JP2006138653A - Method and apparatus for measuring concentration of dissolved gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply measure the concentration of a dissolved gas, using a simple apparatus. <P>SOLUTION: An indicator 33 is attached to the inner surface of the ceiling part of an extraction vessel 32, having an opening part 34 at its lower end and closed at its upper end part. The extraction container 32 is arranged to the liquid surface boundary of a liquid 31 to be measured so that the opening part 34 is sunk in the liquid 31 to be measured, by predetermined quantity to close the opening part 34 by the liquid 31 to be measured, in a state with the gaseous phase above the liquid surface boundary being confined in the extraction vessel 32. Since a specific gas 31 reaches gas/liquid equilibrium in the gaseous phase confined inside the extraction vessel 32, the concentration of the specific gas 31 present on the side of the gaseous phase, when the specific gas reaches the gas/liquid equilibrium is detected from the discoloration of the indicator 33. The dissolved gas concentration of the specific gas, dissolved in the liquid 31 to be measured, is measured on the basis of the correlation of the concentration of the specific gas in the gaseous phase, when the specific gas reaches the gas/liquid equilibrium with the concentration of the dissolved gas on the side of a liquid phase from the detection result. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention measures the dissolved gas concentration of the specific gas dissolved in the liquid phase based on the gas phase concentration of the specific gas detected on the gas phase side when the specific gas reaches the vapor-liquid equilibrium. The present invention relates to a method and apparatus for measuring dissolved gas concentration.

  Conventionally, as one method for sterilizing medical instruments such as endoscopes, ozone gas is dissolved in a liquid phase to produce ozone water, and the medical instruments are immersed in the produced ozone water. The method of sterilizing and disinfecting is used. In this sterilization method, in order to sufficiently obtain the sterilization effect by the ozone water, it is necessary to keep the dissolved gas concentration of the ozone gas dissolved in the liquid phase at a certain level or higher. It is necessary to measure the concentration of ozone gas dissolved in ozone water at the site of manufacturing or the site of sterilization and disinfection using the ozone water.

  As one of the methods for measuring the dissolved gas concentration of the specific gas dissolved in the liquid phase, such as when measuring the concentration of ozone gas dissolved in the ozone water, the specific gas is dissolved. Chemical analysis such as titration using a solution having a known concentration of a substance that reacts with a sample solution (measuring solution), that is, a so-called standard solution, is generally performed.

  Further, in the measurement target liquid in which the specific gas is dissolved, the dissolved gas in the liquid phase is diffused from the water surface to the gas phase side with the passage of time, and the gas concentration of the specific gas in the gas phase ( Hereinafter, the gas phase concentration) gradually increases. At this time, in the sealed container, when a predetermined time has passed, the amount of gas diffused from the liquid phase to the gas phase side with the filling of the specific gas in the gas phase in the container, A so-called gas-liquid equilibrium is reached, in which the amount of gas dissolved from the gas phase to the liquid phase becomes equilibrium. As described above, under the condition that the vapor-liquid equilibrium is reached, the correlation according to Henry's law between the dissolved gas concentration of the specific gas dissolved in the liquid phase and the gas phase concentration of the specific gas. Can be obtained. From this, the dissolved gas concentration and the gas phase concentration in the liquid phase of the specific gas can be mutually converted by a calculation formula using Henry's constant that depends on the temperature of the liquid phase in the container. .

  Therefore, as another method for detecting the dissolved gas concentration of the specific gas dissolved in the liquid phase, using the above principle, the specific gas reaches a vapor-liquid equilibrium in a sealed container. In the past, there has been proposed a method in which the concentration of dissolved gas in the liquid phase is obtained by calculation by detecting the gas phase concentration of the specific gas.

  That is, for example, as shown in FIG. 8, the measurement target liquid 1 in which the specific gas is dissolved is heated (adjusted) to a predetermined temperature in the constant temperature bath 2 and then guided to the extraction bath 3. By forming a required head space (space part) 4 on the top of 3, the liquid to be measured 1 led to the extraction tank 3, that is, the liquid phase and the head space 4 are formed. The specific gas approximately reaches a vapor-liquid equilibrium with the gas phase, and the carrier gas 6 is used as the specific gas 5 existing on the gas phase side when the vapor-liquid equilibrium is reached. Then, the semiconductor gas sensor 7 is led to detect the gas phase concentration of the specific gas 5 by the semiconductor gas sensor 7. Thereafter, the arithmetic processing unit 8 obtains a relational expression between the dissolved gas concentration in the liquid phase of the specific gas 5 and the gas phase concentration when the vapor-liquid equilibrium is reached under the predetermined temperature condition obtained in advance. And the dissolved gas concentration of the specific gas 5 dissolved in the measurement target liquid 1 is calculated based on the detected value of the gas phase concentration of the specific gas 5 detected by the semiconductor gas sensor 7. Things have been proposed in the past. In addition, when heating the liquid 1 to be measured in the thermostatic chamber 2, there is a possibility that a part of the specific gas may be deteriorated, and a loss of time until measurement may cause a response delay and an error. As shown in FIG. 9, the liquid 1 to be measured is guided to the extraction tank 3 similar to the above without passing through the thermostatic chamber for adjusting to a predetermined temperature, and the gas-liquid equilibrium is reached in the head space 4 in the extraction 3. In this manner, the specific gas 5 is guided to the semiconductor gas sensor 7 using the carrier gas 6 in the same manner as described above to detect the gas phase concentration. Thereafter, based on the detected value of the gas phase concentration of the specific gas 5 detected by the semiconductor gas sensor 7, the liquid phase when the specific gas 5 has reached vapor-liquid equilibrium in the arithmetic processing unit 8. When the dissolved gas concentration of the specific gas 5 dissolved in the measurement target liquid 1 is calculated using the relational expression between the dissolved gas concentration in the gas and the gas phase concentration, the temperature detection terminal of the extraction tank 3 is calculated. As described above, the temperature of the liquid 1 to be measured in the extraction tank 3 detected by the temperature detection mechanism 9 provided with 9a, that is, the detected value of the temperature of the liquid phase is used to obtain the temperature of the liquid phase as described above. The change of the dependent Henry's constant and the influence of humidity in the semiconductor gas sensor 7 are established in advance between the temperature of the sample liquid obtained by using a sample liquid whose concentration and temperature are known in advance and the output of the gas sensor 7. Correction (temperature compensation) with the function relationship to It has also been proposed to calculate the dissolved gas concentration of a specific gas 5 definitive (e.g., see Patent Document 1). 8 and 9, reference numeral 10 denotes an amplifier for amplifying the detection signal of the semiconductor gas sensor 7, and 11 denotes A / D conversion of the detection signal amplified by the amplifier 10 to the arithmetic processing unit 8. A / D converter for sending. Reference numeral 12 in FIG. 9 denotes an A / D converter for A / D converting the detection signal of the temperature detection mechanism 9 and sending it to the arithmetic processing unit 7.

  By the way, for example, the concentration of gas in the gas phase by utilizing the property of an indicator that reacts and changes color when exposed to a specific gas, such as the property of blue color when potassium iodide starch paper is exposed to a small amount of oxidizing agent. Conventionally, an indicator has been proposed which can easily measure the above.

  As such an indicator, for example, as shown in FIGS. 10 (a) and 10 (b), an elongated indicator paper 13 such as potassium iodide starch paper is formed in a long shape that is slightly larger than the indicator paper 13. It is placed on the upper side of a transparent film 14 made of a material that prevents passage of a specific gas such as ozone gas, and further, on the upper side, it is made of the same material and shape as the transparent film 14, and one end in the longitudinal direction is formed. By placing the transparent film 15 that can be removed by hand, laminating and pasting the films 14 and 15 and the instruction paper 13, by removing one end of the transparent film 15, A configuration has been proposed in which one end portion of the instruction paper 13 in the longitudinal direction can be exposed to the outside air as the exposed portion 13a. With this configuration, when the indicator is used, a part of the transparent film 15 is removed and the exposed portion 13a is exposed to an atmosphere of ozone gas. The indicator paper 13 is gradually exposed from the one end side in the longitudinal direction on the exposed portion 13a side to the other end side. The color can be changed sequentially. The length of the discoloration region generated at this time depends on the exposure amount of ozone gas, and the exposure amount depends on the time integral value (CT value) of the concentration. Therefore, the length of the discoloration region on the indicator paper 13 is read. The concentration of ozone gas in the gas phase can be detected (for example, see Patent Document 2).

  Further, as an indicator for making it possible to measure the concentration of a specific gas in the gas phase with higher sensitivity, and to make it unnecessary to supply water for clarifying the discoloration region of the indicator layer, for example, FIG. 11 (a) and (b), an indicator layer 17 made of silica gel which retains potassium iodide and water that changes color by reacting with the specific gas, inside an elongated bag-like transparent member 16 having one end opened. A structure in which a diffusion layer 18 such as a filter paper for gradually diffusing the specific gas is provided in a laminated state over the entire length in the longitudinal direction has also been proposed. According to an indicator having such a configuration, when exposed to the atmosphere containing the specific gas, the specific gas enters the transparent member 16 from the opening on one end side and is directed to the other end side through the diffusion layer 18. The indicator layer 17 comes into contact with the diffusion layer 18 in the process of gradually diffusing the diffusion layer 18 from one end side to the other end side. For this reason, since the indicator layer 17 is sequentially discolored from one end side to the other end side in accordance with the diffusion rate of the specific gas in the diffusion layer 18, the discoloration of the indicator layer 17 is performed in the same manner as described above. The exposure amount of the specific gas can be detected with high sensitivity according to the length of the area, and a CT value high accuracy type indicator is obtained (for example, see Patent Document 3).

  Furthermore, as an indicator for making it possible to detect the presence or absence of a lower concentration gas in the gas phase and more clearly measuring the CT value of the gas, FIG. As shown in (b), a passage 20 having one end opened in the longitudinal direction is formed in the gas indicator body 19 having a long and narrow plate shape, and a specific gas to be detected is introduced into the passage 20 from the one end opening. An indicator layer 17 similar to that shown in FIGS. 11 (a) and 11 (b), which is discolored by reacting with the specific gas, is provided along the longitudinal direction at the inner bottom portion of the passage 20 so that it can be introduced. A window 21 for observing the indicator layer 17 from the outside is provided in the ceiling portion of the passage 20 in the gas indicator main body 19, and an opening having a predetermined area is provided outside the opening on one end side of the passage 20. Also proposed in the prior art is a structure in which the specific gas can be immediately brought into contact with the indicator layer 17a exposed at the opening 22 when the indicator body 19 is placed in a specific gas atmosphere. Has been. By having such a configuration, according to the indicator, the indicator layer 17a provided in the opening 22 is immediately exposed and discolored in the specific gas atmosphere, while being provided in the passage 20. Since the indicator layer 17 is sequentially exposed and discolored by the specific gas that is sequentially diffused from the opening on the one end side to the other end side in the passage 20, even if the specific gas has a low concentration, the opening is formed. The presence or absence of the specific gas can be immediately detected based on the presence or absence of the color change of the indicator layer 17a located in the portion 22, and when the indicator layer 17 in the passage 20 changes color, the specific gas is determined based on the length of the color change area. The gas concentration can be accurately obtained using the CT value (see, for example, Patent Document 4).

  Furthermore, like the indicator for detecting the gas concentration in the gas phase, the concentration of dissolved gas in the liquid phase can be measured by utilizing the property of an indicator that reacts and changes color when exposed to a specific gas. An indicator that has been proposed has also been proposed.

  FIG. 13 shows an outline of an example of an indicator used for measurement of the dissolved gas concentration in the liquid phase, and a specific gas such as ozone gas is formed inside the gas inlet 24 on one end side as a rectangular solid cylinder. As a gas concentration display means 25 for displaying the concentration of the specific gas introduced into the case 23 by color change, for example, an indicator layer that changes color in response to the specific gas. 26 and a gas concentration display means 25 comprising a diffusion layer 27 which is a space for gradually diffusing the specific gas entering the case 23 from the gas inlet 24 on the one end side to the other end side. Further, the gas introduction port 24 is configured to be closed by a functional film 28 that allows only gas to pass therethrough. With this configuration, when the indicator for measuring the dissolved gas concentration is submerged for a predetermined time in water in which the specific gas is dissolved, the specific gas permeates the functional film 28 of the gas inlet 24 and the case 23. Introduced in. The specific gas introduced into the case 23 gradually diffuses from the one end side on the gas inlet 24 side to the other end side in the diffusion layer 27 so as to be uniformly dispersed in the case 23. In this process, the indicator layer 26 reacts sequentially with the indicator, and the indicator layer 26 is discolored sequentially from the side closer to the gas inlet 24. The area of this discoloration area corresponds to the CT value of the specific gas, as with the gas concentration detection indicator in the gas phase described above, so that the concentration of dissolved gas in the liquid phase can be detected with high accuracy. Will be able to.

  Further, as shown in FIG. 14, a plurality of types of indicator liquid cells 30 having different concentrations of reacting gases are partitioned and arranged in a case 29 formed in a square dish shape, or the above-mentioned square dish case 29 is arranged. Instead of the indicator liquid cell 30, an indicator sheet with a different concentration of the reacting gas is partitioned and arranged at the inner bottom of the casing 29, and the upper end opening of the case 29 is formed so as to cover the indicator liquid cell or the indicator sheet. The functional film 28 that permeates only the gas is used, so that the exposure time to the gas can be further shortened, and the color of the indicator liquid cell 30 or the indicator sheet in any section is changed. A simple determination type has also been proposed in which the gas concentration can be detected more easily by determining whether or not (see, for example, Patent Document 5).

JP-A-6-258269 Japanese Patent Laid-Open No. 7-49342 JP-A-7-72137 JP-A-8-122318 JP-A-11-125625

  However, when the dissolved gas concentration of the specific gas dissolved in the liquid phase is measured by titration, there are problems that the operation is complicated and a high technique is required of the operator.

  As described in Patent Document 1, the semiconductor gas sensor 7 detects the gas phase concentration of the specific gas 5 on the gas phase side when the inside of the extraction tank 3 is approximately in the condition of gas-liquid equilibrium. The method of calculating the concentration of dissolved gas in the liquid phase from the gas phase concentration of the specific gas 5 calculated using Henry's law has a problem that the apparatus becomes complicated and difficult to downsize. There is also a problem that a carrier gas 6 is required separately in order to introduce the specific gas existing in the gas phase in the extraction tank 3 to the semiconductor gas sensor 7.

  In addition, what is described in Patent Document 2, Patent Document 3 and Patent Document 4 can be used to measure the concentration of the specific gas by utilizing the property of an indicator that reacts and changes color when exposed to the specific gas. Although these are certain indicators, these are all for measuring the gas concentration in the gas phase, and are not directly applicable to the measurement of the concentration of dissolved gas in the liquid phase.

  Moreover, what is described in Patent Document 5 is an indicator for measuring the concentration of dissolved gas in the liquid phase, but by measuring the gas concentration in the gas phase under the condition of gas-liquid equilibrium, The idea of determining the concentration of dissolved gas in the liquid phase is not shown and is not even suggested.

  Therefore, the present invention intends to provide a measuring method and apparatus for the dissolved gas concentration capable of measuring the dissolved gas concentration in the liquid phase without requiring a complicated apparatus or advanced technology.

  In order to solve the above-mentioned problem, the present invention corresponds to the invention according to claim 1, wherein the water surface is provided in an extraction container that covers a required area above the boundary of the water surface of the liquid to be measured in which the specific gas is dissolved The gas phase on the boundary is confined so that the specific gas reaches a gas-liquid equilibrium between the gas phase confined in the extraction container and the liquid to be measured, and the gas-liquid equilibrium is reached. The gas phase concentration of the specific gas in the gas phase is detected by an indicator whose discoloration state changes depending on the concentration of the specific gas, and based on the gas phase concentration of the specific gas detected by the indicator, A dissolved gas concentration measurement method for measuring a dissolved gas concentration of a specific gas in a measurement target liquid.

  Further, the extraction container in the method of claim 1 is a container having an opening at the lower end and closed at the upper end, and the extraction container is immersed in a required amount at the boundary of the water surface of the liquid to be measured. The method is such that the gas phase is confined in an extraction container in which the lower end opening is closed by the measurement target liquid.

  Further, in response to the invention according to claim 3, by injecting a measurement target liquid in which a specific gas is dissolved up to a required level into the extraction container and capping, the water on the boundary of the measurement target liquid is A gas phase is confined so that the specific gas reaches a gas-liquid equilibrium between the gas phase confined in the extraction container and the liquid to be measured, and the gas phase in the gas phase when the gas-liquid equilibrium is reached is reached. The gas phase concentration of the specific gas is detected by an indicator whose color change state changes depending on the concentration of the specific gas, and the measurement target liquid is based on the gas phase concentration of the specific gas detected by the indicator. A method for measuring the dissolved gas concentration of a specific gas in the inside.

  Corresponding to the invention according to claim 4, the extraction container is arranged from above so as to confine the gas phase on the water surface boundary in the required region of the water surface boundary of the liquid to be measured in which the specific gas is dissolved, In addition, a dissolved gas concentration measuring device is provided in which an indicator whose discoloration state changes depending on the gas phase concentration of the specific gas is attached inside the upper end of the extraction container.

  Furthermore, the extraction container in the above configuration has a cylindrical structure having an opening at the lower end and closed at the upper end, and the extraction container can be confined inside the gas phase at the water surface boundary of the liquid to be measured. Thus, it is set as the structure arrange | positioned so that a required amount may be immersed in a lower end opening part.

  In addition, the extraction container having the above-described structure is composed of a cylindrical container body in the vertical direction and a detachable lid that closes the upper end of the container body, and the indicator is detachably held on the inner surface of the lid. It is set as the structure made to do.

  The extraction container in each configuration described above is configured to be able to float at the boundary of the water surface by the balance between the buoyancy and weight due to the gas phase confined in the extraction container.

  Corresponding to the invention according to claim 8, a cylindrical container main body having an opening at the upper end and closing the lower end so that a liquid to be measured in which a specific gas is dissolved can be injected, An indicator whose color change state changes depending on the gas phase concentration of the specific gas is detachably held on the inner surface of the lid of the extraction container comprising a detachable lid that closes the upper end opening of the container body. A measuring device for dissolved gas concentration.

  Further, in the above configuration, instead of holding the indicator detachably on the inner surface of the lid of the container body of the extraction container, an indicator holding body having air permeability is provided at the upper end opening of the container body, The indicator is placed on the upper side of the indicator holder.

According to the present invention, the following excellent effects are exhibited.
(1) A gas phase on the boundary of the water surface is confined in an extraction container that covers a required region of the water surface boundary of the liquid to be measured in which a specific gas is dissolved. The specific gas reaches a vapor-liquid equilibrium between the liquids to be measured, and the gas phase concentration of the specific gas when the vapor-liquid equilibrium is reached depends on the concentration of the specific gas. A dissolved gas concentration measuring method and apparatus for detecting a changing gas concentration and measuring the dissolved gas concentration of the specific gas in the measurement target liquid based on the gas phase concentration of the specific gas detected by the indicator. Therefore, it is possible to easily measure the dissolved gas concentration of the specific gas in the liquid to be measured without requiring an advanced technique, and it is possible to easily reduce the size by simplifying the apparatus configuration.
(2) In the configuration of (1) above, the extraction container is a container having an opening at the lower end and closed at the upper end, and the extraction container is required to have a lower end opening at the water surface boundary of the liquid to be measured. It is arranged to be submerged in volume so that the gas phase is confined in the extraction container whose lower end opening is closed by the liquid to be measured, or the extraction container has an opening at the lower end and the upper end is closed. In the extraction container in which the lower end opening is closed with the measurement target liquid by arranging the extraction container at the boundary of the water surface of the measurement target liquid so that the lower end opening is submerged in a required amount. In this configuration, the gas phase can be easily confined by disposing the gas phase at the boundary of the water surface of the liquid to be measured.
(3) The extraction container is composed of a cylindrical container body in the vertical direction and a detachable lid for closing the upper end of the container body, and the indicator is detachably held on the inner surface of the lid. By adopting such a configuration, the replacement work of the indicator can be facilitated.
(4) Further, the extraction container is configured to be able to float at the boundary of the water surface by the balance between the buoyancy and the weight due to the gas phase confined in the extraction container, so that the inside of the storage tank for storing the liquid to be measured is stored. It is possible to easily cope with large fluctuations in the liquid to be measured.
(5) Injecting a measurement target liquid in which a specific gas is dissolved to a required level into the extraction container and closing the liquid, the gas phase on the water surface boundary of the measurement target liquid is confined to the inside of the extraction container. The specific gas reaches a vapor-liquid equilibrium between the gas phase confined in the gas and the liquid to be measured, and the vapor phase concentration of the specific gas when the vapor-liquid equilibrium is reached is determined by the concentration of the specific gas. The dissolved gas concentration is detected by an indicator whose color change state depends on the gas concentration, and the dissolved gas concentration of the specific gas in the measurement target liquid is measured based on the gas phase concentration of the specific gas detected by the indicator And a cylindrical container main body having an opening at the upper end so that a liquid to be measured in which a specific gas is dissolved can be injected, and a lid for closing the upper end opening of the container main body Above in the extraction container By measuring the dissolved gas concentration of the specific gas in the liquid to be measured at any location, it is easy to carry with the measuring device for the dissolved gas concentration in which the indicator is detachably held on the inner surface of the liquid. Will be able to. In addition, since the dissolved gas concentration of the measurement target liquid can be measured without requiring a storage tank for storing the measurement target liquid, a part of the flowing measurement target liquid is sampled and collected. By injecting into the extraction container, the dissolved gas concentration can be measured.
(6) Also, instead of detachably holding the indicator on the inner surface of the lid of the extraction container, an indicator holding body having air permeability is provided at the upper end opening of the container body of the extraction container, and the indicator By adopting a configuration in which the indicator is placed on the upper side of the holding body, the indicator can be placed on the upper side of the indicator holding body provided at the upper end opening of the container body when the lid is removed from the container body. Thus, the indicator can be replaced more easily.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIGS. 1 to 3 (a) and 3 (b) show an embodiment of the method and apparatus for measuring dissolved gas concentration according to the present invention, and a measurement object in which a specific gas whose dissolved gas concentration is to be measured is dissolved. The extraction container 32 is disposed downward inside the storage tank 37 in which the liquid 31 is stored, and is fixed by, for example, the support member 38. The measurement target liquid 31 in which a specific gas whose dissolved gas concentration is to be measured is stored in the storage tank 37, and the lower end portion of the extraction container 32 is submerged at the water surface boundary (gas-liquid interface). Thus, a required amount of gas is confined in the space in the extraction container 32 in a required region of the water surface boundary so that a gas phase can be formed. Further, the inner side of the upper end portion of the extraction container 32 reacts and changes color when exposed to the specific gas, and the color (gas phase concentration) of the specific gas in the gas phase can be detected by this color change. When the specific gas reaches a gas-liquid equilibrium between the gas phase confined in the extraction container 32 and the liquid 31 to be measured as a liquid phase, the indicator 33 is provided. The indicator 33 can detect the gas phase concentration of the specific gas existing in the gas phase in the extraction container 32.

  More specifically, the extraction container 32 has a cylindrical shape extending in the vertical direction and having an upper end closed and an opening 34 provided at the lower end. More specifically, the extraction container 32 has a cylindrical (mainly cylindrical) container body 35 extending in the vertical direction, and is detachably attached to the upper end of the container main body 35 to attach the upper end of the container main body 35. The lid 36 is configured to be closed. If the lid 36 can be detachably attached to the container body 35, the container body 35 and the lid 36 are provided with screw portions (not shown) that are screwed together, Engage the two parts by screwing them together, or by providing engaging parts such as protrusions and recesses for engaging the container body 35 and the lid 36 with each other. For example, an arbitrary attachment type may be adopted.

  As shown in FIG. 1, the extraction container 32 having the above-described configuration is injected into the storage tank 37 to a predetermined level inside the storage tank 37 for storing the measurement target liquid 31. The lower end opening 34 of the extraction container 32 is disposed at a height position so that a required amount of water is submerged in the water surface of the liquid 31, and the container body 35 is disposed at a required position of the storage tank 37, for example, the storage tank 37. It is attached to the inner surface of one side wall via a support member 38 so as to be fixedly supported. Accordingly, when the measurement target liquid 31 is injected into the storage tank 37 to a predetermined level, the opening 34 at the lower end of the extraction container 32 is submerged in the water surface boundary of the measurement target liquid 31, and the extraction is performed. The opening 34 is closed by the measurement target liquid 31 in a state where the gas phase is confined inside the container 32, and the extraction container 32 is thus closed by the measurement target liquid 31. The specific gas dissolved in the measurement target liquid 31 is diffused with respect to the gas phase confined in the inside, so that the specific gas reaches the vapor-liquid equilibrium in the extraction container 32. . In order to enable the specific gas to quickly reach gas-liquid equilibrium in the gas phase confined in the extraction container 32, the extraction container 32 is provided with a lid 36 as described later. Even if the measurement target liquid 31 injected into the storage tank 37 is slightly shaken by the cross-sectional area that can secure the space for mounting the indicator 33 on the inner surface and the indicator 33 attached to the inner surface of the lid 36, the measurement target liquid 31 It is preferable to make the internal volume as small as possible within a range having a height dimension so that it can be held at a height position so as not to get wet.

  The lid 36 forming the ceiling portion of the extraction container 32 is detachably attached with an indicator 33 on its inner surface that can change color in response to a specific gas. Further, a transparent window 39 is formed at a position corresponding to the attachment position of the indicator 33 on the lid 36 so that the discoloration state of the indicator 33 attached to the inner surface of the lid 36 can be observed from the outside. . It should be noted that the indicator 33 detachably attached to the inner surface of the lid 36 is a member for engagement at a required portion on the inner surface side of the lid 36 as long as the observation of the indicator 33 through the window 39 is not hindered. (Not shown) is provided so that the engagement member can be engaged with and hold the required portion of the outer periphery of the indicator 33, or the outer periphery of the indicator 33 can be detached from the inner surface of the lid 36. Arbitrary attachment formats may be employed, such as attachment via a simple adhesive member.

  As the indicator 33, a simple judgment type as shown in FIGS. 2A and 2B or a high-precision CT value type as shown in FIGS. 3A and 3B is used.

  That is, the simple judgment type indicator 33a as shown in FIGS. 2 (a) and 2 (b) is provided in a square dish-shaped transparent case 40 having the back side as the attachment side to the inner surface of the lid 36 of the extraction container 32. Similarly to the indicator shown in FIG. 14, a plurality of indicator layers (indicator sheets) 41 formed by holding indicators that change color when exposed to a specific gas while maintaining different concentrations of the gas that changes color. For example, the indicator layers 41 having different gas concentrations that change color by reacting with a specific gas are divided into five stages and are arranged in a line. As a result, with the back side of the case 40 attached to the inner surface of the lid 36 of the extraction container 32, the specific gas is vapor-liquid equilibrated in the extraction container 32 at the same time on the surface side of the indicator layer 41 of each section. The extraction container is exposed to the gas phase when it reaches the required time, and by observing and determining which section of the indicator layer 41 in the simple judgment type indicator 33a is discolored by this exposure. The gas-phase concentration of the specific gas can be detected when the gas-liquid equilibrium is reached in the chamber 32.

  In practice, the extraction is performed from the time when the opening 34 is closed by the measurement target liquid 31 in a state where the gas phase is confined in the extraction container 32 in accordance with the injection of the measurement target liquid 31 into the storage tank 37. Although a specific gas is diffused from the measurement target liquid 31 through the opening 34 to the gas phase in the container 32 and the inside of the extraction container 32 reaches a gas-liquid equilibrium, a slight time lag occurs. In consideration of the above, the time required for exposing each indicator layer 41 of the simple judgment type indicator 33a to the gas phase in the extraction container 32 may be set.

  Further, a high-precision CT value indicator 33b as shown in FIGS. 3 (a) and 3 (b) is provided with a transparent case 42 having an opening 43 at one end and a closed end at the other end as an elongated rectangular tube shape. An indicator layer (indicator sheet) 41 that uniformly retains the same indicator as the above and a diffusion layer 44 made of filter paper or space for gradually diffusing the specific gas, the indicator layer 41 is the case. As a laminated state in which the extraction container 32 is arranged near the back surface on the side of the attachment surface of the extraction container 32 to the lid 36, the casing 42 is provided so as to be stored in the case 42 over the entire length in the longitudinal direction. Furthermore, a scale (not shown) may be attached to the back surface of the case 42 along the indicator layer 41 from the one end opening 43. By exposing the case 42 to the gas phase when the specific gas reaches the vapor-liquid equilibrium in the extraction container 32 with the back side of the case 42 attached to the inner surface of the lid 36 of the extraction container 32, the exposure time is required. After the specific gas enters the case 42 through the opening 43, the diffusion layer 44 can be gradually diffused from one end side of the opening 43 to the other end side. The length (area) of the color change region of the indicator layer 41 that changes color due to contact with gas is detected using the scale as a reference, and FIGS. 10 (A), (B), FIG. 11 (A), (B), and FIG. B) Similar to the conventional high-accuracy CT value indicator as shown in (b), the length of the color change area detected depends on the CT value (concentration time integral value) of the specific gas. Based on the above, a vapor-liquid equilibrium is reached in the extraction container 32. The vapor phase concentration of the specific gas when being are to be able to be detected.

  As described above, actually, when the measurement target liquid 31 is injected into the storage tank 37, the opening 34 of the extraction container 32 is closed by the measurement target liquid 31, and the gas phase is confined in the extraction container 32. A certain time lag occurs from when the specific gas is diffused into the gas phase in the extraction container 32 until the gas-liquid equilibrium is reached, but discoloration of the indicator layer 41 of the CT value high-precision indicator 33b. Detecting the gas phase concentration of a specific gas based on the CT value, taking the required exposure time until the length of the region is measured as the exposure time considering the time lag until the inside of the extraction container 32 reaches vapor-liquid equilibrium. Alternatively, the diffusion layer 44 having a low diffusion rate of the specific gas is adopted as the diffusion layer 44 in the high-precision CT value indicator 33b, and the specific gas is diffused in the diffusion layer 44. The time required for the discoloration region of the indicator layer 41 to proceed from one end side to the other end side is set to be sufficiently larger than the time lag required for the inside of the extraction container 32 to reach gas-liquid equilibrium. The time lag may be approximately ignored.

  As the indicator used for the indicator layer 41, for example, when the specific gas to be measured for the dissolved gas concentration is ozone gas, an indicator composed of an indigo dye such as indigo carmine or potassium iodide starch may be used. . In addition, when the specific gas is acrylonitrile, an indicator showing a color reaction from orange to black green using reduction of chromium oxide, and when the specific gas is acetylene, the molybdate is reduced to give molybdenum blue. Indicator that shows a color reaction from pale yellow to brown blue, and when the specific gas is acetone, an indicator that shows a color reaction from orange to dark brown using reduction of chromium oxide, and the specific gas is sulfurous acid gas In the case of, an indicator showing a color reaction from yellow to blue using reduction of dichromate, and when the specific gas is carbon monoxide, from white to brown using the reduction of iodine pentoxide Indicator showing a color reaction, when the specific gas is ethanol, an indicator showing a color reaction from yellow-orange to light green using reduction of dichromate, and when the specific gas is ethylene, molybdenum An indicator that shows a color reaction from pale yellow to blue in which the acid salt is reduced to form molybdenum blue.When the specific gas is chlorine, the color is changed from white to yellow-orange when orthotolidine is oxidized to produce yellow holloquinone. An indicator showing a color reaction, when the specific gas is xylene, an indicator showing a color reaction from white to brown that reacts with iodine pentoxide to release iodine, and when the specific gas is nitrogen dioxide, An indicator that reacts to produce a nitrosoorthotrizine reaction to produce a color reaction from white to pale green-orange. When the specific gas is carbon disulfide, it decomposes with an oxidizing agent to generate sulfurous acid gas. Indicator that shows a color reaction from blue-violet to white due to the reaction of bleaching (dye). When the specific gas is propane, yellow-orange using reduction of potassium dichromate When the specific gas is formaldehyde, the indicator that shows a color reaction from brown to white, the indicator that shows the color reaction from white to orange brown that reacts with an aromatic compound to produce a dehydration-condensation polymer, the specific gas is If the gas contains chlorine ions, the properties of the specific gas whose concentration of dissolved gas should be measured, such as using an indicator that shows a color reaction from brown to white that reacts with silver chromate to produce silver chloride An indicator corresponding to the above may be appropriately selected and used.

  When measuring the dissolved gas concentration of the specific gas dissolved in the measurement target liquid 31 using the dissolved gas concentration measuring apparatus of the present invention having the above-described configuration, the dissolved gas concentration is placed inside the lid 36. The indicator 33, which is an indicator layer 41 of the indicator corresponding to the specific gas to be measured, or the CT value high accuracy type is attached according to the desired measurement accuracy, and the indicator 33 is attached. The lid 36 is attached to the container main body 35 fixedly supported in the storage tank 37, and the extraction container 32 is closed at the upper end. In this state, the measurement target liquid 31 in which the specific gas is dissolved is poured into the storage tank 37 to a predetermined level so that the lower end opening 34 of the extraction container 32 is submerged by a required amount below the water surface. To. Thereby, the opening 34 of the extraction container 32 is closed by the measurement target liquid 31, and a part of the gas phase is confined in the extraction container 32. In the confined gas phase, the specific gas is diffused from the measurement target liquid 31, so that the inside of the extraction container 32 reaches a gas-liquid equilibrium. In the extraction container 32 that has reached this vapor-liquid equilibrium, the indicator gas of the indicator 33 reacts with the specific gas present in the gas phase and the indicator layer 41 is discolored. In the case where the simple judgment type indicator 33 as shown in 2 (a) (b) is used, the extraction container 32 indicates which section of the indicator layer 41 has been discolored after the required exposure time has elapsed. The gas phase concentration of the specific gas in the extraction container 32 is detected by observing through the transparent window 39 of the lid 36. In this case, for example, the discoloration state of the simple judgment type indicator 33a based on the gas phase concentration in the extraction container 32 prepared using a standard solution whose dissolved gas concentration of the specific gas is known in advance, and the liquid phase By comparing the color sample corresponding to the relationship with the dissolved gas concentration on the side and the discolored state of the indicator layer 41 of the indicator 33 that has actually changed color, the specific gas dissolved in the measurement target liquid 31 Find the gas concentration.

  On the other hand, when the high-precision CT value indicator 33b is used as the indicator 33, the length of the discoloration area of the indicator layer 41 is changed to the Detected through the transparent window 39 of the lid 36 of the extraction container 32 on the basis of the scale provided on the back side, and based on the length of the detected discoloration area corresponding to the CT value, the above in the extraction container 32 The gas phase concentration of a specific gas is detected. In this case, for example, the length of the discoloration region in the CT value high accuracy type indicator 33b based on the gas phase concentration in the extraction container 32 prepared in advance using a standard solution having a known dissolved gas concentration of the specific gas. Then, the dissolved gas concentration of the specific gas in the measurement target liquid 31 is obtained by using a calibration curve that can correspond to the relationship between the dissolved gas concentration on the liquid phase side.

  When the specific gas reaches a gas-liquid equilibrium based on Henry's law between the gas phase confined in the extraction container 32 and the liquid phase of the measurement target liquid 31, Henry's constant is temperature-dependent. As a result, the gas phase concentration of the specific gas diffused to the gas phase side in the extraction container 32 changes depending on the temperature of the liquid 31 to be measured which is a liquid phase. In this case, however, a color sample of the simple judgment type indicator 33a under different temperature conditions and a calibration curve for the CT value high accuracy type indicator 33b under different temperature conditions are prepared in advance. When measuring the dissolved gas concentration of the liquid 31, the temperature of the measurement target liquid 31 is measured by a temperature detector (not shown) provided in the storage tank 37, and under the temperature condition corresponding to the measured temperature. Created on Using the color sample of the simple judgment type indicator 33a and the calibration curve for the CT value high accuracy type indicator 33b, the dissolved gas concentration of the measurement target liquid 31 is obtained from the color change state of the indicator 33 in the same manner as described above. That's fine.

  Thus, according to the method and apparatus for measuring the dissolved gas concentration of the present invention, after injecting the measurement target liquid 31 into the storage tank 37, after the elapse of a predetermined exposure time, the inside of the extraction container 32 attached to the storage tank 37. By observing the discolored state of the indicator 33 that is set in advance, it is injected into the storage tank 37 based on the gas phase concentration of the specific gas when the inside of the extraction container 32 has reached gas-liquid equilibrium. The dissolved gas concentration of the specific gas in the measured liquid 31 can be easily measured. Further, as the apparatus, an extraction container 32 to be arranged at the boundary of the water surface of the liquid to be measured 31 and an indicator 33 to be installed in the extraction container 32 may be used, so that no carrier gas is required and the apparatus configuration is simple. Therefore, it is possible to easily reduce the size.

  Further, the extraction container 32 is configured such that a lid 36 can be detachably attached to a container body 35 fixed to the extraction tank 37, and the indicator 33 is provided on the inner surface of the lid 36. Since it is designed to be detachably attached, it can be easily attached and detached when the indicator 33 is exchanged, and can be used repeatedly by replacing the used indicator 33 with a new indicator 33. It becomes possible.

  Next, FIG. 4 shows another embodiment of the present invention, which has an opening 34 at the lower end and an indicator on the inner surface of the ceiling in the same configuration as FIGS. In place of the extraction container 32 to which 33 is attached being fixedly attached to the inner surface of one side wall of the storage tank 37 via a support member 38, the opening 34 is provided at the lower end in the same manner as described above. The extraction container 32a having the indicator 33 attached to the inner surface of the ceiling portion is a floating type, and the extraction container 32a is required inside the water surface boundary of the measurement target liquid 31 injected into the storage tank 37. The gas phase can be floated in a confined state, and has the following configuration.

  In other words, the extraction container 32a has an opening 34 at the lower end, has a cylindrical shape extending in the vertical direction with the upper end closed, and has a weight 45 attached around the opening 34.

  The weight 45 has a balance between the weight 45, the weight of the extraction container 32a and the indicator 33 attached to the extraction container 32a, and the buoyancy obtained by the gas phase confined in the extraction container 32a. The weight is set so as to float in a posture that penetrates the water surface boundary of the measurement target liquid 31 injected into the storage tank 37 in the vertical direction.

  Further, as shown by a two-dot chain line in FIG. 4, the liquid to be measured 31 is introduced into the lower end of the extraction container 32a at a predetermined position on the side wall surface in the lower part of the extraction container 32a, and the water surface in the extraction container 32a is introduced. An adjustment hole 46 for adjusting the weight balance in the vertical direction of the extraction container 32a floating at the water surface boundary may be provided by adjusting the height position.

  Other configurations are the same as those shown in FIGS. 1 to 3 (A) and 3 (B), and the same components are denoted by the same reference numerals.

  In this embodiment, when measuring the dissolved gas concentration of the specific gas, first, a simple determination type using the indicator layer 41 of the indicator corresponding to the specific gas on the inner surface of the ceiling of the extraction container 32a, Alternatively, a high-precision CT value indicator 33 is attached, and the extraction container 32a is placed on the inner bottom surface of the storage tank 37 in such a posture that the opening 34 is downward, and then the storage tank 37, the measurement target liquid 31 is injected. Thereby, when the measurement target liquid 31 to be injected is accumulated in the storage tank 37 and the water surface rises, the opening 34 at the lower end of the extraction container 32a placed on the inner bottom of the storage tank 37 is formed. The liquid to be measured 31 is blocked, and the gas phase is confined inside the extraction container 32a. Thereafter, when the measurement target liquid 31 is further injected into the storage tank 37 and the water level rises, the buoyancy due to the gas phase confined in the extraction container 32a increases, and the measurement target liquid 31 in the storage tank 37 increases. When the water level reaches a required level, the weight of the extraction container 32a, the weight 45, and the indicator 33 balances the buoyancy due to the gas phase confined in the extraction container 32a. Then, it floats at the water surface boundary of the measurement target liquid 31.

  In the extraction container 32a floating on the water surface boundary of the measurement target liquid 31, the lower end opening 34 is the measurement target as in the extraction container 32 in the embodiment shown in FIGS. Since the gas phase is closed by the liquid 31 and the gas phase is confined in the extraction container 32a, the specific gas reaches a vapor-liquid equilibrium in the extraction container 32a after the required time has elapsed. Therefore, the gas phase concentration of the specific gas existing in the gas phase in the extraction container 32a when this vapor-liquid equilibrium is reached is the same as that in the embodiment shown in FIGS. According to the procedure, the discoloration state of the indicator 33 attached to the inner surface of the ceiling of the extraction container 32a is observed and detected, and the dissolved gas concentration of the specific gas dissolved in the measurement target liquid 31 is measured. To.

  Therefore, according to this embodiment, the same effect as that of the embodiment shown in FIGS. 1 to 3 (A) and (B) can be obtained. Furthermore, since the extraction container 32a is a floating type, even when the water surface level of the measurement target liquid 31 in the extraction tank 37 fluctuates significantly, it is possible to easily cope with the measurement target liquid 31. It can be easily applied to various tanks to be stored.

  Next, FIG. 5 shows an application example of the embodiment of FIG. 4 as still another embodiment of the present invention. As shown in FIG. 4, a floating type extraction container 32a is placed around the lower end opening 34. A weight 45 is attached to the extraction container 32a so that the weight of the weight 45, the extraction container 32a and the indicator 33 attached to the extraction container 32a is balanced with the buoyancy obtained by the gas phase confined in the extraction container 32a. Therefore, instead of the configuration in which the measurement target liquid 31 injected into the storage tank 37 can float in a posture that penetrates the water surface boundary in the vertical direction, a float is formed around the lower end opening 34 of the extraction container 32a. 47 is installed over the entire circumference so that the buoyancy of the float 47 allows the extraction container 32a to float above the water surface boundary of the liquid 31 to be measured. At the same time, the lower end opening 34 of the extraction container 32a is closed with the measurement target liquid 31 so that the lower end of the extraction container 32a is slightly submerged, and a gas phase is formed inside the extraction container 32a. Can be confined.

  If the float 47 is made of a material that is not affected by the liquid to be measured 31 or the specific gas to be measured, the large buoyancy for allowing the entire extraction container 32a to float above the water surface boundary of the liquid to be measured 31. For example, a foamed resin or the like may be used.

  Other configurations are the same as those shown in FIG. 4, and the same components are denoted by the same reference numerals.

  Similarly to the embodiment shown in FIG. 4, the measurement device for the dissolved gas concentration according to the embodiment of the present invention is previously placed on the inner bottom surface of the storage tank 37, and then the measurement target liquid 31 is stored in the storage tank 37. The extraction container 32a can be placed in a floating state at the water surface boundary of the liquid to be measured 31, and the lower end opening 34 of the extraction container 32a is confined in the extraction container 32a. Since the measurement target liquid 31 can be closed, the specific gas can reach a vapor-liquid equilibrium in the extraction container 32a. Therefore, according to the present embodiment, the dissolved gas concentration of the specific gas in the measurement target liquid 31 can be measured in the same manner as shown in FIG.

  Further, FIG. 6 shows still another embodiment of the present invention. In the embodiment shown in FIGS. 1 to 3 (A) and (B), the extraction container 32 is injected into the storage tank 37. Instead of covering a part of the boundary of the water surface of the measurement target liquid 31 from above, the extraction container 48 is configured such that a required amount of the measurement target liquid 31 can be injected and held therein. is there. That is, the extraction container 48 is a rectangular tube extending in the vertical direction, and has a container main body 49 having an opening 50 at the upper end and a bottom closed at the lower end, and is detachably attached to the upper end of the container main body 49. The upper end opening 50 of the container main body 49 is configured to be closed, and the container main body 49 is filled with a required amount of the liquid 31 to be measured. It can be made to stand upright. Further, the inner surface of the lid 51, which is the inner surface of the ceiling of the extraction container 48, is similar to the lid 36 of the extraction container 32 in the embodiment shown in FIGS. (B) An indicator 33 such as a simple judgment type indicator 33a as shown in (b) or a CT value high accuracy type indicator 33b as shown in FIGS. 3 (b) and (b) is detachably attached. Further, the entire lid 51 is made of a transparent material so that the color change state of the indicator 33 attached to the inner surface of the lid 51 can be observed from the outside.

  The container body 48 is entirely or partially formed of a transparent material so that the measurement target liquid 31 injected into the container body 48 can be observed from the outside. In addition, a scale 52 for injecting the measurement target liquid 31 in a required amount is engraved at a predetermined height position on the outer surface of the container body 48. The scale is set at a relatively high position, and when the measurement target liquid 31 is injected into the container body 49 up to the scale 52, the lid 51 closes the upper end opening 50 of the container body 49. In order to reduce the volume of the gas phase confined above the water surface boundary of the measurement target liquid 31 in the extraction container 48 as much as possible, the specific gas diffused from the measurement target liquid 31 to the gas phase side. Even if the specific gas is diffused from the measurement target liquid 31 in the extraction container 48 to the gas phase side until the gas-liquid equilibrium is reached, This is preferable from the viewpoint of suppressing a change in the dissolved gas concentration of the specific gas in the measurement target liquid 31.

  A stepped portion 53 is provided on the outer peripheral surface portion of the upper portion of the container main body 49 so that the outer shape of the upper end side of the container main body 49 is slightly narrowed. On the other hand, the lid 51 is provided with an inner shape corresponding to the stepped portion 53 of the container body 49 and an external shape similar to the lower side of the container body 49, and the lid 51 is attached to the container body 49. The lid 51 and the outer surface of the container main body 49 are made flush with each other by being fitted to the stepped portion 53.

  In the embodiment shown in FIG. 6, when measuring the concentration of the dissolved gas of the specific gas in the measurement target liquid 31, first, the indicator layer 41 of the indicator corresponding to the specific gas for which the measurement of the dissolved gas concentration is desired (FIG. 6). The indicator 33 using 2 (a) (b) and FIG. 3 (a) (b)) is appropriately selected according to the desired measurement accuracy and selected from the simple judgment type or the CT value high accuracy type. It is attached to the inner surface of 51. Next, the measurement target liquid 31 is injected into the container body 49 to the position of the scale 52, and then the lid 51 to which the indicator 33 is attached is attached so as to close the upper end opening 50 of the container body 49. Thus, a gas phase confined in the extraction container 48 is formed above the water surface boundary of the measurement target liquid 31 in the upper part of the extraction container 48. In the gas phase confined in the extraction container 48, the specific gas reaches the vapor-liquid equilibrium after the required time elapses. Therefore, when the gas-liquid equilibrium is reached, the gas exists in the gas phase in the extraction container 48. The discoloration state of the indicator 33 attached to the inner surface of the ceiling of the extraction container 48 is determined in accordance with the procedure similar to the embodiment shown in FIGS. 1 to 3 (A) and (B). , And the dissolved gas concentration of the specific gas dissolved in the measurement target liquid 31 is measured.

  Thereby, also in the present embodiment, as in the embodiment shown in FIGS. 1 to 3 (A) and (B), the specific gas in the liquid 31 to be measured is obtained by a simple method and a simple apparatus configuration. Dissolved gas concentration can be measured. Furthermore, since carrying and carrying become easy, it becomes possible to measure the dissolved gas concentration of the measurement target liquid 31 regardless of the place. Furthermore, since the storage tank 37 as shown in FIG. 1 for storing the measurement target liquid 31 can be dispensed with, even if the measurement target liquid 31 is flowing, a part of the measurement target liquid 31 is collected and the By injecting into the extraction container, the dissolved gas concentration can be detected.

  FIG. 7 shows an application example of the embodiment of FIG. 6 as still another embodiment of the present invention. As shown in FIG. 6, a required amount of the measurement target liquid 31 is injected and held therein. Instead of the configuration in which the indicator 33 is detachably attached to the inner surface of the lid 51 that closes the upper end opening 50 of the container body 49 of the extraction container 48, the container body in the extraction container 48 can be replaced. 49 is provided with an air-permeable indicator holding body 54 having, for example, a net-like or lattice-like structure, and the upper side of the indicator holding body 54 is shown in FIGS. An indicator 33 such as a simple judgment type indicator 33a as shown in FIG. 3 or a CT value high accuracy type indicator 33b as shown in FIGS. 3 (A) and 3 (B) is placed as shown by a two-dot chain line in FIG. In addition, the upper end opening 50 of the container main body 49 can be covered and closed together with the indicator holder 54 and the indicator 33 on the indicator holder 54 by the lid 51 from above. .

  The indicator holder 54 may be configured to be fixed to the opening 50 of the container body 49 as long as the indicator holder 54 has a liquid permeability that does not hinder the injection and discharge of the liquid 31 to be measured into the container body 49. Alternatively, the container body 49 may be detachably attached to the opening 50, such as by placing the outer peripheral edge of the indicator holder 54 on the periphery of the opening 50 of the container body 49. You may make it remove at the time of injection | pouring and discharge | emission of the measuring object liquid 31 to.

  Other configurations are the same as those shown in FIG. 6, and the same components are denoted by the same reference numerals.

  In the embodiment shown in FIG. 7, when measuring the concentration of the dissolved gas of the specific gas in the measurement target liquid 31, first, into the container body 49 of the extraction container 48, the embodiment shown in FIG. Similarly, after injecting the measurement target liquid 31 to the position of the scale 52, the indicator corresponding to the specific gas for which the dissolved gas concentration is desired to be measured on the indicator holder 54 provided in the upper end opening 50 of the container body 49. The indicator 33 of the simple judgment type or the CT value high accuracy type using the indicator layer 41 (see FIGS. 2A and 2B and FIGS. 3A and 3B) is placed. Next, the lid 51 is attached to the upper end opening 50 of the container main body 49 so as to cover the indicator 33 from above, and the opening 50 is closed, so that the liquid to be measured is placed on the upper part in the extraction container 48. A gas phase confined in the extraction vessel 48 is formed above the water surface boundary 31. Accordingly, the dissolved gas concentration of the specific gas in the measurement target liquid 31 can be measured in the same manner as in the embodiment shown in FIG. 6, and the same effect as in the embodiment shown in FIG. 6 can be obtained. Furthermore, after the indicator 33 is placed on the indicator holding body 54 provided in the upper end opening 50 of the container body 49 of the extraction container 48, the indicator 33 can be put into the extraction container 48 only by attaching the lid 51 to the container body 49. On the other hand, after removing the lid 51 from the container body 49, it can be removed by removing it from the indicator holder 54 at the upper end opening 50 of the container body 50. This can be easily performed, and the replacement work of the indicator 33 can be made easier.

  In addition, this invention is not limited only to the said embodiment, The indicator used for the indicator layer 41 of the indicator 33 reacts with the specific gas which should measure a dissolved gas concentration, and changes color (color reaction). If it is a thing, you may make it select and use suitably other than the illustrated indicator. In addition, the simple judgment type indicator 33a shown in FIGS. 2 (a) and 2 (b) is provided with an indicator layer 41 that changes color in response to a specific gas having a different gas concentration, or two to four sections, or six sections or more. Further, each section may be arranged other than the arrangement arranged in a line. The high-accuracy CT value indicator 33b shown in FIGS. 3 (a) and 3 (b) gradually diffuses the specific gas from the opening 43 provided at one end to the other end side, in accordance with the diffusion of the specific gas. If the indicator layer 41 that changes color is provided and the length of the color change region corresponds to the CT value of the specific gas, the shape of the transparent case 42 shown in FIGS. 44 and the like may be appropriately changed.

  The extraction containers 32 and 32a in the embodiment of FIGS. 1 to 3 (a) and 3 (b), the embodiment of FIG. 4 and the embodiment of FIG. 5 are closed at the upper end and have an opening 34 at the lower end. As long as the space for attaching the indicator 33 can be secured on the inner surface of the ceiling portion, the cross-sectional shape may not be cylindrical, such as an elliptical shape or a rectangular shape. Further, not only the portion of the window 39 provided on the ceiling portion of the extraction containers 32 and 32a but also the entire extraction containers 32 and 32a are made transparent, or the implementation of FIGS. In the form, the lid 36 of the extraction container 32 may be a transparent member.

  The floating extraction container 32a in the embodiment of FIG. 4 and the embodiment of FIG. 5 has a cylindrical shape in the vertical direction as in the embodiment shown in FIGS. The indicator 33 may be attached to the inner surface of the lid as a configuration comprising the container body and a detachable lid for closing the upper end of the container body. In this case, it can be expected that the attaching / detaching operation for replacing the used indicator 33 attached to the extraction container 32a with a new indicator 33 becomes easier.

  In the embodiment shown in FIGS. 1 to 3B, the extraction container 32 is shown as being fixedly supported on the inner surface of one side wall of the storage tank 37 via a support member 38. Can be placed on the boundary of the water surface of the measurement target liquid 31 to be injected into the storage tank 37, and the target to be fixed may be anything. The extraction container 32 is attached to the support member 38 so as to be slidable in the vertical direction. When the amount of the measurement target liquid 31 to be injected into the storage tank 37 changes, the extraction container 32 is changed. You may enable it to adjust a position of the opening part 34 of the lower end of this to an up-down direction according to the position of the water surface level of the said measurement object liquid 31 in the storage tank 37. FIG. Furthermore, the extraction container 32 may be configured as a cylindrical one with the ceiling portion closed, and the extraction container 32 itself may be detachably attached to the support member 38.

  The indicator holding body 54 in the embodiment of FIG. 7 can place the indicator 33 on the upper side and close the upper end opening 50 of the container main body 49 with a lid 51, thereby allowing the upper gas phase in the extraction container 48 to be closed. When the specific gas reaches vapor-liquid equilibrium in the above, the specific gas reaches vapor-liquid equilibrium in the same manner as described above even in the space where the indicator 33 is disposed between the lid 51 and the indicator holding body 54. As long as the structure has air permeability such that a plate-like member having a large number of ventilation holes can be used, any structure other than a net-like or lattice-like structure can be adopted. Of course, various modifications can be made without departing from the scope of the invention.

It is a general | schematic cutting side view which shows one Embodiment of the measuring method and apparatus of a dissolved gas concentration of this invention. In the apparatus of FIG. 1, the state which employ | adopted the simple judgment type indicator as an indicator is shown, (A) is an enlarged plan view, (B) is an AA direction arrow directional view of (A). In the apparatus of FIG. 1, the state which employ | adopted the CT value high precision type indicator as an indicator is shown, (A) is an enlarged plan view, (B) is a BB direction arrow directional view of (A). . It is a general | schematic cutting side view which shows the other form of implementation of this invention. FIG. 5 is a schematic cut side view showing an application example of FIG. 4 as still another embodiment of the present invention. FIG. 24 is a schematic perspective view showing a state in which a lid is removed from a container main body of an extraction container according to still another embodiment of the present invention. FIG. 7 is a perspective view showing an enlarged main part of the application example of FIG. 6 as still another embodiment of the present invention. It is a schematic diagram which shows an example of the measuring apparatus of the dissolved gas concentration proposed conventionally. It is a schematic diagram which shows another example of the measuring apparatus of the dissolved gas concentration proposed conventionally. An example of the indicator for measuring the gas concentration in the gaseous phase proposed conventionally is shown, (A) is a schematic plan view, (B) is a schematic cut side view. The other example of the indicator for measuring the gas concentration in the gaseous phase proposed conventionally is shown, (A) is a schematic plan view, (B) is a schematic cut side view. The other example of the indicator for measuring the gas concentration in the gaseous phase conventionally proposed is shown, (A) is a schematic plan view, and (B) is a schematic cut side view. It is a general | schematic cutting side view which shows the indicator of a CT value high precision type as an example of the indicator for measuring the dissolved gas concentration in the liquid proposed conventionally. It is a general | schematic cutting side view which shows the indicator of a simple judgment type as another example of the indicator for measuring the dissolved gas concentration in the liquid proposed conventionally.

Explanation of symbols

31 Measurement target liquid 32, 32a Extraction container 33, 33a, 33b Indicator 34 Opening 35 Container body 36 Lid 48 Extraction container 49 Container body 50 Lid 54 Indicator holder

Claims (9)

  A gas phase on the boundary of the water surface is confined in an extraction container that covers a required area of the water surface boundary of the liquid to be measured in which the specific gas is dissolved, and the gas phase confined in the extraction container and the measurement object The specific gas reaches a vapor-liquid equilibrium between the liquids, and the gas phase concentration of the specific gas in the gas phase when the vapor-liquid equilibrium is reached is changed in color depending on the concentration of the specific gas. And detecting the dissolved gas concentration of the specific gas in the liquid to be measured based on the gas phase concentration of the specific gas detected by the indicator. Measuring method.   The extraction container is a container having an opening at the lower end and closed at the upper end, and the extraction container is disposed at the boundary of the water surface of the liquid to be measured so that the required amount of the lower end opening is submerged. The method for measuring a dissolved gas concentration according to claim 1, wherein the gas phase is confined in an extraction container whose lower end opening is closed by the target liquid.   By injecting a liquid to be measured in which a specific gas is dissolved to the required level inside the extraction container and capping, the gas phase on the water surface boundary of the liquid to be measured is confined and confined in the extraction container. The specific gas reaches a gas-liquid equilibrium between the gas phase and the liquid to be measured, and the gas phase concentration of the specific gas in the gas phase when the gas-liquid equilibrium is reached Detecting with an indicator whose color change state depends on the concentration, and measuring the dissolved gas concentration of the specific gas in the measurement target liquid based on the gas phase concentration of the specific gas detected by the indicator Characteristic method for measuring dissolved gas concentration.   An extraction container is arranged from above to confine the gas phase on the water surface boundary in a required region of the water surface boundary of the measurement target liquid in which the specific gas is dissolved, and the specific gas is disposed inside the upper end of the extraction container. An apparatus for measuring a dissolved gas concentration, characterized in that it has a configuration in which an indicator whose discoloration state changes depending on the gas phase concentration is attached.   The extraction container has a cylindrical structure having an opening at the lower end and closed at the upper end, and the lower end opening so that the extraction container can be confined inside the water surface boundary of the liquid to be measured. The apparatus for measuring a dissolved gas concentration according to claim 4, which is arranged so as to submerge a required amount.   The extraction container comprises a cylindrical container body in the vertical direction and a detachable lid that closes the upper end of the container body, and the indicator is detachably held on the inner surface of the lid. Item 6. The dissolved gas concentration measuring device according to Item 5.   The apparatus for measuring a dissolved gas concentration according to claim 4, 5 or 6, wherein the extraction container can float at the boundary of the water surface by a balance between buoyancy and weight due to a gas phase confined in the extraction container.   A cylindrical container body that has an opening at the upper end and that can be injected with a liquid to be measured in which a specific gas is dissolved by closing the lower end, and a detachable lid that closes the upper end opening of the container body The dissolved gas concentration measurement is characterized in that the inner surface of the lid of the extraction container is configured to detachably hold an indicator whose color change state depends on the gas phase concentration of the specific gas. apparatus.   Instead of detachably holding the indicator on the inner surface of the lid of the container body of the extraction container, an indicator holding body having air permeability is provided at the upper end opening of the container body, and the upper side of the indicator holding body is provided. The apparatus for measuring a dissolved gas concentration according to claim 8, wherein an indicator is placed.

Images