JPH11118699A - Calibration method for installation-type turbidity meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a calibration method in which a turbidity meter to be calibrated can be calibrated with sufficient accuracy in its installation place by a method wherein a turbidity meter, for calibration, which is prepared separately is connected to the halfway part of a sample water pipe at a detector, a turbidity standard solution which is created at a site is made to flow to both turbidity meters as sample water and both are compared. SOLUTION: A detector 29, a converter 30, a cable 31 and pipes 26, 27, 28 for a turbidity meter which is calibrated with good accuracy by a manufacturer are prepared so as to be connected as required. A turbidity standard solution is created so as to be supplied from a sample-water entrance 1. Thereby, sample water whose turbidity value and flow rate are identical flows to a turbidity meter to be calibrated and a turbidity meter for calibration. In this state, the indication of the turbidity meter for calibration is used as a reference value, and the indication of the turbidity meter to be calibrated is confirmed so as to be calibrated. As a result, even when the turbidity standard solution is deviated a little from a target turbidity value, the turbidity meter for calibration can be adjusted as a reference value, and the calibration of the turbidity meter to be calibrated can be performed easily. Consequently, the turbidity meter to be calibrated can be calibrated easily in its installation place, and an installation-type turbidity meter can be calibrated with good accuracy so as to have a large effect even without being anxious too much about the creation of the turbidity standard solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water quality meter used in a water purification plant and the like, and particularly to an installation type turbidity meter that counts fine particles in water and measures turbidity, and performs calibration of the turbidity meter at the installation location. It relates to the calibration method when performing.

[0002]

2. Description of the Related Art A water quality meter used in a water purification plant or the like includes a turbidity meter for measuring and controlling the degree of turbidity of water.
The turbidity of water supply in conventional water treatment plants is 2 degrees (pp
m.

[0003] However, the demand for safety of tap water is increasing year by year, and it is no longer possible to cope with the conventional management level. In particular, the problem of toxicity of microorganisms contained in tap water is significant, and in 1996, as a result of a mass infectious disease caused by a protozoa of cryptosporidium of several μm in Japan, filtered water was used as a provisional guideline of the Ministry of Health and Welfare. Turbidity was required to be controlled below 0.1 degrees.

As described above, the turbidity management standard is 1 /
Since the sensitivity was insufficient with the conventional turbidimeter due to the reduction to 20, the development of a high-sensitivity turbidimeter based on a new principle has been demanded.

What meets this requirement is a turbidity meter of a particle counter type used for turbidity measurement of ultrapure water or the like. This employs a method in which the number of fine particles in a predetermined fluid is counted and converted into turbidity. Laser light is used as a light source to detect particles, and when this is irradiated on the fluid to be measured flowing in the measurement cell, the laser light collides with fine particles in the fluid and scatters. The light sensor captures light as light pulses, counts the number of particles passing from the number of changes, and calculates turbidity.

When calibrating a turbidity meter for such low turbidity, the most important thing to pay attention to is how to prepare a turbidity standard solution. The point is the turbidity of zero water (water of which turbidity is essentially zero)
This is the measurement of the amount of zero water and the amount of turbidity input to create the required turbidity standard solution. If these substances are slightly out of order, it is extremely difficult to prepare a turbidity standard solution at an installation site with an accuracy of a few percent, for example, when preparing a standard solution having a turbidity of 0.1 degree. It becomes a situation. Even if a low turbidity standard solution is prepared in advance,
If it is about once, the turbidity may change by several tens of minutes. In addition, there is a problem that the turbidity of the turbidity standard solution varies greatly depending on the person who prepares the turbidity standard solution. Therefore, satisfactory calibration and maintenance of accuracy cannot be achieved even when calibration is performed using these turbidity standard solutions, and mere operation confirmation often ends.

[0007] Due to these problems, when calibrating a stationary turbidity meter for low turbidity, calibration at the installation site is impossible, and it is often troublesome to return it to the manufacturer and carry it out. Has become. These problems are due to the very ambiguous turbidity standards, which are otherwise apparent. Considering these points, when calibrating the turbidity meter at the installation site, even if the turbidity standard solution is somewhat ambiguous, it suffices if there is a reference device that covers it.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an installation-type turbidity meter which eliminates the above-mentioned drawbacks and which can calibrate the installation-type turbidity meter with sufficient accuracy at the installation site even when the turbidity standard solution is somewhat ambiguous. It is to provide a calibration method.

[0009]

According to the present invention, there is provided a calibration turbidity meter serving as a reference which has been calibrated with high accuracy, and the calibration turbidity meter is brought into a place where the stationary turbidity meter is installed to detect the stationary turbidity meter. A turbidity meter for calibration is connected in the middle of the sample water pipe of the instrument, and the turbidity standard solution created at the installation site is used as the sample water, and the same sample water is supplied to both turbidimeters to install the turbidity meter. It is realized by comparing and calibrating.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a stationary turbidimeter according to the present invention will be described with reference to FIG. First, the fluid 2 to be measured supplied from the sample water inlet 1 is supplied to the pipe 3, the pressure reducing valve 4, the regulating valve 5, the pipe 6
Is led to the lower part of the defoaming tank 7. The defoaming tank 7 is composed of a short inner cylinder 8 and a long outer cylinder 9. The outer cylinder 9 further has an overflow port 11 for maintaining the height of the water surface 10 of the fluid to be measured at an upper portion of its outer peripheral surface. Further, at the lower portion of the outer peripheral surface, there are provided outlets 14 for sending out the fluid 2 to be measured to the detector 13 via a pipe 12 which can be attached and detached with one touch.

The detector 13 incorporates a transparent and cylindrical measuring cell 15 for guiding the fluid 2 to be measured and measuring its turbidity, and an optical lens system for irradiating the measuring cell 15 with a laser beam. A laser unit 16 and a light receiving unit 17 for receiving the laser light passing through the measuring cell 15 are arranged.

The fluid 2 to be measured having passed through the measuring cell 15 is discharged from the discharge port 19 under atmospheric pressure through a pipe 18 which can be detached with one touch. The measured fluid 2 overflowing from the discharge port 19 and the overflow port 11 is connected to the pipe 2
0, the water is drained out of the machine through the outlet 21.

On the other hand, the laser unit 16 and the light receiving unit 17 in the detector 13 are electrically connected to the converter 22 via a cable 25, respectively, to supply power and process a detection signal. Further, the converter 22 performs a predetermined operation on the detection signal to obtain a turbidity value of the fluid to be measured, displays the turbidity value, and outputs an output signal 23 corresponding to the displayed value. The converter 22 receives a power supply 24 from outside.

The calibration method according to the present invention will be described with reference to FIG. At the time of calibration, a detector 29, a converter 30, a cable 31, and pipes 26, 27, and 28 for connecting a sample water, which are calibrated with accuracy by a manufacturer, are prepared. The pipe 26 may be the original pipe 12 (see FIG. 1). As shown in FIG. 2, the piping system is assembled, the detector 29, the converter 30, and the cable 31 of the turbidity meter are wired, and the power supply 33 and the output 32 are connected.

In this state, a turbidity standard solution is prepared and supplied from the sample water inlet 1. If a large amount of sample water cannot be produced, the tank may be filled with a turbidity standard solution and poured in a natural flow manner so as to maintain the level of the water surface 10. As a result, the sample water having the same turbidity and the same flow rate flows to both the detector for calibration and the detector for calibration. In this state, the instruction of the turbidimeter to be calibrated is confirmed using the instruction of the turbidimeter for calibration as a reference value, and calibration is performed.

By doing so, even if the turbidity standard solution is slightly deviated from the target turbidity, the turbidity meter for calibration can be adjusted as the reference value, so that calibration can be performed easily. At this time, it goes without saying that the calibration of the calibration turbidity meter is performed by the manufacturer under sufficient measurement control.

In this example, the detector 29, the converter 30, and the cable 31 of the turbidimeter for calibration have been described as being of the same type as the turbidimeter for calibration. If used, it can be used as a calibration turbidity meter. Further, as shown in FIG. 3, the calibration system can be easily assembled using the detector 29 of the calibration turbidimeter and the cables 31 and 35 using the switch 34.

[0018]

According to the present invention, it is possible to easily calibrate the installation type turbidity meter with high accuracy without paying much attention to the preparation of the turbidity reference solution, as well as to facilitate the calibration at the installation place. Is big.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a stationary turbidity meter according to an embodiment of the present invention.

FIG. 2 is a view for explaining the calibration method of FIG. 1;

FIG. 3 is a diagram illustrating a calibration method using the switch of the present invention.

[Explanation of symbols]

2: Fluid to be measured, 12: Piping, 13: Detector to be calibrated, 1
8 ... Piping, 22 ... Converter to be calibrated, 25 ... Cable, 2
6, 27: piping, 29: detector, 30: converter for calibration,
34 ... Switch.

Continued on the front page (72) Inventor Shigeo Nishino 882 Mage, Oaza-shi, Hitachinaka-shi, Ibaraki Pref.

Claims (4)

[Claims] A fluid is sampled and guided to a measurement cell, and the fluid is irradiated with laser light in the cell, and scattered light scattered by particles in the fluid or interference light caused by the scattered light and the irradiated light is detected. A detector that detects scattered light or interference light of each particle as an optical signal, converts the optical signal into an electrical signal, and converts the optical signal into an electrical pulse by a comparator, and the detector is connected to the detector by a signal cable; Calculates the number of particles based on the electric pulse from the device, and calculates, outputs, and displays the number of particles or the converted turbidity. When performing the above, another calibration turbidity meter calibrated with high accuracy is connected in the middle of the sample water pipe of the detector of the stationary turbidity meter, and the turbidity standard solution created at the installation location is used as the sample water. Flow the same sample water through both turbidimeters. Comparison of 該据 with type turbidimeter, calibration methods installation type turbidity meter characterized by carrying out the calibration. 2. The turbidity meter for calibration according to claim 1, which is used for comparison and calibration with the stationary turbidity meter, which is accurately calibrated.
A method for calibrating an installed turbidity meter, wherein the installed turbidity meter is the same type as the installed turbidity meter to be calibrated. 3. The turbidity meter for calibration according to claim 1, which is used for comparison and calibration with the stationary turbidity meter, which is accurately calibrated.
A method of calibrating an installed turbidity meter, which is a table-top turbidity meter using the same principle as the installed turbidity meter to be calibrated. 4. The turbidity meter for calibration according to claim 1, wherein said calibration turbidity meter is used for comparison and calibration with said stationary turbidity meter.
Using only the detector of the stationary turbidimeter of the same type as the stationary turbidimeter to be calibrated, and the cable from the detector to the converter, and in the middle of the cable from the detector to be calibrated to the converter Provide a signal switch, connect the cable from the detector of the turbidimeter to be calibrated to the converter to one inlet of the signal switch, and use the same cable for the cable from the calibrated turbidimeter to the converter. Connected to another inlet of the turbidity meter, and connected to the converter of the turbidimeter to be calibrated by another cable from the outlet of the signal switch. By operating the signal switch, the converter of the turbidimeter to be calibrated is connected. A method for calibrating an installed turbidity meter, which switches between the turbidity meter to be calibrated and the calibrated turbidity meter while comparing and performing comparison and calibration.