Some standard content:
National Metrology Verification Regulations of the People's Republic of China JG 291-2808
Dissolverl Oxygen Meler withCoverel-Membrane-Electrode
2008 - 12 - 23 Issued
2009 -06- 23 Implementation
Issued by the General Administration of Quality Supervision, Inspection and Quarantine 291-2008
Verification Regulations for Dissolved Oxygen Meters with Coverel-Membrane-Electrode Cowered-Membrame-leetradeirKAoNirKa=
JEG291.2008
Replaces G·291·1999
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine on December 23, 2008, and came into effect on June 23, 2009.
Export unit; National Environmental Chemical Metrology Technical Committee Drafting unit: Zhejiang Institute of Metrology Small regulations National Environmental Chemical Metrology Technical Committee is responsible for interpreting this regulation Drafting person:
JJG1291-24
Zhang Yanqun (Zhejiang Institute of Metrology).
Scope·
Overview·
3 Metrology performance requirements·
3.1 Zero value error
Response time
Dissolved oxygen liquid level indication error
3.4 Repeatability·
Temperature indication error
3.6 Dispersion compensation error
4 Tongchuan Technical Requirements...
1..． Appearance…
4.2 Insulation resistance
4.3 Dielectric strength
5 Control of measuring instruments·
5.1 Verification conditions
5.2 Verification items…
Verification method
Treatment of verification results
Verification cycle·
Appendix A
Preparation of verification water
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
Structure diagram of the device for preparing verification water
J3G 291208
Saturated concentration of oxygen in water at different temperatures. Table of saturated vapor pressure of pure water at fixed temperature. Verification record
Verification certificate, verification result notice (inner page) format TKNirKa-
(1)
(4)
JIG 291-2088
Verification procedure for membrane electrode dissolved oxygen meter This procedure is applicable to the initial verification, subsequent verification and market inspection of laboratory and portable membrane electrode dissolved oxygen meters (hereinafter referred to as instruments) with a maximum working range of (0~20)m/L. 2
The instrument is used to determine the dissolved oxygen concentration (DO) in water. The instrument is generally composed of an electrode, an electronic unit and a display. The measurement performance requirements are as follows:
Zero value error
The zero error of the instrument should not exceed 0.
3.2 Response time
The response time of the instrument should not exceed 60s
3.3 Dissolved content indication error
The indication error of dissolved oxygen concentration of the instrument is
±0.60 mg/
3.4 Repeatability
0.30 mg/L! Subsequent calibrations should not exceed
The instrument's error should not exceed 0.15 mg/L for the first calibration, and should not exceed 0.20 mg/L for subsequent calibrations. 3.5 Temperature display error
The temperature display error of the instrument should not exceed
The salinity compensation error of the instrument should not exceed
General technical requirements
4.1 Appearance
4.1.1: The instrument should be marked with the manufacturer's name
Model "date of manufacture". Domestic instruments should also have the metering license mark and number. The accessories should be complete, and the instrument instructions should be attached. 4.1.2 The instrument should have a good appearance, clear and complete display, reliable electrode lead connection, and no loose fasteners. 4.1.3 The inner cavity of the electrode should have a supporting electrolyte, no gas pool, and the coating should be smooth and intact. .2 Insulation resistance
The insulation resistance of the instrument power phase and neutral line to the ground should be not less than 5 Ω2. 1.3 Insulation degree
When a 50Hz, 1500V chordal AC voltage is applied to the instrument power phase and line to the ground for 1 minute, there should be no breakdown phenomenon.
Measuring instrument control
Verification conditions
5.1.1 Environmental conditions
JJG291-2408
5.1.1.1 Ambient temperature (15~25)℃, temperature fluctuation during verification shall not exceed: 2℃5.1.1.2 There shall be no electromagnetic interference that may affect the normal operation of the instrument; 5.1.1.3 Power supply: (220=22)V, (50=1)Hz; 5.1.1.4 Temperature: 85%RH
5.1.2 Verification equipment and its requirements
Verification water: For the preparation of verification water, see Appendix A; 5.7.2.1
TrKoNirKa=
Precision constant temperature water bath: machine temperature range (0~~50)℃, temperature fluctuation shall not exceed ±0.2℃, stirring speed 5.1.2. 2
temperature stable, and equipped with a porous plastic floating cover, see Appendix 13; 5. 1.2. 3
5. 1. 2. 4
5. 1. 2. 5
5. 1. 2. 6
5. 1. 2. 7
5. 1. 2. 8
Stopwatch: graduation value 0.1s
Second-class standard mercury thermometer: measuring range (0-~50)℃: graduation value 0.1℃; barometer: graduation value l0Pa:
Bubble curtain: porous!
Sodium sulfite (NazSO): analytically pure reagent: ...diamond salt: analytically pure reagent;
Insulation resistance meter: 500V (DC):
5. 1. 2. 9
5. 1. 2. 10
Insulation strength tester: voltage greater than 1.5kV. Verification items
The inspection items are shown in Table 1.
Table 1 List of verification items
Qualified items
Zero value error
Insulation resistance!
Insulation strength
Response time
Dissolved oxygen meter indication error
Repeatability
Overflow meter indication error
Salinity compensation error
Note: 1 "+" instrument verification, \
First verification
No verification required
Subsequent verification
In-use inspection
2 If the maintenance of the instrument has a significant impact on the measurement performance, the subsequent verification items shall be carried out according to the initial verification items. 2
5.3 Verification method
5.3.1 Appearance
J.IG 291—2008
Use visual and hand feeling method according to the requirements of 4.1. 5.3.2 Verification of insulation resistance
The instrument screen is not connected to the power supply, and the power supply is connected. Connect the two ends of the insulation resistance meter to the phase and middle connecting wires of the instrument input terminal, and the other end to the instrument protective grounding terminal (casing). Apply a test voltage of 500V for 5s. Measure the insulation resistance.
5.3.3 Verification of insulation strength
The instrument is not connected to the power supply: Turn on the power switch and connect the two test wires of the insulation strength tester to the phase and middle connecting wires of the power input terminal and the grounding terminal (or casing) respectively: Apply a test voltage of 1500V, the current is set to 5mA, the rise and fall time is (5~20)s, keep for 1min, and then steadily reduce the voltage to 0V. During the test process, there should be no breakdown and flying phenomenon
5.3.4 Verification of zero value error
5.3.4.1 Connect the instrument manual to the normal calibration. 5.3.4.2 Connect the electrodes to the newly prepared oxygen-free water at a temperature of (20±5)℃. For the preparation of chlorine-free water, see A. c in Appendix A.
5.3.4. The instrument indication after 35 minutes is the zero error from the zero current. 5.3.5 Verification of response time
5.3.5.1 Control the temperature of the constant temperature water bath at (20 ± 1), and prepare saturated dissolved oxygen water for verification according to the requirements of A.2 in Appendix A.
5.3.5.2 Take the electrode out of the constant temperature water bath, quickly immerse it in oxygen-free water, and start timing 5.3.5.3 When the instrument shows 90% of the stable value, stop timing. The stopwatch reading at this time is the response time. 5.3.6 Checking the error of oxygen concentration indication
5.3.6.1 Recalibrate the instrument.
5.3.6.2 Adjust the temperature of the constant temperature water bath to 10, 20, and 30°C respectively. 5.3.6.3 At each temperature point, place the electrode out of the air into the warm water bath and gently swing it. Read the indication after it stabilizes. Repeat twice: get the average value of the instrument indication: calculate the indication error of dissolved oxygen concentration according to formula (1): Acc
ch=c.101325-p
Note: It is derived from the national standard CB/T11313-1989 "Determination of water quality by electrochemical exchange method" in Experiment A1. In the formula: (-) - solubility of oxygen at (Pa) atmospheric pressure, g/: c saturated solubility of oxygen at 101325Pa atmospheric pressure, refer to Appendix C, mg/L... atmospheric pressure. a
p - saturated water vapor pressure when in contact with air at the selected temperature, refer to Appendix 1. Pa: take the largest absolute value. It is the indication error of dissolved oxygen concentration of the instrument. 5.3.7 Repeatability verification
5.3.7.1 Repeatability verification of the instrument should be carried out in saturated dissolved oxygen water with a constant temperature water bath temperature close to room temperature. 3
JIG 291-2808
TKAoNrKAca
5.3.7.2 Repeat the measurement of stable saturated dissolved oxygen water for 6 times. Record the instrument indications respectively and calculate the repeatability of the instrument according to formula (3):
Where: c
The first measurement value: mg/L:
---The arithmetic mean of the measurement values, img/L.5.3.8 Verification of the indication error
While verifying the indication error of dissolved oxygen, the reading should be checked at two temperature points. During the verification, place the electrode and the precision thermometer at a constant temperature and measure: The instrument indication is obtained at two temperatures. Average value T: Calculate the temperature indication error of the instrument according to formula (4) (4)
Instrument indication value, ℃;
Where: T
T.\Precision temperature reading value,.
Take the absolute value as the temperature indication error of the instrument 5.3.9 Verification of salt compensation error
5.3.9.1 Fill a beaker with 11% distilled water and place it in a constant temperature water bath (15+0.2)℃. Stop agitation after 1h and let it stand for 10 seconds.
Measure the dissolved oxygen concentration N at zero salt. The dissolved oxygen concentration N of water with a salt content of n (g/L) is calculated according to formula:
6.-055 9
-salt ac grams, nrj 10, 2ag
Where: n-
Note: 0.0559 fee to find leakage 15, now the total amount) when the pain group of the chemical (4). Bureau 11913--1989 Appendix A.
5.3.9.2 Keep the pure water film at 15℃, add salt braid, and adjust it into a salt content of 10g/l and dissolved oxygen water, measure N twice, and take the average). Use the same method to adjust the water to a saturated dissolved oxygen content of 20, 30#/L and measure N2c, so respectively. Calculate the salinity compensation error of the instrument:
Where: N.
The dissolved oxygen content of salt water is N:N, Nac
Take the absolute maximum △N as the instrument salinity compensation error, 5.4 Processing of calibration results
5.4.1 If the electrode performance is poor during the calibration process, it is allowed to replace the electrode electrolyte and film, and re-calibrate after replacement.
5.4.2 For instruments that pass the calibration according to this regulation, a calibration certificate will be issued. For unqualified instruments, a calibration result notice will be issued, indicating the unqualified items.
5.5 Calibration cycle
The calibration cycle of the instrument is generally 1 year,
Han Meng A
A Preparation without water
Test water
Add 250l of distilled water to a 500mL beaker. Then add 500mg of sodium sulfoxide (Na2SO4) and trace amount of divalent cobalt salt, such as hydrated chlorinated carbonate (CoC: 60) as catalyst. After stirring evenly, use A.2 to prepare dissolved oxygen water. 3152 0.0 A.2, pour 2.0 tt.2 solution (drug) into the quasi-constant temperature bath, and float the porous material in water (see addition record 3). Adjust the water temperature to the required temperature when the test is completed, start the mixing water sample, and at the same time, the bubbler (air pump) continuously builds up water into the water for more than min
A.2.2 Stop positive instant
Stationary ratio 30m
Appendix B
IIG 291--2008
Structure diagram of the device for preparing water for test
Thermometer
Sensitive bubbler
Plastic floating cover
Precision constant temperature water bath
Figure B.2 Plastic floating cover (Material: lightweight plastic sheet: can float on the water surface)irKAoNirKa=
Appendix C
Wen Ling/C
JG 291---2088
Oxygen saturation concentration table in water at different temperatures (atmospheric pressure 101325Pa, condensation 100%RH: salt content 0%) dissolved oxygen/(mg/L)
Temperature/℃
Dissolved oxygen/(g/L)
Note: Extracted from national standard G3/T11913-1989, essential reduction/℃
Dissolved oxygen/(mg/l)
Determination of dissolved hydrogen
Good chemical probe method
Attached green"
Temperature/
14 20---2098
Do not care about the saturated steam surface of the water
pressure/kta
flow: from the actual source of medicine (131-90) 8
temperature ℃
E force/kP
. 998 7
TKAONrKAa=2. Keep the pure water film at 15℃, add salt, and adjust it into saturated dissolved oxygen water with a salt content of 10g/l. Measure N twice and take the average. Use the same method to adjust the water into saturated dissolved oxygen with a salt content of 20 and 30#/L to measure N2c and N2so respectively. Calculate the salinity compensation error of the instrument:
Where: N.
The salinity dissolved oxygen test of salt water is N: N, Nac
Take the absolute maximum △N as the instrument salinity compensation error. 5.4 Processing of verification results
5.4.1 If the electrode performance is poor during the verification process, it is allowed to replace the electrode electrolyte and the film, and re-verification is required after replacement.
5.4.2 For instruments that pass the verification according to this regulation, a verification certificate will be issued. For unqualified instruments, a verification result notice will be issued, indicating the unqualified items.
5.5 Calibration cycle
The calibration cycle of the instrument is generally 1 year.
Han Meng A
A Preparation of water without impurities
In a 500mL beaker, add 250L of distilled water. Then add 500mg of sodium sulfoxide (Na2SO4) and a trace amount of divalent cobalt salt, such as hydrated chloride (CoC: 60) as a catalyst. After stirring evenly, use A.2 to prepare dissolved oxygen water
3152 0
A.2, pour 2
2% of the solution (medicine) in a quasi-constant temperature bath, and float the porous material in water (see addition record 3). Adjust the water temperature to the required temperature when the test is completed, start the mixing water sample, and at the same time, the bubbler (air pump) continuously builds up water into the water for more than min
A.2.2 Stop positive instant
Stationary ratio 30m
Appendix B
IIG 291--2008
Structure diagram of the device for preparing water for test
Thermometer
Sensitive bubbler
Plastic floating cover
Precision constant temperature water bath
Figure B.2 Plastic floating cover (Material: lightweight plastic sheet: can float on the water surface)irKAoNirKa=
Appendix C
Wen Ling/C
JG 291---2088
Oxygen saturation concentration table in water at different temperatures (atmospheric pressure 101325Pa, condensation 100%RH: salt content 0%) dissolved oxygen/(mg/L)
Temperature/℃
Dissolved oxygen/(g/L)
Note: Extracted from national standard G3/T11913-1989, essential reduction/℃
Dissolved oxygen/(mg/l)
Determination of dissolved hydrogen
Good chemical probe method
Attached green"
Temperature/
14 20---2098
Do not care about the saturated steam surface of the water
pressure/kta
flow: from the actual source of medicine (131-90) 8
temperature ℃
E force/kP
. 998 7
TKAONrKAa=2. Keep the pure water film at 15℃, add salt, and adjust it into saturated dissolved oxygen water with a salt content of 10g/l. Measure N twice and take the average. Use the same method to adjust the water into saturated dissolved oxygen with a salt content of 20 and 30#/L to measure N2c and N2so respectively. Calculate the salinity compensation error of the instrument:
Where: N.
The salinity dissolved oxygen test of salt water is N: N, Nac
Take the absolute maximum △N as the instrument salinity compensation error. 5.4 Processing of verification results
5.4.1 If the electrode performance is poor during the verification process, it is allowed to replace the electrode electrolyte and the film, and re-verification is required after replacement.
5.4.2 For instruments that pass the verification according to this regulation, a verification certificate will be issued. For unqualified instruments, a verification result notice will be issued, indicating the unqualified items.
5.5 Calibration cycle
The calibration cycle of the instrument is generally 1 year.
Han Meng A
A Preparation of water without impurities
In a 500mL beaker, add 250L of distilled water. Then add 500mg of sodium sulfoxide (Na2SO4) and a trace amount of divalent cobalt salt, such as hydrated chloride (CoC: 60) as a catalyst. After stirring evenly, use A.2 to prepare dissolved oxygen water
3152 0
A.2, pour 2
2% of the solution (medicine) in a quasi-constant temperature bath, and float the porous material in water (see addition record 3). Adjust the water temperature to the required temperature when the test is completed, start the mixing water sample, and at the same time, the bubbler (air pump) continuously builds up water into the water for more than min
A.2.2 Stop positive instant
Stationary ratio 30m
Appendix B
IIG 291--2008
Structure diagram of the device for preparing water for test
Thermometer
Sensitive bubbler
Plastic floating cover
Precision constant temperature water bath
Figure B.2 Plastic floating cover (Material: lightweight plastic sheet: can float on the water surface)irKAoNirKa=
Appendix C
Wen Ling/C
JG 291---2088
Oxygen saturation concentration table in water at different temperatures (atmospheric pressure 101325Pa, condensation 100%RH: salt content 0%) dissolved oxygen/(mg/L)
Temperature/℃
Dissolved oxygen/(g/L)
Note: Extracted from national standard G3/T11913-1989, essential reduction/℃
Dissolved oxygen/(mg/l)
Determination of dissolved hydrogen
Good chemical probe method
Attached green"
Temperature/
14 20---2098
Do not care about the saturated steam surface of the water
pressure/ktabzxz.net
flow: from the actual source of medicine (131-90) 8
temperature ℃
E force/kP
. 998 7
TKAONrKAa=
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