JP7747982B2 - Measurement equipment and method - Google Patents

Description

The present invention relates to a measurement device and a measurement method.

Measuring devices are used to measure the water quality (e.g., total nitrogen concentration, total phosphorus concentration, heavy metal concentration, COD (Chemical Oxygen Demand) concentration, etc.) of environmental water (such as industrial wastewater, lakes, rivers, or seawater). In such measuring devices, reagents suitable for the measurement are added to the water to be measured (hereinafter referred to as "sample water") collected using a water sampling pump. Various pumps are used to transport and measure these reagents, and various motors are used to operate the pumps (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-27039

In recent years, there has been a demand for reducing the amount of liquid used in measuring devices, primarily for the purpose of reducing costs. Reducing the amount of reagent used to reduce liquid consumption without improving the reagent's measurement accuracy inevitably leads to larger measurement errors and the measurement device's specifications not being met. For high-precision reagent measurement, a pump using a stepping motor, whose rotation amount is controlled by pulses, is suitable. However, stepping motors are relatively expensive. Therefore, using a pump with a stepping motor for each reagent increases the manufacturing cost of the measuring device. Furthermore, air bubbles can become mixed into the reagent drawn into the pump. When the amount of reagent used is reduced, the proportion of air bubbles in the reagent increases, even if the amount is small. As a result, the impact of air bubbles on measurement results becomes greater.

The present invention aims to provide a measuring device and a measuring method that can accurately measure and deliver multiple reagents from which air bubbles have been removed without increasing manufacturing costs.

The measuring device according to the present invention is a measuring device for measuring the quality of sample water, and includes a first syringe pump unit arranged vertically to aspirate and discharge a first solution, a second syringe pump unit arranged vertically to aspirate and discharge a second solution, a first tank for storing the first solution, a second tank for storing the second solution, a reaction tank to which the sample water, the first solution discharged from the first syringe pump unit, and the second solution discharged from the second syringe pump unit are delivered, a first valve for switching the destination of the first solution, a first tank pipe connecting the first valve and the first tank, a first common pipe connecting the first valve and the upper end of the first syringe pump unit, a first liquid delivery pipe connecting the first valve and the reaction tank, a second valve for switching the destination of the second solution, a second tank pipe connecting the second valve and the second tank, a second common pipe connecting the second valve and the upper end of the second syringe pump unit, and a reaction tank to which the second valve and the reaction tank are delivered. a second liquid transfer pipe connected to the tank; a stepping motor that simultaneously and identically operates the first syringe pump unit and the second syringe pump unit; and a control unit that controls the operation of the first valve, the second valve, and the stepping motor, respectively. When a first solution is transferred from the first syringe pump unit to the reaction tank, the control unit operates the stepping motor to connect the first common pipe and the first liquid transfer pipe to the first valve and the second common pipe and the second tank pipe to the second valve, and so that a first required amount of the first solution is discharged from the first syringe pump unit; and when a second solution is transferred from the second syringe pump unit to the reaction tank, the control unit operates the stepping motor to connect the first common pipe and the first tank pipe to the first valve and the second common pipe and the second liquid transfer pipe to the second valve, and so that a second required amount of the second solution is discharged from the second syringe pump unit.

The measurement method of the present invention is a method for measuring water quality using the aforementioned measurement device, and is characterized by including a first solution delivery step in which the control unit controls the operation of the first valve, the second valve, and the stepping motor after the sample water has been delivered to the reaction tank to deliver a first required amount of first solution to the reaction tank, and a second solution delivery step in which the control unit controls the operation of the first valve, the second valve, and the stepping motor after the first required amount of first solution has been delivered to deliver a second required amount of second solution to the reaction tank.

The present invention provides a measuring device and a measuring method that can accurately measure and deliver multiple reagents from which air bubbles have been removed without increasing manufacturing costs.

1 is a schematic diagram illustrating an embodiment of a measuring device according to the present invention. FIG. 2 is a schematic front view of a first reagent pump provided in the measurement device of FIG. 1 . 3 is a schematic side view of the first reagent pump of FIG. 2 as viewed from an arrow A. FIG. FIG. 3 is a partially enlarged cross-sectional view of the first reagent pump taken along line BB in FIG. 2 . 10 is a flowchart showing an example of a normal measurement process included in the operation of the measurement device of FIG. 1 . 5 is a schematic diagram showing an example of the operation of the first reagent liquid delivery mechanism and the second reagent liquid delivery mechanism provided in the measurement device of FIG. 1 during the normal measurement process of FIG. 5, where (a) to (c) show the oxidation process included in the normal measurement process, and (d) to (e) show the oxidation stop process included in the normal measurement process. 10 is a flowchart showing an example of a low concentration measurement process included in the operation of the measurement apparatus of FIG. 1 . 4 is a flowchart showing an example of a simple span calibration process included in the operation of the measurement apparatus of FIG. 1 .

●Measuring equipment●
Embodiments of a measuring apparatus (hereinafter referred to as "the apparatus") according to the present invention and a measuring method (hereinafter referred to as "the method") according to the present invention will be described below. In the following description, reference will be made to the drawings as appropriate. In the drawings, identical members and elements are designated by the same reference numerals, and duplicated descriptions will be omitted. In addition, in the drawings, the shape and size of each member may be intentionally distorted from their actual dimensions in order to clearly and concisely show the configuration of each member.

A "measuring device" is, for example, a device that calculates (measures) the concentration of a target component contained in sample water (analyte solution) after each treatment. In this embodiment, this device is described as a chemical oxygen demand (COD) measuring device that measures COD concentration.

"Sample water" refers to water containing the components to be measured by this device, such as wastewater from a factory or business.

In the present invention, the sample water is not limited to wastewater. That is, for example, the sample water may be environmental water such as river, lake, or sea water.

The "measurement target component" refers to the component contained in the sample water that is the target of measurement by this device, and in this embodiment, it is an oxidizable substance.

In the present invention, the device may be any device that requires highly accurate measurement of reagents, and is not limited to a COD measurement device. For example, the device may be a total nitrogen concentration measurement device or a total phosphorus concentration measurement device.

In the following description, this device measures COD concentration according to JIS K 0102, Section 17. [Oxygen consumption by potassium permanganate at 100°C (COD _Mn )]. Specifically, a potassium permanganate solution is added as an oxidizing agent to sample water acidified with sulfuric acid to produce an analysis solution. The analysis solution is then heated for 30 minutes to promote the oxidation reaction of oxidizable substances in the analysis solution. Next, a sodium oxalate solution is added to the analysis solution to stop the oxidation reaction. Finally, titration with the oxidizing agent (potassium permanganate) is performed, and the COD concentration of the sample water is measured based on the amount of oxidizing agent consumed.

Therefore, in this device, sulfuric acid is used as a reagent to acidify the sample water, potassium permanganate solution is used as an oxidizing agent and titration reagent, and sodium oxalate solution is used as a reaction reagent (reducing agent) that reacts with the oxidizing agent and titration reagent, respectively, and as an oxidizable substance. The potassium permanganate solution is an example of a first solution in the present invention, containing potassium permanganate that has been standardized and whose exact concentration is known (known concentration). The sodium oxalate solution is an example of a second solution in the present invention, containing sodium oxalate of a known concentration.

In the following description, the "upstream side" of a pipe refers to the upstream side in the flow of liquid within that pipe, and the "downstream side" refers to the downstream side in the flow of liquid within that pipe. That is, for example, the "downstream side" refers to the syringe pump side in the flow from each tank to the syringe pump, and the reaction tank side in the flow from the syringe pump to the reaction tank. In other words, the reaction tank side in the flow including the sample water toward the reaction tank is the "downstream side," and the waste tank is the most downstream side in the flow of waste liquid from the reaction tank toward the waste tank.

Configuration of Measuring Apparatus FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present apparatus.

This device 1 measures the water quality (COD concentration) of sample water. It includes a reaction tank 2, a heating tank 3, a heater 4, a thermometer 5, an electrode 6, a control unit 7, a first reagent tank T1, a second reagent tank T2, a third reagent tank T3, a fourth reagent tank T4, a pure water tank T5, a water receiving tank T6, a waste liquid tank T7, a first reagent pipe L1, a second reagent pipe L2, a third reagent pipe L3, a fourth reagent pipe L4, a pure water pipe L5, a sample water pipe L6, an air pipe L7, a waste liquid pipe L8, a first reagent pump P1, a third reagent pump P2, a fourth reagent pump P3, a pure water pump P4, a sample water pump P5, an air pump P6, a waste liquid pump P7, a first valve V1, a second valve V2, a third valve V3, and a fourth valve V4.

Here, the first reagent tank T1, first reagent pump P1, first reagent piping L1, and first valve V1 constitute the first reagent liquid delivery mechanism M1. The second reagent tank T2, first reagent pump P1, second reagent piping L2, and second valve V2 constitute the second reagent liquid delivery mechanism M2. The third reagent tank T3, third reagent pump P2, and third reagent piping L3 constitute the third reagent liquid delivery mechanism M3. The fourth reagent tank T4, fourth reagent pump P3, and fourth reagent piping L4 constitute the fourth reagent liquid delivery mechanism M4. The pure water tank T5, pure water pump P4, pure water piping L5, and third valve V3 constitute the pure water liquid delivery mechanism M5. The water receiving tank T6, sample water pump P5, and sample water piping L6 constitute the sample water liquid delivery mechanism M6.

The configuration of this device 1, other than the first reagent liquid delivery mechanism M1 and the second reagent liquid delivery mechanism M2, is common to the configuration of known COD measurement devices. Therefore, in the following explanation, detailed explanation of the configuration other than the first reagent liquid delivery mechanism M1 and the second reagent liquid delivery mechanism M2 will be omitted.

Reaction tank 2 is a tank that temporarily stores the delivered sample water and each reagent, causing a chemical reaction. The lower part of reaction tank 2 is immersed in the bath of heating tank 3. Heating tank 3 heats the lower part of reaction tank 2, thereby heating the analytical solution in reaction tank 2. Heating tank 3 is, for example, an oil bath or boiling water bath. Heater 4 heats heating tank 3. Thermometer 5 measures the temperature of heating tank 3.

Electrode 6, which detects the endpoint of the titration, is, for example, a platinum electrode. Electrode 6 is inserted into reaction vessel 2.

The control unit 7 controls the overall operation of the device 1. The control unit 7 is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory) which functions as the CPU's working area, and ROM (Read Only Memory) which stores various information such as measurement programs.

A measurement program runs in the control unit 7, and works in cooperation with the hardware resources of the device 1 to realize the measurement method described below. Furthermore, by having the processor (CPU) constituting the control unit 7 execute the measurement program, the measurement program can cause the processor to function as the control unit 7 and execute the measurement method. Similarly, by having a computer execute the measurement program, the measurement program can cause the computer to function as the control unit 7.

In the present invention, the measurement program may be stored on a storage medium (not shown) such as a flash memory. Alternatively, the measurement program may be stored in an installable file format or an executable file format on a non-transitory storage medium (e.g., a CD (Compact Disc), a DVD (Digital Versatile Disc), a USB (Universal Serial Bus) memory, etc.) and provided to the device 1 via a dedicated read-only medium.

The first reagent tank T1 stores the first reagent (potassium permanganate solution). The second reagent tank T2 stores the second reagent (sodium oxalate solution). The third reagent tank T3 stores the third reagent (sulfuric acid). The fourth reagent tank T4 stores the fourth reagent (silver nitrate). The pure water tank T5 stores pure water. The water receiving tank T6 receives sample water delivered by a water sampling pump (not shown). The first reagent tank T1 is an example of the first tank in the present invention, and the second reagent tank T2 is an example of the second tank in the present invention.

The first reagent pump P1 operates under the control of the control unit 7 to deliver the first and second reagents to the reaction chambers 2. The configuration of the first reagent pump P1 will be described in detail below.

The third reagent pump P2 delivers the third reagent to the reaction tank 2, and the fourth reagent pump P3 delivers the fourth reagent to the reaction tank 2. The third reagent pump P2 and the fourth reagent pump P3 are each a well-known syringe pump operated by, for example, an AC motor (not shown).

The pure water pump P4 delivers pure water to the reaction tank 2. The pure water pump P4 is, for example, a known syringe pump operated by a stepping motor (not shown).

The sample water pump P5 delivers sample water to the reaction tank 2. The sample water pump P5 is, for example, a known roller pump powered by an AC motor (not shown).

Air pump P6 pumps air under pressure into each of the pipes L1 to L5. Air pump P6 is a known air pump powered, for example, by an AC motor (not shown).

The operation of each pump P1 to P7 is controlled by the control unit 7.

The first reagent pipe L1 is a path through which the first reagent stored in the first reagent tank T1 is delivered to the reaction tank 2. A first valve V1 is connected to the first reagent pipe L1. The first reagent pipe L1 includes a first tank pipe L11, a first common pipe L12, and a first delivery pipe L13.

One end (upstream end) of the first tank pipe L11 is connected to the first reagent tank T1, and the other end (downstream end) of the first tank pipe L11 is connected to the first valve V1. One end of the first common pipe L12 is connected to the first reagent pump P1 (first pipe mounting hole 18c described below: see Figure 4), and the other end of the first common pipe L12 is connected to the first valve V1. One end (upstream end) of the first liquid supply pipe L13 is connected to the first valve V1, and the other end (downstream end) of the first liquid supply pipe L13 is connected to the reaction tank 2.

In this embodiment, the volume "V12" of the first common pipe L12 is smaller than the volume "V11" of the first tank pipe L11 and the volume "V13" of the first liquid supply pipe L13. The volume "V11" of the first tank pipe L11 is larger than the volume "V13" of the first liquid supply pipe L13.

The second reagent pipe L2 is a path through which the second reagent stored in the second reagent tank T2 is delivered to the reaction tank 2. A second valve V2 is connected to the second reagent pipe L2. The second reagent pipe L2 includes a second tank pipe L21, a second common pipe L22, and a second delivery pipe L23.

One end (upstream end) of the second tank pipe L21 is connected to the second reagent tank T2, and the other end (downstream end) of the second tank pipe L21 is connected to the second valve V2. One end of the second common pipe L22 is connected to the first reagent pump P1 (second pipe mounting hole 18d described below: see Figure 4), and the other end of the second common pipe L22 is connected to the second valve V2. One end (upstream end) of the second liquid supply pipe L23 is connected to the second valve V2, and the other end (downstream end) of the second liquid supply pipe L23 is connected to the reaction tank 2.

In this embodiment, the volume "V22" of the second common pipe L22 is smaller than the volume "V21" of the second tank pipe L21 and the volume "V23" of the second liquid supply pipe L23. The volume "V21" of the second tank pipe L21 is larger than the volume "V23" of the second liquid supply pipe L23. The volume "V21" of the second tank pipe L21 is the same as the volume "V11" of the first tank pipe L11, the volume "V22" of the second common pipe L22 is the same as the volume "V12" of the first common pipe L12, and the volume "V23" of the second liquid supply pipe L23 is the same as the volume "V13" of the first liquid supply pipe L13.

The third reagent pipe L3 is a path through which the third reagent stored in the third reagent tank T3 is delivered to the reaction tank 2. One end (upstream end) of the third reagent pipe L3 is connected to the third reagent tank T3, and the other end (downstream end) of the third reagent pipe L3 is connected to the reaction tank 2. A third reagent pump P2 is connected to the third reagent pipe L3.

The fourth reagent pipe L4 is a path through which the fourth reagent stored in the fourth reagent tank T4 is delivered to the reaction tank 2. One end (upstream end) of the fourth reagent pipe L4 is connected to the fourth reagent tank T4, and the other end (downstream end) of the fourth reagent pipe L4 is connected to the reaction tank 2. A fourth reagent pump P3 is connected to the fourth reagent pipe L4.

The pure water pipe L5 is a path through which pure water stored in the pure water tank T5 is delivered to the reaction tank 2. A third valve V3 is connected to the pure water pipe L5. The pure water pipe L5 includes a tank pipe L51, a common pipe L52, and a liquid delivery pipe L53.

One end (upstream end) of the tank pipe L51 is connected to the pure water tank T5, and the other end (downstream end) of the tank pipe L51 is connected to the third valve V3. One end of the common pipe L52 is connected to the pure water pump P4, and the other end of the common pipe L52 is connected to the third valve V3. One end (upstream end) of the liquid supply pipe L53 is connected to the third valve V3, and the other end (downstream end) of the liquid supply pipe L53 is connected to the reaction tank 2.

The sample water pipe L6 is a path through which the sample water stored in the receiving tank T6 is sent to the reaction tank 2. A sample water pump P5 is connected to the sample water pipe L6. One end (upstream end) of the sample water pipe L6 is connected to the receiving tank T6, and the other end (downstream end) of the sample water pipe L6 is connected to the reaction tank 2.

Air pipe L7 is a path through which air from air pump P6 is blown into each of pipes L1 to L5. One end (upstream end) of air pipe L7 is connected to air pump P6. The other end (downstream end) of air pipe L7 branches into multiple parts and is connected to first liquid supply pipe L13, second liquid supply pipe L23, third reagent pipe L3, fourth reagent pipe L4, and liquid supply pipe L53.

The first valve V1 to the fourth valve V4 are, for example, solenoid valves whose operation is controlled by the control unit 7. The first valve V1 to the third valve V3 are three-way valves, and the fourth valve V4 is a normally closed valve.

As described above, the first valve V1 is connected to the first tank pipe L11, the first common pipe L12, and the first liquid supply pipe L13, and is controlled by the control unit 7 to connect the first tank pipe L11 to the first common pipe L12, or the first common pipe L12 to the first liquid supply pipe L13. Similarly, the second valve V2 is controlled by the control unit 7 to connect the second tank pipe L21 to the second common pipe L22, or the second common pipe L22 to the second liquid supply pipe L23. Similarly, the third valve V3 is controlled by the control unit 7 to connect the tank pipe L51 to the common pipe L52, or the common pipe L52 to the liquid supply pipe L53.

FIG. 2 is a schematic front view of the first reagent pump P1.
FIG. 3 is a schematic side view of the first reagent pump P1 as viewed from the arrow A in FIG.
FIG. 4 is a partially enlarged cross-sectional view of the first reagent pump P1 taken along line BB in FIG.

In the following description of the first reagent pump P1 and in Figures 2 to 4, unless otherwise noted, when three mutually orthogonal axes in space are defined as the X-axis, Y-axis, and Z-axis, respectively, the "X-axis direction" is the direction along the X-axis, i.e., the left-right direction. The "Y-axis direction" is the direction along the Y-axis, i.e., the front-to-back direction. The "Z-axis direction" is the direction along the Z-axis, i.e., the up-to-down direction. Furthermore, the "+X direction" is the left, the "-X direction" is the right, the "+Y direction" is the front, the "-Y direction" is the rear, the "+Z direction" is the up, and the "-Z direction" is the down. Figure 1 will be referenced as appropriate in the following description.

The first reagent pump P1 includes a base plate 10, a motor 11, a coupling 12, a shaft 13, a slider 14, a holding member 15, a first syringe pump unit 16, a second syringe pump unit 17, a connecting member 18, two sealing members 19 and 20, a first joint 21, and a second joint 22.

The substrate 10 supports the motor 11, shaft 13, slider 14, and connecting member 18. The substrate 10 is, for example, a rectangular plate whose longitudinal direction is along the vertical direction (Z-axis direction). A slit-shaped through-hole 10a is arranged in the center of the substrate 10, extending along the vertical direction.

The motor 11 generates a rotational force that moves the slider 14 back and forth in the vertical direction via the coupling 12 and shaft 13. The motor 11 is a well-known stepping motor. The motor 11 is attached to the rear surface of the substrate 10 with its rotation axis 11a facing downward (in the -Z direction). The operation of the motor 11 is controlled by the control unit 7.

The coupling 12 transmits the rotational force of the motor 11 to the shaft 13. The coupling 12 is attached to the rotating shaft 11a of the motor 11.

The shaft 13 rotates in response to the rotational force of the motor 11 transmitted via the coupling 12, causing the slider 14 to move back and forth in the vertical direction. The shaft 13 is attached to the rear side of the base plate 10 so that its axis is aligned vertically.

The slider 14 moves up and down along the shaft 13 in response to the rotation of the shaft 13. The slider 14 is, for example, cubic in shape. The slider 14 has a female threaded hole (not shown) that corresponds to the male threaded surface of the shaft 13. The female threaded hole passes through the slider 14 in the vertical direction. The shaft 13 is inserted into the female threaded hole.

The holding member 15 holds the first plunger 16b and second plunger 17b (described below). The holding member 15 is attached to the lower part of the front surface of the slider 14. The holding member 15 passes through the through hole 10a and moves back and forth in the up-down direction together with the slider 14. The holding member 15 is, for example, rectangular parallelepiped-shaped. In the up-down direction, a slit hole 15a is located in the center of the holding member 15, into which the lower ends of the first plunger 16b and the second plunger 17b (the first flange portion 16e and the second flange portion 17e (described below)) are fitted. The slit hole 15a opens forward (in the +Y direction) and left-right (in the X-axis direction) of the holding member 15. Plunger mounting grooves 15b and 15c are located above the slit hole 15a (in the +Z direction) of the holding member 15. The plunger mounting grooves 15b and 15c open to the right and top surfaces of the holding member 15 and to the slit hole 15a. The plunger mounting grooves 15b and 15c are aligned in the front-to-rear direction.

The first syringe pump unit 16 aspirates and dispenses the first reagent from the first reagent tank T1. The first syringe pump unit 16 is, for example, a known microsyringe. The first syringe pump unit 16 is detachably attached to the holding member 15 and the connecting member 18 so that its axis is aligned vertically. In this embodiment, the maximum suction capacity of the first syringe pump unit 16 is designed to be greater than the total amount of the first reagent and the second reagent dispensed in the oxidation process (S13) and oxidation termination process (S14) described below. The first syringe pump unit 16 includes a first syringe 16a, a first plunger 16b, and a first gasket 16c.

The first syringe 16a is cylindrical and extends in the vertical direction. The upper end of the first syringe 16a has a reduced diameter, forming a first mounting portion 16d. The outer surface of the first mounting portion 16d is a male threaded surface.

The first plunger 16b is cylindrical and extends in the vertical direction. The first plunger 16b is inserted into the first syringe 16a from the lower end side thereof and is capable of reciprocating (advancing and retreating) in the vertical direction relative to the first syringe 16a. The lower end of the first plunger 16b has an enlarged diameter and forms a disk-shaped first flange portion 16e.

The first gasket 16c is cylindrical and extends in the vertical direction. The first gasket 16c is attached to the upper end of the first plunger 16b. The first gasket 16c, together with the first plunger 16b, can move back and forth (advance and retreat) in the vertical direction relative to the first syringe 16a in a liquid-tight manner.

The first mounting portion 16d is removably fitted (screwed) from below into the first syringe mounting hole 18a (described below). The first flange portion 16e is removably fitted into the slit hole 15a of the holding member 15. The portion of the first plunger 16b adjacent to the first flange portion 16e is fitted into the plunger mounting groove 15b of the holding member 15. As a result, the first plunger 16b moves back and forth (advances and retreats) in the vertical direction relative to the first syringe 16a in response to the vertical reciprocating movement of the holding member 15.

The second syringe pump unit 17 aspirates and dispenses the second reagent from the second reagent tank T2. The second syringe pump unit 17 is, for example, a known microsyringe. The second syringe pump unit 17 is detachably attached to the holding member 15 and the connecting member 18 so that its axis is aligned in the vertical direction. The configuration of the second syringe pump unit 17 is the same as the configuration of the first syringe pump unit 16. That is, the second syringe pump unit 17 includes a second syringe 17a, a second plunger 17b, a second gasket 17c, a second mounting portion 17d, and a second flange portion 17e.

The second mounting portion 17d is removably fitted (screwed) from below into the second syringe mounting hole 18b (described below). The second flange portion 17e is fitted into the slit hole 15a of the holding member 15. The portion (lower portion) of the second plunger 17b adjacent to the second flange portion 17e is fitted into the plunger mounting groove 15c of the holding member 15. As a result, the second syringe pump portion 17 is positioned in front of and alongside the first syringe pump portion 16. In response to the up-down reciprocating movement of the holding member 15, the second plunger 17b moves up-down (advanced and retreated) relative to the second syringe 17a.

The connecting member 18 connects the first syringe pump unit 16 and the second syringe pump unit 17 to the first reagent pipe L1 (first common pipe L12) and the second reagent pipe L2 (second common pipe L22). The connecting member 18 is, for example, rectangular. The connecting member 18 is attached to the upper front surface of the substrate 10 and is positioned above the first syringe pump unit 16 and the second syringe pump unit 17. The connecting member 18 includes a first syringe mounting hole 18a, a second syringe mounting hole 18b, a first tube mounting hole 18c, a second tube mounting hole 18d, a first communication hole 18e, and a second communication hole 18f.

The first syringe mounting hole 18a is a cylindrical hole with a bottom that opens to the underside of the connecting member 18. The inner surface of the first syringe mounting hole 18a is an internally threaded surface that corresponds to the externally threaded surface of the first mounting portion 16d.

The second syringe mounting hole 18b is a cylindrical hole with a bottom that opens to the underside of the connecting member 18. The inner surface of the second syringe mounting hole 18b is an internally threaded surface that corresponds to the externally threaded surface of the second mounting portion 17d. The second syringe mounting hole 18b is located in front of and alongside the first syringe mounting hole 18a.

The first pipe mounting hole 18c is a cylindrical hole with a bottom that opens to the upper surface of the connecting member 18. The inner surface of the first pipe mounting hole 18c is a female threaded surface that corresponds to the male threaded surface of the first fitting 21, which will be described later. The first pipe mounting hole 18c is located above the first syringe mounting hole 18a.

The second pipe mounting hole 18d is a cylindrical hole with a bottom that opens to the upper surface of the connecting member 18. The inner surface of the second pipe mounting hole 18d is a female threaded surface that corresponds to the male threaded surface of the second fitting 22 described below. The second pipe mounting hole 18d is located above the second syringe mounting hole 18b.

The first communication hole 18e is a cylindrical through-hole that opens to the bottom surface 18g of the first syringe mounting hole 18a and the bottom surface 18h of the first tube mounting hole 18c.

The second communication hole 18f is a cylindrical through-hole that opens to the bottom surface 18i of the second syringe mounting hole 18b and the bottom surface 18j of the second tube mounting hole 18d.

The seal members 19 and 20 are, for example, O-rings. The seal member 19 is housed in the first syringe mounting hole 18a, and the seal member 20 is housed in the second syringe mounting hole 18b. The seal member 19 provides a liquid-tight seal between the upper end surface 16f of the first mounting portion 16d of the first syringe pump unit 16 and the bottom surface 18g of the first syringe mounting hole 18a. The seal member 20 provides a liquid-tight seal between the upper end surface 17f of the second mounting portion 17d of the second syringe pump unit 17 and the bottom surface 18i of the second syringe mounting hole 18b.

In the present invention, the sealing member housed in the first syringe mounting hole (second syringe mounting hole) may be a ring-shaped gasket. Also, the device does not necessarily have to be equipped with a sealing member housed in the first syringe mounting hole (second syringe mounting hole).

The first fitting 21 is a known fitting with a sealing member 21a that connects the first reagent pipe L1 (first common pipe L12) and the connecting member 18. The outer peripheral surface of the lower end of the first fitting 21 is a male threaded surface that corresponds to the female threaded surface of the first pipe mounting hole 18c. The first fitting 21 is fitted (screwed) into the first pipe mounting hole 18c from above. One end of the first common pipe L12 is inserted into the first fitting 21. As a result, one end of the first common pipe L12 is connected to the first mounting portion 16d of the first syringe pump unit 16 via the first fitting 21 and the connecting member 18.

The sealing member 21a provides a liquid-tight seal between the first fitting 21 and the first pipe mounting hole 18c. The sealing member 21a is, for example, inverted funnel-shaped. The upper part of the sealing member 21a is inserted into the lower end of the first fitting 21 (first common pipe L12). The lower part of the sealing member 21a is sandwiched between the lower end surface 21b of the first fitting 21 and the bottom surface 18h of the first pipe mounting hole 18c, providing a liquid-tight seal between them.

The second fitting 22 is a known fitting with a sealing member 22a that connects the second reagent pipe L2 (second common pipe L22) and the connecting member 18. The configuration of the second fitting 22 is the same as that of the first fitting 21. The second fitting 22 is fitted (screwed) into the second pipe mounting hole 18d from above. One end of the second common pipe L22 is inserted into the second fitting 22. As a result, one end of the second common pipe L22 is connected to the second mounting portion 17d of the second syringe pump unit 17 via the second fitting 22 and the connecting member 18.

The upper part of the seal member 22a is inserted into the lower end of the second joint 22 (second common pipe L22). The lower part of the seal member 22a is sandwiched between the lower end surface 22b of the second joint 22 and the bottom surface 18j of the second pipe mounting hole 18d, creating a liquid-tight seal between them.

In the first reagent pump P1 configured in this manner, the holding member 15 reciprocates vertically in response to the rotation of the motor 11. At this time, the first plunger 16b and the second plunger 17b reciprocate (advance and retreat) vertically with the same stroke, simultaneously, relative to the first syringe 16a and the second syringe 17a, respectively. In other words, the motor 11 causes the first syringe pump unit 16 and the second syringe pump unit 17 to perform the same operation simultaneously.

The first syringe pump unit 16 can be easily attached to the holding member 15 and connecting member 18 by simply fitting the first mounting portion 16d into the first syringe mounting hole 18a and fitting the first flange portion 16e into the slit hole 15a. The first syringe pump unit 16 can be easily removed from the holding member 15 and connecting member 18 by simply removing the first mounting portion 16d from the first syringe mounting hole 18a and removing the first flange portion 16e from the slit hole 15a. The same applies to the second syringe pump unit 17.

●Operation of the measuring device●
Next, the operation of the present apparatus 1, i.e., the present method, will be described. In the following description, Figures 1 to 4 will be referred to as appropriate. The present apparatus 1 executes a normal measurement process (S1), a low concentration measurement process (S2), and a simple span calibration process (S3) under the control of the control unit 7.

Normal Measurement Process FIG. 5 is a flowchart showing an example of the normal measurement process (S1).
6 is a schematic diagram showing an example of the operation of the first reagent delivery mechanism M1 and the second reagent delivery mechanism M2 in the normal measurement process (S1), where (a) to (c) show the oxidation process (S13) described below, and (d) to (e) show the oxidation stop process (S14) described below. In the figure, the flow of reagents is indicated by thick arrows.

The "normal measurement process (S1)" is a COD concentration measurement process performed when the oxidizable substances contained in the sample water are within the measurement range of the device 1.

First, the sample water introduction process (S11) is performed. In the sample water introduction process (S11), a predetermined amount of sample water is sent to the reaction tank 2 by the sample water pump P5.

Next, pretreatment (S12) is performed. In pretreatment (S12), a predetermined amount of third reagent (sulfuric acid) is pumped into reaction tank 2 by third reagent pump P2 to acidify the sample water. Furthermore, a predetermined amount of fourth reagent (silver nitrate) is pumped into reaction tank 2 by fourth reagent pump P3 to remove chloride ions from the sample water. As a result, a post-pretreatment (S12) sample water (analyte solution) is produced.

In the present invention, the fourth reagent (silver nitrate) may be added to the sample water depending on the specifications of the measuring device and the sample water (e.g., sample water containing chloride ions), and the fourth reagent (silver nitrate) may not be added in some cases.

Next, an oxidation process (S13) is performed. In the oxidation process (S13), the required amount of first reagent is delivered to the analysis solution in the reaction vessel 2. Specifically, in the oxidation process (S13), an aspiration process (first aspiration step), a bubble removal process (first bubble removal step), a solution delivery process (first solution delivery step), and a heating process are performed in that order.

The "required amount" in the oxidation treatment (S13) is an amount greater than the amount of oxidizable substances contained in the sample water (analyte solution). The required amount is set, for example, based on the results of past measurements of the COD concentration of the sample water. In other words, the required amount is variable. The required amount in the oxidation treatment (S13) is an example of the first required amount in the present invention.

In this embodiment, the acidic potassium permanganate method (acidic method) using sulfuric acid is used. Alternatively, the present invention can also be realized using the alkaline potassium permanganate method (alkaline method) using sodium hydroxide.

Referring also to FIG. 6(a), during the suction process, the control unit 7 controls the operation of the first valve V1 to connect the first tank pipe L11 and the first common pipe L12, and controls the operation of the second valve V2 to connect the second tank pipe L21 and the second common pipe L22. Next, the control unit 7 controls the operation of the motor 11 to lower the slider 14 by the maximum amount. As a result, the first syringe pump unit 16 aspirates the maximum amount of the first reagent (potassium permanganate solution), and the second syringe pump unit 17 aspirates the maximum amount of the second reagent (sodium oxalate solution).

The bubble removal process removes air bubbles that may be mixed into the first and second reagents. Because the first syringe pump unit 16 is arranged vertically, air bubbles in the first syringe 16a collect at the upper end (first mounting portion 16d). After the first reagent is aspirated, air bubbles may also be mixed into the first reagent remaining in the path from the first reagent tank T1 to the first syringe pump unit 16, i.e., the first tank pipe L11, the first valve V1, the first common pipe L12, and the connecting member 18 (sealing member 19, first communicating hole 18e, and the lower part of sealing member 21a). Similarly, air bubbles may also be mixed into the path through which the second reagent is aspirated.

Referring also to FIG. 6(b), the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that a small amount of the first reagent is ejected from the first syringe pump unit 16. The amount of the ejected first reagent is set to be greater than the volume "V12" of the first common pipe L12. Specifically, the amount of the ejected first reagent is set to be equal to the combined volume "V11/2 + V12" of the first common pipe L12 and approximately half the volume "V11" of the first tank pipe L11. As a result, at least the first reagent in the path from the upper end (first mounting portion 16d) of the first syringe pump unit 16 to the first valve V1 is returned to the first tank pipe L11 together with air bubbles. That is, of the first reagent aspirated from the first reagent tank T1, the first reagent between the upper end of the first syringe pump unit 16 and the first valve V1 is returned to the first tank pipe L11 (first reagent tank T1) together with air bubbles. Therefore, the first reagent remaining from the first syringe pump unit 16 to the first valve V1 does not contain air bubbles. Similarly, at least the second reagent in the path from the upper end (second mounting portion 17d) of the second syringe pump unit 17 to the second valve V2 is returned to the second tank pipe L21 together with air bubbles. That is, of the second reagent aspirated from the second reagent tank T2, the second reagent between the upper end of the second syringe pump unit 17 and the second valve V2 is returned to the second tank pipe L21 (second reagent tank T2) together with air bubbles. Therefore, the second reagent remaining from the second syringe pump unit 17 to the second valve V2 does not contain air bubbles.

Referring also to FIG. 6(c), in the liquid transfer process, the control unit 7 first controls the operation of only the first valve V1 to connect the first common pipe L12 and the first liquid transfer pipe L13. Next, the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that the required amount of first reagent is transferred from the first syringe pump unit 16 to the reaction tank 2. As a result, the required amount of first reagent is transferred to the reaction tank 2. Because the motor 11 is a stepping motor, the first reagent is transferred with high precision. As described above, the bubble removal process is performed immediately before the liquid transfer process, so no air bubbles are mixed into the reaction tank 2. At this time, the second syringe pump unit 17 is also operating simultaneously, and an amount of the second reagent equal to the required amount of the first reagent is returned to the second reagent tank T2. Next, the control unit 7 controls the operation of only the first valve V1 to connect the first tank pipe L11 and the first common pipe L12. The liquid delivery process is an example of the first solution delivery step of the present invention.

During the heating process, the analytical solution in the reaction tank 2 is heated to 100°C for 30 minutes. This heating is performed by heating the heating tank 3 with the heater 4. As a result, the oxidizable substances contained in the analytical solution are oxidized by the potassium permanganate.

Next, the oxidation stopping process (S14) is performed. In the oxidation stopping process (S14), the required amount of second reagent is delivered to the analysis solution in the reaction vessel 2. Specifically, in the oxidation stopping process (S14), a bubble removal process (second bubble removal step) and a solution delivery process (second solution delivery step) are performed in sequence. As a result, any unreacted potassium permanganate remaining in the analysis solution reacts with sodium oxalate, thereby stopping the oxidation reaction of the oxidizable substance.

The "required amount" in the oxidation stopping process (S14) is determined by the amount of potassium permanganate solution delivered in the oxidation process (S13). In other words, the required amount is variable. The required amount in the oxidation stopping process (S14) is an example of the second required amount in the present invention.

During the 30-minute heating process, gas dissolved in the second reagent may form as bubbles inside the second syringe pump unit 17 and the path from the second syringe pump unit 17 to the second valve V2. The control unit 7 executes a bubble removal process to remove any bubbles that may form in the second reagent. Also see FIG. 6(d), the bubble removal process of the oxidation stop process (S14) performs the same operation as the bubble removal process of the oxidation process (S13). As a result, the second reagent remaining from the second syringe pump unit 17 to the second valve V2 does not contain any bubbles. Similarly, the first reagent remaining from the first syringe pump unit 16 to the first valve V1 also does not contain any bubbles.

In the present invention, if no bubbles are generated in the second reagent during the heating process (or if bubbles are generated, the amount is extremely small), the device does not need to perform the second bubble removal step.

Referring also to FIG. 6(e), in the liquid transfer process, the control unit 7 controls the operation of only the second valve V2 to connect the second common pipe L22 and the second liquid transfer pipe L23. Next, the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that the required amount of second reagent is transferred from the second syringe pump unit 17 to the reaction tank 2. As a result, the required amount of second reagent is transferred to the reaction tank 2. Because the motor 11 is a stepping motor, the second reagent is transferred with high precision. As described above, the bubble removal process is performed immediately before the liquid transfer process, so no air bubbles are mixed into the reaction tank 2. At this time, the first syringe pump unit 16 is also operating simultaneously, and an amount of the first reagent equal to the required amount of the second reagent is returned to the first reagent tank T1. Next, the control unit 7 controls the operation of only the second valve V2 to connect the second tank pipe L21 and the second common pipe L22. The liquid delivery process is an example of the second solution delivery step of the present invention.

Next, the titration process (S15) is performed. In the titration process (S15), the first reagent is titrated into the analysis liquid. Specifically, in the titration process (S15), an aspiration process (second aspiration step), an air bubble removal process (third air bubble removal step), and a liquid delivery process (third solution delivery step) are performed.

The suction process performs the same operations as the suction process of the oxidation process (S13). Similarly, the bubble removal process performs the same operations as the bubble removal process of the oxidation process (S13). As a result, the first reagent remaining from the first syringe pump unit 16 to the first valve V1 does not contain any bubbles. Similarly, the second reagent remaining from the second syringe pump unit 17 to the second valve V2 does not contain any bubbles.

During the liquid delivery process, the control unit 7 first controls the voltage between the two electrodes 6, 6 so that a constant current flows between them. Next, the control unit 7 controls the operation of only the first valve V1 to connect the first common pipe L12 and the first liquid delivery pipe L13. Next, the control unit 7 controls the operation of the motor 11 to gradually raise the slider 14 so that the first reagent is delivered in small amounts from the first syringe pump unit 16 to the reaction tank 2. Because the motor 11 is a stepping motor, the first reagent is delivered with high precision. During this process, the control unit 7 measures the potential difference between the electrodes 6, 6, and determines the point at which the potential difference suddenly changes and reaches its maximum as the equivalence point, obtaining the amount of first reagent delivered up to that point. Next, the control unit 7 calculates the COD concentration of the analysis solution based on the amount of first reagent delivered. During titration of the first reagent, the second syringe pump unit 17 also operates simultaneously, returning the second reagent to the second reagent tank T2 in an amount equal to the amount of the first reagent delivered. Next, the control unit 7 controls the operation of only the first valve V1 to connect the first tank pipe L11 and the first common pipe L12.

As mentioned above, the motor 11 is a stepping motor. Therefore, the first reagent pump P1 can deliver each of the first and second reagents with high precision during the normal measurement process (S1). Furthermore, during the normal measurement process (S1), the first reagent pump P1 can perform a highly accurate bubble removal process that corresponds to the volume of each of the paths for the first and second reagents. Furthermore, during the normal measurement process (S1), air bubbles contained in each of the first and second reagents are removed immediately before each of the first and second reagents is delivered to the reaction tank 2. Therefore, with this device 1, even if the amount of sample water and each reagent used is reduced, highly accurate delivery that is not affected by air bubbles can be achieved.

In this manner, in the present device 1, the control unit 7 simultaneously operates the first syringe pump unit 16 and the second syringe pump unit 17 using a single motor 11. That is, in the present device 1, two syringe pumps are operated by the operation of a single stepping motor, delivering two types of reagents with high precision. As a result, compared to conventional measuring devices (hereinafter referred to as "conventional devices") in which only one pump is operated by a single motor, the present device 1 reduces the number of motors, lowers manufacturing costs, and reduces power consumption. Furthermore, in the present device 1, the use of a stepping motor and a bubble removal process reduces the amount of each reagent used in the delivery process. Furthermore, the control unit 7 controls the operation of the first valve V1 and the second valve V2 to switch the connection destinations of the first common pipe L12 and the second common pipe L22, thereby switching the delivery destinations of the first and second reagents. Therefore, in this device 1, the suction process, bubble removal process, and liquid delivery process can be performed for two reagents during one stroke of each of the first plunger 16b and the second plunger 17b. As a result, this device 1 does not require the suction process for each reagent and the bubble removal process (excluding dissolved components), which shortens the time required for a single measurement and suppresses deterioration of the first gasket 16c and the second gasket 17c. In this device 1, the total advance/retract distance of the first gasket 16c and the second gasket 17c is exactly the same, so the replacement intervals for the first syringe 16a and the second syringe 17a are the same, reducing the complexity of maintenance.

Low Concentration Measurement Process FIG. 7 is a flowchart showing an example of the low concentration measurement process (S2).

The "Low Concentration Measurement Process (S2)" is a COD concentration measurement process performed when the concentration of oxidizable substances contained in the sample water is lower than the measurement range of the device 1. Because sodium oxalate functions as an oxidizable substance, in the Low Concentration Measurement Process (S2), the concentration of oxidizable substances contained in the sample water is adjusted (increased) by sodium oxalate to fall within the measurement range (range) of 0 to 20 mg O/L, as specified in JIS K 0806, "Automatic Chemical Oxygen Demand (COD) Meter." The Low Concentration Measurement Process (S2) is common to the Normal Measurement Process (S1) except for the inclusion of the Concentration Adjustment Process (S21), described below. Therefore, in the following description of the Low Concentration Measurement Process (S2), steps common to the Normal Measurement Process (S1) are assigned the same process numbers as the Normal Measurement Process (S1), and detailed descriptions are omitted.

In the low-concentration measurement process of the present invention, the concentration of the oxidizable substance should be adjusted to a measurement range of 0.5 to 11 mgO/L (2.5 to 55% of the full scale of 20 mgO/L), as described in the notes of JIS K 0806, 5. Measurement Range.

First, the sample water introduction process (S11) is performed.

Next, the concentration adjustment process (S21) is performed. Specifically, in the concentration adjustment process (S21), a suction process, a bubble removal process, and a liquid delivery process are performed in that order.

During the suction process, the first and second reagents are respectively aspirated, similar to the suction process of the oxidation process (S13).

In the bubble removal process, similar to the bubble removal process in the oxidation process (S13), bubbles contained in both the first and second reagents are removed.

During the liquid transfer process, the control unit 7 first controls the operation of only the second valve V2 to connect the second common pipe L22 and the second liquid transfer pipe L23. Next, the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that the required amount of second reagent is transferred from the second syringe pump unit 17 to the reaction tank 2. As a result, the required amount of second reagent is transferred to the reaction tank 2. As a result, a pseudo-sample water is generated in the reaction tank 2, in which the concentration of oxidizable substances contained in the sample water has been adjusted (increased) by the second reagent (sodium oxalate) to within the measurement range of the device 1. At this time, the first syringe pump unit 16 is also operating simultaneously, and an amount of the first reagent equal to the required amount of the second reagent is returned to the first reagent tank T1. Next, the control unit 7 controls the operation of only the second valve V2 to connect the second tank pipe L21 and the second common pipe L22.

The "required amount" in the concentration adjustment process (S21) is the amount required to adjust the concentration of the oxidizable substance contained in the simulated sample water until it falls within the measurement range of the device 1.

Next, pretreatment (S12), oxidation treatment (S13), oxidation termination treatment (S14), and titration treatment (S15) are performed. In the titration treatment (S15), the control unit 7 calculates the original COD concentration of the sample water by subtracting the increase in the amount of oxidizable substances in the concentration adjustment treatment (S21) from the calculated COD concentration. Here, since the volume of the sample water increases by the volume of sodium oxalate solution added to increase the concentration of oxidizable substances, the volume is corrected as necessary when calculating the COD concentration of the sample water.

● Simple span calibration process (automatic preparation of span liquid and span calibration)
FIG. 8 is a flowchart showing an example of the simple span calibration process (S3).

The "simplified span calibration process (S3)" involves diluting the second reagent, which is sodium oxalate, with pure water to automatically prepare a pseudo-analyte solution of the same concentration as the span calibration solution, and then automatically performing span calibration of the device 1 using the pseudo-analyte solution. In the following description of the simplified span calibration process (S3), steps that are common to the normal measurement process (S1) are assigned the same process numbers as the normal measurement process (S1), and detailed descriptions will be omitted.

First, the pure water introduction process (S31) is performed. In this process, a predetermined amount of pure water is pumped into the reaction tank 2 by the pure water pump P4. Specifically, in this process, a suction process, a bubble removal process, and a liquid delivery process are performed in that order.

During the suction process, the control unit 7 controls the operation of the third valve V3 and the pure water pump P4, causing the pure water pump P4 to suction the maximum amount of pure water.

In the bubble removal process, the control unit 7 controls the operation of the third valve V3 and the pure water pump P4 to remove bubbles contained in the pure water, similar to the bubble removal process in the oxidation process (S13).

During the liquid delivery process, the control unit 7 controls the operation of the third valve V3 and the pure water pump P4 to deliver a predetermined amount of pure water (the amount required for dilution) to the reaction tank 2.

Next, the reagent introduction process (S32) is performed. In the reagent introduction process (S32), a predetermined amount of the second reagent is first delivered to the reaction vessel 2 by the first reagent pump P1. Specifically, in the reagent introduction process (S32), a suction process, a bubble removal process, and a delivery process are performed in that order.

During the suction process, the first and second reagents are respectively aspirated, similar to the suction process of the oxidation process (S13).

In the bubble removal process, similar to the bubble removal process in the oxidation process (S13), bubbles contained in both the first and second reagents are removed.

During the liquid transfer process, the control unit 7 first controls the operation of only the second valve V2 to connect the second common pipe L22 and the second liquid transfer pipe L23. Next, the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that the required amount of second reagent is transferred from the second syringe pump unit 17 to the reaction tank 2. As a result, the required amount of second reagent is transferred to the reaction tank 2, and a pseudo-analyte solution containing sodium oxalate of a known concentration (the same concentration as the span calibration solution) is prepared (generated). At this time, the first syringe pump unit 16 is also operating simultaneously, and an amount of first reagent equal to the required amount of second reagent is returned to the first reagent tank T1. Next, the control unit 7 controls the operation of only the second valve V2 to connect the second tank pipe L21 and the second common pipe L22. In this way, because the second solution is diluted with pure water, the concentration of sodium oxalate contained in the pseudo-analyte solution is lower than the concentration of sodium oxalate contained in the second solution.

The "required amount" in the reagent introduction process (S32) is the amount required to dilute the sodium oxalate added to the pure water so that its concentration (i.e., COD concentration) is the same as the concentration in the span calibration solution. The required amount of the second reagent in the reagent introduction process (S32) is different from the required amount of the second reagent in the oxidation stop process (S14).

In the present invention, the "required amount" in the reagent introduction process may be changed depending on the purpose, and pseudo-analyte solutions containing other known concentrations of sodium oxalate may be prepared.

Next, the solution obtained by adding the second reagent to pure water undergoes the same pretreatment (S12), oxidation treatment (S13), and oxidation stop treatment (S14) as the normal measurement treatment (S1). That is, predetermined amounts of the third reagent (sulfuric acid) and fourth reagent (silver nitrate) are added to the solution, the required amount of the first solution is added to the resulting solution, and the resulting solution is heated at 100°C for 30 minutes. The oxidation reaction is then stopped by adding the required amount of sodium oxalate solution to the heated solution. Through these treatments, the span calibration solution is prepared.

In the present invention, if the fourth reagent (silver nitrate) is not added to the sample water, the fourth reagent is not added when preparing the span calibration solution. Furthermore, if the normal measurement process is performed using the alkaline method, the same processes are performed on the span calibration solution as on the sample water.

Next, a span calibration process (S33) is performed. In the span calibration process (S33), a process similar to the titration process (S15) is performed. In this case, the amount of the first solution delivered in the titration process (S15) is an example of the first required amount in the present invention.

In this way, the present device 1 can automatically prepare the span calibration solution. Therefore, the user of the device 1 does not need to manually prepare the span calibration solution, making span calibration simple (easy). Furthermore, the present device 1 can easily deliver any amount of second reagent to prepare the span calibration solution (pseudo-analyte solution) using only one first reagent pump P1. The present device 1 also allows for the preparation of pseudo-analyte solutions with multiple COD concentrations, making it easy to confirm the linearity of the measurement results. Furthermore, the present device 1 allows for the repeated preparation of pseudo-analyte solutions with the same concentration and measurement of COD concentration, making it easy to confirm the reproducibility of the measurement results. In this way, the present device 1 can deliver different amounts of reagent using only one first reagent delivery mechanism M1. In contrast, conventional devices, which use a leveling method to measure the reagent by sucking up the unnecessary amount, require separate piping and valves for each reagent concentration.

Furthermore, if a measurement value is determined to be abnormal due to factors that affect the measurement value (e.g., threshold, trend, coefficient of variation (CV value), bubbles, measurement accuracy, other measurement processing, etc.), the device 1 can confirm whether or not there is an abnormality in the measurement device by preparing a pseudo-analyte solution of known concentration using a simple span calibration process (S3) and measuring the pseudo-analyte solution. In this case, the measurement of the pseudo-analyte solution may be performed manually by the user. Furthermore, the concentration of the pseudo-analyte solution is not limited to the concentration of the span calibration solution. That is, for example, the concentration of the pseudo-analyte solution may be adjusted to a concentration that is close to the concentration normally observed in sample water. Similarly, the device 1 can easily confirm, as needed, that the obtained measurement value is accurate without being affected by the aforementioned factors (i.e., the soundness of the measurement results).

Furthermore, for example, if the concentration of a potassium permanganate solution fluctuates over time, the concentration of the potassium permanganate solution can be determined using a sodium oxalate solution of known concentration. That is, by performing a simple span calibration process (S3) using a sodium oxalate solution prepared according to the method described in JIS K 0806, the potassium permanganate solution can be standardized (factor determined) from its equivalence point. In this case, the fourth reagent (silver nitrate) is not added, and the solution is heated to approximately 60°C (preferably 55°C to 60°C).

As mentioned above, even if a potassium permanganate solution of unknown concentration is used, the device 1 can determine (standardize) the concentration of the potassium permanganate solution by performing the simple span calibration process (S3). These operations are controlled by the control unit 7, and the result is calculated as the concentration (or factor) of the potassium permanganate solution, rather than as a COD value.

In the simplified span calibration process of the present invention, the pure water introduction process may be performed after the reagent introduction process. That is, the second reagent may be delivered to the reaction tank before the pure water is delivered to the reaction tank.

Summary According to the embodiment described above, when the first solution is delivered to the reaction vessel 2, the control unit 7 connects the first common pipe L12 and the first delivery pipe L13 to the first valve V1, connects the second common pipe L22 and the second tank pipe L21 to the second valve V2, and operates the motor 11 so that a required amount of the first solution is discharged from the first syringe pump unit 16. On the other hand, when the second solution is delivered to the reaction vessel 2, the control unit 7 connects the first common pipe L12 and the first tank pipe L11 to the first valve V1, connects the second common pipe L22 and the second delivery pipe L23 to the second valve V2, and operates the motor 11 so that a required amount of the second solution is discharged from the second syringe pump unit 17. According to this configuration, the present device 1 can simultaneously operate the first syringe pump unit 16 and the second syringe pump unit 17 by operating a single motor 11, thereby delivering the first and second reagents in desired amounts with high precision. Therefore, the present device 1 has a reduced number of motors, which reduces manufacturing costs and power consumption compared to conventional devices. Furthermore, while the first reagent is being delivered, the second reagent is returned to the second tank line L21 (second reagent tank T2) along with air bubbles. Similarly, while the second reagent is being delivered, the first reagent is returned to the first tank line L11 (first reagent tank T1) along with air bubbles. Therefore, the present device 1 reduces the influence of air bubbles on COD concentration measurement. In this way, the present device 1 can deliver the first and second reagents with high precision while suppressing the influence of air bubbles without increasing manufacturing costs.

Furthermore, according to the embodiment described above, the control unit 7 performs a bubble removal process immediately before the liquid delivery process. During the bubble removal process, the control unit 7 operates the motor 11 so that the first syringe pump unit 16 ejects a volume of the first reagent greater than the volume "V12" of the first common line L12. Similarly, during the bubble removal process, the control unit 7 operates the motor 11 so that the second syringe pump unit 17 ejects a volume of the second reagent greater than the volume "V22" of the second common line L22. With this configuration, the first reagent present in the path from the upper end (first mounting portion 16d) of the first syringe pump unit 16 to the first valve V1 is reliably returned to the first tank line L11 along with any air bubbles. Similarly, the second reagent present in the path from the upper end (second mounting portion 17d) of the second syringe pump unit 17 to the second valve V2 is reliably returned to the second tank line L21 along with any air bubbles. Therefore, with this device 1, bubbles do not affect the measurement of COD concentration.

Furthermore, according to the embodiment described above, the control unit 7 controls the operation of the first valve V1, the second valve V2, and the motor 11 so that the bubble removal process and the liquid delivery process for the first reagent are performed while the first plunger 16b moves forward and backward one stroke relative to the first syringe 16a. In addition to this control, the control unit 7 also controls the operation of the first valve V1, the second valve V2, and the motor 11 so that the bubble removal process and the liquid delivery process for the second reagent are performed while the second plunger 17b moves forward and backward one stroke relative to the second syringe 17a. In other words, the bubble removal process and the liquid delivery process are performed for the first reagent and the second reagent, respectively, while the first plunger 16b and the second plunger 17b move forward and backward one stroke. With this configuration, the device 1 does not require the suction process for each reagent and the bubble removal process (excluding dissolved components). As a result, the time required for one measurement is shortened, the number of strokes of the first plunger 16b and the second plunger 17b in one measurement is reduced, and deterioration of the first gasket 16c and the second gasket 17c is suppressed.

Furthermore, according to the embodiment described above, the device 1 executes a low-concentration measurement process (S2). With this configuration, the device 1 can accurately measure the COD concentration even for sample water with a concentration lower than the measurement range of the device 1.

Furthermore, according to the embodiment described above, the device 1 executes a simple span calibration process (S3). With this configuration, the device 1 can automatically perform span calibration between normal measurement processes (S1). Therefore, the device 1 eliminates the need for the user of the device 1 to manually prepare span calibration solution, making span calibration simple (easy). Furthermore, with this configuration, by preparing pseudo-analyte solutions of multiple COD concentrations, the linearity of measurement results can be easily confirmed. Furthermore, with the device 1, the preparation of pseudo-analyte solutions of the same concentration and the measurement of COD concentration can be repeated, making it easy to confirm the reproducibility of measurement results.

Furthermore, according to the embodiment described above, the first pipe mounting hole 18c is located above the first syringe mounting hole 18a, and the gap between the lower end surface 21b of the first fitting 21 and the bottom surface 18h of the first pipe mounting hole 18c is liquid-tightly sealed by a seal member 21a. The second pipe mounting hole 18d is located above the second syringe mounting hole 18b, and the gap between the lower end surface 22b of the second fitting 22 and the bottom surface 18j of the second pipe mounting hole 18d is liquid-tightly sealed by a seal member 22a. With this configuration, during the bubble removal process, air bubbles do not remain within the first pipe mounting hole 18c, nor do they enter between the male threaded surface of the first fitting 21 and the female threaded surface of the first pipe mounting hole 18c. Similarly, air bubbles do not remain within the second pipe mounting hole 18d, nor do they get between the male threaded surface of the second fitting 22 and the female threaded surface of the second pipe mounting hole 18d.

Other Embodiments In the bubble removal process of the present invention, the ejection volume of the first reagent may be greater than the volume "V12" of the first common tube, and is not limited to the above-described embodiment. That is, for example, the ejection volume of the first reagent may be greater than the combined volume "V11 + V12" of the first common tube and the volume "V11" of the first tank tube. In this configuration, the first reagent present at the upper end of the first syringe pump unit is reliably returned to the first tank tube or the first reagent tank together with any air bubbles. Similarly, in the bubble removal process of the present invention, the ejection volume of the second reagent may be greater than the volume "V22" of the second common tube, and is not limited to the above-described embodiment.

Furthermore, in the normal measurement process of the present invention, the control unit may execute the titration process while the first plunger and the second plunger each advance and retract one stroke. In other words, in the normal process, the control unit does not need to execute the second suction step. In this case, the capacity of each of the first syringe pump unit and the second syringe pump unit is set to be larger than the same capacity in the embodiment described above. With this configuration, the number of strokes of each of the first plunger and the second plunger in a single measurement is further reduced, further suppressing deterioration of each of the first gasket and the second gasket.

Furthermore, in the present invention, the control unit may move each of the first plunger and the second plunger forward and backward by one stroke during each of the oxidation process, oxidation termination process, and titration process. In this configuration, the capacity of each of the first syringe and the second syringe can be reduced.

Furthermore, in the present invention, the sealing member provided in the first fitting may be an O-ring or gasket placed between the tip of the first fitting and the bottom surface of the first pipe mounting hole. Similarly, the sealing member provided in the second fitting may be an O-ring or gasket placed between the tip of the second fitting and the bottom surface of the second pipe mounting hole.

Furthermore, in the present invention, the first reagent pump may include three or more syringe pump units. That is, for example, the first reagent pump may also include a syringe pump unit that draws in and discharges pure water. In this case, a pure water pump is not required, further reducing the manufacturing costs of the device. The motor only needs to have a torque that can withstand the load generated when each plunger moves forward and backward.

Furthermore, in the present invention, the first syringe pump unit and the second syringe pump unit may be arranged side by side in the X-axis direction.

Furthermore, in the present invention, the first and second reagents may each be selected according to the components to be measured by the measurement device that functions as the present apparatus. In other words, the first reagent is not limited to a potassium permanganate solution, and the second reagent is not limited to a sodium oxalate solution.

Furthermore, in the present invention, the relationship between the volumes of the various pipes need only be suitable for the bubble removal process and is not limited to this embodiment.

Furthermore, in the present invention, the arrangement and number of each pipe and each valve are not limited to those shown in Figure 1. That is, for example, the device may be equipped with other valves, and the air pipe may be connected to the sample water pipe or the waste liquid pipe.

Furthermore, in the present invention, the device does not necessarily have to be equipped with a fourth reagent delivery mechanism.

1 Measuring device 2 Reaction tank 7 Control unit 11 Motor (stepping motor)
16 First syringe pump section 16a First syringe 16b First plunger 17 Second syringe pump section 17a Second syringe 17b Second plunger 18 Connecting member 18a First syringe mounting hole 18b Second syringe mounting hole 18c First pipe mounting hole 18d Second pipe mounting hole 21 First joint 21a Sealing member (first sealing member)
22 Second joint 22a Seal member (second seal member)
L11 First tank pipe L12 First common pipe L13 First liquid supply pipe L21 Second tank pipe L22 Second common pipe L23 Second liquid supply pipe M5 Pure water supply mechanism T1 First reagent tank (first tank)
T2 Second reagent tank (second tank)
V1 First valve V2 Second valve

Claims (8)

A measuring device for measuring the water quality of a water sample,
a first syringe pump unit disposed along the vertical direction and configured to suck in and discharge the first solution;
a second syringe pump unit disposed along the vertical direction and configured to suck in and discharge the second solution;
a first tank for storing the first solution;
a second tank for storing the second solution;
a reaction tank to which the sample water, the first solution discharged from the first syringe pump unit, and the second solution discharged from the second syringe pump unit are delivered;
a first valve that switches the destination of the first solution;
a first tank pipe connected to the first valve and the first tank;
a first common pipe connected to the first valve and an upper end of the first syringe pump unit;
a first liquid transfer pipe connected to the first valve and the reaction tank;
a second valve that switches the destination of the second solution;
a second tank pipe connected to the second valve and the second tank;
a second common pipe connected to the second valve and an upper end of the second syringe pump unit;
a second liquid transfer pipe connected to the second valve and the reaction tank;
a stepping motor that always causes the first syringe pump unit and the second syringe pump unit to perform the same operation simultaneously;
a control unit that controls the operations of the first valve, the second valve, and the stepping motor;
and
The control unit
When the first solution is delivered from the first syringe pump unit to the reaction tank,
The first common pipe and the first liquid supply pipe are connected to the first valve,
The second valve is connected to the second common pipe and the second tank pipe,
operating the stepping motor so that a first required amount of the first solution is discharged from the first syringe pump unit through the first liquid supply pipe into the reaction tank , and the second solution is discharged from the second syringe pump unit through the second tank pipe into the second tank ;
When the second solution is delivered from the second syringe pump unit to the reaction tank,
The first common pipe and the first tank pipe are connected to the first valve,
The second common pipe and the second liquid supply pipe are connected to the second valve,
operating the stepping motor so that a second required amount of the second solution is discharged from the second syringe pump unit into the reaction tank through the second liquid delivery pipe, and the first solution is discharged from the first syringe pump unit into the first tank through the first tank pipe ;
A measuring device characterized by: The control unit
before the first required amount of the first solution is discharged from the first syringe pump unit,
The first common pipe and the first tank pipe are connected to the first valve,
The second valve is connected to the second common pipe and the second tank pipe,
operating the stepping motor so that the first solution is discharged from the first syringe pump unit in a volume greater than the volume of the first common tube;
before the second required amount of the second solution is discharged from the second syringe pump unit;
The first common pipe and the first tank pipe are connected to the first valve,
The second valve is connected to the second common pipe and the second tank pipe,
operating the stepping motor so that the second solution is discharged from the second syringe pump unit in an amount greater than the volume of the second common tube;
The measuring device according to claim 1 . The control unit
before the first required amount of the first solution is discharged from the first syringe pump unit,
operating the stepping motor so that the first solution is discharged from the first syringe pump unit in a volume greater than the combined volume of the first common pipe and the first tank pipe;
before the second required amount of the second solution is discharged from the second syringe pump unit;
operating the stepping motor so that the second solution is discharged from the second syringe pump unit in an amount greater than the combined volume of the second common pipe and the second tank pipe;
The measuring device according to claim 2 . The first syringe pump unit includes:
a cylindrical first syringe;
a first plunger inserted into the first syringe from a lower end side of the first syringe;
With
The second syringe pump unit includes:
a cylindrical second syringe;
a second plunger inserted into the second syringe from a lower end side of the second syringe;
With
the stepping motor moves the first plunger forward and backward relative to the first syringe and simultaneously moves the second plunger forward and backward relative to the second syringe,
The control unit
While the first plunger moves forward and backward by one stroke relative to the first syringe,
controlling the operations of the first valve, the second valve, and the stepping motor so that the first solution is discharged from the first syringe pump unit in a volume greater than the capacity of the first common pipe, thereby discharging the first required amount of the first solution;
While the second plunger moves forward and backward by one stroke relative to the second syringe,
controlling the operations of the first valve, the second valve, and the stepping motor so that the second solution is discharged from the second syringe pump unit in an amount greater than the volume of the second common pipe, thereby discharging the second required amount of the second solution.
4. The measuring device according to claim 2 or 3. the measuring device is a chemical oxygen demand (COD) measuring device that measures a COD concentration of the sample water,
the first solution is a potassium permanganate solution;
the second solution is a sodium oxalate solution;
The control unit
The second solution is discharged from the second syringe pump unit so that the sample water sent to the reaction tank contains sodium oxalate at a concentration within a predetermined concentration range, thereby generating a pseudo sample water in which the concentration of an oxidizable substance contained in the sample water is adjusted by the sodium oxalate,
controlling operations of the first valve, the second valve, and the stepping motor so that the first required amount of the first solution is delivered to the reaction tank after the pseudo water sample is produced;
controlling operations of the first valve, the second valve, and the stepping motor so that, after the first required amount of the first solution has been delivered, the second required amount of the second solution is delivered to the reaction tank;
4. The measuring device according to claim 1. The measuring device is
a pure water delivery mechanism that delivers pure water to the reaction tank based on the control of the control unit;
and
The second solution is
a known concentration of an oxidizable substance,
Including,
The control unit
causing the pure water delivery mechanism to deliver a predetermined amount of the pure water to the reaction tank;
before or after the pure water is fed, operations of the first valve, the second valve, and the second syringe pump unit are controlled so that an amount of the second solution different from the second required amount is fed to the reaction tank, thereby preparing a pseudo-analyte solution having a lower concentration than the known concentration and containing the oxidizable substance at a known concentration;
controlling operations of the first valve, the second valve, and the first syringe pump unit so that the first required amount of the first solution is delivered to the reaction vessel after the pseudo-analyte solution has been prepared;
controlling operations of the first valve, the second valve, and the stepping motor so that, after the first required amount of the first solution has been delivered, the second required amount of the second solution is delivered to the reaction tank;
4. The measuring device according to claim 1. a connecting member disposed above each of the first syringe pump unit and the second syringe pump unit and connected to the upper end portion of each of the first syringe pump unit and the second syringe pump unit;
a first joint that connects the first common pipe and the connecting member;
a second joint that connects the second common pipe and the connecting member;
and
The connecting member is
a first syringe mounting hole into which the upper end of the first syringe pump portion is fitted from below;
a second syringe mounting hole into which the upper end of the second syringe pump portion is fitted from below;
a first pipe mounting hole disposed above the first syringe mounting hole and into which a lower end of the first joint is fitted from above;
a second pipe mounting hole disposed above the second syringe mounting hole and into which a lower end of the second joint is fitted from above;
With
The first joint is
a first seal member that provides a liquid-tight seal between a lower end surface of the first joint and a bottom surface of the first pipe mounting hole;
With
The second joint is
a second seal member that provides a liquid-tight seal between a lower end surface of the second joint and a bottom surface of the second pipe mounting hole;
Equipped with
The measuring device according to claim 1 . A method for measuring the water quality using the measurement device according to any one of claims 1 to 3, comprising:
The control unit
a first solution delivery step of delivering the first required amount of the first solution to the reaction tank by controlling the operations of the first valve, the second valve, and the stepping motor after the sample water has been delivered to the reaction tank;
a second solution delivery step of delivering the second required amount of the second solution to the reaction vessel by controlling operations of the first valve, the second valve, and the stepping motor after the first required amount of the first solution has been delivered;
Including,
A measuring method characterized by: