Measuring device

Abstract

To provide a measuring device of which housing of a detector becomes corrosive less easily.SOLUTION: A measuring device (1) according to the present invention includes a detector (100) immersed in sample water (W) to detect water quality. The detector (100) includes: a first-metal housing (10); and an anti-corrosive unit (70) attached to the outside of the housing (10), the anti-corrosive unit preventing corrosion of the housing (10). The anti-corrosive unit (70) is electrically connected to the housing (10) and has an anti-corrosive member (71) made of a second metal having a less noble electrode potential than that of the first metal.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a measuring device.

Background Art

[0002] Measuring devices for measuring water quality (e.g., organic pollutants, turbidity, suspended solids (SS), etc.) are used to measure the water quality of environmental water such as lakes, rivers, or seawater, or the wastewater of factories. Such a measuring device includes a detector that detects the measurement target substance contained in the water to be measured (hereinafter referred to as "sample water") and the properties of the sample water, and measures the water quality based on the detection result of the detector. Generally, when continuously measuring the water quality, a measuring device equipped with an immersion type detector in which the detector is installed below the water surface of the sample water is used (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the measuring device disclosed in Patent Document 1, since the detector is immersed in the sample water, a material resistant to corrosion (e.g., stainless steel, etc.) is used for the housing of the detector. However, as described above, there are various types of sample water. For example, when the sample water contains a large amount of salt or iron, the housing may may cor can corrode.

[0005] An object of the present invention is to provide a measuring device that suppresses corrosion of the housing of the detector.

Means for Solving the Problems

[0006] The measuring device according to the present invention comprises a detector that is immersed in a sample of water to detect water quality, the detector comprising a first metal housing and a corrosion protection unit attached to the outside of the housing to prevent corrosion of the housing, the corrosion protection unit comprising a second metal corrosion protection member that is electrically connected to the housing and has an electrode potential less noble than the first metal. [Effects of the Invention]

[0007] According to the present invention, corrosion of the detector housing can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an embodiment of the measuring device according to the present invention. [Figure 2] This is a side view of the detector included in the measuring device shown in Figure 1. [Figure 3] Figure 2 is a partially enlarged cross-sectional view of the detector in the AA line. [Figure 4] Figure 2 is a partially enlarged cross-sectional view of the corrosion protection unit portion of the detector along line AA. [Figure 5] Figure 4 is an exploded cross-sectional view of the corrosion protection unit. [Figure 6] Figure 5 is a bottom view of the corrosion protection member provided in the corrosion protection unit. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the measuring device according to the present invention (hereinafter referred to as "the device") will be described with reference to the drawings. In the following description, elements having the same structure or function will be denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, the dimensional ratios of each element may be exaggerated for the sake of explanation and are not limited to the ratios shown in each drawing.

[0010] ● Measuring device ● ● Configuration of the measuring device Figure 1 is a schematic diagram showing an embodiment of this device.

[0011] The device 1 is, for example, an absorbance measurement device that measures the organic pollutants in the sample water W using UV (ultraviolet) light. The device 1 includes a detector 100 and a converter 200.

[0012] The "sample water W" is the water that is the object of water quality measurement by the device 1. The sample water W is, for example, the wastewater from a factory.

[0013] Note that the sample water in the present invention is not limited to the wastewater from a factory. That is, for example, the sample water may be environmental water such as lake water, river water, or seawater.

[0014] The detector 100 emits light to the sample water W and receives the light transmitted through the sample water W, thereby detecting the water quality (absorbance) of the sample water W. The detector 100 is installed below the water surface of the sample water W. That is, the detector 100 is immersed in the sample water W during use. The configuration of the detector 100 will be described later. The detector 100 is electrically connected to the converter 200 via a cable C.

[0015] In the following description, "upward" is the direction in which the water surface is located with respect to the detector 100 immersed in the sample water W (above the paper surface of FIG. 1). "Downward" is the opposite direction to upward (below the paper surface of FIG. 1).

[0016] The converter 200 calculates and converts the water quality (organic pollutants, turbidity, SS concentration, etc.) of the sample water W based on the absorbance detected by the detector 100. The converter 200 is at a position higher than the water surface and is installed, for example, above the detector 100.

[0017] ● Configuration of the detector FIG. 2 is a side view of the detector 100. FIG. 3 is a partial enlarged cross-sectional view of the detector 100 taken along line AA in FIG. 2. For the sake of explanation, FIG. 3 omits and simplifies the illustration of a part of the internal structure of the detector 100.

[0018] The detector 100 includes a housing 10, a light emitting unit 20, a light receiving unit 30, a motor 40, a rotating shaft 50, a wiper unit 60, and a corrosion prevention unit 70.

[0019] The housing 10 houses the light emitting unit 20, the light receiving unit 30, the motor 40, and the rotating shaft 50. The housing 10 is a substantially cylindrical body along the vertical direction. The housing 10 is made of a metal having corrosion resistance (for example, stainless steel such as SUS316). Stainless steel is an example of the first metal in the present invention. The housing 10 includes a unit holding portion 11, a first cover 12, and a second cover 13.

[0020] The unit holding portion 11 holds the light emitting unit 20, the light receiving unit 30, and the rotating shaft 50. The unit holding portion 11 includes a first holding portion 111, a second holding portion 112, and two columnar portions 113 and 114.

[0021] The first holding portion 111 holds the light emitting unit 20. The first holding portion 111 is a bottomed cylindrical shape with the bottom facing upward. The first holding portion 111 includes a window mounting hole 111h. The window mounting hole 111h is disposed on the ceiling wall 111a (bottom) of the first holding portion 111 and penetrates the ceiling wall 111a. The window mounting hole 111h is disposed so as to face a cell space CS described later.

[0022] The second holding portion 112 holds the light receiving unit 30 and the rotating shaft 50. The second holding portion 112 is a bottomed cylindrical shape. The second holding portion 112 includes a window mounting hole 112h and a rotating shaft mounting hole (not shown; the same applies hereinafter). The window mounting hole 112h and the rotating shaft mounting hole are disposed on the bottom wall 112a of the second holding portion 112 and penetrate the bottom wall 112a. The window mounting hole 112h and the rotating shaft mounting hole are disposed so as to face a cell space CS described later.

[0023] The two columnar sections 113 and 114 connect the first holding section 111 and the second holding section 112 such that the upper surface 111b of the ceiling wall 111a and the lower surface 112b of the bottom wall 112a face each other. A cell space CS filled with sample water W (see Figure 1; the same applies hereafter) is formed between the upper surface 111b and the lower surface 112b.

[0024] The two window mounting holes 111h and 112h are located on the same virtual axis along the vertical direction. That is, the two window mounting holes 111h and 112h are located opposite each other, with the cell space CS in between.

[0025] The first cover 12 is a bottomed cylindrical shape. The first cover 12 is liquid-tight and detachably attached to the first retaining part 111. As a result, the first retaining part 111 and the first cover 12 form a first housing space S1 in which the light source 21, described later, is housed. The first cover 12 is provided with a female screw hole 12a (see Figure 4; the same applies hereinafter). The female screw hole 12a is located in the center of the outer surface (bottom surface 12c: see Figure 4 for both; the same applies hereinafter) of the bottom 12b of the first cover 12. The female screw hole 12a does not penetrate the bottom 12b.

[0026] The second cover 13 is cylindrical. The second cover 13 is liquid-tight and detachably attached to the second holding part 112. As a result, the second holding part 112 and the second cover 13 form a second housing space S2 in which the light receiving part 31, the motor 40, and the rotating shaft 50, which will be described later, are housed.

[0027] The light-emitting unit 20 generates light and emits the generated light into the sample water W in the cell space CS. The light-emitting unit 20 comprises a light source 21 and an emission window 22. The light source 21 is a semiconductor light-emitting element such as a light-emitting diode (LED). The light source 21 is an example of a light-emitting part in the present invention. The light source 21 is housed in a first containment space S1 and held in a first holding part 111. The emission window 22 is made of sapphire glass, for example, and is liquid-tightly attached to a window mounting hole 111h. The upper surface of the emission window 22 is positioned to protrude slightly towards the cell space CS from the upper surface of the ceiling wall 111a.

[0028] The light-receiving unit 30 receives light transmitted through the sample water W in the cell space CS. The light-receiving unit 30 comprises a light-receiving section 31 and an incident window 32. The light-receiving section 31 is, for example, a semiconductor light-receiving element such as a photodiode. The light-receiving section 31 is housed in a second housing space S2 and held by a second holding section 112. The incident window 32 is, for example, made of sapphire glass and is attached to a window mounting hole 112h. The lower surface of the incident window 32 is positioned to protrude slightly towards the cell space CS than the lower surface of the bottom wall 112a. The incident window 32 is positioned parallel to and opposite the exit window 22.

[0029] The motor 40 supplies power to move the wiper unit 60. The motor 40 is housed in the second housing space S2 with its rotation axis facing downwards.

[0030] The rotating shaft 50 transmits power from the motor 40 to the wiper unit 60, causing the wiper unit 60 to reciprocate. The rotating shaft 50 is housed in the second housing space S2 and is liquid-tight and rotatably mounted in the rotating shaft mounting hole. The lower end portion 50a of the rotating shaft 50 protrudes into the cell space CS.

[0031] The wiper unit 60 cleans the outlet window 22 and the inlet window 32. The wiper unit 60 comprises a wiper support member 61, a wiper 62, and a pair of wiper retaining plates 63 and 64. The wiper 62 is attached to the wiper support member 61 while being sandwiched between the wiper retaining plates 63 and 64. The wiper support member 61 is attached to the lower end 50a of the rotating shaft 50.

[0032] The wiper unit 60 is positioned in the cell space CS and is configured to reciprocate (reciprocating rotation) in the circumferential direction of the rotation axis 50 in accordance with the reciprocating rotational motion of the rotation axis 50. At this time, the wiper 62 is configured to move across the space between the outlet window 22 and the inlet window 32 (part of the cell space CS) while in contact with the outlet window 22 and the inlet window 32. In other words, the wiper 62 is configured to reciprocate within the sample water W filling the cell space CS. As the wiper 62 reciprocates, contaminants adhering to the outlet window 22 and the inlet window 32 are removed.

[0033] Figure 4 is a partially enlarged cross-sectional view of the corrosion protection unit 70 portion of the detector 100 along line AA in Figure 2. Figure 5 is an exploded cross-sectional view of the corrosion protection unit 70 shown in Figure 4.

[0034] The corrosion protection unit 70 is attached to the outside of the housing 10 to prevent corrosion of the housing 10. The corrosion protection unit 70 comprises a corrosion protection member 71, a first bolt 74, a nut 75, a first washer 76, a second bolt 77, a washer 78, and a second washer 79.

[0035] The corrosion-preventive member 71 prevents corrosion of the housing 10. The corrosion-preventive member 71 is made of a metal that has an electrode potential that is relatively noble (has a high ionization tendency) relative to the metal that makes up the housing 10. That is, for example, the corrosion-preventive member 71 is made of a metal mainly composed of zinc.

[0036] "Zinc-based metal" refers to a metal containing 50% or more pure zinc or zinc alloy, and may contain other components different from pure zinc or zinc alloy. The type and number of other components are arbitrary, as long as the corrosion-preventive member 71 has an electrode potential that is relatively less noble than the metal (stainless steel) that constitutes the housing 10, but preferably the other components are aluminum and / or magnesium, which have an electrode potential that is relatively less noble than zinc. Furthermore, the zinc-based metal may be a metal with a pure zinc or zinc alloy content of 100% (or approximately 100%). In this embodiment, the corrosion-preventive member 71 is made of high-purity (e.g., 4N) zinc.

[0037] The corrosion-resistant member 71 comprises a main body portion 72 and a housing portion 73.

[0038] The main body portion 72 is cylindrical in shape along the vertical direction. The outer diameter of the main body portion 72 is the same as the outer diameter of the first cover 12 (housing 10). The main body portion 72 includes an upper surface 72a, a lower surface 72b, a through hole 72c, and a guide groove 72d (see Figure 6; the same applies hereinafter). The through hole 72c is a through hole through which the first bolt 74 is inserted. The through hole 72c is located on the central axis of the main body portion 72 and penetrates the main body portion 72 in the vertical direction. The through hole 72c includes a large diameter portion 72e and a small diameter portion 72f having an inner diameter smaller than the inner diameter of the large diameter portion 72e. The upper part of the through hole 72c (for example, the upper half) is the large diameter portion 72e, and the part of the through hole 72c below the large diameter portion 72e (for example, the lower half) is the small diameter portion 72f. The inner surface of the small diameter portion 72f is a female threaded surface that corresponds to the male threaded surface of the first bolt 74, which will be described later.

[0039] In this invention, the length of the small diameter portion in the vertical direction is sufficient to ensure electrical connection with the contact portion described later and to allow the shaft portion to hold the corrosion-preventive member, and does not need to be precisely the length of the lower half of the insertion hole. Also, the length of the large diameter portion in the vertical direction is sufficient to be set according to the vertical length of the head of the first bolt described later, and does not need to be precisely the length of the upper half of the insertion hole.

[0040] Figure 6 is a bottom view of the corrosion protection member 71. The guide groove 72d guides air bubbles that have entered the housing portion 73 to the ventilation hole 73a, which will be described later. The guide groove 72d is located on the diameter line of the main body portion 72 on the lower surface 72b of the main body portion 72. In a side view, the guide groove 72d is arc-shaped. The outer edge of the lower surface 72b of the main body portion 72 extends downward to form a cylindrical housing portion 73. That is, the housing portion 73 is integrally formed with the main body portion 72.

[0041] Return to Figures 4 and 5. The housing section 73 accommodates the protruding portion 74g of the first bolt 74 (described later), the nut 75, the first washer 76, the head 77a of the second bolt 77 (described later), the washer 78, and the second washer 79. The outer diameter of the housing section 73 is the same as the outer diameter of the first cover 12 (housing 10). The housing section 73 is provided with a pair of ventilation holes 73a. The ventilation holes 73a are arranged to be continuous with the guide groove 72d at the upper end portion 73b of the housing section 73 (the end portion on the main body side). That is, the ventilation holes 73a are arranged on the same diameter line as the guide groove 72d.

[0042] The first bolt 74 holds the corrosion-resistant member 71 and electrically connects the housing 10 and the corrosion-resistant member 71. The first bolt 74 is made of the same metal as the housing 10. The first bolt 74 is a hollow bolt having a head 74a, a shaft portion 74b, and an insertion hole 74c. The first bolt 74 is an example of a cylindrical member in the present invention. The head 74a is an example of a cylindrical head in the present invention. The shaft portion 74b is an example of a cylindrical shaft portion in the present invention.

[0043] The head 74a is cylindrical and has an upper surface 74d and a lower surface 74e. The upper surface 74d of the head 74a is flat and has no irregularities such as markings. The inner edge of the lower surface 74e of the head 74a extends downward to form the shaft portion 74b. The outer circumferential surface of the shaft portion 74b is a male threaded surface corresponding to the female threaded surface of the small diameter portion 72f of the insertion hole 72c of the corrosion-resistant member 71. The shaft portion 74b is an example of a cylindrical male threaded portion in the present invention. The outer diameter of the head 74a is larger than the outer diameter of the shaft portion 74b. The insertion hole 74c is located on the central axis of the first bolt 74 and penetrates the head 74a and the shaft portion 74b in the vertical direction. The first bolt 74 is inserted into the insertion hole 72c from above, the shaft portion 74b is inserted into the small diameter portion 72f, and the head 74a is located in the large diameter portion 72e. The lower surface 74e of the head 74a abuts against the bottom surface 72g of the large diameter portion 72e. In the vertical direction, the length of the head 74a is slightly longer than the length of the large diameter portion 72e, and the length of the shaft portion 74b is longer than the length of the small diameter portion 72f. Therefore, the upper end of the head 74a protrudes slightly above the main body portion 72, and the upper surface 74d of the head 74a is positioned above the upper surface 72a of the main body portion 72. The upper part of the shaft portion 74b is a contact portion 74f that is screwed into (fitted with) the small diameter portion 72f and abuts against the inner surface of the small diameter portion 72f. That is, the contact portion 74f is located inside the small diameter portion 72f, and the outer surface of the contact portion 74f abuts against the inner surface of the small diameter portion 72f. In the vertical direction, the length of the contact portion 74f is approximately the same as the length of the small diameter portion 72f. The portion of the shaft portion 74b below the contact portion 74f is a protruding portion 74g that protrudes downward from the lower surface 72b of the main body portion 72. The protruding portion 74g is located (housed) within the housing portion 73. The lower end surface 74h of the shaft portion 74b is flat and free of burrs or other irregularities.

[0044] The nut 75 is, for example, a hexagonal nut. The nut 75 is made of the same metal as the housing 10. The nut 75 is housed in the housing portion 73 and is attached (fitted) to the protruding portion 74g of the shaft portion 74b of the first bolt 74. As a result, the nut 75, together with the head 74a of the first bolt 74, clamps the body portion 72 via the first washer 76. At this time, the lower end surface 74h of the shaft portion 74b is positioned below the nut 75.

[0045] The first washer 76 is, for example, a flat washer. The first washer 76 is made of the same metal as the housing 10. The inner diameter of the first washer 76 is larger than the outer diameter of the shaft portion 74b of the first bolt 74. The first washer 76 is housed in the housing portion 73, and the protruding portion 74g of the shaft portion 74b is inserted through the first washer 76. The first washer 76 is positioned between the nut 75 and the lower surface 72b of the main body portion 72. The first washer 76 is pressed upward by the nut 75 and pressed against the lower surface 72b of the main body portion 72.

[0046] The second bolt 77 attaches the first bolt 74 to the housing 10. The second bolt 77 is an example of a mounting member in the present invention. The second bolt 77 is made of the same metal as the housing 10. The second bolt 77 is a known socket head cap bolt comprising a head 77a and a shaft portion 77b. The head 77a comprises an upper surface 77c and a lower surface 77d. The central part of the upper surface 77c of the head 77a extends upward to form the shaft portion 77b. The upper part of the shaft portion 77b (for example, the upper half) is a male threaded portion 77e, on which a male threaded surface corresponding to the female threaded hole 12a of the housing 10 (first cover 12) is formed on its outer circumferential surface. The outer diameter of the head 77a is larger than the outer diameter of the shaft portion 77b and larger than the inner diameter of the insertion hole 74c of the first bolt 74. The outer diameter of the shaft portion 77b is smaller than the inner diameter of the insertion hole 74c of the first bolt 74. In the vertical direction, the length of the shaft portion 77b is greater than the length of the first bolt 74. The second bolt 77 is inserted from below into the insertion hole 74c of the first bolt 74. That is, the second bolt 77 is inserted into the corrosion-resistant member 71. The upper end portion 77f of the shaft portion 77b (male thread portion 77e) of the second bolt 77 protrudes above the head 74a of the first bolt 74. The upper end portion 77f is an example of the tip portion in this invention.

[0047] The washer 78 is, for example, a known anti-loosening washer. The washer 78 is made of the same metal as the housing 10. The washer 78 is, for example, composed of a pair of ring-shaped plate members, and is configured such that when the second bolt 77 loosens, the ring-shaped plate members move away from each other, increasing the axial force of the second bolt 77. The inner diameter of the washer 78 is smaller than the outer diameter of the head 77a of the second bolt 77 and larger than the outer diameter of the shaft portion 77b of the second bolt 77. The washer 78 is housed in the housing portion 73, and the shaft portion 77b of the second bolt 77 is inserted through the washer 78. The washer 78 is positioned between the head 77a of the second bolt 77 and the second washer 79.

[0048] The second washer 79 is, for example, a flat washer. The second washer 79 is made of the same metal as the housing 10. The inner diameter of the second washer 79 is larger than the outer diameter of the shaft portion 77b of the second bolt 77. The second washer 79 is housed in the housing portion 73, and the shaft portion 77b of the second bolt 77 is inserted through the second washer 79. The second washer 79 is positioned between the washer 78 and the lower end surface 74h of the shaft portion 74b of the first bolt 74.

[0049] The corrosion protection unit 70, configured in this way, is attached to the lower surface 12c of the first cover 12 (housing 10) by screwing (fitting) the upper end 77f (male threaded portion 77e) of the shaft portion 74b of the first bolt 74 into the female threaded hole 12a of the first cover 12 (housing 10). At this time, the first bolt 74 is sandwiched between the head 77a of the second bolt 77 and the lower surface 12c of the first cover 12 via a washer 78 and a second washer 79. As a result, the corrosion protection member 71 is attached to the first cover 12 (housing 10) via the first bolt 74. In addition, the upper surface 74d of the head 74a of the first bolt 74 abuts against the lower surface 12c of the first cover 12, while the upper surface 72a of the main body portion 72 does not abut against the lower surface 12c. In other words, in the corrosion protection unit 70, only the first bolt 74 and the second bolt 77 are in contact with the housing 10, while the corrosion protection member 71 is not in contact with the housing 10. Therefore, the corrosion protection member 71 is electrically connected to the housing 10 via the first bolt 74, and also electrically connected to the housing 10 via the second bolt 77, washer 78, second washer 79, and first bolt 74. As mentioned above, the upper surface 74d of the head 74a and the lower end surface 74h of the shaft portion 74b are flat surfaces without irregularities, so the electrical connection via the first bolt 74 is stable.

[0050] As mentioned above, the metal (zinc) constituting the corrosion-preventive member 71 has an electrode potential that is relatively less noble (has a higher ionization tendency) compared to the metal (stainless steel) constituting the housing 10 (first bolt 74, nut 75, first washer 76, second bolt 77, washer 78, second washer 79). Therefore, as shown in Figure 1, when the detector 100 is immersed in the sample water W, the corrosion-preventive member 71 functions as a so-called sacrificial anode relative to the housing 10, and the housing 10 functions as a cathode relative to the sacrificial anode. As a result, a so-called corrosion-preventive current flows from the corrosion-preventive member 71, which is the sacrificial anode, to the housing 10, and corrosion of the housing 10 is prevented by the corrosion of the corrosion-preventive member 71 itself.

[0051] Here, as the corrosion-preventive member 71 corrodes, zinc ions dissolve into the sample water W, and the corrosion-preventive member 71 dissolves into the sample water W. Furthermore, the corrosion of the corrosion-preventive member 71 progresses rapidly on its outer surface, especially on the outer surface with a large wetted area. As a result, as the corrosion of the corrosion-preventive member 71 progresses, the outer diameter of the corrosion-preventive member 71 decreases, and the thin-walled housing portion 73 disappears first. The corrosion of the corrosion-preventive member 71 also progresses on the upper surface 72a and lower surface 72b of the main body portion 72. Finally, the corrosion of the corrosion-preventive member 71 progresses to the fastening portion (fitting portion) between the small-diameter portion 72f and the shaft portion 74b (contact portion 74f) of the first bolt 74, and the main body portion 72 also disappears.

[0052] In this way, the corrosion-resistant member 71 is held by the first bolt 74 and electrically connected to the housing 10 during the progression of corrosion, and does not fall off during the corrosion process. That is, the first bolt 74 functions as a so-called core during the progression of corrosion. Furthermore, the first bolt 74 is not embedded in the corrosion-resistant member 71 by molding or the like, but is easily attached to the corrosion-resistant member 71 by screwing it into the small-diameter portion 72f.

[0053] Furthermore, as mentioned above, the first bolt 74 is not held by the corrosion-preventive member 71, but is sandwiched between the head 77a of the second bolt 77 and the lower surface 12c of the first cover 12 via a washer 78 and a second washer 79. Therefore, even if the corrosion-preventive member 71 disappears, the first bolt 74 will not fall into the sample water W. In addition, a washer 78, which is a loosening prevention washer, is sandwiched between the lower end surface 74h of the shaft portion 74b of the first bolt 74 and the head 77a of the second bolt 77. Therefore, even if a force is applied to the second bolt 77 in a direction that would loosen it due to vibration of the detector 100, the washer 78 pushes down the second bolt 77, increasing the axial force of the second bolt 77 and thus increasing the tightening force of the second bolt 77. Therefore, the second bolt 77 does not fall into the sample water W, and the first bolt 74, nut 75, first washer 76, washer 78, and second washer 79 also do not fall into the sample water W.

[0054] Furthermore, the nut 75 and the first washer 76 are attached to the protruding portion 74g of the first bolt 74, and the first washer 76 is pressed against the lower surface 72b of the main body portion 72. As a result, the intrusion of the sample water W into the small diameter portion 72f is suppressed and prevented. Therefore, the contact between the small diameter portion 72f and the shaft portion 74b (contact portion 74f) of the first bolt 74 is stably maintained until the final stages of corrosion of the corrosion-resistant member 71. In other words, the electrical connection between the corrosion-resistant member 71 and the housing 10 is stably maintained until the final stages of corrosion of the corrosion-resistant member 71.

[0055] Furthermore, a ventilation hole 73a is provided at the upper end 73b of the housing section 73, and a guide groove 72d continuous with the ventilation hole 73a is provided at the lower surface 72b of the main body section 72. Therefore, even if air bubbles in the sample water W enter the housing section 73, the air bubbles are guided by the guide groove 72d and released to the outside of the corrosion-preventive member 71 through the ventilation hole 73a. As a result, no air bubbles remain in the housing section 73, and interference with the corrosion of the corrosion-preventive member 71 by air bubbles is prevented. Consequently, the corrosion-preventive member 71 can exert the corrosion-preventive effect on the housing 10 as designed.

[0056] Furthermore, the outer diameter of the corrosion protection member 71 is the same as the outer diameter of the housing 10. Therefore, when the corrosion protection unit 70 is attached to the housing 10, the detector 100 has a single cylindrical appearance. For this reason, the detector 100 can be housed in, for example, a cylindrical protective device (not shown).

[0057] Furthermore, the corrosion protection unit 70 is modularized and can be easily attached to and detached from the housing 10 simply by fastening and unfastening with the second bolt 77.

[0058] ●Summary According to the embodiment described above, the apparatus 1 includes a detector 100 that measures the water quality of a sample water W using light and detects the water quality by being immersed in the sample water W. The detector 100 includes a housing 10, a light source 21, a light receiving unit 31, and a corrosion protection unit 70. The light source 21 emits light, and the light receiving unit 31 receives light from the light source 21. The housing 10 is made of stainless steel and houses the light source 21 and the light receiving unit 31. The corrosion protection unit 70 is attached to the outside of the housing 10 and prevents corrosion of the housing 10. The corrosion protection unit 70 is electrically connected to the housing 10 and includes a corrosion protection member 71 made of metal (zinc) having an electrode potential lower than the metal constituting the housing 10. With this configuration, when the detector 100 is immersed in the sample water W, the corrosion protection member 71 functions as a so-called sacrificial anode relative to the housing 10, and the housing 10 functions as a cathode relative to the sacrificial anode. As a result, a so-called corrosion-preventive current flows from the sacrificial anode, the corrosion-preventive member 71, to the housing 10, causing the corrosion-preventive member 71 itself to corrode, thereby preventing corrosion of the housing 10.

[0059] Furthermore, according to the embodiment described above, the corrosion protection unit 70 comprises a first bolt 74 and a second bolt 77. The first bolt 74 is made of the same metal as the metal constituting the housing 10. A corrosion protection member 71 is attached to the first bolt 74. The second bolt 77 is inserted through the first bolt 74, attaching the first bolt 74 to the housing 10. The first bolt 74 is sandwiched between the housing 10 (first cover 12) and a part of the second bolt 77 (head 77a). With this configuration, even if the corrosion protection member 71 disappears, the first bolt 74 will not fall into the sample water W. Therefore, the first bolt 74 does not remain in the sample water W as a foreign object, and the corrosion protection unit 70 can be recovered except for the corrosion protection member 71.

[0060] Furthermore, according to the embodiment described above, the corrosion-preventive member 71 is provided with a through hole 72c through which the first bolt 74 is inserted. The outer surface of the shaft portion 74b of the first bolt 74 is in contact with the inner surface of the through hole 72c (small diameter portion 72f). The corrosion-preventive member 71 is not in contact with the housing 10. With this configuration, the corrosion-preventive member 71 is held by the first bolt 74 during the progression of corrosion and does not fall off during the corrosion process. In other words, the first bolt 74 functions as a so-called core during the progression of corrosion.

[0061] Furthermore, according to the embodiments described above, the first bolt 74 is a hollow bolt comprising a head 74a, a shaft portion 74b extending from the head 74a, and a through hole 74c that penetrates the head 74a and the shaft portion 74b. The shaft portion 74b of the first bolt 74 is inserted through the through hole 74c. The through hole 72c comprises a small-diameter portion 72f through which the shaft portion 74b is inserted, and a large-diameter portion 72e where the head 74a is located. The inner surface of the small-diameter portion 72f is a female threaded surface, and the shaft portion 74b is screwed into the small-diameter portion 72f. With this configuration, the corrosion-preventive member 71 is securely held by the first bolt 74 by the screw fit and does not fall off during corrosion. That is, the first bolt 74 functions as a so-called core metal during the progression of corrosion.

[0062] Furthermore, according to the embodiment described above, the corrosion protection unit 70 comprises a nut 75 and a first washer 76. The nut 75 is attached to a protruding portion 74g of the shaft portion 74b that protrudes from the small diameter portion 72f. The protruding portion 74g is inserted through the first washer 76, and the first washer 76 is positioned between the nut 75 and the corrosion protection member 71. With this configuration, the intrusion of the sample water W into the small diameter portion 72f is suppressed and prevented. Therefore, the contact between the small diameter portion 72f and the shaft portion 74b (male thread portion) of the first bolt 74 is stably maintained until the final stages of corrosion of the corrosion protection member 71. That is, the electrical connection between the corrosion protection member 71 and the housing 10 is stably maintained until the final stages of corrosion of the corrosion protection member 71.

[0063] Furthermore, according to the embodiment described above, the second bolt 77 comprises a head 77a and a shaft portion 77b extending from the head 77a. The outer circumferential surface of the shaft portion 77b is a male threaded surface. The housing 10 (first cover 12) is provided with a female threaded hole 12a into which the shaft portion 77b is screwed. The first bolt 74 is sandwiched between the housing 10 and the head 77a. With this configuration, the first bolt 74 is easily fixed to the housing 10 by screwing the second bolt 77 into the female threaded hole 12a. As a result, even if the corrosion protection member 71 disappears, the first bolt 74 does not fall into the sample water W. Therefore, the first bolt 74 does not remain as a foreign object in the sample water W, and the corrosion protection unit 70 can be recovered except for the corrosion protection member 71.

[0064] Furthermore, according to the embodiment described above, the corrosion-preventive member 71 comprises a main body portion 72 in which an insertion hole 72c is located, and a housing portion 73 extending from the main body portion 72. The housing portion 73 houses a part of the first bolt 74 (protruding portion 74g) and a part of the second bolt 77 (head portion 77a). The housing portion 73 is provided with a ventilation hole 73a located at the end of the housing portion 73 on the main body portion 72 side (upper end portion 73b) and penetrating the housing portion 73. With this configuration, even if air bubbles in the sample water W enter the housing portion 73, the air bubbles are released to the outside of the corrosion-preventive member 71 through the ventilation hole 73a. Therefore, no air bubbles remain in the housing portion 73, and interference with the corrosion of the corrosion-preventive member 71 by air bubbles is prevented. As a result, the corrosion-preventive member 71 can exhibit the corrosion-preventive effect designed for the housing 10.

[0065] ●Other Embodiments● In this invention, it is sufficient that the cell space of the detector and the corrosion protection unit are immersed in the sample water, and the entire detector does not need to be immersed in the sample water.

[0066] Furthermore, in the present invention, the device only needs to be equipped with an immersion-type detector and is not limited to a device that measures the water quality of a sample water using light (absorbance measuring device). That is, for example, the device may be a turbidity measuring device (turbidimeter), a dissolved oxygen meter, a residual chlorine meter, a pH meter, a conductivity meter, etc.

[0067] Furthermore, in the present invention, the material of the housing may be any metal having an electrode potential that is relatively noble (has a low ionization tendency) with respect to the metal constituting the corrosion-preventive member 71, and is not limited to stainless steel.

[0068] Furthermore, the shape of the corrosion-preventive member is not limited to this embodiment. That is, for example, the main body may be in the shape of a rectangular parallelepiped.

[0069] Furthermore, in the present invention, the corrosion-preventive member does not necessarily have to have a housing portion. That is, for example, the corrosion-preventive member may be cylindrical.

[0070] Furthermore, in the present invention, the insertion hole of the corrosion-preventive member does not necessarily have a large-diameter portion and a small-diameter portion. That is, for example, the inner diameter of the insertion hole may be the same from the upper end to the lower end.

[0071] Furthermore, in the present invention, the inner surface of the small-diameter portion does not have to be a female threaded surface. In this case, the outer circumferential surface of the male threaded portion of the first bolt is not a male threaded surface, and this portion may be fitted into the small-diameter portion.

[0072] Furthermore, in the present invention, the insertion hole for the corrosion-preventive member only needs to be positioned so that the corrosion-preventive member can be held by the first bolt, and does not need to be positioned on the central axis of the main body.

[0073] Furthermore, in the present invention, the main body does not necessarily have to be equipped with a guide groove.

[0074] Furthermore, in the present invention, the first bolt does not need to have a head.

[0075] Furthermore, in the present invention, the insertion hole for the first bolt only needs to be positioned so that the first bolt can be sandwiched between the head of the second bolt and the lower surface of the first cover, and does not need to be positioned on the central axis of the first bolt.

[0076] Furthermore, in the present invention, the guide groove and the ventilation hole may be inclined such that, in a vertical cross-sectional view, they are directed diagonally upward from the radial center of the main body toward the outer edge.

[0077] Furthermore, the cylindrical member in the present invention may be any cylindrical shape and is not limited to a hollow bolt. That is, for example, the cylindrical member in the present invention may be a cylindrical tube. In this case, the tube may have a shaft portion that is fitted into the small diameter portion and a head portion that has a larger outer diameter than the shaft portion and is located in the large diameter portion. Alternatively, the outer diameter of the tube may be the same from the top end to the bottom end.

[0078] Furthermore, in the present invention, the corrosion protection unit does not necessarily have to include a nut and a first washer. In this case, the fastening portion between the small diameter portion and the contact portion may be sealed with resin or the like to prevent the sample water from entering the small diameter portion.

[0079] Furthermore, in the present invention, the nut, the first washer, and a portion of the lower surface of the main body (the portion surrounding the first washer) may be covered with a sealant or the like to prevent the sample water from entering the small diameter portion.

[0080] Furthermore, in the present invention, the corrosion protection unit does not necessarily have to include a washer.

[0081] Furthermore, in the present invention, it is sufficient that the corrosion protection member is electrically connected to the housing, and the position where the corrosion protection unit is attached is not limited to the lower surface of the first cover. That is, for example, the corrosion protection unit may be attached to the circumferential surface of the first cover or the second cover. [Explanation of Symbols]

[0082] 1. Measuring device 100 detectors 10 cabinets 12a Female threaded hole 21 Light source (light-emitting part) 22 Ejection window 31 Light receiving part 32 Entrance window 70 Corrosion Protection Unit 71 Corrosion-resistant material 72 Main body 72c Through hole 72e Large diameter section 72f Small diameter section 73 Accommodation 73a Ventilation holes 73b Upper end (end on the main body side) 74. First bolt (cylindrical member) 74a Head (tubular head) 74b Shaft portion (cylindrical shaft portion) 74g protrusion 75 Nut 76. First washer (washer) 77. Second bolt (mounting component) 77a head 77b Shaft 77f Upper end (tip) 78 Washers

Claims

1. A detector that is immersed in the sample water to detect the water quality of the sample water. It has, The detector is First, a metal casing, A corrosion protection unit is attached to the outside of the housing to prevent corrosion of the housing, Equipped with, The aforementioned corrosion protection unit is A second metal corrosion-preventive member is electrically connected to the housing and has an electrode potential less noble than the first metal, The first metal cylindrical member to which the corrosion-preventive member is attached, The first metal mounting member is inserted through the cylindrical member and attaches the cylindrical member to the housing, Equipped with, The cylindrical member is sandwiched between the housing and a part of the mounting member. A measuring device characterized by the following features.

2. The aforementioned corrosion protection member is The insertion hole through which the cylindrical member is inserted, Equipped with, The outer surface of the cylindrical member abuts against the inner surface of the insertion hole, The corrosion-preventive member does not come into contact with the housing. The measuring device according to claim 1.

3. The aforementioned cylindrical member is A cylindrical head, A cylindrical shaft portion extending from the cylindrical head, A through hole is provided through the cylindrical head and the cylindrical shaft portion, through which the mounting member is inserted, It is a hollow bolt having the following features: The insertion hole of the corrosion-preventive member is The small diameter portion through which the cylindrical shaft portion is inserted, The large-diameter portion where the cylindrical head is arranged, Equipped with, The inner surface of the small diameter portion is a female thread surface. The cylindrical shaft portion is screwed into the small diameter portion. The measuring device according to claim 2.

4. A nut is attached to the protruding portion of the cylindrical shaft portion that protrudes from the small diameter portion, A washer through which the protruding portion is inserted and which is positioned between the nut and the corrosion-preventive member, Having, The measuring device according to claim 3.

5. The aforementioned mounting member is The head and A shaft portion extending from the head, Equipped with, Of the aforementioned shaft portion, at least the outer circumferential surface of the tip portion is a male threaded surface. The aforementioned enclosure is The female screw hole into which the tip portion is screwed, Equipped with, The cylindrical member is sandwiched between the housing and the head. The measuring device according to any one of claims 2 to 4.

6. The aforementioned corrosion protection member is The main body portion in which the insertion hole is located, A cylindrical housing portion extending from the main body portion, which houses a part of the cylindrical member and a part of the mounting member, Equipped with, The aforementioned housing section is A ventilation hole is located at the end of the housing portion on the main body side, and penetrates the housing portion. Equipped with, The measuring device according to claim 2.

7. The first metal is stainless steel, The second metal is zinc, or an alloy of zinc with aluminum and / or magnesium. The measuring device according to claim 1.

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