AU632720B2

AU632720B2 - Water quality monitor

Info

Publication number: AU632720B2
Application number: AU88935/91A
Authority: AU
Inventors: Satoshi Kohno; Takeshi Mori; Hiromi Ohkawa
Original assignee: Horiba Ltd
Current assignee: Horiba Ltd
Priority date: 1990-12-30
Filing date: 1991-12-10
Publication date: 1993-01-07
Anticipated expiration: 2011-12-10
Also published as: JPH07113630B2; AU8893591A; DE69112196T2; JPH04249765A; DE69112196D1

Description

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: WATER QUALITY MONITOR.

The following statement is a full description of this invention, including the best method of performing it known to me:- 4(41* 2 The present invention relates to a water quality monitor used for measuring water quality and the like of, for example, rivers.

In measurement of water quality of, for example, rivers, it is necessary to measure many items such as pH, dissolved oxygen, conductivity and turbidity. So, a water quality nmonitor provided with several kinds of measuring sensors has been developed so as to carry out these respective measurements at a single stroke.

In such a water quality monitor, it has been necessary to calibrate the respective measuring sensors prior to an actual measurement and said calibration has been carried out in the following manner in conventional water quality monitors.

For example a solution of phthalate having a pH of 4 as a standard solution for use in calibration is put in a beaker as a calibration container. Measuring sensors other than a dissolved oxygen-measuring sensor can be calibrated by the use of this standard solution as it is but an operation of saturating the standard solution with air is carried out in order to use this standard solution also for calibrating the dissolved oxygen-measuring sensor. This saturation with air is carried out by bubbling, in short sending air into the standard solution.

After finishing the bubbling, the respective measuring sensors are immersed in the standard solution at one time to carry out the calibration of the respective measuring sensors under this condition. That is to say, the calibration of the respective measuring sensors is carried out on the basis of measured data from the standard solution by the respective measuring sensors. At this time, in order to obtain an 3 accurate measured value in the case of the dissolved oxygen-measuring sensor, it is necessary to make the solution flow to some extent to bring it into contact with a surface of a diaphragm of the sensor. To this end, the standard solution has been stirred by the use of a stirrer during calibration of the conventional water quality monitor.

However, in the above described conventional water quality monitor, problems have occurred in that for example not only the bubbling operation, which is not required for other measuring sensors, is required in the calibration of the dissolved oxygen-measuring sensor and thus the calibrating operation takes time but also a stirrer for making the standard solution flow is required and thus the water quality monitor is complicated in construction and large-sized.

In view of the above described conventional disadvantages, it is an object of the present invention to provide a water quality monitor simple in construction capable of easily carrying out a calibration of plural kinds of measuring sensor including a dissolved oxygen-measuring sensor.

The present invention provides a water quality monitor comprising; a sensor member body provided with plural kinds of S measuring sensors including a dissolved oxygen-measuring (€4410 sensor at one end portion thereof; a calibration container for containing a standard solution for use in calibration of said measuring sensors; wherein said calibration container is provided with a partition wall portion for isolating said dissolved oxygen-measuring 4 sensor outside thereof when other measuring sensors protrude into the calibration container so that the dissolved oxygen measuring sensor is exposed to outside air for calibration.

Thus, when the measuring sensors are immersed in said standard solution within the calibration container to carry out a calibration of the measuring sensors, other measuring sensors can be immersed in the standard solution within the calibration container under the condition that the dissolved oxygen-measuring sensor is isolated outside of the calibration container. Accordingly, all of these measuring sensors can be simultaneously calibrated by calibrating the dissolved oxygen-measuring sensor with air requiring no bubbling and stirring as a standard gas for use in calibration and by other measuring sensors using the standard solution.

The present invention also provides a water quality monitor comprising; a sensor member body provided with plural kinds of measuring sensor including a dissolved oxygen-measuring sensor at one end portion thereof; wherein a sensing portion of said dissolved oxygen-measuring sensor is arranged at a position closer to said sensor member body as compared with sensing portions of other measuring sensors so that when the other measuring sensors are inserted S into a calibration container, the sensing portion of the dissolved oxygen-measuring sensor is exposed to air for Acalibration.

Thus, when the measuring sensors are immersed in the standard solution housed in the container to carry out said calibration, said sensing portion of the dissolved oxygen-measuring sensor can be held at a height where it is not immersed in the standard solution and all of said sensing 5 portions of other measuring sensors can be held at a height where they are immersed in the standard solution by regulating a height of said sensor member body relatively to a liquid level of the standard solution. Accordingly, also in this case, all of these measuring sensors can be simultaneously calibrated by calibrating the dissolved oxygen-measurirj sensor with air as said standard gas for use in calibration and other measuring sensors by using the standard solution.

The preferred embodiments of the present invention will be below described with reference to the drawings in which: Figure 1 is a perspective view showing an external appearance of a water quality monitor according to one preferred embodiment of the present invention.

Figure 2 is a perspective view showing procedures of calibrating measuring sensors in said water quality monitor according to the above described preferred embodiment.

Figure 3 is a longitudinal sectional view showing a positional relation between a sensor member and a calibration container during a calibration of said measuring sensors in the water quality monitor according to the above described preferred embodiment.

Figure 4 is a perspective view showing a calibration S container in a water quality monitor according to another preferred embodiment of the present invention.

Figure 5 is a longitudinal sectional view showing said calibration container in said water quality monitor according to the above described other preferred embodiment.

Figure 6 is a view of a third embodiment; and 6 Figure 7 is a cross sectional view along the -ine IIV-IIV of figure 6.

Fig. 1 is a perspective view showing an external appearance of a water quality monitor according to the present invention.

A water quality monitor according to this preferred embodiment comprises a sensor member 1, a monitor body 3 electrically connected with said sensor member 1 through a cable 2, a protecting tube 4 detachably mounted on the sensor member 1 and a calibration container 5 for containing a standard solution for use in calibration.

The sensor member 1 comprises a sensor member body 6 having a circular lower end portion and plural kinds of water quality sensors projecting down from a lower end surface of said sensor member body 6. That is to say, here, a pH-measuring glass electrode 7 and a reference electrode 8, a conductivity cell 9 for measuring conductivity, a DO sensor for meauring dissolved oxygen and a turbidity cell 11 for I: measuring turbidity are provided. In particular, said DO sensor 10 is arranged at a position closer to a circumferential portion of said lower end surface.

The monitor body 3 is a device for receiving signals measured by the respective measuring sensors through said ~cable 2 to calibrate the measuring sensors themselves and provide measured results for the respective items of water quality when the device is in use. Said operation is automatically carried out by means of a microcomputer into which instruction are input by an operating button 3a and the operation results are displayed by means of a display portion 3b.

The protecting tube 4 is a member having a roughly cylindrical shape and surrounding the respective measuring 7 7 sensors provided in said lower end portion of the sensor member body 6 to protect the measuring sensors from shocks and the like. The protecting tube 4 is mounted on and detached from the lower end portion of the sensor member body 6 by a Bayonet structure. The protecting tube 4 is provided with an opening 4a and a guide member 4b projecting on an inner circumferential side at a circumferential position corresponding to a position, where the DO sensor 10 is mounted, formed on a circumferential wall thereof under the condition that it is mounted on the sensor member body 6.

The calibration container 5 is a roughly cylindrical ii. container having an outside diameter insertable into the protecting tube 4 and provided with a partition wall portion a 0 formed by recessing a part of a circumferential wall f thereof toward an inner circumferential side for isolating only the DO sensor 10 outside thereof when the measuring sensors are calibrated. Said partition wall portion 5a is used also as a groove, which is guided by said guide member 4b of the protecting tube 4, when the measuring sensors of the sensor member 1 are immersed in the standard solution S within the calibration container 5 to carry out a calibration.

Fig. 2 is a perspective view showing an operation of immersing the measuring sensors of the sensor member 1 in the standard solution 12 within the calibration container 5 when ~the water quality monitor is calibrated; and i Fig. 3 is a longitudinal sectional view showing a condition that the measuring sensors are immersed in the standard solution 12.

Operating procedures in the calibration of the water quality monitor will be below described with reference to Figs. 2, 3.

8 The protecting tube 4 is mounted on the lower end portion of the sensor member body 6, so the sensor member 1 can be inserted from above into the calibration container in which the standard solution 12 consisting of for example an aqueous solution of phthalate having the pH of 4 is housed, as shown in Fig. 2. At this time, the position of the guide member 4b of the protecting tube 4 is registered with the partition wall portion 5a of the calibration container 5. The sensor member 1, which is guided by the guide member 4a and the partition wall portion 5a, is arranged at a position where the DO sensor 10 is positioned in a recess portion consisting of the partition wall portion of the circumferential wall of the calibration container as shown in Fig. 3. That is to say, the DO sensor 10 is positioned outside of the calibration container 5 to be exposed to the air. On the contrary, other measuring sensors are immersed in the standard solution within the calibration container Accordingly, the DO sensor 10 detects a concentration of oxygen in the atmosphere under this condition and a calibration with air as a standard gas for use in calibration is carried out on the basis of the detected signal in the monitor body 3. As to the calibration of other measuring sensors, it is carried out in the same manner as in the conventional water quality monitor on the basis of signals detected by these measuring sensors from the standard S solution 12. Since the calibration of the DO sensor 10 is carried out with air as the standard gas for use in K calibration, the operations, which have been carried out in the conventional water quality monitor, such as the bubbling treatment for the standard solution 12 and the stirring of the standard solution 12 by means of a stirrer, can be omitted.

Since the protecting tube 4 is provided with said opening 4a formed at said circumferential position

I_

-7 9 corresponding to said position where the DO sensor 10 is installed, the DO sensor 10 can be sufficiently exposed to the air without being hindered by the protecting tube 4. In addition, the protecting tube 4 functions also as a standing member when the sensor member 1 is put on a floor and the like.

Fig. 4 is a perspective view showing a calibration container 15 in another preferred embodiment of a water quality monitor according to the present invention; and Fig. 5 is a longitudinal sectional view showing said S calibration container 15 shown in Fig. 4.

In this preferred embodiment, the calibration container is provided with a cylindrical inner circumferential wall, which is used as a partition wall portion 15a for isolating the DO sensor 10 outside of the calibration container formed at a center of a bottom portion thereof.

Corresponding to this, the DO sensor 10 is installed in a central portion of the lower end surface of the sensor member body 6 while other measuring sensors are arranged around the S DO sensor 10 so as to surround the DO sensor

II

I

4 I 4 I 4 I'iin io e Also in this case, since merely the DO sensor 10 is exposed to the air under the condition that other measuring sensors are immersed in the standard solution 12, the same calibration as that in the preceding preferred embodiment can be carried out.

In addition, although the calibration container 5, 15 is provided with the partition wall portion 5a, 15a for isolating the DO sensor 10 outside thereof respectively. It would also be possible to hold the sensing portion of the DO sensor 10 at a position higher than the liquid level of the standard solution 12 within the calibration container during the calibration. Thus the sensing portions of other measuring sensors are such that they are immersed in the standard solution 12 within the calibration container 5 and the position of the sensing portion of the DO sensor 10 in the lower end surface of the sensor member body 6 is sufficiently higher than the position of the sensing portions of the other measuring sensors. In short the position of the i DO sensor is closer to the lower end surface of the sensor member body 6. The preferred embodiment having such a construction is shown in Figs. 6 7.

The sensor member body 6 comprises an upper frame 16 and a lower frame 17 and a join between these frames is sealed through an 0-ring 32. The sensor member body 6 is provided with a glass tube 13 with an upper end and a lower end opened as a transparent cylindrical tube which forms a vertical turbidity cell 11 passing therethrough from said upper frame to said lower frame 17.

The glass tube 13 is fixed by means of a lower fixing screw 18 screwed in a concavedly sunk portion 17a of the lower frame 17, through which the glass tube 13 passes, on S the side of said lower end thereof. An 0-ring 19 is disposed between an upper end of said lower fixing screw 18 and said concavedly sunk portion 17a of the lower frame 17 to seal a lower end portion of the glass tube 13 and the lower frame 17.

I a In addition, the glass tube 13 is fixed by means of an C4 0 upper fixing screw 20 screwed in a concavedly sunk portion S 16a of the upper frame 16, through which the glass tube 13 passes, on the side of said upper end thereof.

An 0-ring 21 is disposed between a lower end of said upper fixing screw 20 and said concavedly sunk portion 16a of the upper frame 16 to seal an upper end portion of the glass tube 13 and the upper frame 16.

T7 11 In addition, the glass tube 13 is provided with a reinforcing tube member 22 therearound and lateral cylindrical members 22a, 22b formed at opposite positions on both sides thereof and a separate lateral cylindrical member 22c formed at a position spaced from said lateral cylindrical member 22b by an appointed turning angle so as to be opened toward the glass tube 13, respectively, said lateral cylindrical member 22a being provided with a LED 23 as a light source, the lateral cylindrical member 22b being provided with a photodiode 24 as a transmitted light-receiving element, and said lateral cylindrical member 22c being provided with a separate photodiode 25 as a scattered light-receiving element. Said LED 23, said photodiode 24 and said photodiode 25 are provided with caps 26, 27, 28 having a slit for limiting spurious light in order to avoid irradiation of unwanted light and a receipt of unnecessary light at a pointed end thereof, respectively.

In the turbidity-measuring cell 11 of the water quality monitor, the glass tube 13 forming a cell v.Undow is provided so as to vertically pass through the sensor member body 6, so that, for example in the case where the sensor member 1 is put in water in the measurement of water quality of rivers, not only water as the sample liquid enters the sensor member 1 from the side of the lower end of the glass tube 13 but also air within the glass tube 13 goes out from the side of the upper end of the glass tube 13, so that the replacement of air with the sample liquid can be smoothly carried out SA without requiring the groove in the conventional water quality monitor.

Beams transmitting through the sample liquid in the glass tube 13 from the LED 23 are received by the transmitted light-receiving photodiode 24 while beams scattered by the midway sample liquid are received by the scattered lightreceiving photodiode 25 and the turbidity of the sample liquid is measured from a ratio of a quantity of the 12 transmitted light to that of the scattered light in the same manner as in case of the turbidity-measuring sensor of the conventional water quality monitor.

In the above described manner, in this preferred embodiment the glass tube 13 which forms the turbiditymeasuring cell 11 is arranged vertically to the sensor member body 6 in the same manner as in other measuring sensors, so that the turbidity-measuring cell 11 can be compactly arranged without limiting the arrangement of other measuring sensors.

In addition, the inside of the glass tube 13, in which the sample liquid is received and which forms a cell window of the turbidity-measuring cell 11, is a smooth and continuous circumferential surface without steps, so that bubbles, dirt and stains are difficult to stick to the inside of the glass tube 13, so that not only an error of measurement resulting from said stains and the like can be avoided but also cleaning for removing any stains can be easily carried out.

Besides, if a sample liquid-supplying tube is connected with the side of one end of the glass tube 13 of the turbidity-measuring cell 11 and a sample liquid-discharging tube is connected with the side of the other end of the glass tube 13, it can be used also as a flow cell for continuously measuring the sample liquid.

The first and second embodiments have the above described constructions, the calibration container being provided with the partition wall portion for isolating merely the dissolved oxygen-measuring sensor from other measuring sensors to put it out of the calibration container formed therein, and the respective measuring sensors being mounted on the sensor member body so that the position of the sensing portion of the dissolved oxygen-measuring sensor may be L la~slC~lr 111i 13 I closer to the sensor member body as compared with the sensing portions of other measuring sensors, so that merely the dissolved oxygen-measuring sensor can be exposed to the air under the condition that other measuring sensors are immersed in the standard solution within the calibration container and thus the dissolved oxygen-measuring sensor can be calibrated with the air as the standard gas for use in calibration while all measuring sensors can be easily calibrated by the simple construction without bubbling the standard solution and stirring the standard solution by means of a stirrer.

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Claims

1. A water quality monitor comprising; a sensor member body provided with plural kinds of measuring sensors including a dissolved oxygen-measuring sensor at one end portion thereof; a calibration container for containing a standard solution for use in calibration of said measuring sensors; wherein said calibration container is provided with a partition wall portion for isolating said dissolved oxygen-measuring sensor outside thereof when other measuring sensors protrude into the calibration container so that the dissolved oxygen measuring sensor is exposed to outside air for calibration.

2. A water quality monitor comprising; a sensor member body provided with plural kinds of measuring sensor including a dissolved oxygen-measuring sensor at one end portion thereof; wherein a sensing portion of said dissolved oxygen-measuring sensor is arranged at a position closer to said sensor member S body as compared with sensing portions of other measuring sensors so that when the other measuring sensors are inserted a into a calibration container, the sensing portion of the dissolved oxygen-measuring sensor is exposed to air for calibration.

3. A water quality monitor according to claim 1 wherein said partition wall portion is formed as a recess in the side surface of said calibration container. LI I~i~lI~

4. A water quality monitor of claim 1 wherein said partition wall portion is a cylindrical wall arranged centrally of said calibration container.

A water quality monitor according to claim 1 PT;a including a protecting tube for surrounding said measuring sensors, said protecting tube having a guide portion which registers with said partition wall portion to guide the dissolved oxygen measuring sensor into the partition wall portion and the other sensors into the calibration container.

6. A water quality monitor substantially as hereinbefore described with reference to figures 1 to 3 or 4 and 5 or 6 and 7 of the accompanying drawings. DATED THIS 10TH DAY OF DECEMBER 1991 HORIBA, LTD. By its Patent Attorneys: GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia 4A4 !T Ir -rl 4