 4 between the detection electrode 5 and the counter electrode 6. A power supply 7 and a current meter 8 for measuring the magnitude of the current are provided. The display device 9 is connected to the ammeter 8 to recognize and display the current value measured by the ammeter 8 as the residual chlorine concentration.

An external drive unit 1 is provided inside the closed container 4.
Stirring blade 1 fixedly attached to the lower end of drive shaft 11 hung vertically from 0
2 is provided and is filled with a beaded abrasive material 13 such as ceramic beads for polishing the surface of the detection electrode 5 to prevent sensitivity deterioration, and a thermistor 14 for measuring the temperature of the test liquid S and performing temperature compensation is provided. ing.

In this structure, the inlet 2 to the outlet 3
The test liquid S is circulated toward the test liquid S, the test liquid S in the closed container 4 is stirred by the stirring blade 11, and a constant voltage Va is applied between the detection electrode 5 and the counter electrode 6 by the power supply 7. The magnitude ia of the current at that time is measured by the ammeter 8 and the measured current value is recognized and displayed as the residual chlorine concentration on the display device 9.

The principle of measuring the residual chlorine concentration is as follows. When a voltage is externally applied between the detection electrode 5 and the counter electrode 6 in the test liquid S containing chlorine, a reduction reaction of Cl ₂ + 2e ⁻ → 2Cl ⁻ occurs on the detection electrode 5, as shown in FIG. Such a current-voltage curve (polarogram) depending on the chlorine concentration is obtained. As is clear from FIG. 3, in the current-voltage curve, when the applied voltage is changed to lower the potential of the detection electrode with respect to the counter electrode, the reaction rate increases and the current increases (region (1)). When the potential is further lowered, the current value does not change at all (region (2)).

This is because if the reaction rate becomes sufficiently fast (infinite), the diffusion of chlorine toward the detection electrode where chlorine is reduced and consumed cannot keep up with the reaction, and the diffusion rate dominates the reaction. Therefore, if the diffusion rate is kept constant, the reduction reaction of chlorine on the detection electrode will occur in proportion to the chlorine concentration in the test liquid, and the current of a magnitude corresponding to the reduction reaction, that is, This is because a current having a magnitude proportional to the chlorine concentration flows. For this reason, when measuring the residual chlorine concentration, apply a voltage of an appropriate magnitude that makes the reaction rate sufficiently fast (infinite) and keep the test solution at a constant rate so that the diffusion rate becomes constant. I'm trying to stir in.

[0008]

By the way, when measuring the residual chlorine concentration in the liquid to be inspected by the above-mentioned residual chlorine meter, it is necessary to calibrate the residual chlorine meter prior to the measurement. As the method, a zero calibration is performed with the container open and the input is open, and a span calibration is performed using the test liquid whose concentration has been previously analyzed by another analysis method, and a zero standard that does not contain chlorine. There is a standard solution calibration method in which zero calibration is performed using a solution and span calibration is performed using a span standard solution containing a known concentration of chlorine.

In order to accurately measure the residual chlorine concentration, the standard solution calibration method should be carried out.
Dechlorination water as a zero standard solution must be prepared, or a unit capable of preparing dechlorination water must be attached to the residual chlorine meter, and the standard solution calibration method requires more labor and cost than the general calibration method. There is a problem.

There is also a problem that the standard solution calibration method requires a longer working time than the general calibration method. Therefore, it is a technical subject to ensure the measurement accuracy equivalent to that of the standard solution calibration method by the general calibration method.

[0011]

In order to solve the above-mentioned problems, the method for calibrating a residual chlorine meter of the present invention is to circulate a test liquid in a certain direction in a container provided with a detection electrode and a counter electrode, While stirring the liquid to be inspected in the container, apply a constant voltage between the detection electrode and the counter electrode, measure the magnitude of the applied current with an ammeter, and recognize the measured current value as the residual chlorine concentration. When calibrating the residual chlorine meter configured to do so, the zero standard solution containing no chlorine is preliminarily circulated in the container, the current value at that time is stored, and the container is emptied in the input open state. When performing zero calibration,
The current value is measured in the input open state, the previously stored current value is added to the measured current value, and the added current value is made to correspond to zero chlorine concentration.

In the residual chlorine meter of the present invention, the liquid to be inspected is circulated in a fixed direction in a container having a detection electrode and a counter electrode therein, and the liquid to be inspected in the container is agitated while the detection electrode and the counter electrode are connected to each other. A constant voltage is applied between the two, and the magnitude of the applied current is measured with an ammeter, and in the residual chlorine meter configured to recognize the measured current value as the residual chlorine concentration, connect it to the ammeter. A storage means for storing a current value when a zero standard solution containing no chlorine is circulated in the container, and a storage means for storing a current value measured in an input open state in which the container is empty. And a calculation means for adding the current values stored by.

In the residual chlorine meter as described above, generally, in the same manner as the liquid to be inspected, a zero standard liquid containing no chlorine is circulated in the container and the liquid to be inspected in the container is agitated while the detection electrode is being stirred. When a constant voltage is applied between the counter electrode and the counter electrode, and the magnitude of the current at the time of application is measured by an ammeter, the measured current value is the shape of the container, the shape of the detection electrode and the counter electrode,
It is a unique value determined by conditions such as the arrangement of the detection electrode, the counter electrode, and other members.

Therefore, the zero standard solution containing no chlorine is circulated in the container in advance, the current value at that time is stored in the storage means, and the stored current value is input in an open state with the container empty. By adding the measured current value to the measured current value and making the added current value correspond to a chlorine concentration of zero, zero calibration can be performed almost in the same manner as introducing the zero standard solution into the container.

[0015]

Embodiments of the present invention will be described below. In FIG. 1, the residual chlorine meter according to the embodiment of the present invention has substantially the same configuration as the conventional residual chlorine meter described with reference to FIG. The same reference numerals are given and the description is omitted.

The residual chlorine meter 15 of this embodiment differs from the conventional one in that the ammeter 8 is connected to the ammeter 8 by lines 16 and 17, and a memory device 18 and an arithmetic unit 19 are provided. Is connected by a line 20, and the arithmetic unit 19 is connected by a line 21 to the display device 9.

The operation of the above configuration will be described. In the residual chlorine meter 15, the zero standard solution S ₁ containing no chlorine such as dechlorinated water is circulated in the container 4 in the same manner as in the method for measuring the residual chlorine in the liquid S to be inspected as described above. While stirring the zero standard solution, the constant voltage Va is applied between the detection electrode 5 and the counter electrode 6, and the magnitude of the current at the time of application is measured by the ammeter 8. The measured current value ib is stored in the storage device 18.

When performing zero calibration before measuring the residual chlorine in the liquid to be inspected, the voltage Va is applied between the detection electrode 5 and the counter electrode 6 in an input open state in which the container 4 is empty. The voltage is applied and the magnitude of the applied current is measured by the ammeter 8.

Then, when the magnitude of the current is measured in the input open state, the measured current value ic and the current value ib stored in the storage device 18 are added in the arithmetic unit 19, and the added current is added. Since the residual chlorine concentration corresponding to the value (ib + ic) is displayed on the display device 9, the display device 9 is adjusted and calibrated so that zero residual chlorine concentration is displayed.

After that, the current value id is obtained by using the test liquid S ₂ whose concentration has been previously analyzed by another analysis method, and span calibration is performed. In the above method, the current value when a zero standard solution containing no chlorine is circulated depends on conditions such as the residual chlorine meter, the shape of the container, the shape of the detection electrode and the counter electrode, the arrangement of the detection electrode and the counter electrode and other members. Since it is a unique value determined by, the current value is obtained and stored in advance.
This is used for zero calibration in the general calibration method.

This makes it possible to perform zero calibration almost as easily as the standard solution calibration method in which a zero standard solution is introduced, though it is a simple operation equivalent to the zero calibration of the general calibration method. Prepare dechlorinated water as liquid,
It is not necessary to equip the residual chlorine meter with a unit capable of preparing dechlorinated water, and the working time is shortened.

[0022]

As described above, according to the present invention, the current value when a constant voltage is applied by flowing zero standard liquid such as dechlorinated water is stored, and this current value is stored in the general calibration method. By using it for zero calibration in, it is possible to perform zero calibration almost equivalent to the standard solution calibration method. As a result, it is possible to secure higher measurement accuracy than the conventional calibration method, and prepare dechlorinated water or install a unit that can prepare dechlorinated water at each zero calibration compared to the standard solution calibration method. Since it is not necessary, the labor and cost can be reduced, and the working time can be shortened.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a residual chlorine meter according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an overall configuration of a conventional residual chlorine meter.

FIG. 3 is a current-voltage curve of a liquid to be inspected for explaining the basic measurement principle in the conventional and the residual chlorine meters of the present invention.

[Explanation of symbols]

4 container 5 detection electrode 6 counter electrode 8 ammeter 9 display device 15 residual chlorine meter 18 storage device 19 arithmetic unit Va constant voltage S inspected solution ia current value S ₁ zero standard solution ib current value ic current value

Claims (2)

[Claims] 1. A test liquid is circulated in a fixed direction in a container provided with a detection electrode and a counter electrode, and a constant voltage is applied between the detection electrode and the counter electrode while stirring the test liquid in the container. Then, when measuring the magnitude of the applied current with an ammeter and calibrating the residual chlorine meter configured to recognize the measured current value as the residual chlorine concentration, a zero standard that does not contain chlorine in the container is used. When the liquid is circulated in advance and the current value at that time is stored and the zero calibration is performed in the open input state where the inside of the container is empty, the magnitude of the current is measured in the open input state and the measured current A method for calibrating a residual chlorine meter, characterized by adding the previously stored current value to the value and making the added current value correspond to a chlorine concentration of zero. 2. A test liquid is circulated in a fixed direction in a container having a detection electrode and a counter electrode inside, and a constant voltage is applied between the detection electrode and the counter electrode while stirring the test liquid in the container. Then, measure the magnitude of the applied current with an ammeter, and in the residual chlorine meter configured to recognize the measured current value as the residual chlorine concentration, connect it to the ammeter to store chlorine in the container. A storage means for storing a current value when a zero standard solution containing no liquid is circulated, and a current value when measured in an input open state in which the inside of the container is empty, the current value stored by the storage means is stored. A residual chlorine meter characterized by being provided with a computing means for adding.