Instrument for on-line automatic pH calibration

Abstract

The invention discloses an instrument for online automatic pH calibration. The instrument aims at solving the problems that the maintenance amount of an existing manual pH calibration electrode is large, system errors are easily generated through manual operation, the calibration time interval cannot be controlled, and the workload of maintenance personnel is increased. The instrument comprises a sample introduction pipe, a first buffer solution bottle, a second buffer solution bottle, a measuring cell, a pH electrode and a controller, a third electromagnetic valve is mounted on the sample introduction pipe, the sample introduction pipe is communicated with the measuring cell through the third electromagnetic valve, and the first buffer solution bottle is communicated with the measuring cell through the first electromagnetic valve. The buffer solution with the pH value of 6.86 is added into the first buffer solution bottle, the buffer solution with the pH value of 4.00 or 9.18 is added into the second buffer solution bottle, the first buffer solution bottle and the second buffer solution bottle are sequentially opened according to the calibration sequence, zero calibration and slope calibration are automatically carried out on the pH electrode, the system error is small, the calibration time interval is better controlled, and the workload of manually calibrating the pH electrode in the prior art is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of pH electrode calibration, and in particular relates to an instrument for online automatic pH calibration. Background Art

[0002] The pH meter measurement method can achieve the control of the pH value of the water vapor system, but the pH electrode needs to be calibrated regularly to ensure the accuracy of the pH measurement results. This calibration method mainly includes: 1. Prepare pH buffer solution (usually pH 4.00, 6.86 and 9.18), distilled water, washing bottles, waste liquid cups and other equipment; 2. Wash the electrode thoroughly with a 6.86 buffer solution, then place the electrode in a buffer solution with a pH value of 6.86 for zero calibration. Gently shake the beaker, press the positioning button, adjust the pH to 6.86, and the zero calibration is completed; 3. Take out the electrode and place it in a buffer solution with a pH value of 4.00 or 9.18 to perform slope calibration. Gently shake the beaker and press the slope button to adjust the pH to 4.00 or 9.18. The slope calibration is completed.

[0003] The above manual calibration method of pH electrode requires a lot of maintenance and is heavily dependent on the professional ability of the operator. Each calibration has a certain system error caused by manual operation, and the calibration time interval cannot be controlled. As the electrode is used for a longer time, the calibration cycle will become more frequent, increasing the workload of the maintenance personnel. Summary of the invention

[0004] (1) Technical issues to be resolved In view of the deficiencies in the prior art, the purpose of the present invention is to provide an online automatic pH calibration instrument, which aims to solve the problems of existing manual calibration of pH electrodes, high maintenance requirements, easy generation of system errors during manual operation, inability to control the calibration time interval, and increased workload of maintenance personnel.

[0005] (2) Technical solution In order to solve the above technical problems, the present invention provides an instrument for online automatic pH calibration, which includes an injection tube, a first buffer solution bottle, a second buffer solution bottle, a measuring cell, a pH electrode and a controller. A third solenoid valve is installed on the injection tube, the injection tube is connected to the measuring cell through the third solenoid valve, the first buffer solution bottle is connected to the measuring cell through the first solenoid valve, the second buffer solution bottle is connected to the measuring cell through the second solenoid valve, the pH electrode is installed inside the measuring cell, a drain pipe is installed at the liquid outlet end of the measuring cell, and the third solenoid valve, the first solenoid valve and the second solenoid valve are all electrically connected to the controller.

[0006] Preferably, a flow meter and a manual regulating valve are installed on the sample inlet tube, and the flow meter and the manual regulating valve are installed at the liquid inlet end of the third solenoid valve.

[0007] Furthermore, a connecting pipe is installed at the liquid inlet end of the measuring cell, and a three-way pipe is installed at the other end of the connecting pipe. The second solenoid valve is a three-way reversing valve. One end of the three-way pipe is connected to the third solenoid valve, and the other end of the three-way pipe is connected to the liquid outlet end of the second solenoid valve. One end of the second solenoid valve is connected to the second buffer solution bottle, and the other end of the second solenoid valve is connected to the first solenoid valve.

[0008] Furthermore, the first solenoid valve is a three-way reversing valve, one end of the first solenoid valve is connected to the first buffer solution bottle, the other end of the first solenoid valve is installed with a shut-off valve, and the other end of the shut-off valve is connected to an offline sample water bottle.

[0009] Furthermore, a flow limiting device is installed between the second solenoid valve and the three-way pipe.

[0010] Furthermore, a sewage discharge solenoid valve is installed on the sewage discharge pipe, and the sewage discharge solenoid valve is electrically connected to the controller.

[0011] Furthermore, the other end of the sewage pipe is located inside the sewage tank, and the injection pipe, sewage pipe and connecting pipe are all polytetrafluoroethylene tubes.

[0012] Beneficial Effects Compared with the prior art, the present invention has the following beneficial effects: The present invention sets the first solenoid valve as a three-way reversing valve, and installs a shut-off valve and an offline sample water bottle at the other end of the first solenoid valve, so that the manually sampled water can be poured into the offline sample water bottle, and then the controller closes the first solenoid valve, the second solenoid valve, and the third solenoid valve, and then opens the shut-off valve, and the manually sampled water enters the measuring pool through the current limiting device and the connecting pipe. At this time, the pH electrode inside the measuring pool measures the sample, so that the pH value of the manually sampled water can be dynamically measured offline in a flowing state.

[0013] The present invention adds a buffer solution of pH 6.86 into a first buffer solution bottle, adds a buffer solution of pH 4.00 or pH 9.18 into a second buffer solution bottle, and a controller closes the third solenoid valve, and opens the first solenoid valve and the second solenoid valve in a calibration sequence, so that the buffer solution enters a measuring cell through a current limiting device, and performs zero calibration and slope calibration on a pH electrode, thereby achieving the purpose of timed automatic calibration of the pH electrode through automatic control and hardware improvement, and the system error is small, the calibration time interval is better controlled, and the workload of the existing manual calibration of the pH electrode is effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the connection structure of the present invention.

[0015] Figure 2 It is a structural schematic diagram of the liquid inlet tube sample injection of the present invention.

[0016] Figure 3 It is a structural schematic diagram of the first buffer solution bottle injection of the present invention.

[0017] Figure 4 It is a structural schematic diagram of the second buffer solution bottle injection of the present invention.

[0018] Figure 5 It is a schematic diagram of the circuit connection structure of the present invention.

[0019] The markings in the attached drawings are: 1. injection tube; 2. first buffer solution bottle; 3. second buffer solution bottle; 4. measuring cell; 5. pH electrode; 6. controller; 7. third solenoid valve; 8. first solenoid valve; 9. second solenoid valve; 10. drain pipe; 11. flow meter; 12. manual regulating valve; 13. connecting pipe; 14. three-way pipe; 15. shut-off valve; 16. current limiting device; 17. drain solenoid valve; 18. drain tank; 19. offline sample water bottle. DETAILED DESCRIPTION

[0020] This specific embodiment is an instrument for online automatic pH calibration, and its structural schematic diagram is shown as follows: Figure 1-Figure 5 As shown, the instrument includes a sample injection tube 1, a first buffer solution bottle 2, a second buffer solution bottle 3, a measuring cell 4, a pH electrode 5 and a controller 6. When in use, a buffer solution of pH 6.86 is added to the first buffer solution bottle 2, and a buffer solution of pH 4.00 or 9.18 is added to the second buffer solution bottle 3. The first buffer solution bottle 2 and the second buffer solution bottle 3 are 500 ml transparent materials with scales, and the remaining standard solution can be observed. Filling up the buffer standard solution once can achieve at least ten automatic calibrations. A third solenoid valve 7 is installed on the sample injection tube 1, and the sample injection tube 1 passes through the third solenoid valve 7 is connected to the measuring pool 4, the first buffer solution bottle 2 is connected to the measuring pool 4 through the first solenoid valve 8, the second buffer solution bottle 3 is connected to the measuring pool 4 through the second solenoid valve 9, the pH electrode 5 is installed inside the measuring pool 4, the pH electrode 5 is a gel-filled glass pure water electrode with a diameter of 12 mm and a length of 120 mm, the measuring pool 4 is made of stainless steel, with a diameter of 20 mm and an insertion depth of 140 mm, which matches the pH electrode 5, and a sewage pipe 10 is installed at the liquid outlet end of the measuring pool 4, and the third solenoid valve 7, the first solenoid valve 8 and the second solenoid valve 9 are all electrically connected to the controller 6.

[0021] like Figure 1 As shown: In this embodiment, a flow meter 11 and a manual regulating valve 12 are installed on the sample injection tube 1, and the flow meter 11 and the manual regulating valve 12 are installed at the liquid inlet end of the third solenoid valve 7.

[0022] The flow meter 11 is set as an acrylic transparent rotor flow meter, and the flow meter 11 and the manual regulating valve 12 are used to control the water inlet flow rate.

[0023] like Figure 1-Figure 5 As shown: In this embodiment, a connecting pipe 13 is installed at the liquid inlet end of the measuring cell 4, and a three-way pipe 14 is installed at the other end of the connecting pipe 13. The second solenoid valve 9 is a three-way reversing valve. One end of the three-way pipe 14 is connected to the third solenoid valve 7, and the other end of the three-way pipe 14 is connected to the liquid outlet end of the second solenoid valve 9. One end of the second solenoid valve 9 is connected to the second buffer solution bottle 3, and the other end of the second solenoid valve 9 is connected to the first solenoid valve 8.

[0024] In this way, when the second solenoid valve 9 is closed, the first solenoid valve 8 is connected to the three-way pipe 14, and the three-way pipe 14 is disconnected from the second buffer solution bottle 3; when the second solenoid valve 9 is opened, the first solenoid valve 8 and the three-way pipe 14 are disconnected, and the three-way pipe 14 is connected to the second buffer solution bottle 3.

[0025] like Figure 3 and Figure 4 As shown: In this embodiment, the first solenoid valve 8 is a three-way reversing valve, one end of the first solenoid valve 8 is connected to the first buffer solution bottle 2, the other end of the first solenoid valve 8 is installed with a shut-off valve 15, and the other end of the shut-off valve 15 is connected to an offline sample water bottle 19.

[0026] In this way, the manual sampling water is poured into the offline sample water bottle 19, the controller 6 closes the first solenoid valve 8, the second solenoid valve 9, and the third solenoid valve 7, and then opens the shut-off valve 15, and the manual sampling water enters the measuring cell 4 through the current limiting device 16 and the connecting pipe 13. At this time, the pH electrode 5 inside the measuring cell 4 measures the sample, and after the measurement, the sewage solenoid valve 17 is opened, and the sewage flows into the sewage tank 18 to complete the measurement of the manual sampling water, so that the pH value of the manual sampling water can be dynamically measured offline in a flowing state.

[0027] like Figure 1-Figure 5 As shown: In this embodiment, a flow limiting device 16 is installed between the second solenoid valve 9 and the three-way pipe 14.

[0028] The flow limiting device 16 is made of acrylic material, which can limit the flow of the liquid to 50 ml / min. The flow limiting device 16 is used to control the stability of the standard solution and the offline sample.

[0029] like Figure 1 and Figure 2 As shown: In this embodiment, a sewage discharge solenoid valve 17 is installed on the sewage discharge pipe 10, and the sewage discharge solenoid valve 17 is electrically connected to the controller 6. This arrangement can control the sewage discharge pipe 10 and make measurement more convenient.

[0030] In this embodiment, the other end of the sewage pipe 10 is located inside the sewage tank 18, and the injection tube 1, the sewage pipe 10 and the connecting pipe 13 are all polytetrafluoroethylene tubes. This arrangement can collect the discharged water to prevent pollution.

[0031] Working principle: when in use, add a buffer solution of pH 6.86 into the first buffer solution bottle 2, and add a buffer solution of pH 4.00 or 9.18 into the second buffer solution bottle 3. Figure 2 As shown, during normal measurement, the controller 6 closes the first solenoid valve 8, closes the second solenoid valve 9, and opens the third solenoid valve 7. After the water sample passes through the sample inlet tube 1, the manual regulating valve 12, and the third solenoid valve 7, it enters the measuring cell 4 along the connecting tube 13. At this time, the pH electrode 5 inside the measuring cell 4 measures the sample. After the measurement, the sewage discharge solenoid valve 17 is opened, and the sewage flows into the sewage discharge tank 18 to complete the measurement. Then the controller 6 performs automatic calibration by setting the time, as shown in FIG. Figure 3 As shown, during calibration, the controller 6 opens the first solenoid valve 8, closes the second solenoid valve 9, and closes the third solenoid valve 7. At this time, the buffer solution of pH 6.86 added to the first buffer solution bottle 2 enters the measuring cell 4 through the current limiting device 16 and the connecting pipe 13. At this time, the buffer solution of pH 6.86 performs zero-point calibration on the pH electrode 5 inside the measuring cell 4. After calibration, the sewage solenoid valve 17 is opened, and the sewage flows into the sewage tank 18 to complete the calibration. Figure 4 As shown, the controller 6 then closes the first solenoid valve 8, opens the second solenoid valve 9, and closes the third solenoid valve 7. At this time, a buffer solution of pH 4.00 or 9.18 is added to the second buffer solution bottle 3 and enters the measuring cell 4 through the current limiting device 16 and the connecting pipe 13. At this time, the buffer solution of pH 4.00 or 9.18 performs slope calibration on the pH electrode 5 inside the measuring cell 4. After the slope calibration, the sewage solenoid valve 17 is opened, and the sewage flows into the sewage tank 18 to complete the calibration. Thus, the purpose of timed automatic calibration of the pH electrode 5 is achieved through automatic control and hardware improvement, and the system error is small, the calibration time interval is better controlled, and the workload of the existing manual calibration of the pH electrode 5 is effectively reduced.

[0032] All technical features in this embodiment can be freely combined according to actual needs.

[0033] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the protection scope of the present invention.

Claims

1. An instrument for online automatic pH calibration, the instrument comprising a sample injection tube (1), a first buffer solution bottle (2), a second buffer solution bottle (3), a measuring cell (4), a pH electrode (5) and a controller (6), characterized in that: A third solenoid valve (7) is installed on the sample injection tube (1), the sample injection tube (1) is connected to the measuring cell (4) through the third solenoid valve (7), the first buffer solution bottle (2) is connected to the measuring cell (4) through the first solenoid valve (8), the second buffer solution bottle (3) is connected to the measuring cell (4) through the second solenoid valve (9), the pH electrode (5) is installed inside the measuring cell (4), a sewage pipe (10) is installed at the liquid outlet end of the measuring cell (4), and the third solenoid valve (7), the first solenoid valve (8) and the second solenoid valve (9) are all electrically connected to the controller (6); A flow meter (11) and a manual regulating valve (12) are installed on the sample injection tube (1); the flow meter (11) and the manual regulating valve (12) are installed at the liquid inlet end of the third solenoid valve (7); and a flow limiting device (16) is provided between the second solenoid valve (9) and the measuring cell (4); The first solenoid valve (8) is a three-way reversing valve. One end of the first solenoid valve (8) is connected to the first buffer solution bottle (2). The other end of the first solenoid valve (8) is provided with a shut-off valve (15). The other end of the shut-off valve (15) is connected to an offline sample water bottle (19).

2. The online automatic pH calibration instrument according to claim 1, characterized in that: A connecting pipe (13) is installed at the liquid inlet end of the measuring cell (4), and a three-way pipe (14) is installed at the other end of the connecting pipe (13). The second solenoid valve (9) is a three-way reversing valve. One end of the three-way pipe (14) is connected to the third solenoid valve (7), and the other end of the three-way pipe (14) is connected to the liquid outlet end of the second solenoid valve (9). One end of the second solenoid valve (9) is connected to the second buffer solution bottle (3), and the other end of the second solenoid valve (9) is connected to the first solenoid valve (8).

3. The online automatic pH calibration instrument according to claim 2, characterized in that: A flow limiting device (16) is installed between the second solenoid valve (9) and the three-way pipe (14).

4. The online automatic pH calibration instrument according to claim 1, characterized in that: A sewage discharge solenoid valve (17) is installed on the sewage discharge pipe (10), and the sewage discharge solenoid valve (17) is electrically connected to the controller (6).

5. The online automatic pH calibration instrument according to claim 4, characterized in that: The other end of the sewage discharge pipe (10) is located inside the sewage discharge tank (18), and the sample injection tube (1), sewage discharge pipe (10) and connecting pipe (13) are all polytetrafluoroethylene tubes.

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