Some standard content:
National Metrology Verification Regulations of the People's Republic of China JJG 975—2002
Chemical Oxygen Demand (COD) Meters
Chemical Oxygen Demand (Con) Meters2002-11-04 Issued
2003 - 02 - 04 Implementation
The General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China issued JJG975—2HI2
Chemical Oxygen Demand (COD) Meters
Verification Regulations
Verification of ChemicalOxygen Demand (cOD) Meters
JJG 975--2002
This regulation was approved by the State Quality Supervision, Inspection and Quarantine Administration on November 4, 2002, and will be implemented on [4] November 25, 2003. Responsible unit: National Environmental Chemistry Certification and Accreditation Technical Committee Drafting unit: National Standardized Substance Research Center This regulation is entrusted to the National Environmental Chemistry Metrology Technical Committee to interpret this regulation. Main drafters:
Shi Naijie
Li Yunqiao
JJG 975—20MP2
(National Research Center for Standard Materials)
(National Research Center for Standard Materials)
3 Performance requirements
3.1 Class A instruments
3.2 Class A instruments
4 Technical requirements for sound
..External regulations...
1.2 Safety performance
5 Design basis and control
5.1 Verification conditions
5.2 Verification conditions t||5.3 Inspection method
5.4 Treatment of inspection results
Inspection period
Appendix A Format of inspection record (Class A instruments)
Appendix B Format of inspection record (Class H instruments)
JH:975—2002
Format of inspection report (Class A instruments)
Appendix D
Appendix E
Format of inspection certificate (Class B instruments)
Format of inspection result report (Class B instruments)】 Format (Class 1 Instrument) f
(2)
Scope
J3GI9TS20M02
Chemical Oxygen Demand [COD] Meter Verification Procedure This procedure is used for the initial verification, subsequent verification and in-use inspection of chemical oxygen demand meters: the calibration of online chemical oxygen demand meters can be referred to. 2 Overview
Chemical Oxygen Demand (COD) is the number of oxidants consumed by substances in water that are easily oxidized by oxidants. It is used to evaluate the water It is an important indicator of the content of relative substances and carbon dioxide in the body. It is mainly used for environmental monitoring in the fields of petroleum, chemical industry, medicine and biology. Chemical oxygen depletion analyzer can be divided into two categories according to the technical principle. One is the spectrophotometric principle: using sodium chromate to hydrogenate water under certain conditions to convert hexavalent chromium into monovalent chromium, and using the absorption peak at 61nm of hexavalent chromium or the absorption peak at 420nm of hexavalent chromium to determine COD by photometric method. This type of instrument is divided into the combustion part, the measuring part, and the schematic diagram of the instrument is called "Class 1". 1. Principle of photometric method Instrument structure diagram
General library system
The other is the electrochemical principle: using a certain amount of potassium dichromate under certain conditions, heating and refluxing the sample, the ions produced by the decomposition method react with the remaining hexavalent chromium. When the hexavalent chromium is completely consumed, the electrolysis result is: the COD content in the consumed sample is: The principle is shown in Figure 2 (hereinafter referred to as Class B).
Beijing source
Electrolysis end point circuit
Figure 2 Chemical identification instrument structure diagram
3. Performance requirements
3.1 Class 4 instruments
3.1.1 Temperature indication error
When working in the mountain belt, the temperature minimum value error should not exceed +? 9: 3.1.2 Temperature field uniformity
The average value of the artificial field is not more than 3 lines.
3.1.3 The error of the display signal during the digestion time
The error of the display value of the artificial digestion time is not more than 2%. 3.1.1 Display error
J.IG 9752002
Under the condition of the standard, the error of the value should not exceed 3.1.5 Fluctuation
Under the condition of the standard, the reproducibility of the measured value should not exceed 10 3%. 3.1.6 Thermal products
change less than 6ng1. or absorbance value less than (for instruments with non-linear indication (HH) value)
3.23 Instrument
3.7.1 Value error
Under the specified conditions: the instrument indication should be confirmed to be 2.0. 3.2.2 Straightness
The instrument should be marked with the following: instrument name, model, factory number, manufacturer, etc. 4.2 Safety performance
The insulation of the instrument is not less than 2 meters. 1
5 Measuring instrument control
The instrument is controlled: the device is controlled, and the post-inspection is carried out. S.1 Control conditions
5.1.1 Equipment temperature limit: Test range 100200 (0.5 level) 3.1.1.1
5.1.1.250, 1 00, 30m, 1000r.1 (01 drop standard material, the uncertainty is not normal T-21.
5.1.1.3: (.05mol/1/6K (T.) liquid process material: the uncertainty should not be +1.%: (=2) 5.1.1.4
Electronic autumn.
Editing edge electric clothes: 500 numbers.
5.1.2 Environmental conditions
S.1.2.1 Environmental temperature original 5.35
5 1.2.2 Do not consider the risk of using the equipment. 5.12.3 Do not affect the normal operation of the equipment and the need for movement. 5.2 Check these items as shown in Table 1 and Table 2. Check items JIG 9752002 Table 1 A-type instrument calibration items list
piece calibration
anti-quantity requirements
no six uncles to promote production
deep company small direct installation learning
bo knowledge related
yan record life
yan edit 4 area
more items
related and other items
after qualification determination
morality + cooperative inspection
2 good and difficult is the heart road to let the middle R this older company, continue the full safety self-learning
table 2B The following table contains the following items: 1. The “+” indicates that some items must be followed by others. 2. 5.3 Verification method
5.3.1 Appearance and normal visual requirements
Use three-view method
5.3.2 Use carbon dioxide electric current to connect the power supply line of the market, and stop the instrument from seeing the edge of the electric current. 5.3.34 Accumulated verification method
Temperature detection After preheating for 11 seconds, the temperature of 6 digestion holes is divided into two parts, and the thermometer is logged in for digestion. After the isotherm is set, the time required for reading the maximum number of times is 1rm. If the average value is not calculated, the formula is used! The formula (technical temperature field uniformity): a, = TT
formula: T
The set temperature of the simple digestion;
JJG: 97S2002
The average temperature of the digestion furnace hole.T;
The average temperature reading of the 3rd hole is the number of single holes,
W = T-T.
Wherein: Tm—the temperature indication value of the hole with the highest temperature,℃: the humidity value of the hole with the lowest temperature,..
5.3.3.2 Digestion time indication error
When the instrument is stable, press the button to digest, and at the same time, stop the timing at the end of digestion, and collect the new digestion time. Repeat 3 times: According to formula (4), the relative indication error of the digestion time is obtained (4,)- =x1%
Wherein:,—the relative indication error of the digestion time; Digestion time setting value:
The average value of 3 measurements during the digestion is:
5.3.3.3 Indication error
After the instrument is stable, calibrate the solution according to the standard. The instrument is 0~5D. Torr. 50, 100mL COD liquid standard material is measured 3 times. At 0150)mg/1.0: 3 (K, 1)mg/LCOD liquid standard material is measured 3 times: Calculate the indication error according to formula (5): (4c) G.- C.
X10 yuan
Formula: - Instrument indication parallax:
℃. - Average of 3 measurements:
C: Standard value of COD solution.
The minimum error is taken, and the maximum value is the instrument indication error. The calibration conclusion is: 5.3.3.4 Repeatability
After the instrument is stabilized, calibrate the instrument according to the instructions. At the (~15%mg/E) position of the instrument, measure the H/LCOD liquid standard material 6 times. At the 0-.1500/1. position of the instrument, measure the Dm%/(N) liquid standard material 6 times. Calculate the repeatability (S,) according to formula (6). Ec-cy
x: S, Repeatability
C. The t 4
5.3.3.5 Stability
JJG9752002
After the instrument is delayed, follow the instructions 1 to the measurement, then fill the cell with enough distilled water, adjust the zero point to the lowest absorbance or COn, 0,00K), observe for 2 min, record every 2 mim, and calculate the stability (D,)e
P.-A according to formula (7) -...
: - stability;
A.- maximum indication;
A minimum,
5.3.4 Instrument calibration method
5.3.4.1 Indication error
After measuring, add 45ml water and 17ml deep acid, cool, add 70.5mm sodium solution, cool to room temperature, connect the electrodes according to the instructions, and stir constantly to carry out pre-electrolysis. Then As 0.50, 1.00, 2.50ml, 0.05ruu/L1/GK.Cr.0, solution, point measurement 3 times: according to formula (8 calculate the instrument indication error,
3r.=c,-40.0V
wherein: As
instrument indication error;
-30.0V average value:
0.05mr/T16C drop of liquid number of liters:
elimination column 0 ml. (F,ns) mnl/. 1/k,T,t, Liquid, the corresponding value, the reported value is set to be different, the maximum value in the error test result is the error test result of the instrument, 5.3.4.2 Repeatability
In the test cup, add 4 distilled water and 17 concentrated sulfur film, cool it down to 0.5 ferric sulfate solution, cool it to room temperature, connect the electrodes as required: set the stirring speed for pre-electrolysis, then add 1.00ml 0.05mul/L 1/6K,Cr,0, drop the liquid for determination, read the indicated value, and weigh it. Repeat 6 times: Calculate the effective repeatability (s.) according to formula (6).
5.4 Processing of calibration results
For instruments that pass the calibration according to the requirements of this regulation, a calibration certificate will be issued. For instruments that fail the calibration, a calibration result notice will be issued, and the failure will be noted on page 7
5.5 Brief calibration period
The calibration period is generally not more than one year
Appendix
Instrument name
Manufacturer!
Change inspection number
Inspection unit
Test result
Appearance inspection:
JJG9752002
Test record format (Class A instrument)
Test temperature
Adjuster
Certificate and number
Record sieve number
Temperature indication value difference, temperature field uniformity
Aperture number
Temperature field uniformity| |tt||Indication error
Determination error of the digestion time (set time x sequence number
Measurement value
Relative indication error/%
A.4 Measurement and verification
Measurement value
Light qualitative
Indication error
COD liquid standard material (mgL)
4.6 Instrument repeatability
- 150 mp/L
JJG 975--2002
Measurement color (mgL)
Reproducibility/%
U -- 1 50 2ogrL
A.7 Conclusion:
Determined mw:
Order %
Average value: (mg)
Indication error%
Appendix B
Instrument name
Manufacturer code
Production code
Inspection unit
Verification result
Appearance inspection:
Indication error
0.0SmolrL
1/k,Ga,o, nT.
Friendliness
Measurement value: (mgL)
Reproducibility/%
B.4 Conclusion:
JJG975—2002
Calibration record format (R type instrument)
Calibration temperature
Career
Criteria
Criteria period
Area number
Measurement times
Average driving value
Display benefit4 Handling of verification results
Instruments that pass the verification according to the requirements of this regulation shall be issued with a verification certificate, and those that fail shall be issued with a verification result notice and an indication of failure. Page 7
5.5 Brief verification period
The verification period shall generally not exceed one year
Appendix
Instrument name
Manufacturer!
Verification number
Inspection unit
Verification results
Appearance inspection:
JJG9752002
Verification record format (Class A instruments)
Verification temperature
Adjuster
Certificate and number
Record sieve number
Temperature indication value difference, temperature field uniformity
Aperture number
Temperature field uniformity| |tt||Indication error
Determination error of the digestion time (set time x sequence number
Measurement value
Relative indication error/%
A.4 Measurement and verification
Measurement value
Light qualitative
Indication error
COD liquid standard material (mgL)
4.6 Instrument repeatability
- 150 mp/L
JJG 975--2002
Measurement color (mgL)
Reproducibility/%
U -- 1 50 2ogrL
A.7 Conclusion:
Determined mw:
Order %
Average value: (mg)
Indication error%
Appendix B
Instrument name
Manufacturer code
Production code
Inspection unit
Verification result
Appearance inspection:
Indication error
0.0SmolrL
1/k,Ga,o, nT.
Friendliness
Measurement value: (mgL)
Reproducibility/%
B.4 Conclusion:
JJG975—2002
Calibration record format (R type instrument)
Calibration temperature
Career
Criteria
Criteria period
Area number
Measurement times
Average driving value
Display benefit4 Handling of verification results
Instruments that pass the verification according to the requirements of this regulation shall be issued with a verification certificate, and those that fail shall be issued with a verification result notice and an indication of failure. Page 7
5.5 Brief verification period
The verification period shall generally not exceed one year
Appendix
Instrument name
Manufacturer!
Verification number
Inspection unit
Verification resultswww.bzxz.net
Appearance inspection:
JJG9752002
Verification record format (Class A instruments)
Verification temperature
Adjuster
Certificate and number
Record sieve number
Temperature indication value difference, temperature field uniformity
Aperture number
Temperature field uniformity| |tt||Indication error
Determination error of the digestion time (set time x sequence number
Measurement value
Relative indication error/%
A.4 Measurement and verification
Measurement value
Light qualitative
Indication error
COD liquid standard material (mgL)
4.6 Instrument repeatability
- 150 mp/L
JJG 975--2002
Measurement color (mgL)
Reproducibility/%
U -- 1 50 2ogrL
A.7 Conclusion:
Determined mw:
Order %
Average value: (mg)
Indication error%
Appendix B
Instrument name
Manufacturer code
Production code
Inspection unit
Verification result
Appearance inspection:
Indication error
0.0SmolrL
1/k,Ga,o, nT.
Friendliness
Measurement value: (mgL)
Reproducibility/%
B.4 Conclusion:
JJG975—2002
Calibration record format (R type instrument)
Calibration temperature
Career
Criteria
Criteria period
Area number
Measurement times
Average driving value
Display benefit
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