JPH04231856A - Method and apparatus for calibrating residual chlorine meter - Google Patents

Abstract

PURPOSE:To perform the span calibration of a residual chlorine meter over a long period of time. CONSTITUTION:A calibration apparatus 2 is constituted by connecting a span calibration liquid tank 8 and a zero point calibration tank 9 to the solvent pipe 4 between the membrane separation part 5 and an electric conductivity detector 7 by a T-shape calibration liquid pipe 10 and providing a change-over valve 11 and a cutoff value 12 to the calibration liquid pipe 10. A span calibration liquid 15 is prepared from a hydrochloric acid or sulfuric acid solution so as to show the change of electric conductivity same to that of electric conductivity due to the change of the concn. of residual chlorine.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for calibrating a residual chlorine meter used in water purification plants and the like.

0002

[Prior Art] Conventionally, when performing span calibration on this type of residual chlorine meter, it has been customary to prepare a span calibration solution using a sodium hypochlorite solution, etc., and use this span calibration solution as a standard for calibration. Span calibration was performed using

0003

[Problem to be Solved by the Invention] However, according to the conventional calibration method described above, the properties of residual chlorine in the span calibration solution are extremely unstable, so it is necessary to perform calibration immediately after preparing the span calibration solution. Therefore, there was a problem in that it was not possible to store span calibration liquid and automatically perform span calibration unattended for a long period of time.

The object of the present invention is to improve the conventional calibration method and solve these problems.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the method for calibrating a residual chlorine meter of the present invention involves gasifying residual chlorine dissolved in sample water and separating it from water and gas using a gas permeable membrane. In a residual chlorine meter that detects the residual chlorine concentration in sample water by dissolving it in a solvent and measuring the electrical conductivity of the solvent with an electrical conductivity detector, it is used as a span calibration solution for the electrical conductivity detector. , using a solution that shows the same change in electrical conductivity as a result of a change in the concentration of residual chlorine and that does not contain residual chlorine and has stable properties, This is used to calibrate the span of the rate detector.

In order to achieve the above object, the residual chlorine meter calibration device of the present invention communicates the middle of the sample water tube with the middle of the solvent tube through a gas permeable membrane. In a residual chlorine meter with an electrical conductivity detector installed on the downstream side of the sensor, a switching valve is installed between the gas permeable membrane of the solvent pipe and the electrical conductivity detector to connect the span calibration liquid tank and the zero point calibration liquid tank. The connection is selectable via the .

[0007]

[Operation] In order to perform span calibration of a residual chlorine meter using the calibration device configured as described above, a span calibration solution prepared from a solution that does not contain residual chlorine and has stable properties is stored in the span calibration solution tank, and a zero point calibration solution is stored in the span calibration solution tank. is stored in the zero point calibration liquid tank. First, connect the zero point calibration liquid tank to the solvent pipe using the switching valve, supply the zero point calibration liquid to the electrical conductivity detector, measure the electrical conductivity of the zero point calibration solution, and calculate the residual chlorine Set to zero concentration point. Next, use the switching valve to disconnect the zero point calibration liquid tank from the solvent pipe, connect the span calibration liquid tank to the solvent pipe, supply the span calibration liquid to the electrical conductivity detector, and measure the electrical conductivity of the span calibration liquid. Then, this electrical conductivity is set to the residual chlorine concentration of the corresponding conventional residual chlorine solution for span calibration. In this way, the span calibration of the residual chlorine meter is completed.Since the span calibration liquid of the present invention has stable properties, it can be stored for a long period of time. It can be done.

[0008]

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a residual chlorine meter, and 2 is a calibration device according to the present invention. The residual chlorine meter 1 connects the middle of the sample water tube 3 and the middle of the solvent tube 4 in a cylindrical membrane separation section 5 through a porous tube-shaped gas permeable membrane 6. An electrical conductivity detector 7 is interposed on the downstream side of the detector 5. The calibration device 2 also connects a span calibration liquid tank 8 and a zero point calibration liquid tank 9 to the middle of the solvent pipe 4 between the membrane separation section 5 and the electrical conductivity detector 7 through a T-shaped calibration liquid pipe 10. However, a switching valve 11 and a shutoff valve 12 are interposed in the calibration liquid pipe 10. The switching valve 11 selectively connects the span calibration liquid tank 8 and the zero point calibration liquid tank 9 to the solvent pipe 4, and the cutoff valve 12 opens and closes the calibration liquid pipe 10.

The residual chlorine meter 1 configured as described above gasifies the residual chlorine in the sample water 13 flowing through the sample water tube 3 with an acidic solution, and the gasified residual chlorine is passed through the gas permeable membrane 6 in the membrane separation section 5. The solvent 1 is separated into air and water and flows through the solvent pipe 4.
Dissolve in 4. The solvent 14 is pure water or an alkaline solution having a certain electrical conductivity. The residual chlorine concentration in the sample water 13 is then detected by measuring the electrical conductivity of the solvent 14 in which the residual chlorine is dissolved using the electrical conductivity detector 7.

[0010] Furthermore, in order to perform span calibration of the residual chlorine meter 1 using the calibration device 2 having the above configuration, a span calibration liquid 15 prepared from a solution containing no residual chlorine and having stable properties is added to the span calibration liquid tank 8 in advance. In addition to storing zero point calibration liquid 1
6 is stored in the zero point calibration liquid tank 9. Span calibration liquid 1
5 shows the same change in electrical conductivity as the conventional residual chlorine solution for span calibration prepared from sodium hypochlorite etc. shows as a result of a change in the residual chlorine concentration. It is prepared from potassium chloride solution etc. Furthermore, pure water or the like is used as the zero point calibration liquid 16. First, operate the switching valve 11, open the shutoff valve 12, connect the zero point calibration liquid tank 9 to the solvent pipe 4, supply the zero point calibration liquid 16 to the electrical conductivity detector 7, and perform zero point calibration. The electrical conductivity of the liquid 16 is measured, and this electrical conductivity is set at the point where the residual chlorine concentration is zero. Next, once the shutoff valve 12 is closed to disconnect the zero point calibration liquid tank 9 from the solvent pipe 4, the switching valve 11 is switched and the shutoff valve 12 is opened again to connect the span calibration liquid tank 8 to the solvent pipe 4. Span calibration liquid 15
is supplied to the electrical conductivity detector 7 to measure the electrical conductivity of the span calibration liquid 15, and this electrical conductivity is set to the residual chlorine concentration of the corresponding conventional residual chlorine solution for span calibration. In this way, the span calibration of the residual chlorine meter 1 is completed.

As mentioned above, the span calibration liquid 15 does not contain residual chlorine and has stable properties, so it can be stored for a long period of time.Therefore, the span calibration of the residual chlorine meter 1 can be automatically performed unattended for a long period of time. be able to.

0012

As described above, according to the present invention, as a span calibration solution for a residual chlorine meter, the electrical conductivity is the same as the change in electrical conductivity that a conventional residual chlorine solution for span calibration exhibits due to a change in the residual chlorine concentration. The span calibration solution can be stored for a long period of time because the change in rate is shown by the change in solution concentration and the solution is stable in properties and does not contain residual chlorine. Therefore, span calibration of the residual chlorine meter can be automatically performed unattended for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a calibration device for a residual chlorine meter showing an embodiment of the present invention.

[Explanation of symbols]

1 Residual chlorine meter 2 Calibration device 3 Sample water tube 4 Solvent tube 6 Gas permeable membrane 7 Electric conductivity detector 8 Span calibration liquid tank 9 Zero point calibration liquid tank 11 Switching valve 13 Sample water 14 Solvent 15 Span calibration liquid

Claims (2)

[Claims] [Claim 1] Residual chlorine dissolved in the sample water is gasified and separated into air and water using a gas permeable membrane, then dissolved in a solvent, and the electrical conductivity of the solvent is measured with an electrical conductivity detector. In a residual chlorine meter that detects the residual chlorine concentration in sample water, the span calibration solution for the electrical conductivity detector is a residual chlorine solution that has the same electrical conductivity as the change in electrical conductivity caused by a change in the residual chlorine concentration. A method for calibrating a residual chlorine meter, which is characterized by performing span calibration of an electrical conductivity detector using a solution that indicates changes in solution concentration and is stable in properties and does not contain residual chlorine. 2. In a residual chlorine meter in which the middle of the sample water tube and the middle of the solvent tube are connected through a gas permeable membrane, and an electrical conductivity detector is interposed on the downstream side of the gas permeable membrane of the solvent tube. , a calibration device for a residual chlorine meter, characterized in that a span calibration liquid tank and a zero point calibration liquid tank are selectively connected via a switching valve between a gas permeable membrane of a solvent pipe and an electrical conductivity detector. .