Abstract:
The present invention realizes a compact optical measuring device in which a sample solution sampling mechanism and a cleaning fluid producing mechanism are integrated with each other. Provided is an optical measuring device which applies light from a light emitting element to a sample solution in a measuring chamber provided in a measuring cell through a first light guide portion and which detects light from the sample solution by a light receiving element through a second light guide portion, including: a flow passage section formed in the measuring cell and adapted to guide the sample solution into or out of the measuring chamber; a flow control section attached to the measuring cell and serving to open and close the flow passage section; and a filtering section connected to the measuring cell and communicating with the measuring chamber.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an optical measuring device which applies light from a light emitting element to a sample solution in a measuring chamber provided in a measuring cell through a first light guide portion, and which detects light from the sample solution by a light receiving element through a second light guide portion.  
         [0003]     2. Description of the Related Art  
         [0004]     In order to measure the concentration of a specific component in water, such as suspended matter, hardness component, dissolved oxygen, and residual chlorine, scattered light detecting type and transmitted light detecting type optical measuring devices are widely used. Generally, those optical measuring devices stores sample water in a measuring cell provided with a pair of light transmitting windows. Light from a light emitting element is applied to the sample water through one light transmitting window, and light from the sample water is detected by a light receiving element through the other light transmitting window.  
         [0005]     In a measuring operation, the optical measuring devices usually correct the intensity of the light from the sample water (i.e., transmitted light intensity or scattered light intensity) using the intensity of light from clean blank water (i.e., transmitted light intensity or scattered light intensity), whereby zero-point drift generated through contamination of the light transmitting windows, fluctuations in ambient temperature, etc. is canceled, thereby securing a predetermined measuring accuracy. Thus, as disclosed in JP 08-178913 A, in the optical measuring devices, a filter is provided in a water intake system, and clean water (i.e., blank water) is produced on-site.  
         [0006]     Further, in the optical measuring devices, when the sample water contains a contaminant component, such as a colloidal substance or an organic substance, such the contaminant component adheres to the light transmitting windows, which may attenuate the quantity of light applied from the light emitting element and the quantity of light detected by the light receiving element, thereby substantially deteriorating the measuring accuracy. In particular, in the case of underground water, industrial water or the like, the sample water often contains a contaminant component, and the contamination of the light transmitting windows is likely to be promoted. In view of this, as proposed in JP 01-128150 U and JP 05-002055 U, in the optical measuring devices, clean washing water is ejected from a nozzle against the light transmitting windows, thus periodically recovering the light transmitting performance. In this connection, as disclosed in JP 01-128150 U, in the optical measuring devices, a filter is provided in the water intake system, and clean water (i.e., washing water) is produced on-site.  
         [0007]     As disclosed in JP 08-178913 A, when a filter is provided in the water intake system for the purpose of light intensity correction and nozzle- washing the light transmitting windows with clean water, it is general practice to connect a bypass pipe to the sample water sampling pipe leading to the measuring cell and to provide the above-mentioned filter in the bypass pipe. Alternatively, as disclosed in JP 01-128150 U, it is also general practice to connect a water feed pipe for feeding tap water or the like to the sample water sampling pipe leading to the measuring cell and to provide the filter in the water feed pipe. In those constructions, however, the connection of the pipes and the like is complicated, and it is necessary to provide the pipes with a valve mechanism for switching between the sampling of sample water and the sampling of clean water. As a result, the optical measuring device, including the water intake system, becomes large, and it takes time to install the optical measuring device on-site, to perform maintenance thereon, and the like. Further, a flow passage from the filter to the nozzle becomes long; thus, due to a reduction in pressure, the amount of clean water ejected against the light transmitting windows per unit time is reduced, so there is a possibility of allowing the contaminant component to remain.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention has been made in view of the above-mentioned problems in the prior art. It is a first object of the present invention to realize a compact optical measuring device in which a sample solution sampling mechanism and a cleaning fluid producing mechanism are integrated with each other. It is a second object of the present invention to realize an optical measuring device capable of performing nozzle-washing without involving a reduction in the pressure with which the cleaning fluid is supplied.  
         [0009]     The present invention has been made in order to attain the above-mentioned object. According to a first aspect of the present invention, there is provided an optical measuring device which applies light from a light emitting element to a sample solution in a measuring chamber provided in a measuring cell through a first light guide portion and which detects light from the sample solution by a light receiving element through a second light guide portion, the optical measuring device including: a flow passage section formed in the measuring cell and adapted to guide the sample solution into or out of the measuring chamber; a flow control section attached to the measuring cell and serving to open and close the flow passage section; and a filtering section connected to the measuring cell and communicating with the measuring chamber.  
         [0010]     According to the first aspect of the present invention, the optical measuring device is equipped with the measuring cell constituting the sample solution measuring section, the flow passage section and the flow control section corresponding to the sample solution sampling mechanism, and the filtering section corresponding to the cleaning fluid producing mechanism. The flow passage section is formed in the measuring cell itself, the flow control section is attached to the measuring cell, and the filtering section is connected to the measuring cell. That is, in the optical measuring device, the sampling mechanism and the producing mechanism are integrally incorporated together with the measuring section, so the requisite mounting space is relatively small. Further, the optical measuring device can be used solely by being connected to predetermined sampling and drain lines.  
         [0011]     Further, according to a second aspect of the present invention, there is provided an optical measuring device according to the first aspect, in which a nozzle for ejecting a cleaning fluid from the filtering section against the first light guide portion and the second light guide portion is provided in a communicating portion between the measuring chamber and the filtering section.  
         [0012]     According to the second aspect of the present invention, the cleaning fluid produced in the filtering section is directly supplied to the nozzle without being passed through supply piping. Thus, the cleaning fluid from the filtering section reaches the nozzle without involving a reduction in pressure, so it is possible to maintain the flow velocity of the cleaning fluid ejected against the light guide portions within a predetermined range.  
         [0013]     According to the present invention, there is realized a compact optical measuring device in which the sample solution sampling mechanism and the cleaning fluid producing mechanism are integrated with each other. Further, there is realized an optical measuring device capable of performing nozzle-washing without involving a reduction in the pressure with which the cleaning fluid is supplied. As a result, it is possible to perform installation of the device on-site, maintenance thereon, etc. in a short period of time. Further, it is possible to maintain a predetermined measuring accuracy by effectively removing the contaminant component adhering to the light transmitting windows. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     In the accompanying drawings:  
         [0015]      FIG. 1  is a full view of a turbidity measuring device according to a first embodiment of the present invention;  
         [0016]      FIG. 2  is a sectional view taken along the line II-II of  FIG. 1 ;  
         [0017]      FIG. 3  is a view showing a liquid flow in the turbidity measuring device according to the first embodiment of the present invention;  
         [0018]      FIG. 4  is a schematic view of a filtering system to which the turbidity measuring device according to the first embodiment of the present invention is connected;  
         [0019]      FIG. 5  is a longitudinal sectional view of the turbidity measuring device according to the first embodiment of the present invention;  
         [0020]      FIG. 6  is a sectional view taken along the line V-V of  FIG. 1 ;  
         [0021]      FIG. 7  is an explanatory view illustrating a first measuring process for the turbidity measuring device according to the first embodiment of the present invention;  
         [0022]      FIG. 8  is an explanatory view illustrating a second measuring process for the turbidity measuring device according to the first embodiment of the present invention; and  
         [0023]      FIG. 9  is an explanatory view illustrating a washing process for the turbidity measuring device according to the first embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     First Embodiment  
       [0024]     In the following, the first embodiment of the present invention will be described in detail with reference to the drawings.  FIG. 1  is a full view of a turbidity measuring device to which an optical measuring device according to the present invention is applied.  FIG. 2  is a sectional view taken along the line II-II of  FIG. 1 .  FIG. 3  is a view showing a liquid flow in the turbidity measuring device.  FIG. 4  shows a filtering system to which the turbidity measuring device is connected. A turbidity measuring device  1  of  FIG. 1  can effect switching in the introduction of a plurality of sample waters, making it possible to measure the turbidity of each of them, and is equipped with a measuring section  2 , a flow control section  3 , and a filtering section  4 .  
         [0025]     The measuring section  2  is a section for measuring 90° scattered light of water sample. The measuring section  2  is mainly equipped with a measuring cell  5 , a first casing member  6 , and a second casing member  7 . The flow control section  3  is a section for controlling the introduction of sample water, the introduction of raw water for producing clean water, the discharge of sample water, or the discharge of clean water. The flow control section  3  is equipped with a first valve  8 , a second valve  9 , a third valve  10 , and a fourth valve  11  that are attached to the top portion of the measuring cell  5 . There are no particular limitations regarding the valves  8 ,  9 ,  10 , and  11  as long as they can control the flow of a fluid; for example, it is possible to use various valve mechanisms, such as electromagnetic valves or motor valves. The filtering section  4  is a section for producing clean water from raw water. The filtering section  4  is mainly equipped with a first filter casing  12 , which is connected to the lower portion of the measuring cell  5 , and a second filter casing  13 .  
         [0026]     On the front side of the measuring cell  5 , there are provided a first sample water inlet  14  for introducing a first sample water, and a second sample water inlet  15  for introducing a second sample water. On the rear side of the measuring cell  5 , there are provided a sample water outtake  16  for supplying the second sample water to the filtering section  4  to produce clean water therefrom, and a drainage outlet  17  for discharging sample water or clean water out of the measuring cell  5 . A joint (not shown), such as a tube fitting, is mounted to each of the first sample water inlet  14 , the second sample water inlet  15 , the sample water outtake  16 , and the drainage outlet  17 , making it possible to easily connect a predetermined sampling line, drainage line, etc. The first casing member  6  is attached to the left-hand surface of the measuring cell  5 , and a light emitting element is accommodated in the first casing member  6 . On the other hand, the second casing member  7  is attached to the rear surface of the measuring cell  5 , and a light receiving element is accommodated in the second casing member  7 .  
         [0027]     As shown in  FIGS. 2 and 3 , a measuring chamber  18  for storing sample water is formed in the measuring cell  5 . Further, in the measuring cell  5 , a flow passage section  19  for guiding sample water into or out of the measuring chamber  18  is formed. The flow passage section  19  is composed of a first flow passage  20 , a second flow passage  21 , a third flow passage  22 , a fourth flow passage  23 , a fifth flow passage  24 , a sixth flow passage  25 , a seventh flow passage  26 , and an eighth flow passage  27 . To be more specific, the first flow passage  20  is formed in an L-shaped configuration so as to extend from the first sample water inlet  14  to the upper surface of the measuring cell  5 . The second flow passage  21  is formed in an L-shaped configuration so as to extend from the inner peripheral surface of the measuring chamber  18  to the upper surface of the measuring cell  5 . The first flow passage  20  and the second flow passage  21  are opened or closed by the first valve  8 . The third flow passage  22  is formed in an L-shaped configuration so as to extend from the second sample water inlet  15  to the upper surface of the measuring cell  5 . The fourth flow passage  23  is formed in an L-shaped configuration so as to extend from the inner peripheral surface of the measuring chamber  18  to the upper surface of the measuring cell  5 . The third flow passage  22  and the fourth flow passage  23  are opened or closed by the second valve  9 . Further, on the second sample water inlet  15  side, a check valve  28  is provided in the third flow passage  22 .  
         [0028]     The fifth flow passage  24  is formed in an L-shaped configuration so as to extend from the sample water outtake  16  to the upper surface of the measuring cell  5 . The sixth flow passage  25  is formed in an L-shaped configuration so as to communicate with the third flow passage  22  and to extend to the upper surface of the measuring cell  5 . The fifth flow passage  24  and the sixth flow passage  25  are opened or closed by the third valve  10 . The seventh flow passage  26  is formed in an L-shaped configuration so as to extend from the drainage outlet  17  to the upper surface of the measuring cell  5 . The eighth flow passage  27  is formed so as to extend at a predetermined angle from the top portion of the measuring chamber  18  to the upper surface of the measuring cell  5 . The seventh flow passage  26  and the eighth flow passage  27  are opened or closed by the fourth valve  11 .  
         [0029]     To monitor the filtering performance of various filtering apparatuses, the turbidity measuring device  1  to be used is incorporated, for example, into a filtering system as shown in  FIG. 4 . In  FIG. 4 , a filtering system  29  is mainly equipped with a raw water tank  30 , a filtering apparatus  31 , and a treated water tank  32 . The raw water tank  30  is connected to a water supply source (not shown), such as a well, through a raw water supply line  33 . Further, the raw water tank  30  is connected to the filtering apparatus  31  through a raw water feed line  34 . A raw water feed pump  35  is provided in the raw water feed line  34 . The treated water tank  32  is connected to the filtering apparatus  31  through a treated water supply line  36 . Further, the treated water tank  32  is connected to a use point (not shown) through a treated water feed line  37 . A treated water feed pump  38  is provided in the treated water feed line  37 .  
         [0030]     To introduce raw water before being supplied to the filtering apparatus  31  and treated water having passed through the filtering apparatus  31 , the turbidity measuring device  1  is connected to the raw water feed line  34  and the treated water supply line  36  through a raw water sampling line  39  and a treated water sampling line  40 , respectively. That is, the raw water sampling line  39  is connected to the first sample water inlet  14 , and the treated water sampling line  40  is connected to the second sample water inlet  15 . Further, a drain line  41  extending to a drain pit (not shown) is connected to the drainage outlet  17 .  
         [0031]     Next, the construction of the turbidity measuring device  1  will be described in more detail with reference to  FIGS. 5 and 6 .  FIG. 5  is a longitudinal sectional view of the measuring section  2  and the filtering section  4 .  FIG. 6  is a sectional view taken along the line V-V of  FIG. 1 . The measuring cell  5  has the measuring chamber  18 , and, from the viewpoint of preventing generation of reflected light and stray light in the measuring cell  5 , is formed of a non-light-transmitting material (e.g., a plastic material colored in black or a stainless steel material painted in black).  
         [0032]     The measuring cell  5  is equipped with a first perforated path  42  and a second perforated path  43  that extend horizontally from the outside into the measuring chamber  18 . The axes of the perforated paths  42  and  43  are orthogonal to each other in the same plane. A first light guide portion  44  and a second light guide portion  45  are fitted into the perforated paths  42  and  43 , respectively, from the outer side of the measuring cell  5 . Each of the light guide portions  44  and  45  is formed by attaching a first seal member  47  and a hold member  48  to a transparent rod  46 . Further, on the outer surface side of the measuring cell  5 , a second seal member  49  is attached to the hold member  48 . That is, in each of the perforated paths  42  and  43 , there are provided step portions (not indicated by reference numerals) corresponding to the first seal member  47 , the hold member  48 , and the second seal member  49 .  
         [0033]     The transparent rod  46  is a member functioning as a light transmitting window, and is formed, for example, by machining a round rod of quartz glass having an outer diameter of 3 to 10 mm. The transparent rod  46  is set to a predetermined length (e.g., 20 to 50 mm) so as to reach the measuring chamber  18  from the outer surface of the measuring cell  5 , and the end portions thereof are polished into smooth vertical surfaces perpendicular to the axis. The first seal member  47  is an annular packing, such as an O-ring, and is attached to a position on the transparent rod  46  near the center thereof. The hold member  48  is a cylindrical member for preventing detachment of the first seal member  47 , and one end thereof is set to be long enough to reach the outer surface of the measuring cell  5 . The second seal member  49  is an annular packing, such as an O-ring.  
         [0034]     The first light guide portion  44  fitted into the first perforated path  42  is sealed by the first casing member  6  from the outer side of the measuring cell  5 . To be more specific, the light emitting side surface of the first casing member  6  is held in contact with the second seal member  49  on the side of the first light guide portion  44 , and the first casing member  6  is held in intimate contact with the measuring cell  5  by bolts  50 . In this state, the space between the first perforated path  42  and the transparent rod  46  is kept liquid-tight and airtight through the first seal member  47  fixed at a predetermined position by the hold member  48 . Further, detachment of the transparent rod  46  and the hold member  48  due to the inner pressure from the measuring chamber  18  is prevented by holding their end surfaces situated on the outer surface side of the measuring cell  5  in intimate contact with the light emitting side surface of the first casing member  6 .  
         [0035]     The second light guide portion  45  fitted into the second perforated path  43  is sealed from the outer side of the measuring cell  5  by the second casing member  7 . To be more specific, the light receiving side surface of the first casing member  7  is held in contact with the second seal member  49  on the side of the second light guide portion  45 , and the second casing member  7  is held in intimate contact with the measuring cell  5  by bolts (not shown). In this state, the space between the second perforated path  43  and the transparent rod  46  is kept liquid-tight and airtight through the first seal member  47  fixed at a predetermined position by the hold member  48 . Further, detachment of the transparent rod  46  and the hold member  48  due to the inner pressure from the measuring chamber  18  is prevented by holding their end surfaces situated on the outer surface side of the measuring cell  5  in intimate contact with the light receiving side surface of the second casing member  7 .  
         [0036]     In the first casing member  6 , there is accommodated a light emitting circuit board  52  to which a light emitting element  51  (e.g., an LED) is attached. To be more specific, at the position of the first casing member  6  corresponding to the transparent rod  46 , there is provided a first perforated hole  53 , in which the light emitting element  51  is accommodated. Here, the diameter of the first perforated hole  53  is set to be smaller than the outer diameter of the transparent rod  46 . The light emitting circuit board  52  is fixed in position within the first casing member  6  by a screw  54 . The light emitting circuit board  52  is sealed in the first casing member  6  by filling the casing member with a resin material  55 . In this state, the light emitting element  51  is isolated from the outside by being accommodated in the first perforated hole  53 , and is tightly sealed in the first casing member  6  by the second seal member  49  and the resin material  55 .  
         [0037]     On the other hand, in the second casing member  7 , there is accommodated a light receiving circuit board  57  to which a light receiving element  56  (e.g., a photodiode) is attached. To be more specific, at the position of the second casing member  7  corresponding to the transparent rod  46 , there is provided a second perforated hole  58 , in which the light receiving element  56  is accommodated. Here, the diameter of the second perforated hole  58  is set to be smaller than the outer diameter of the transparent rod  46 . The light receiving circuit board  57  is fixed in position within the second casing member  7  by the screws  54 . The light receiving circuit board  57  is sealed in the second casing member  7  by filling the casing member with the resin material  55 . In this state, the light receiving element  56  is isolated from the outside by being accommodated in the second perforated hole  58 , and is tightly sealed in the second casing member  7  by the second seal member  49  and the resin material  55 .  
         [0038]     In the lower portion of measuring chamber  18 , there is provided an intermediate chamber  59  open in the lower surface of the measuring cell  5 . The diameter of the intermediate chamber  59  is set to be larger than that of the measuring chamber  18 . In the lower portion of the intermediate chamber  59 , there is formed a first female screw portion  60  for connecting the filtering section  4 . That is, the intermediate chamber  59  constitutes a communicating portion between the measuring chamber  18  and the filtering section  4 , and a nozzle  61  is arranged in the communicating portion. The nozzle  61  is equipped with a cylindrical nozzle body  62  and a flange portion  63  and a support portion  64  provided under the nozzle body  62 . Formed in the nozzle body  62  is a clean water supply chamber  65  open in the lower surface of the support portion  64 . The nozzle  61  is retained within the measuring cell  5  by inserting the nozzle body  62  into the measuring chamber  18  through a third seal member  66 , such as an O-ring, bringing the flange portion  63  into contact with the step portion (not indicated by a reference numeral) between the measuring chamber  18  and the intermediate chamber  59 , and then supporting the lower surface of the support portion  64  by the upper surface of the first filter casing  12 .  
         [0039]     The nozzle  61  is equipped with a first nozzle hole  67  and a second nozzle hole  68  that extend from the interior of the clean water supply chamber  65  to the upper surface of the nozzle body  62 . The first nozzle hole  67  is set at an angle such that the center line thereof passes through the center of the end surface of the transparent rod  46  on the first light guide portion  44  side. The second nozzle hole  68  is set at an angle such that the center line thereof passes through the center of the end surface of the transparent rod  46  on the second light guide portion  45  side. Each of the first nozzle hole  67  and the second nozzle hole  68  is set to have a hole diameter such that clean water is ejected at a predetermined flow velocity (e.g. in the range of 4 to 11 m/s when the water pressure in the clean water supply chamber  65  is 0.1 to 0.49 MPa).  
         [0040]     The first filter casing  12  and the second filter casing  13  are hollow members accommodating filter cartridges to be described below. The filter casings  12  and  13  form an integral container through connection of a first male screw portion  69  formed on the lower portion of the filter casing  12  with a second female screw portion  70  formed on the upper portion of the second filter casing  13 . A second male screw portion  71  is formed on the upper portion of the first filter casing  12 ; by connecting the second male screw portion  71  with the first female screw portion  60 , the filtering section  4  and the measuring cell  5  are connected to each other.  
         [0041]     On the upper surface of the first filter casing  12 , there is provided a cylindrical first projecting portion  73  to which a fourth seal member  72 , such as an O-ring, is attached. The first projecting portion  73  is fitted into the clean water supply chamber  65 . A first hollow portion  74  of the first projecting portion  73  communicates with a connection hole  75  formed in the first filter casing  12 . In the lower portion of the second filter casing  13 , there is provided a sample water intake  76  for introducing raw water (that is, the second sample water) from the sample water outtake  16  into the filtering section  4 . Here, the sample water intake  76  is connected to the sample water outtake  16  through a sample water supply line  77 , such as a tube.  
         [0042]     A filter cartridge  78  is accommodated in the container formed by the filter casings  12  and  13 . The filter cartridge  78  is formed in a reverse-cup-like configuration, and contains a filter medium  79 , such as a hollow fiber filter or a string wound filter. At the top portion of the cartridge  78 , there is provided a cylindrical second projecting portion  81  to which a fifth seal member  80 , such as an O-ring, is attached, and the second projecting portion  81  is fitted into the connection hole  75 . Here, a second hollow portion  82  of the second projecting portion  81  communicates with the transmission side of the filter medium  79 . That is, the raw water introduced from the sample water intake  76  is purified by the filter medium  79 , and then supplied into the clean water supply chamber  65  through the second hollow portion  82  and the first hollow portion  74 . In this construction, the clean water produced in the filtering section  4  is supplied directly to the nozzle  61  without passing through supply piping. Thus, the clean water from the filtering section  4  reaches the nozzle  61  without undergoing a reduction in pressure, so it is possible to maintain the flow velocity of the clean water ejected against the light guide portions  44  and  45  within a predetermined range.  
         [0043]     In order to maintain the filtering capacity of the filter medium  79 , the filter cartridge  78  is periodically replaced (when, for example, the number of times that the measuring operation to be described below is performed reaches a predetermined value). The used filter cartridge  78  can be easily extracted by separating the second filter casing  13  from the first filter casing  12 . Conversely, the new filter cartridge  78  can be easily incorporated by fitting the second projecting portion  81  into the connection hole  75  and connecting the second filter casing  13  to the first filter casing  12 .  
         [0044]     The valves  8 ,  9 ,  10 , and  11 , the light emitting circuit board  52 , and the light receiving circuit board  57  are each connected to a controller (not shown), and are operated in accordance with a command signal from the controller.  
         [0045]     In the above-mentioned construction, in the turbidity measuring device  1 , the flow control section  3  and the flow passage section  19 , which constitute a sample water sampling mechanism, and the filtering section  4 , which constitutes a clean water producing mechanism, are integrally incorporated together with the measuring section  2 , so the requisite space for installation is fairly small. Further, the turbidity measuring device  1  can be used solely by being connected to the raw water sampling line  39 , the treated water sampling line  40 , and the drain line  41 .  
         [0046]     In the following, the measuring operation of the turbidity measuring device  1  according to the first embodiment of the present invention will be described in detail with reference to  FIGS. 7 through 9 . For every predetermined measuring interval time (e.g., 30 minutes to 6 hours) set for the controller (not shown), the turbidity measuring device  1  performs a series of measuring operations, more specifically, a first measuring process, a second measuring process, and a washing process in that order.  
         [0047]     As shown in  FIG. 7 , in the first measuring process, the first valve  8  and the fourth valve  11  are set in the open state in accordance with the command signal from the controller. On the other hand, the second valve  9  and the third valve  10  are set in the closed state. The raw water flowing through the raw water sampling line  39  (that is, the raw water before being supplied to the filtering apparatus  31 ) is introduced into the measuring chamber  18  from the first sample water inlet  14  through the first flow passage  20  and the second flow passage  2 l. The raw water flows from the upper portion of the measuring chamber  18  to the drainage outlet  17  through the eighth flow passage  27  and the seventh flow passage  26  while extruding the clean water stored in the measuring chamber  18  in the previous washing process. Then, the water from the drainage outlet  17  is continuously discharged to the exterior of the system through the drain line  41 . When a lift type valve is used as the second valve  9 , raw water containing a suspended substance may leak from the raw water sampling line  39 , which is on the high pressure side, to the treated water sampling line  40 , which is on the low pressure side; however, due to the action of the check valve  28 , it is possible to prevent raw water from being mixed into treated water.  
         [0048]     When a predetermined period of time (e.g., 30 seconds to 5 minutes) during which the clean water in the measuring chamber  18  is totally replaced by raw water, has elapsed, the first valve  8  and the fourth valve  11  are set in the closed state. As a result, a predetermined amount of raw water is stored in the measuring chamber  18  as the sample water. Next, light from the light emitting element  51  is applied to the sample water in the measuring chamber  18  through the first light guide portion  44 , and 90° scattered light from the sample water is detected by the light receiving element  56  through the second light guide portion  45 . Then, the intensity of the scattered light at this time is stored in a memory in the controller as a measurement value (A). When the measurement value (A) is obtained, the procedure for the turbidity measuring device  1  advances to the second measuring process.  
         [0049]     As shown in  FIG. 8 , in the second measuring process, the second valve  9  and the fourth valve  11  are set in the open state in accordance with the command signal from the controller. On the other hand, the first valve  8  and the third valve  10  are set in the closed state. The treated water flowing through the treated water sampling line  40  (that is, the treated water having passed through the filtering apparatus  31 ) is introduced into the measuring chamber  18  from the second sample water inlet  15  through the third flow passage  22  and the fourth flow passage  23 . The treated water flows from the upper portion of the measuring chamber  18  to the drainage outlet  17  through the eighth flow passage  27  and the seventh flow passage  26  while extruding the raw water stored in the measuring chamber  18  in the first measuring process. Then, the water from the drainage outlet  17  is continuously discharged to the exterior of the system through the drain line  41 .  
         [0050]     When a predetermined period of time (e.g., 30 seconds to 5 minutes) during which the raw water in the measuring chamber  18  is totally replaced by treated water, has elapsed, the second valve  9  and the fourth valve  11  are set in the closed state. As a result, a predetermined amount of treated water is stored in the measuring chamber  18  as the sample water. Next, light from the light emitting element  51  is applied to the sample water in the measuring chamber  18  through the first light guide portion  44 , and 90° scattered light from the sample water is detected by the light receiving element  56  through the second light guide portion  45 . Then, the intensity of the scattered light at this time is stored in memory in the controller as a measurement value (B). When the measurement value (B) is obtained, the procedure for the turbidity measuring device  1  advances to the washing process.  
         [0051]     As shown in  FIG. 9 , in the washing process, the third valve  10  and the fourth valve  11  are set in the open state in accordance with the command signal from the controller. On the other hand, the first valve  8  and the second valve  9  are set in the closed state. The treated water flowing through the treated water sampling line  40  (that is, the treated water having passed through the filtering apparatus  31 ) is supplied from the second sample water inlet  15  to the sample water outtake  16  through the third flow passage  22 , the sixth flow passage  25 , and the fifth flow passage  24  as the raw water for producing clean water. Further, this raw water is supplied to the sample water intake  76  through the sample water supply line  77 , and introduced into the filter cartridge  78 . In the filter cartridge  78 , clean water is produced by passing the raw water through the filter medium  79 . This clean water is supplied into the clean water supply chamber  65  through the second hollow portion  82  and the first hollow portion  74 , and then injected into the measuring chamber  18  through the nozzle  61  as washing water.  
         [0052]     The washing water ejected from the first nozzle hole  67  at a predetermined flow velocity hits the end surface of the transparent rod  46  on the first light guide portion  44  side, and washes away a contaminant component allowed to adhere thereto in the measuring processes while separating it therefrom. On the other hand, the washing water ejected from the second nozzle hole  68  at a predetermined flow velocity hits the end surface of the transparent rod  46  on the second light guide portion  45  side, and washes away the contaminant component allowed to adhere thereto in the measuring processes while separating it therefrom. Thus, the contamination of the end surfaces of the transparent rods  46  is suppressed, and a predetermined measuring accuracy is maintained. The used cleansing water flows from the upper portion of the measuring chamber  18  to the drainage outlet  17  through the eighth flow passage  27  and the seventh flow passage  26 , and is continuously discharged to the exterior of the system through the drain line  41 .  
         [0053]     When the washing of the transparent rods  46  is executed for a predetermined period of time (e.g., 30 seconds to 5 minutes), the third valve  10  and the fourth valve  11  are set in the closed state. As a result, a predetermined amount of clean water is stored in the measuring chamber  18  as blank water. Next, light from the light emitting element  51  is applied to the blank water in the measuring chamber  18  through the first light guide portion  44 , and 90° scattered light from the blank water is detected by the light receiving element  56  through the second light guide portion  45 . The intensity of the scattered light at this time is stored in the memory as a blank value (C). When the blank value (C) is obtained, the turbidity measuring device  1  performs a judgment processing on the turbidity of the raw water and the treated water.  
         [0054]     First, in the controller, the measurement value (A) and the blank value (C) are read out of the memory, and the difference (A-C) in scattered light intensity is obtained; then, the turbidity of the raw water is judged from the value of the difference (A-C) based on a previously stored analytical curve. Next, in the controller, the measurement value (B) and the blank value (C) are read out of the memory, and the difference (B-C) in scattered light intensity is obtained; then, the turbidity of the treated water is judged from the value of the difference (B-C) based on the analytical curve. That is, in this judgment processing, the measurement value (A) and the measurement value (B) are corrected by the blank value (C), whereby the zero-point drift generated due to fluctuations in ambient temperature, etc. is canceled, thereby achieving an enhancement in judgment accuracy. The judged turbidity of the raw water and that of the treated water are output, for example, to a display (not shown). When the turbidity of the raw water and that of the treated water have been output, the turbidity measuring device  1  is kept on standby until the next measuring operation. Here, during standby of the turbidity measuring device  1 , clean water is kept stored in the measuring chamber  18 , so adhesion of the contaminant component to the transparent rods  46  is suppressed, and a predetermined measuring accuracy is maintained.  
         [0055]     According to the first embodiment of the present invention described above, it is possible to realize a compact optical measuring device in which the sample water sampling mechanism and the clean water producing mechanism are integrated with each other. Further, there is realized an optical measuring device capable of performing nozzle-washing without involving a reduction in the pressure with which clean water is supplied. As a result, it is possible to perform installation on-site and maintenance in a short period of time. Further, it is possible to effectively remove a contaminant component adhering to the light transmitting windows, making it possible to maintain a predetermined measuring accuracy.  
       Second Embodiment  
       [0056]     In the optical measuring device of the first embodiment of the present invention described above, turbidity is measured from the 90° scattered light of the sample water. However, the optical measuring device according to the present invention may also adopt a construction in which the first light guide portion  44  and the second light guide portion  45  are arranged at a predetermined angle other than 90°, whereby it is possible to measure turbidity from, for example, 45° scattered light or 135° scattered light of the sample water. Further, it is also possible for the optical measuring device according to the present invention to adopt a construction in which the first light guide portion  44  and the second light guide portion  45  are arranged to be opposed to each other, whereby turbidity measurement is effected from the transmitted light of the sample water.  
       Third Embodiment  
       [0057]     In the first and second embodiments of the present invention described above, the optical measuring device measures the turbidity of the sample water. However, the optical measuring device according to the present invention is also applicable to the measurement of the concentration of a specific component of the sample water, for example, the concentration of a hardness component, dissolved oxygen, residual chlorine, whole chlorine, alkali component, hydrogen ions (pH), or silica by a calorimetric method using a coloring reagent. In this case, the first light guide portion  44  and the second light guide portion  45  are usually arranged to be opposed to each other to detect the transmitted light of a sample water. Further, a chemical supply device is connected to the measuring cell  5  so that a chemical containing a coloring reagent can be added to the sample water in the measuring chamber  18 . Further, it is also desirable to provide the measuring cell  5  with an agitating device in order to uniformly mix the sample water and chemicals with each other.