JPH046452A - Residual chlorine meter - Google Patents

Abstract

PURPOSE:To obtain the stabilized output for a long period by using a CPU based on the data of a span drift which has been empirically obtained beforehand, operating the compensating amount for the drift with respect to the elapsed time by a program, and compensating the span drift. CONSTITUTION:The detected signal of an A/D converter circuit 9 is inputted from an I/O 10a in a CPU 10d. Then, a span coefficient and parameters which are stored in a RAM 10c and used in operation are automatically changed with the elapse of time by a program stored in a ROM 10b with respect to the signal from time to time. The rate of the change is changed. Thus, the concentration of residual chlorine at this time is operated. Namely, the detected signal is changed from time to time with the elapse of time based on the span coefficient, the parameters and the program, and the rate of change is changed. Thus, the compensating amount of a drift is operated with respect to the elapsed time. The operation for compensating the span drift can be performed. Thus, the stabilized output for a long period can be obtained.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a residual chlorine meter used in a water distribution monitor that requires no maintenance for a long period of time, for example about 3 months. This relates to a residual chlorine meter that has been improved to compensate for drift over time.

<Conventional technology> FIG. 3 is a diagram for explaining the outline of the residual chlorine meter.

In FIG. 3, the residual chlorine meter is equipped with a residual salt detection sensor 5 consisting of a silver electrode 3 and a rotating electrode 4 in a container 2 through which sample water 1 flows in and out. It is inserted into an abrasive material 6 such as glass or ceramic beads, and while the surface of the rotating electrode is being polished in this state, the residual chlorine in the sample water 2 is calculated in the calculation circuit 7 based on the measured value of the residual salt detection sensor 5.・It has a structure to be measured.

<Problems to be Solved by the Invention> This technology has the following problems.

Span calibration is generally performed at short intervals depending on drift, and measurements are performed with the rotating electrode in a polished state as shown in Figure 3. However, it is not possible to think of a configuration that can automatically adjust the span, and currently there is no span liquid that can stably supply the span point for a long period of time.

The present invention has been made in view of these problems of the conventional technology, and its purpose is to
A CPU is used to calculate a drift compensation amount for elapsed time by a program to compensate for span drift, thereby providing a residual chlorine meter that is stable and highly reliable for a long period of time.

Means for Solving the Problems> In order to achieve the above object, the present invention provides a residual salt detection sensor in the sample water, and detects residual chlorine in the sample water based on the measured value of the residual salt detection sensor. In the residual chlorine meter that measures The detection signal related to residual chlorine contained in the sample water detected by the residual salt detection sensor is taken in, and the detection signal is calculated over time using the span coefficient, parameters, and pre-programmed calculation formula. residual chlorine concentration calculation means for calculating the drift compensation amount by automatically changing the rate of change from time to time or changing the rate of change, performing calculations to compensate for span drift, and calculating the residual chlorine concentration at that time. It is characterized by the fact that

<Example> Examples will be described with reference to the drawings.

In the following drawings, parts that overlap with those in FIG. 3 are given the same numbers, and their explanations will be omitted.

FIG. 1 is a diagram for explaining a specific embodiment of the residual chlorine meter of the present invention.

Figure 2 is a diagram used to explain Figure 1, and shows the characteristics of the span drift of the residual chlorine meter when the horizontal axis represents the elapsed time (1) and the vertical axis represents the span (F) of the residual salt concentration. Show a curve.

In FIGS. 1 and 2, reference numeral 8 denotes a preamplifier to which a detection signal related to residual chlorine contained in the sample water 2 detected by the residual salt detection sensor 5 is guided.

9 is an A/D for A/D (analog/digital) conversion of the detection signal of the residual salt detection sensor 5 amplified by the preamplifier 8;
It is a conversion circuit. Reference numeral 10 refers to condition setting means such as a predetermined arithmetic expression and operation keys (hereinafter referred to as "operation keys"), which takes in the signal digitally converted by the A/D conversion circuit 8.
The residual chlorine concentration can be calculated based on the span coefficients and parameters (compensation coefficients) used in the calculations set by 11, and the calculation results can be output to be displayed on the display unit 12. If the D/A (digital/'analog) conversion circuit 7113 is used to supply an analog output therein, the residual chlorine concentration calculation means outputs the calculation result to a D/A (digital/'analog) conversion circuit 7113 for supplying an analog output thereto. In addition, D/
The A conversion circuit 13 is provided as necessary,
Needless to say, it may be provided within the residual chlorine concentration calculation means 10.

By the way, in order to configure the residual chlorine concentration calculating means 10 to achieve the above object, specifically, for example, l10 (input/output interface) 10a ROM
(read only memory) 10b, RAM (random access memory) 10c, and a calculation control unit (CPU) that has control functions such as calculation/commands that output calculation results to the outside
The main component is iOd. Then, predetermined (programmed) arithmetic expressions and the like are stored in the ROM 10b. In addition, the RAM 10c stores span coefficients and parameters (compensation parameters) determined based on span drift data determined experimentally in advance and used in calculations by operating and setting the operation keys 11, which are input via the l1010a. coefficient) etc.

Therefore, in the CPU 10d, from 1.1010a to A
When the detection signal of the /D conversion circuit 9 is input, the span coefficients and parameters used in the calculation stored in the RAM 10c are automatically changed over time by the program stored in the ROM 10b. The residual chlorine concentration (residual salt concentration) at that time is calculated by changing the rate of change from moment to moment.

Here, the span F of the residual salt concentration is as shown in Figure 2.
As time t passes, it decreases according to the time opening function /(α, 1>. In other words, when expressed in the formula, F=F, −/(α・t)
...It can be expressed as (1) [
However, FO is the initial value of the span, and α is a constant that determines the function, that is, a parameter (compensation coefficient) that determines the function].

Therefore, the inverse function of the function/(α・t) (1/f(α・1)
) and multiplying it by the span F, the span change can be compensated for.

If the compensation value for span change is F-, then this is (
From formula 1), F-=F ・(1// (a・t) l = Fo'
・It can be obtained as '(2). That is, the span factor.

Depending on the parameters and program, it is possible to calculate the drift compensation amount for the elapsed time t and further to compensate for the span drift by changing the detection signal moment by moment or changing the rate of change with respect to the elapsed time t. It is possible to calculate the current residual chlorine concentration (residual salt concentration), which is stable and reliable for a long period of time.

Note that the parameter (compensation coefficient) α can be arbitrarily set using the operation key 10.

<Effects of the Invention> Since the present invention is configured as described above, it produces the following effects.

(2) It can be configured to automatically compensate for Nispan drift 1 through program calculation.

■: This allows stable output to be obtained over a long period of time.

■: This makes it possible to create a product that requires no maintenance for a long period of time.

■: It can be realized easily and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a specific embodiment of the residual chlorine meter of the present invention, FIG. 2 is a diagram for explaining FIG. 1, and FIG. 3 is a diagram for explaining the outline of the residual chlorine meter. . 2... Sample water, 5... Residual salt detection sensor, 8...
Preamplifier, 9...A/D conversion circuit, 10...Residual calculation concentration calculation means, 11...Condition setting means (operation keys), 12...Display unit.

Claims (1)

[Scope of Claims] A residual chlorine meter is provided with a residual salt detection sensor in the sample water, and measures residual chlorine in the sample water based on the measured value of the residual salt detection sensor. a condition setting means for setting span coefficients and parameters to be used in calculations based on span drift data; and a condition setting means for setting span coefficients and parameters to be used in calculations based on span drift data; A detection signal related to chlorine is taken in, and the detection signal is automatically changed from moment to moment or the rate of change is changed over time using the span coefficients, parameters, and pre-programmed arithmetic expressions. A residual chlorine concentration calculation means for calculating a drift compensation amount, calculating a span drift compensation amount, and calculating a residual chlorine concentration at that time.