JP6337448B2 - Flow-type electrode device - Google Patents

Description

  The present invention relates to a flow-type electrode device that can be used for pH measurement in water quality management of high-purity water such as boiler water and ultrapure water.

Conventionally, in order to manage water quality such as boiler water and ultrapure water, a flow-type electrode device that measures the pH of a test solution through a test solution through a flow cell in which a measurement electrode and a comparison electrode are arranged has been used. As the measurement electrode, one having a glass electrode having sensitivity to pH as a sensitive part is generally used. Moreover, as a comparative electrode, generally, a liquid electrode having a liquid junction support that supports a liquid junction formed of porous ceramic or the like and allowing an internal liquid such as a KCl aqueous solution to exude through the liquid junction is used.

  In thermal power plants and nuclear power plants, pure water having an electrical conductivity as low as 100 μS / cm or less is used as boiler water. In addition, in semiconductor factories and the like, ultrapure water having an extremely low electric conductivity of 0.1 μS / cm or less is used as cleaning water. Such high-purity water has high electrical resistance, and thus it is difficult to measure pH stably. This is considered to be due to the fact that the internal liquid that exudes from the liquid junction part of the comparison electrode diffuses and moves to the sensitive part of the measurement electrode, so that the liquid-liquid potential and the streaming potential fluctuate and affect the measurement value.

  Therefore, in the flow type electrode device, in general, the liquid junction is arranged downstream of the sensitive part in the flow cell. Further, there are the following means for preventing the internal liquid that has oozed from the liquid junction from diffusing to the sensitive part and affecting the indicated value.

  Patent Document 1 describes that the liquid junction part of the reference electrode is disposed in a hole part dug deeper than the flow path of the flow cell, and the internal liquid is discharged together with the test liquid through a small hole provided in the lower part of the hole part. ing. Further, in Patent Document 2, a reverse osmosis membrane is provided between the internal liquid storage part of the comparison electrode and the flow path part of the test liquid in the flow cell, so that the internal liquid and the flow path in the storage part flow. It describes that the test solution is separated. Further, Patent Document 3 discloses that a cylindrical guide pipe is attached to the outer periphery of the electrode body of the composite electrode in which the measurement electrode and the comparison electrode are concentrically integrated, and a liquid junction portion of the comparison electrode is provided. It is described that the internal liquid that exudes from the liquid does not diffuse and move to the sensitive part of the measurement electrode.

JP 59-65756 A Japanese Patent Laid-Open No. 3-216545 JP 2007-178236 A

  Since the apparatus described in Patent Document 3 uses a composite electrode in which a glass electrode and a comparative electrode are concentrically integrated in a flow cell, it has an advantage that the structure is relatively simple and the size can be easily reduced. is there. However, in this apparatus, the measured value may become unstable when the pH of water with an extremely high purity of 0.5 μS / cm or less is measured. One reason may be that the internal flow rate is difficult to control.

  On the other hand, the apparatus described in Patent Document 2 can provide a stable instruction even when the pH of extremely pure water is measured. However, since the structure is relatively complicated using a reverse osmosis membrane, it is disadvantageous for downsizing of the apparatus, and the maintenance work tends to be complicated.

  On the other hand, the device described in Patent Document 1 has a relatively simple structure, but the comparison is made close to the small hole provided in the lower part of the hole part where the liquid junction part of the reference electrode is dug deeper than the flow path of the flow cell. Since the liquid junction of the electrode is disposed, the size of the apparatus in the longitudinal direction tends to increase. In addition, there is a concern that maintenance may take time due to clogging of small holes due to use.

  In the configuration in which the measurement electrode and the comparison electrode are arranged next to each other as described in Patent Document 1, for example, the depth of the hole in which the liquid junction of the comparison electrode is arranged is relatively shallow, and the sensitivity of the measurement electrode is reduced. When the liquid junction part of the reference electrode and the liquid junction part of the reference electrode are brought close to each other, the internal liquid diffuses to the sensitive part side. Therefore, in the pH measurement of water having an electric conductivity of 1 μS / cm or less, the liquid potential, The indicated value may become unstable due to potential fluctuations.

  In the above, the conventional problem has been described in detail by taking the case of pH measurement as an example, but the same can be said for a flow-type electrode device in which the sensitive portion of the measurement electrode is sensitive to ion concentrations other than hydrogen ions.

  Accordingly, an object of the present invention is to provide a flow-type electrode device that can measure a test liquid having a lower electric conductivity more stably with a simple configuration.

  Another object of the present invention is to provide a flow type electrode device that can be easily operated during maintenance.

The above object is achieved by the flow type electrode device according to the present invention. In summary, the present invention provides a measurement electrode having a sensitive part, a comparative electrode having a liquid junction support that supports the liquid junction part and is arranged adjacent to the sensitive part, and more than the sensitive part. An inflow port provided below, an outflow port provided above the sensitive portion, a flow path for the test liquid flowing in from the inflow port and flowing out of the outflow port, and containing the sensitive portion And a flow cell that is in communication with the flow path portion and accommodates the liquid junction portion and stores a component of the internal liquid that exudes from the liquid junction portion, and the flow cell includes: A flow cell body having a flow port portion extending downward from a bottom portion of the flow channel portion, and an upper end portion having an opening at the upper end portion. A tubular body fitted into the hole so that the side protrudes upward from the bottom of the flow path portion; And, said liquid junction support is inserted into the tubular body inside through front KiHiraki opening, front KiHiraki opening is located above the end portion of the lower of the sensitive part, of the tubular body In the flow type electrode device, at least a part of a portion protruding upward from the bottom of the flow path is disposed between the sensitive part and the liquid junction support .

  According to the present invention, it is possible to measure a test liquid having a lower electric conductivity more stably with a simple configuration. In addition, according to the present invention, the maintenance work can be simplified by making the cylindrical body forming the storage portion detachable from the flow cell main body.

It is a fragmentary sectional view of the flow type electrode device concerning one example of the present invention. It is an expanded sectional view which shows the attachment or detachment part of the cylindrical body in the flow type electrode apparatus of FIG. FIG. 2 is an enlarged partial cross-sectional view showing the vicinity of a sensitive part of a measurement electrode and a liquid junction part of a reference electrode in the flow type electrode device of FIG. It is a graph which shows the measurement result of pH by the flow type electrode apparatus of FIG. It is a graph which shows the measurement result of pH by the flow type electrode apparatus of a comparative example. It is a schematic diagram for demonstrating the influence of the internal liquid with respect to the measurement result of pH.

  Hereinafter, the flow type electrode device according to the present invention will be described in more detail with reference to the drawings.

Example 1
FIG. 1 is a partial cross-sectional view of a flow-type electrode device according to the present invention. In addition, regarding the flow-type electrode device, “upper” and “lower” refer to the upper and lower sides in the vertical direction during normal use, respectively.

  The flow-type electrode device 1 includes a composite electrode 2 and a flow cell 3 on which the composite electrode 2 is mounted. The flow-type electrode device 1 has a shape that is long in one direction as a whole, and is usually used with its longitudinal direction (hereinafter, also simply referred to as “device longitudinal direction”) arranged along the vertical vertical direction. .

  First, the configuration of the composite electrode 2 will be described. The composite electrode 2 includes a measurement electrode 4, a comparison electrode 5, and an electrode body 6.

  The measurement electrode 4 includes a sensitive part 41 and a sensitive part support 42 that supports the sensitive part 41. In this embodiment, the sensitive part 41 is a substantially spherical pH glass sensitive film that is sensitive to pH. Further, in the present embodiment, the sensitive part support 42 is a tubular member extending in the vertical direction having a substantially circular horizontal cross section. The sensitive part 41 is supported at the lower end of the sensitive part support 42. A measurement electrode inner pole (not shown) is disposed inside the sensitive part support 42 and is filled with a measurement electrode inner liquid.

  The comparison electrode 5 includes a liquid junction support 52 that supports the liquid junction 51 and is disposed adjacent to the sensitive portion 41. In this embodiment, the liquid junction 51 is a substantially columnar member made of porous ceramics. In the present embodiment, the liquid junction support 52 is a tubular member extending in the vertical direction with a substantially circular horizontal cross section. The liquid junction 51 is enclosed and supported by the lower end (end surface) of the liquid junction support 52. The inside of the liquid junction support 52 communicates with the inside of an internal liquid storage portion (not shown) formed inside the electrode main body 6 described later, and the liquid junction portion is connected via the internal liquid storage portion of the electrode main body 6. A reference electrode internal liquid (also simply referred to as “internal liquid”) I is replenished in the support 52. Further, a reference electrode inner electrode (not shown) is disposed inside the internal liquid storage portion of the electrode body 6. The liquid junction 51 penetrates from the outside to the inside of the liquid junction support 52, and the internal liquid I exudes from the inside of the liquid junction support 52 to the outside through the liquid junction 51. Thereby, electrical continuity is established between the reference electrode inner pole disposed inside the electrode body 6 and the test solution S introduced into the flow cell 3. The reference electrode 5 is configured by the liquid junction 51, the liquid junction support 52, the internal liquid storage part formed inside the electrode body 6, the internal electrode of the comparison electrode arranged inside the internal liquid storage part, and the like. The

  The electrode body 6 supports the measurement electrode 4 and the liquid junction support 52 and can take out an electric signal through the measurement electrode inner electrode and the comparison electrode inner electrode. Further, the internal liquid I is continuously replenished into the internal liquid storage portion formed inside the electrode main body 6 through the replenishing port 21 provided in the electrode main body 6, and the internal liquid I Further, the liquid junction support 52 is continuously replenished. The measurement electrode 4 is screwed into and detached from the electrode body 6 so that a part of the sensitive part 41 and the sensitive part support 42 protrude downward from the lower end part (end surface) of the electrode body 6. Fixed to. Further, the liquid junction support 51 of the comparative electrode 5 is also formed so that the liquid junction 51 and a part of the liquid junction support 52 protrude downward from the lower end (end surface) of the electrode body 6. The main body 6 is screwed and fixed detachably. The measurement electrode 4 and the liquid junction support 52 protruding from the lower end of the electrode body 6 are adjacent to each other in the horizontal direction and extend in the vertical direction. The liquid junction support 52 is located downstream of the sensitive part 41 in the flow direction of the test solution S.

Next, the flow cell 3 will be described. The flow cell 3 includes an inlet 31 provided below the sensitive part 41, an outlet 32 provided above the sensitive part 41, a flow path part 33, and a storage part 34. The flow path portion 33 forms a flow path of the test solution S that flows in from the inflow port 31 and flows out of the outflow port 32, and accommodates the sensitive portion 41. The storage portion 34 communicates with the flow path portion 33 at the opening 34a at the upper end portion, and extends in the vertical direction to the lower bottom portion 34b. In addition, the reservoir 34 stores the liquid junction 51 and stores the component of the internal liquid I that exudes from the liquid junction 51. Here, the liquid junction support 52 is inserted into the reservoir 34 through the opening 34 a at the upper end of the reservoir 34. And the opening part 34a of this storage part 34 is comprised so that it may be located above the lower end part of the sensitive part 41. FIG. Thereby, as will be described in detail later, the internal liquid I does not diffuse or is difficult to diffuse on the sensitive part 41 side.

  More specifically, the flow cell 3 has a flow cell main body 35, and a flow path portion 33 is formed at a substantially central portion of the flow cell main body 35. In the present embodiment, the flow path portion 33 is configured by a columnar space having a substantially circular horizontal cross section. The composite electrode 2 is inserted into the flow path portion 33 from the lower end side through the main body opening 33 a formed on the upper end side of the flow path portion 33. The composite electrode 2 is detachably fixed to the flow cell 3 by screwing the fixing portion 61 of the electrode main body 6 into the fixed portion 35a of the flow cell main body 35.

  The inflow port 31 is formed below the sensitive part 41, in the present embodiment at the bottom 33 b of the flow path part 33, so that the test solution S flows into the flow path part 33 from the upstream side of the sensitive part 41. . In particular, in this embodiment, the inflow port 31 is located directly below the sensitive part 41. In the present embodiment, the inflow port 31 is circular in plan view. The inflow port 31 communicates with a supply source of the test liquid S outside the flow cell main body 35. Here, in the present embodiment, the bottom 33b of the flow path portion 33 is formed substantially flat along a substantially horizontal direction. The lower end portion of the sensitive portion 41 is disposed close to the bottom portion 33 b of the flow path portion 33. In particular, in the present embodiment, the inflow port 31 is formed immediately below the sensitive portion 41, so that the sensitive portion 41 is disposed close to the inflow port 31.

  The outflow port 32 is located above the sensitive portion 41, in the present embodiment, on the side surface on the end portion side so that the test solution S flows out from the flow passage portion 33 on the downstream side of the sensitive portion 41. Is formed. The outlet 32 communicates with the discharge destination of the test solution S outside the flow cell body 35.

  In the present embodiment, the flow cell main body 35 is formed with a hole 36 that extends from the bottom 33 b of the flow path portion 33 to the outside of the flow cell main body 35 and extends in the vertical direction. A cylindrical body (sleeve-like member) 37 that forms the storage portion 34 is attached to the hole portion 36. The cylindrical body 37 includes an opening 37 a at the upper end, a bottom 37 b on the lower end, and a predetermined range on the upper end projects upward from the bottom 33 b of the flow path 33. Thus, it fits in the hole 36. The opening 37 a of the cylindrical body 37 constitutes the opening 34 a of the storage part 34, and the bottom 37 b of the cylindrical body 37 constitutes the bottom 34 b of the storage part 34. The liquid junction support body 52 is inserted into the tubular body 37 through the opening 37 a of the tubular body 37. As a result, the liquid junction 51 is accommodated in the reservoir 34 formed by the cylindrical body 37. In the present embodiment, the liquid junction portion 51 is inserted into the deep portion of the storage portion 34 so as to be positioned below the end portion of the sensitive portion 41 and further below the bottom portion 33 b of the flow path portion 33. In addition, at least a part of a portion of the cylindrical body 37 protruding above the bottom 33b of the flow path portion 33 is disposed between the sensitive portion 41 and the liquid junction support 52 in the horizontal direction.

  Thus, in the present embodiment, at least a part of the portion of the cylindrical body 37a that protrudes upward from the bottom 33b of the flow path portion 33 extends upward from the lower end of the sensitive portion 41 of the measurement electrode 4. The shielding part B that shields the internal liquid I from the sensitive part 41 is configured to overlap with at least a part of the region.

  In the present embodiment, the hole 36 formed in the flow cell main body 35 is configured by a cylindrical space having a substantially circular horizontal cross section. Therefore, the cylindrical body 37 is configured by a tubular member having a substantially circular horizontal cross section and a bottom portion 37 b sealed so as to be fitted to the hole portion 36. In the bottom 33 b of the flow path portion 33, the inlet 31 and the opening 36 a of the hole 36 are opened adjacent to each other. In the present embodiment, the liquid junction support 52 is disposed at a substantially central portion of the tubular body 37 in plan view so that the tubular body 37 surrounds the space with a space therebetween. In the present embodiment, the liquid junction support 52 has a predetermined lower portion including a portion disposed in the storage portion 34 having a smaller diameter than a portion disposed in the flow path portion 33 above the predetermined portion. It is said that. Thereby, it becomes possible to make the internal diameter of the hole part 36 smaller, for example, it can prevent that the thickness between the inflow port 31 and the hole part 36 becomes thin too much.

  In this embodiment, the cylindrical body 37 is detachable from the flow cell main body 35. As shown in FIG. 2, in this embodiment, the cylindrical body 37 has a coupling portion (screw portion) 37d below the cylindrical portion 37c, and an operation portion (knob) 37e below the screw portion 37d. . Further, an O-ring 37f as a sealing means for liquid-tightly sealing the hole 36 of the flow cell main body 35 is disposed at the lower end of the coupling portion 37d. When mounted, the cylindrical body 37 is inserted into the hole 36 from the outside of the flow cell main body 35 with the cylindrical portion 37c at the top. Then, the coupling portion 37d of the cylindrical body 37 is screwed into a coupled portion (main body screw portion) 36b formed on the inner periphery of the lower end portion of the hole portion 36, so that the cylindrical body 37 is a flow cell. The main body 35 is detachably fixed. In addition, the cylindrical body 37 can be removed from the flow cell main body 35 by turning in the direction opposite to that at the time of mounting. This attachment / detachment operation can be easily performed by the operator pinching and rotating the operation portion 37e of the cylindrical body 37.

  As a material for forming the flow cell main body 35 and the cylindrical body 37, any suitable material such as glass and resin can be used, but a resin is preferable in terms of ease of manufacture and handling, for example, an acrylic resin is preferable. Can be used.

Now, when the test liquid S is introduced from the inlet 31 into the flow path section 33, the test liquid S fills the flow path section 33 and the storage section 34 and then flows out from the outlet 32. Thereafter, the test liquid S continues to be introduced from the inflow port 31, so that the test solution S flows in the flow path portion 33 and flows out from the outflow port 32 as indicated by an arrow in FIG. 1. The internal solution I come exuded in the storage unit 34 through the liquid junction 51. Thereafter, the internal liquid I continues to exude through the liquid junction 51, the internal liquid I flows into the flow path portion 33 through the open mouth 37a, the flow then flows in the flow path portion 33 together with the test solution S It flows out from the outlet 32.

  At this time, in the present embodiment, the cylindrical body 37 that forms the shielding part B that shields the internal liquid I from the sensitive part 41 is disposed so as to cover the liquid junction support 52. And the clearance gap between the internal peripheral surface of the cylindrical body 37, and the outer peripheral surface of the liquid junction part support body 52 acts as a 2nd liquid junction part, and is higher than the lower edge part of the sensitive part 41 ( That is, the internal liquid I flows out from the storage part 34 to the flow path part 33 little by little on the downstream side in the flow direction of the test liquid S from the lower end part of the sensitive part 41. Thereby, the internal liquid I does not diffuse or hardly diffuses to the sensitive part 41 side of the measurement electrode 4. In addition, when flowing into the flow path portion 33 from the inflow port 31, it is not disturbed or hardly disturbed by the test solution S that spreads from the edge of the inflow port 31 and flows to the storage portion 34 side. The liquid interface with the liquid S hardly shakes. Therefore, fluctuations in the liquid potential and the streaming potential can be reduced, and stable pH measurement is possible up to ultrapure water having an electric conductivity of 0.5 μS / cm or less, for example, about 0.1 μS / cm.

  In the present embodiment, the cylindrical body 37 is detachable from the flow cell main body 35. Therefore, when the cylindrical body 37 is removed, the hole portion 36 formed in the flow cell main body 35 functions as a drain, and the flow path portion 33 and the like can be easily cleaned. Further, the cylindrical body 37 constituting the storage portion 34 can be easily cleaned, and the cylindrical body 37 can be replaced as desired. For example, when the flow type electrode device 1 is used for measuring the pH of boiler water, the inside of the flow cell 3 may be contaminated with rust and the like, so that it is very advantageous to be easily cleaned.

  Further, in the present embodiment, the bottom 33b of the flow path portion 33 formed in the flow cell main body 35 is flat, and the opening 34a (37a) of the storage portion 34 is attached to the sensitive portion 41 by mounting the cylindrical body 37. It was located above the lower end. Thereby, it becomes easy to process the flow path part 33 in the flow cell main body 35, and cleaning of the bottom 33b of the flow path part 33 and the like becomes easier by removing the cylindrical body 37.

Here, FIG. 3 is an enlarged partial sectional view showing in more detail the arrangement relationship in the vicinity of the sensitive part 41 and the liquid junction part 51 in the flow type electrode device 1 of the present embodiment. Note that L1 to L5 represent horizontal dimensions, and H1 to H6 represent vertical dimensions (vertical directions). The center distance L1 between the measurement electrode 4 projecting downward from the electrode body 6 and the liquid junction support 52 is preferably about 10 to 20 mm. If L1 is too large, the measurement sensitivity may be lowered, and it is difficult to make L1 too small for manufacturing reasons. In this embodiment, L1 = 13 mm. The inner diameter L2 of the storage portion 34 (that is, the cylindrical portion 37c of the cylindrical body 37) can be set as appropriate according to the relationship with the outer diameter L3 of the liquid junction support body 52 disposed in the storage portion 34. However, it is preferable to set so that L2−L3 = 0.5 to 3 mm. If this value is too large, there is a concern that a flow potential may be generated between the test liquid S flowing in the flow path portion 33 and the internal liquid I in the storage portion 34 to affect the indicated value. There is a concern that if the value is too small, the outflow amount of the internal liquid I becomes too small. In this embodiment, L2 = 10 mm and L3 = 9 mm. The inner diameter L4 of the inflow port 31 can be appropriately set according to the flow rate of the test solution S, the relationship with the maximum outer diameter L5 of the sensitive portion 41, and the like. Usually, about 5 to 20 mm is suitable. In this embodiment, L4 = 10 mm and L5 = 7 mm. The height H1 of the lower end portion of the sensitive portion 41 with respect to the bottom portion 33b (inflow port 31 in this embodiment) of the flow path portion 33 is appropriately set according to the relationship with the position of the liquid junction portion 51 to be described later. However, about 0 to 5 mm is preferable. When H1 is too large, there is a concern about a decrease in responsiveness. In this embodiment, H1 = 1 mm. The height H2 of the upper end of the sensitive portion 41 with respect to the bottom 33b of the flow path portion 33 can be appropriately set according to the size of the sensitive portion 41 and the like, but is generally about 5 to 15 mm. is there. In this embodiment, H2 = 10 mm. The height H3 of the opening 34a of the storage part 34 with respect to the bottom 33b of the flow path part 33 (in this embodiment, the opening 37a of the cylindrical body 37) is appropriately determined according to the relationship with H1 and H2 above. Although it can be set, the height H4 of the opening 34a of the reservoir 34 relative to the lower end of the sensitive portion 41 (ie, H3-H1) from the lower end of the sensitive portion 41 to the upper end It is preferable to set the ratio (overlap amount) to the height H5 (that is, H2-H1) of 30% or more. If the overlap amount is too small, it is difficult to obtain the effect of shielding the internal liquid I from the sensitive part 41 by the shielding part B. Further, the height H3 of the opening 34a of the storage part 34 may be set higher than the height H2 of the upper end of the sensitive part 41, and the overlap amount may be 100% or more, but the overlap amount is not so much. Even if it enlarges, the further improvement of the said effect is hard to be acquired. Therefore, the overlap amount is preferably 70% or less. In this embodiment, H3 = 5 mm and the overlap amount is about 40%. The depth H6 of the storage part 34 is preferably about 10 to 30 mm. If H6 is too large, it is feared that it becomes difficult to handle, and if it is too small, the concentration of the internal liquid I in the reservoir 34 increases, so that the concentration difference with the test solution S becomes large, and noise may be generated. Is done. Further, the test solution S is generally continuously supplied to the flow cell 3 at a predetermined flow rate of about 50 to 500 mL / min. Further, as the internal liquid I of the reference electrode 5, a 3 mol / L or higher potassium chloride (KCl) aqueous solution is used, and the internal liquid I exudes through the liquid junction 51 at a rate of 0.1 to 1 mL / day. .
(Specific example 1)
Using the flow-type electrode device 1 of this example, the pH of ultrapure water having an electric conductivity of 0.17 μS / cm was adjusted, and the flow rates of the pure water were 50 mL / min, 100 mL / min, 150 mL / min, 200 mL / It changed to min and 300 mL / min, and each measured it for the fixed time. The results are shown in FIG.

  Further, as a comparative example, the cylindrical body 37 was removed from the flow type electrode device 1 of this example, and the same measurement was performed on the flow type electrode device in which the hole portion 36 in this example was used as the storage part 34. The bottom part 34a of the storage part 34 in the comparative example was provided at a height position equivalent to the case of the present example. The results are shown in FIG. In addition, also about a comparative example, the same code | symbol is attached | subjected and demonstrated to the element corresponding to the thing of a present Example.

  As can be seen from FIG. 5, in the comparative example, the pH indication value becomes unstable at a flow rate of a certain level (100 mL / min or more). This is considered due to the following reasons. That is, as schematically shown in FIG. 6A, the internal liquid I flowing out from the opening 36a on the flow path 33 side of the hole 36 is not obstructed by the sensitive part 41. Diffuses to the sensitive portion 41 side of the measuring electrode 4. In addition, the internal liquid I flowing out from the hole 36 is disturbed by the test liquid S that spreads from the edge of the inlet 31 and flows toward the hole 36 when flowing into the flow path part 33 from the inlet 31. The liquid interface between the internal liquid I and the test liquid S is shaken. For this reason, the inter-liquid potential and the streaming potential fluctuate, and the indicated value of pH becomes unstable.

  On the other hand, as can be seen from FIG. 4, according to the present embodiment, it is possible to stably measure pH regardless of the flow rate. As shown in FIG. 6 (b), the cylindrical body 37 blocks the internal liquid I in the reservoir 34 from the sensitive part 41 of the measuring electrode 4, and the internal liquid I is sensitive to the measuring electrode 4. This is considered to be because fluctuations between the liquid and the flow potential can be reduced because the liquid interface between the internal liquid I and the test liquid S hardly fluctuates.

  As described above, according to the present embodiment, it is possible to measure a test solution having a lower electric conductivity more stably with a simple configuration. Further, according to the present embodiment, the cylindrical body 37 can be detached from the flow cell main body 35, so that the maintenance work is easy.

Others While the present invention has been described with reference to specific embodiments, the present invention is not limited to the above-described embodiments.

  For example, the liquid junction portion of the comparative electrode is not limited to the porous ceramic type described above, and has a known shape or type such as a sleeve type, a fiber type, or a pinhole type by rubbing glass sleeves. Good.

  Further, the present invention can be suitably used in pH measurement of a test solution having low electrical conductivity such as boiler water or ultrapure water, but the measurement electrode is a sensitive material such as a pH glass sensitive film that responds to pH. It is not limited to what has a part (pH electrode). For example, the measurement electrode may have a sensitive part (ion electrode) such as a glass sensitive film sensitive to ions other than hydrogen ions, and the same effect can be obtained by applying the principle of the present invention in the same manner. Is possible.

  In addition, since the liquid junction may become dirty due to use, it is preferable that the measurement electrode and the liquid junction (or comparison electrode) of the reference electrode can be replaced separately from the standpoint of reducing running costs. The present invention can be applied even if it is not possible to replace the switch.

  In addition, the measurement electrode and the reference electrode are not limited to being able to be integrated as a composite electrode, and even if the measurement electrode and the comparison electrode are separated and cannot be integrated, The invention is applicable.

  In addition, the above-described advantageous effect can be obtained by making the cylindrical body forming the storage portion detachable from the flow cell main body. However, the cylindrical body can be easily attached to the flow cell main body if desired. It may be fixed so that it cannot be detached. Moreover, although the above advantageous effect can be acquired by forming a storage part with a cylindrical body, you may process the storage part according to this invention directly in a flow cell main body if desired. For example, the bottom part of the flow path part of the part where the storage part is formed is made higher upward than the bottom part of the flow part of the part where the inlet is formed, and the opening part of the storage part is the lower end of the sensitive part It can be made to be located above the part.

DESCRIPTION OF SYMBOLS 1 Flow type electrode apparatus 2 Composite electrode 3 Flow cell 4 Measurement electrode 5 Comparison electrode 33 Flow path part 34 Storage part 36 Hole part 37 Cylindrical body 41 Sensing part 51 Liquid junction part 52 Liquid junction part support body

Claims (5)

A measuring electrode with a sensitive part;
A reference electrode including a liquid junction support that supports the liquid junction and is disposed adjacent to the sensitive portion;
An inflow port provided below the sensitive portion, an outflow port provided above the sensitive portion, and a flow path for the test liquid flowing in from the inflow port and flowing out of the outflow port are formed in the sensitive area. A flow cell comprising: a flow channel portion that accommodates a portion; and a reservoir portion that communicates with the flow channel portion and accommodates the liquid junction portion and stores components of the internal liquid that exudes from the liquid junction portion;
Have
The flow cell includes a flow cell main body having a flow port portion extending downward from a bottom portion of the flow inlet portion, the flow outlet portion, the flow passage portion, and the flow passage portion, and an opening portion at an upper end thereof. A cylindrical body that is fitted into the hole so that the end side protrudes upward from the bottom of the flow path part, and
The liquid junction support is inserted into the tubular body inside through front KiHiraki opening, front KiHiraki opening is located above the end portion of the lower of the sensitive part, the flow of the tubular body At least a part of a portion protruding upward from the bottom of the passage is disposed between the sensitive part and the liquid junction support . The hole extends from the bottom in the vertical direction through to the outside of the flow cell the body, the tubular body, according to claim 1, characterized in Tei Rukoto includes a bottom end portion side of the lower lateral 2. The flow type electrode device according to 1.   The flow-type electrode device according to claim 2, wherein the cylindrical body is detachable from the flow cell main body.   The flow-type electrode device according to any one of claims 1 to 3, wherein the inflow port is located immediately below the sensitive part and formed at a bottom part of the flow path part.   The flow type electrode device according to any one of claims 1 to 4, wherein the liquid junction part is located below an end part below the sensitive part.

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