JPH0729486Y2 - Residual chlorine meter - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a residual chlorine meter with an automatic calibration function.

<Prior Art> Conventionally, automatic calibration has not been performed in a residual chlorine meter. Conventional calibration methods include ortho-tolidine method (OT method), diethyl-p-phenylenediamine method (DPD method), iodometric titration method, amperometric titration method, etc. It is calibrated so that the indicated value of the residual chlorine meter agrees with this measured value. Calibration work by manual analysis is complicated and time-consuming.

The main reason why automatic calibration is not possible with a residual chlorine meter is that chlorine water as a calibration standard solution is unstable and its concentration changes over time, so chlorine water cannot be stored for a long time.

<Problems to be Solved by the Invention> A technical problem to be solved by the present invention is to enable automatic calibration in the residual chlorine meter without resorting to complicated manual analysis.

<Means for solving the problem> In order to achieve such an object, the present invention measures the effective chlorine concentration in the measurement solution in a residual chlorine meter for measuring the effective chlorine concentration in the measurement solution by a polarographic method. Sensor, a salt water supply means for supplying a constant concentration of NaCl aqueous solution, a purified water supply means for supplying purified water, and a predetermined amount of NaCl aqueous solution introduced from the salt water supply means is electrolyzed to generate a constant concentration of available chlorine. Standard solution generating means, a constant current source for supplying a constant current for electrolysis between electrodes provided in the standard solution generating means, purified water supplied from the purified water supply means and supplied from the standard solution generating means A flow path through which the calibration standard solution is flowed, and a flow path switching means for connecting the flow path through which the measurement solution flows to the sensor by switching, and performing calculation on the detection signal from the sensor. Provided with a calculation control unit for generating a seed control signal, while performing a zero calibration of the sensor based on the purified water supplied to the sensor from the purified water supply means through the flow path switching means, to the calibration standard solution It is characterized by performing span calibration based on the above.

<Operation> The above technical means operates as follows. That is, when a calibration start signal is applied, a predetermined amount of purified water and a NaCl aqueous solution are introduced from the purified water supply means and the salt water supply means into the standard solution generating means, and the standard solution generating means is filled with a NaCl solution having a constant concentration. . The NaCl aqueous solution is stable and its concentration does not change with time. After that, an electric current is caused to flow between the electrodes in the standard liquid generating means for a certain period of time from the constant current generating source to generate a certain amount of available chlorine by electrolysis. As a result, the calibration standard solution having a constant effective chlorine concentration is stored in the standard solution generating means, and the calibration standard solution is flowed to the sensor for automatic calibration.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the basic configuration of the apparatus of the present invention. In the figure, 1 is a flow path through which the solution to be measured M is supplied, 2 is a three-way solenoid valve that switches between the flow path 1 and the flow path 3 through which the calibration standard solution S is flown, and 4 is on the downstream side of the three-way solenoid valve 2. The constant flow pumps 5 provided are residual chlorine sensors for measuring the effective chlorine concentration in the measurement liquid by the polarographic method, and the drainage is discharged from the flow path 6.

7 is a salt water supply means for supplying a constant high concentration NaCl aqueous solution,
Reference numeral 8 is purified water supply means for supplying purified water, and 9 is salt water supply means 7.
And a predetermined amount of NaCl aqueous solution and purified water are introduced from the purified water supply means 8, the metal inert electrode pair is immersed in the mixed solution thereof, and the standard solution generation means for obtaining available chlorine (standard chlorine) at a constant concentration is used. is there. The NaCl aqueous solution may be used as it is without being diluted with purified water. In this case, the two-way solenoid valve shown in FIG. 2 is closed. 10 is a constant current source for supplying a constant current between the electrodes of the standard solution generating means, 11 is various kinds of arithmetic processing (including sensitivity adjustment) on the detection signal of the sensor 5,
This is an arithmetic control unit that gives a control signal to the constant current source 10, the three-way solenoid valve 2, and the like.

The basic operation of the device configured in this manner is to switch the three-way solenoid valve 2 to the flow path 1 side at the time of measurement and supply the measured liquid M to the sensor 5 by the constant flow rate pump 4. The detection output S ₁ from the sensor 5 is given to the calculation control unit 11 and subjected to various calculation processes, and then output as an instruction output S ₂ .

Calibration is performed as follows. When the signal for starting the calibration is input, the purified water from the purified water supply means 8 becomes the standard solution generating means 9 →
It is given to the sensor 5 through the three-way solenoid valve 2 → the constant flow pump 4. Zero adjustment is performed with this purified water.

When the zero adjustment is completed, a control signal is added from the arithmetic control unit 11 to the purified water supply means 8 and the salt water supply means 7, and a predetermined amount of purified water and NaCl aqueous solution are introduced into the standard solution generation means 9. After stirring to make the concentration uniform, the constant current source 10 is turned on, and a current is passed between the electrodes of the standard solution generating means 9 for a certain period of time. As a result, a certain amount of available chlorine is generated, and the standard solution generating means 9
A standard solution S for calibration having a constant effective chlorine concentration is stored in.
After that, the three-way solenoid valve 2 is switched to the standard liquid generating means 9 side,
The standard solution S is supplied to the sensor 5 to perform automatic calibration. In the automatic calibration, for example, sensitivity adjustment is automatically performed so that an instruction output corresponding to the effective chlorine concentration of the standard solution S is output. After calibration,
The three-way solenoid valve 2 is switched, the measured liquid M is supplied to the sensor 5 by the constant flow pump 4, and the measurement is returned to.

The specific configuration of the standard liquid generating means 9 will be described in detail with reference to the configuration diagram of FIG. In FIG. 2, elements that are substantially the same as the elements in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted. The part indicated by the broken line corresponds to the standard solution generating means 9 in FIG. 1, and the details of the configuration will be described below. Reference numeral 9a is a container of the standard solution generating means 9, and the inside is partitioned by a diaphragm 9b, which is electrically conductive like a Teflon film but does not allow molecules larger than a certain size to pass therethrough, forming chambers A and B. Has been done. Among them, the anode 9c is in the chamber A and NaCl is in the chamber B.
A cathode 9d is provided which is filled with an electrolytic solution.

12, 13 and 14 are flow paths connected to the chamber A, 15 is a stirrer for stirring the liquid in the container 9a, 16 is a three-way solenoid valve provided in the flow path 12, and the other two connection ports are salt water. It is connected to the supply means 7 and the drain 17. 18 is a two-way solenoid valve provided in the flow path 13,
Reference numeral 19 is a three-way solenoid valve provided in the flow path 14. Reference numeral 20 is a Cl ₂ remover, which is connected to the purified water supply means 8 via a pressure regulating valve 21. 22 and 23 are flow paths through which the purified water from which Cl ₂ has been removed by this Cl ₂ remover flows, and the flow path 22 is connected to the two-way solenoid valve 18 and the flow path 23
Is connected to a three-way solenoid valve 19. The other one of the connection ports of the three-way solenoid valve is connected to the three-way solenoid valve 2. twenty four
Is a flow meter provided between the three-way solenoid valve 2 and the constant flow pump 4.

With such a configuration, when the signal for starting the calibration is input, the three-way solenoid valves 19 and 2 are switched, and the purified water from the purified water supply means 8 is the Cl ₂ remover 20 → the three-way solenoid valve 19 → the three-way solenoid valve 2 → It is given to the sensor 5 through the constant flow pump 4. The filter 20 is filled with activated carbon, and the residual chlorine concentration of the purified water passing through this portion becomes zero. Zero adjustment is performed using this purified water.

At the same time, the two-way solenoid valve 18 is opened, the three-way solenoid valve 16 is opened in the direction of the drain 17, the purified water from the Cl ₂ remover 20 is introduced into the container 9a of the standard solution generating means 9, and the NaCl from the salt water supply means 7 is supplied. The aqueous solution is drained.

After a sufficient time has elapsed to fill the container 9a with purified water, the two-way solenoid valve 18 is closed and the three-way solenoid valve 16 is switched to the salt water supply means 7 side. Further, the three-way solenoid valves 19 and 2 are switched to form the flow path of the standard liquid generating means 9 → three-way solenoid valve 19 → three-way solenoid valve 2 → constant flow rate pump 4. The constant flow rate pump 4 is rotated for a certain period of time, and a certain amount of a high concentration NaCl solution is supplied from the salt water supply means 7 to the container.
Install in 9a. During this time, purified water is being supplied to the sensor 5 from the bottom of the standard liquid generating means 9.

The dilution rate of high-concentration NaCl is determined by the rotation time of the constant flow pump 4, and after this time has elapsed, the three-way solenoid valves 19 and ₂ are switched and the Cl ₂ remover 20 → three-way solenoid valve 19 → three-way solenoid valve 2 →
Flow purified water in the direction of constant flow pump 4 → sensor 5, and
The three-way solenoid valve 16 is switched to the drain 17 direction.

After stirring the solution in the container 9a with the stirrer 15 to make the NaCl concentration uniform, the constant current source 10 is turned on and a current is passed between the electrodes 9c and 9d for a certain period of time. As a result, a certain amount of Cl ₂
Occurs. Chlorine concentration depends on the energization time. still,
It has been experimentally confirmed that the chlorine concentration depends only on the energization time if the NaCl concentration is above a predetermined value.
The dilution ratio of NaCl does not matter so much.

After generating a certain amount of Cl ₂ , the three-way solenoid valves 19 and 2 are switched, and the standard liquid generating means 9 → three-way solenoid valve 19 → three-way solenoid valve 2 →
The flow path of the constant flow pump 4 → sensor 5 is formed, and the standard solution of known effective chlorine concentration is supplied from the standard solution generating means 9 to the sensor 5 to perform span calibration. After the calibration is completed, the three-way solenoid valves 19 and 2 are switched to supply the measured liquid M to the sensor 5 by the constant flow rate pump 4 and return to the measurement.

Since the inside of the container 9a is partitioned by the diaphragm 9b, the anode 9c
Cl ₂ generated in the reverse electrolysis at the cathode 9d, or the cathode 9d
It is not consumed by reacting with H ₂ generated at.

<Effects of the Invention> According to the present invention, a calibration standard solution with a constant effective chlorine concentration is stored by storing a stable and high-concentration NaCl aqueous solution whose concentration does not change with time and by electrolyzing chlorine as necessary. Since a stable calibration standard solution is obtained, automatic calibration can be performed. Furthermore, since the high-concentration NaCl aqueous solution is diluted and used, the frequency of replenishing the NaCl aqueous solution can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of the device of the present invention, and FIG. 2 is a configuration diagram showing the main part of the device of the present invention. 2: Three-way solenoid valve, 4: Constant flow pump, 5: Sensor, 7: Salt water supply means for supplying a constant high-concentration NaCl aqueous solution, 8: Purified water supply means, 9: Standard solution generation means, 9a: Container, 9b: Diaphragm, 9c: Anode, 9
d: cathode, 10: constant current source, 11: arithmetic control unit, 15: stirrer, 16:
Three-way solenoid valve, 17: Drain, 18: Two-way solenoid valve, 19: Three-way solenoid valve, 20: Cl ₂ remover

Claims (1)

[Scope of utility model registration request] 1. A residual chlorine meter for measuring the effective chlorine concentration in a measurement solution by a polarographic method, a sensor for measuring the effective chlorine concentration in the measurement solution, a salt water supply means for supplying an NaCl aqueous solution of a constant concentration, and purified water. And a standard solution generating means for electrolyzing a predetermined amount of NaCl aqueous solution introduced from the salt water supplying means to generate effective chlorine of a constant concentration, and an electrode provided between the standard solution generating means. A constant current source for flowing a constant current for electrolysis, a flow path through which purified water supplied from the purified water supply means and a calibration standard solution supplied from the standard solution generation means flow, and a flow of the measurement solution. The flow path switching means is provided with a flow path switching means for switching and connecting a path to the sensor, and a calculation control section for performing a calculation on a detection signal from the sensor and generating various control signals. A residual chlorine meter characterized by performing zero calibration of the sensor on the basis of purified water supplied to the sensor from the purified water supply means through the above, and performing span calibration on the basis of the calibration standard solution.