CN212989232U - Calibration device for oxidation-reduction potential tester - Google Patents
Calibration device for oxidation-reduction potential tester Download PDFInfo
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- CN212989232U CN212989232U CN202021646859.7U CN202021646859U CN212989232U CN 212989232 U CN212989232 U CN 212989232U CN 202021646859 U CN202021646859 U CN 202021646859U CN 212989232 U CN212989232 U CN 212989232U
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Abstract
The utility model provides an oxidation-reduction potential tester calibrating device, a pH meter calibrating instrument is configured to output mV value to the ORP tester, a high resistance resistor R and a switch K are connected in series on an output circuit of the ORP tester connected by the pH meter calibrating instrument so as to detect the electric meter potential indication value error, the electric meter potential repeatability, the electric meter input current and the electric meter input impedance of the ORP tester; two standard bottles are configured for containing two different ORP standard solutions and are stored in a constant-temperature water tank, and the ORP measuring instrument is calibrated by means of an oxidation-reduction depolarization automatic measuring instrument and one of the standard solutions; the two standard solutions are used for detecting the electrode indication value error and repeatability of the ORP measuring instrument, the ORP measuring instrument is calibrated by adopting the device, the problem that results cannot be unified due to different expression modes under different standards is solved, and the traceability is good, accurate and reliable.
Description
Technical Field
The utility model relates to a calibration field, specific theory has related to an oxidation reduction potential apparatus calibrating device.
Background
The Oxidation-Reduction Potential (ORP) reflects the overall redox capacity of a system, which characterizes the relative degree of Oxidation or Reduction of the system. The ORP measuring instrument is widely applied to the fields of water quality monitoring, soil environment monitoring, resource surveying, marine exploration, bioengineering, environmental protection, wine industry and the like.
Measurement principle of an ORP (oxidation-reduction potential) measuring instrument: the measuring electrode does not participate in redox reaction and has the function of transferring electrons, the measuring electrode (a platinum electrode is commonly used) is used for potential measurement due to the property of withstanding chemical impact, and the reference electrode is commonly a calomel electrode or a silver-silver chloride electrode.
By the nernst equation:
E=
in the formula: r-gas constant (8.314J/K.mol);
t-absolute temperature (K);
n is the number of electrons transferred in the half reaction;
F-Faraday constant (96500C/moL);
e-actual ORP (mV);
E0-standard electrode potential (mV) of redox electron pair;
[ Oxid ] is the molar concentration of oxidant (moL/L);
[ Red ] is the molar concentration of the reducing agent (moL/L).
It is known that, under certain conditions, the ORP meter measures the potential value (mV) in the solution to obtain the ratio of the concentration of the oxidizing substance to the concentration of the reducing substance, thereby reflecting the relative degree of oxidation or reduction of the system.
Because of the increasing number of ORP measuring instruments which need tracing at present, but no corresponding detection rules or calibration specifications, the ORP measuring instruments, the pH (acidity) meters, the ion meters and the automatic potentiometric titrators are all composed of an electrometer part and an electrode part. Therefore, the ORP measuring instrument is mostly calibrated by referring to the JJG 119-2018 laboratory pH (acidity) meter verification protocol, the JJJG 757-2018 laboratory ion meter verification protocol or the JJG 814-2015 automatic potentiometric titrator verification protocol.
With reference to the above protocol, the electrometer portion may be suitable, but the electrode portion may not. The JJG 119-2018 laboratory pH (acidity) meter test procedure requires that the electrode part uses a pH electrode to measure a pH standard solution, and the measurement result is expressed as pH; JJG 757-2018 laboratory ion meter assay protocol requires that the electrode section measure F- (or other ions) using a fluoride ion electrode (or other ion-selective electrode), with the measurement being denoted pX; JJG 814-2015 Autotitrator assay protocol requires that the electrode part uses a pH electrode to perform acid-base neutralization titration, while the ORP meter electrode measurement results are expressed in mV values.
The performance of only part of the ORP meter can be reflected by referring to the above regulation, and the performance of the electrode part of the ORP meter cannot be completely and accurately reflected.
SUMMERY OF THE UTILITY MODEL
The utility model provides an oxidation reduction potential apparatus calibrating device realizes the traceability of ORP apparatus, ensures that ORP apparatus measured value is accurate and reliability.
In order to realize the purpose, the utility model discloses the technical scheme who adopts is:
a calibration device for an oxidation-reduction potential tester comprises a pH meter calibrator, a thermometer, a constant-temperature water tank, a standard solution bottle, an oxidation-reduction depolarization automatic tester, a calibration regulation module, a control switch module and a power supply;
the reference electrode of the automatic determinator for oxidation-reduction depolarization adopts a calomel electrode, the measuring electrode adopts a platinum electrode, the auxiliary electrode adopts a silver-silver chloride electrode, the reference electrode, the measuring electrode and the auxiliary electrode are all immersed in a liquid standard bottle,
the pH meter verification instrument is configured to output a mV value to the ORP meter so as to detect an electric meter potential indication value error, electric meter potential repeatability, electric meter input current and electric meter input impedance of the ORP meter; the pH meter verification instrument is connected with the output end of the ORP measuring instrument through a calibration regulation and control module, and the calibration regulation and control module comprises a high-resistance resistor and a short-circuit switch for short-circuiting the high-resistance resistor in parallel;
the thermometer is arranged in the constant-temperature water tank, and two standard bottles are also arranged in the constant-temperature water tank and are used for containing an ORP standard solution with a first standard value and an ORP standard solution with a second standard value, wherein the ORP standard solution with the first standard value and the oxidation-reduction depolarization automatic determinator are used for calibrating the ORP determinator; then, the ORP standard solution with the second standard value and the oxidation-reduction depolarization automatic determinator are used for checking electrode indication errors and repeatability of the ORP determinator;
the control switch module is arranged in the oxidation-reduction depolarization automatic determinator and used for controlling the connection between the electrode and the power supply.
The control switch module comprises two three-level selection switches and a polarization selection switch, wherein a movable contact of the first three-level selection switch is connected to the measuring electrode, three fixed contacts of the first three-level selection switch are respectively connected to the anode, the cathode and the blank electrode of the power supply, a movable contact of the second three-level selection switch is connected to the auxiliary electrode, and three fixed contacts of the second three-level selection switch are respectively connected to the anode, the cathode and the blank electrode of the power supply; the movable contact of the polarization selection switch is connected to an oxidation-reduction depolarization automatic tester; the two stationary contacts of the polarization selection switch are connected to the measuring electrode and the auxiliary electrode.
The utility model discloses utilize the pH meter to examine and determine the appearance for oxidation reduction potential apparatus output mV value to combine the cooperation of high resistance, according to oxidation reduction potential apparatus's reading, calculate respectively electric meter potential indicating value error, electric meter potential indicating value repeatability, electric meter input current, electric meter input impedance, then compare with the standard value respectively, examine the self electric meter performance of ORP apparatus; and then, carrying out depolarization processing on the electrode by an oxidation-reduction depolarization automatic determinator, calibrating by using a first standard value ORP standard solution, and calculating electrode indication error and repeatability of the oxidation-reduction potential determinator by using a second standard value ORP standard solution to realize calibration of the electrode performance based on the electrometer performance.
Drawings
FIG. 1 is a circuit diagram of the ORP meter calibration configuration of the present invention.
FIG. 2 is a schematic diagram of the electric potential measurement circuit of the mid-ORP meter by depolarization method.
Detailed Description
The technical solution of the present invention will be described in further detail through the following embodiments.
A calibration device for an oxidation-reduction potential tester comprises a pH meter calibrator, a thermometer, a constant-temperature water tank, a standard solution bottle, an oxidation-reduction depolarization automatic tester, a calibration regulation module, a control switch module and a power supply;
the reference electrode of the automatic determinator for oxidation-reduction depolarization adopts a calomel electrode, the measuring electrode adopts a platinum electrode, the auxiliary electrode adopts a silver-silver chloride electrode, the reference electrode, the measuring electrode and the auxiliary electrode are all immersed in a liquid standard bottle,
the pH meter verification instrument is configured to output a mV value to the ORP meter so as to detect an electric meter potential indication value error, electric meter potential repeatability, electric meter input current and electric meter input impedance of the ORP meter; the pH meter verification instrument is connected with the output end of the ORP measuring instrument through a calibration regulation and control module, and the calibration regulation and control module comprises a high-resistance resistor R and a short-circuit switch K which are connected in parallel and used for short-circuiting the high-resistance resistor; the resistance value of the high resistance resistor R is equal to 1000M omega.
The pH meter calibrator has the advantages of small volume, convenient carrying and use and high precision, so that special voltage output equipment is not required to be equipped, and the pH meter calibrator is more convenient and reliable.
The thermometer is arranged in the constant-temperature water tank, and two standard bottles are also arranged in the constant-temperature water tank and are used for containing an ORP standard solution with a first standard value and an ORP standard solution with a second standard value, wherein the ORP standard solution with the first standard value and the oxidation-reduction depolarization automatic determinator are used for calibrating the ORP determinator; then, the ORP standard solution with the second standard value and the oxidation-reduction depolarization automatic determinator are used for checking electrode indication errors and repeatability of the ORP determinator; in the embodiment, the temperature of the constant-temperature water tank is controlled at 25 ℃, wherein one standard ORP standard solution is pH =4, and the other standard ORP standard solution is pH =6.86, and then one of the standard solutions is stored in the constant-temperature water tank and used for calibrating the ORP measuring instrument by virtue of an oxidation-reduction depolarization automatic measuring instrument and the ORP standard solution with pH = 6.86; the electrode readings for the ORP meter were checked for error and repeatability with the help of a standard solution of pH = 4.
The control switch module is arranged in the oxidation-reduction depolarization automatic determinator and used for controlling the connection between the electrode and the power supply.
The control switch module comprises two three-level selection switches and a polarization selection switch, wherein a movable contact 4 of the first three-level selection switch is connected to the measuring electrode, three fixed contacts of the first three-level selection switch are respectively connected to the anode 5, the cathode 7 and the blank electrode 6 of the power supply, a movable contact 11 of the second three-level selection switch is connected to the auxiliary electrode, and three fixed contacts of the second three-level selection switch are respectively connected to the anode 8, the cathode 10 and the blank electrode 9 of the power supply; the movable contact 3 of the polarization selection switch is connected to an oxidation-reduction depolarization automatic tester; the two stationary contacts 1 and 2 of the polarization selection switch are connected to the measuring electrode and the auxiliary electrode.
The specific calibration process is as follows:
as shown in figure 1, step 1) switches on a switch K, short-circuits a high-resistance resistor R, and adjusts the output standard potential E of the pH meter calibratorbdSequentially inputting 0mV, +/-1 mV, +/-10 mV, +/-100 mV, +/-500 mV, +/-1000 mV and full-scale potential value +/-E to an ORP measuring instrumentfMeasuring and recording ORP meter reading EcdAnd measuring and recording the ORP meter reading E once each in a manner that the one-way input increases and the one-way input decreasescdCalculating the potential average value of the ammeter
Then calculating the potential indicating value error of the electric meter according to the formula (1)
In this embodiment, the potentiometer error requirement is as follows: not more than +/-2 mV.
Step 2) turning off the switch K, turning on the high-resistance resistor R, adjusting the pH meter calibration instrument to output 300mV to the ORP measuring instrument, and measuring and recording the reading E of the ORP measuring instrumentdiRepeat 7 times and calculate the mean
Calculating the potential repeatability s of the potentiometer according to the formula (2)dIn this embodiment, the repeatability of the potentiometer is as follows: not exceeding 2 mV.
Step 3) switching on the switch K, short-circuiting the high-resistance resistor R, and adjusting the output of the pH meter calibrator to the ORP tester0mV, measurement and recording of ORP meter reading EL0(ii) a Then the switch K is switched off, the high resistance R is switched on, and the reading E of the ORP measuring instrument is recordedH0(ii) a The measurement was repeated 3 times, and the average value was calculated 3 times:
、
calculating the input current I of the electricity meter according to the formula (3), in this embodiment, the input current of the electricity meter is required not to exceed 1 × 10-11A。
Step 4) switching on the switch K, short-circuiting the high-resistance resistor R, adjusting the pH meter calibrator to output 300mV to the ORP tester, and measuring and recording the reading E of the ORP tester0Then the switch K is switched off, the high resistance R is switched on, and the reading E of the ORP meter is recorded1(ii) a The measurement was repeated 3 times, and the average value was calculated 3 times:
、
calculating the input impedance R of the meter according to equation (4)SIn this embodiment, the input impedance of the ammeter is required not to exceed 3 × 1011Ω。
After the electric meter performance of the ORP measuring instrument is detected through the steps, a calibration process is started;
step 5) adding quinone hydroquinone reagents into standard solutions with pH =4 and pH =6.86 respectively to enable the quinone hydroquinone to be in a saturated state, preparing two ORP standard solutions, storing the two ORP standard solutions into two jars respectively, placing the jars into a constant-temperature water tank, and keeping the water temperature of the constant-temperature water tank constant;
as shown in fig. 2, a platinum electrode and a saturated calomel electrode provided in the ORP meter are respectively used as a measuring electrode, a reference electrode and a silver-silver chloride electrode provided in the ORP meter are respectively connected to an oxidation-reduction depolarization automatic meter, a silver-silver chloride electrode provided in the oxidation-reduction depolarization automatic meter is used as an auxiliary electrode and is connected to the oxidation-reduction depolarization automatic meter, and the platinum electrode, the calomel electrode and the silver-silver chloride electrode are placed in an ORP standard solution with pH = 4;
the anode depolarizes, collecting a set of data, and then the cathode depolarizes, collecting a set of data.
In this process, the anode and cathode depolarizes in the following manner: the polarization voltage is adjusted to 600mV, when the wave band switches 4 and 5 are connected, the platinum electrode is connected to the positive pole of the power supply, 2 and 3 are connected, 10 and 11 are connected, and the silver-silver chloride electrode is connected to the negative pole of the power supply, then the anode is polarized; the wave band switches 4 and 6 are connected, the wave band switches 9 and 11 are connected, and the wave band switches 1 and 3 are connected, so that the anode depolarizes; the potential of the platinum electrode is monitored during depolarization, the depolarization time is 15 seconds, the time interval for data acquisition is 2 seconds, and 6 data are acquired.
The wave band switches 4 and 7 are connected, the platinum electrode is connected to the negative electrode of the power supply, 2 and 3 are connected, 8 and 11 are connected, the silver-silver chloride electrode is connected to the positive electrode of the power supply, and the cathode is polarized; the wave band switches 4 and 6 are connected, the wave band switches 9 and 11 are connected, the wave band switches 1 and 3 are connected, the cathode depolarizes, the potential of the platinum electrode is monitored during depolarization, the depolarization time is 15 seconds, the time interval for collecting data is 2 seconds, and 6 data are collected.
And (3) monitoring the voltage by an automatic chemical reduction depolarization tester in the depolarization process, automatically calculating the equilibrium potential, and measuring the potential of the ORP standard solution.
Comparing the acquired data with a standard value under the same condition, wherein the error between the acquired data and the standard value is not more than +/-5 mV, completing calibration, and carrying out next detection and measurement; if the error of the platinum electrode and the pure water is less than +/-5 mV, the platinum electrode is placed into a nitric acid solution with the ratio of 1:1, slowly heated to be nearly boiled, kept in a nearly boiling state for 5min, placed and cooled, taken out and washed by the pure water, the above process is repeated until the error of the platinum electrode and the pure water is less than +/-5 mV, and then the next detection and measurement are carried out.
The measurement was performed by placing the electrode in ORP standard solution of pH =6.86, the measurement was repeated 7 times, and the average value was calculated
Calculating instrument electrode indicating value error according to formula (5), and calculating instrument electrode repeatability s according to formula (6)yThe error of the electrode indication value of the instrument does not exceed +/-10 mV; the repeatability of the electrode of the instrument is not more than 2 mV.
According to the method, the pH meter calibrating instrument is matched with a designed circuit to detect various performances of the ORP measuring instrument, then the electrode depolarization and ORP standard solution are calibrated by an oxidation-reduction depolarization method, and finally another ORP standard solution is used for performance test of electrode indication error and repeatability, so that the comprehensive integral calibration of the ORP measuring instrument and the electrode is achieved, the complete performance of the ORP measuring instrument is reflected, the relative precision of the equipment related to the measuring precision can be known, and the ORP measuring instrument has better traceability capability. Since the platinum electrode is not inert, and the surface of the platinum electrode can form an oxide film or adsorb other substances, which affects the electron exchange rate of each redox couple on the platinum electrode, the establishment of the equilibrium potential is very slow, and the measurement error is large. The calibration device adopts a polarization method to measure the potential of the ORP measuring instrument, the result can be obtained within 3 minutes, and the error is not more than 10 mV.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the same; although the present invention has been described in detail with reference to preferred embodiments, it should be understood by those skilled in the art that: the invention can be modified or equivalent substituted for some technical features; without departing from the spirit of the present invention, it should be understood that the scope of the claims is intended to cover all such modifications and variations.
Claims (2)
1. A calibration device for an oxidation-reduction potential tester is characterized in that: the device comprises a pH meter calibrator, a thermometer, a constant-temperature water tank, a liquid level bottle, an oxidation-reduction depolarization automatic determinator, a calibration regulation module, a control switch module and a power supply;
the reference electrode of the automatic determinator for oxidation-reduction depolarization adopts a calomel electrode, the measuring electrode adopts a platinum electrode, the auxiliary electrode adopts a silver-silver chloride electrode, the reference electrode, the measuring electrode and the auxiliary electrode are all immersed in a liquid standard bottle,
the pH meter verification instrument is configured to output a mV value to the ORP meter so as to detect an electric meter potential indication value error, electric meter potential repeatability, electric meter input current and electric meter input impedance of the ORP meter; the pH meter verification instrument is connected with the output end of the ORP measuring instrument through a calibration regulation and control module, and the calibration regulation and control module comprises a high-resistance resistor and a short-circuit switch for short-circuiting the high-resistance resistor in parallel;
the thermometer is arranged in the constant-temperature water tank, and two standard bottles are also arranged in the constant-temperature water tank and are used for containing an ORP standard solution with a first standard value and an ORP standard solution with a second standard value, wherein the ORP standard solution with the first standard value and the oxidation-reduction depolarization automatic determinator are used for calibrating the ORP determinator; then, the ORP standard solution with the second standard value and the oxidation-reduction depolarization automatic determinator are used for checking electrode indication errors and repeatability of the ORP determinator;
the control switch module is arranged in the oxidation-reduction depolarization automatic determinator and used for controlling the connection between the electrode and the power supply.
2. The oxidation-reduction potentiometric calibration device according to claim 1, wherein: the control switch module comprises two three-level selection switches and a polarization selection switch, wherein a movable contact of the first three-level selection switch is connected to the measuring electrode, three fixed contacts of the first three-level selection switch are respectively connected to the anode, the cathode and the blank electrode of the power supply, a movable contact of the second three-level selection switch is connected to the auxiliary electrode, and three fixed contacts of the second three-level selection switch are respectively connected to the anode, the cathode and the blank electrode of the power supply; the movable contact of the polarization selection switch is connected to an oxidation-reduction depolarization automatic tester; the two stationary contacts of the polarization selection switch are connected to the measuring electrode and the auxiliary electrode.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113340968A (en) * | 2021-06-23 | 2021-09-03 | 深圳科瑞德健康科技有限公司 | Water solution oxidation reduction potential meter capable of adjusting water flow speed |
| CN113406176A (en) * | 2021-07-05 | 2021-09-17 | 深圳科瑞德健康科技有限公司 | Water solution oxidation reduction potential value rapid testing device with mechanical stirring function |
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2020
- 2020-08-10 CN CN202021646859.7U patent/CN212989232U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113340968A (en) * | 2021-06-23 | 2021-09-03 | 深圳科瑞德健康科技有限公司 | Water solution oxidation reduction potential meter capable of adjusting water flow speed |
| CN113340968B (en) * | 2021-06-23 | 2022-03-11 | 深圳科瑞德健康科技有限公司 | Water solution oxidation reduction potential meter capable of adjusting water flow speed |
| CN113406176A (en) * | 2021-07-05 | 2021-09-17 | 深圳科瑞德健康科技有限公司 | Water solution oxidation reduction potential value rapid testing device with mechanical stirring function |
| CN113406176B (en) * | 2021-07-05 | 2022-03-22 | 深圳科瑞德健康科技有限公司 | Water solution oxidation reduction potential value rapid testing device with mechanical stirring function |
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