JJG 631-2013 (JJG631-2013) & related versions
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JJG 631-2013
JJG
National Metrological Verification Regulations
of the People’s Republic of China
Ammonia-Nitrogen Automatic Analyzers
ISSUED ON. AUGUST 15, 2013
IMPLEMENTED ON. FEBRUARY 15, 2013
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine
Verification Regulation of
Ammonia-Nitrogen Automatic Analyzers
Replacing JJG 631-2004
Administrative organization.
National Environment Chemistry Metrology Technical Committee
Main Drafting organizations.
Shanghai Metrology and Testing Institute
Jiangsu Province Metrology Institute
Shanghai Electronics Scientific Instrument Co., Ltd.
National Environment Chemistry Metrology Technical Committee is entrusted
to be responsible for the explanation of this Regulation.
Main drafters of this Regulation.
Ding Min (Shanghai Metrology and Testing Institute)
Gong Feiyan (Shanghai Metrology and Testing Institute)
Xie Luyun (Shanghai Metrology and Testing Institute)
Participating drafters of this Regulation.
Cai Yeqiang (Jiangsu Province Metrology Institute)
Xing Jinjing (Jiangsu Province Metrology Institute)
Wang Qiaomei (Shanghai Electronics Scientific Instrument Co., Ltd.)
Table of Contents
Introduction ... 5
1 Scope ... 6
2 Overview ... 6
3 Measuring performance requirements ... 6
4 General technical requirements ... 7
5 Measuring instrument control ... 8
6 Processing of verification results ... 12
7 Verification cycle-time ... 12
Appendix A ... 13
Appendix B ... 14
Appendix C ... 17
Introduction
This regulation is the revision to JJG 631-2004 "Ammonia automatic analyzers”.
Compared with JJG 631-2004, in addition to editorial changes, the main
technical changes are as follows.
- Change the regulation’s name to "Ammonia-nitrogen automatic analyzers";
- The scope is extended from "applicable to ammonia automatic analyzers
(gas sensing electrode method)" to "applicable to online ammonia-nitrogen
automatic analyzers that is based on electrode method
and Spectrophotometry (see Article 1);
- Modify the instrument’s classification (see Article 3);
- Modify indicated value error’s performance requirements (see Table 1);
- Modify metrology device’s control requirements. Delete the requirements
to new ex-factory instruments that all requirements must be verified
according to Class A and Class B instruments (see Article 5);
- Modify the list of verification items in metrology device control. Add item
“response time” in “Use inspection” for electrode instrument (see Table 2);
- Modify the standard substances’ concentrations which are used for
verification of instrument’s indicated value error, stability, repeatability, and
response time (see Articles 5.3.2, 5.3.3, 5.3.4, 5.3.5);
- Modify the test result processing. Verification certificate is required to
provide the qualified category (see Article 6).
The historical version of JJG 631-2004 "Ammonia automatic analyzers" is.
- JJG 631-1989 "Ammonia automatic analyzers".
Ammonia-Nitrogen Automatic Analyzers
1 Scope
This regulation applies to initial verification, subsequent verification, and use
inspection of online ammonia-nitrogen automatic analyzers which is based on
electrode method and spectrophotometry.
2 Overview
Ammonia-nitrogen automatic analyzers can automatically and continuously
monitor the ammonia-nitrogen concentration in water bodies such as
groundwater, surface water, sewage, and industrial waste.
Measurement methods of ammonia-nitrogen automatic analyzers (hereinafter
referred to as the instrument) can be divided in electrode method and
spectrophotometry. Spectrophotometry includes salicylic acid
spectrophotometry and Nessler reagent spectrophotometry etc. Its principle is.
after ammonia or ammonium ions in water reacts with the indicator reagent, it
shows in color. At specific wavelength, the absorbance of the solution is
proportional to the ammonia-nitrogen content, so as to achieve the quantitative
analysis of ammonia-nitrogen in water sample. Electrode method includes gas-
sensitive electrode method and ammonia ion selection method. Through
measuring the electrode potential, the instrument obtains the ammonia-
nitrogen content in the water sample.
3 Measuring performance requirements
According the different use occasions of ammonia-nitrogen automatic
analyzers, the instrument is divided into Class A and Class B. Class A
instrument is used in occasion of low concentrations. Class B instrument is
used in occasion of high concentrations. For those occasions using both
classes, the instrument must meet all requirements of Class A and Class B.
Measuring instrument’s performance requirements are shown in Table 1.
5.3.4 Stability
In accordance with the instrument specifications and requirements, perform
preheating stability and calibration to the instrument. For Class A instrument,
use the ammonia-nitrogen standard solution with concentration of 2.0 mg/L to
measure. For Class B instrument, use the ammonia-nitrogen standard solution
with concentration of 25 mg/L to measure. Measure 1 time for each 0.5 h.
Continuously measure for 4 h. According to formula (6), calculate the relative
change amplitude of initial value for each measured value. Take the maximum
absolute value as the verification result of instrument stability.
Where.
M - instrument stability, %;
Ci – Instrument’s i-th measured value, mg/L;
c0 - initial measured value, mg/L.
5.3.5 Response time
The system is firstly cleaned with ammonia-free water. For Class A instrument,
use the ammonia-nitrogen standard solution with concentration of 2.0 mg/L to
measure. For Class B instrument, use the ammonia-nitrogen standard solution
with concentration of 25 mg/L to measure. When the test solution enters into
the instrument detection tank, it is as the starting point. Record the time when
the instrument’s indicated value reaches the 90% of stable indicated value.
Repeatedly measure for 3 times. Take the average value as the verification
result of response time.
5.3.6 Safety performance
5.3.6.1 Insulation resistance
Power plug is not connected to the grid. The power switch is at ON position.
Use insulation resistance meter to apply 500 V d.c. test voltage between the
power inlet-line and chassis. After it is stable for 5 s, measure the insulation
resistance.
5.3.6.2 Insulation strength
Power plug is not connected to the grid. The power switch is at ON position.
Use voltage-withstand tester to respectively apply test voltage between the
power inlet line and chassis. The test voltage is gradually increased to 1.5 kV,
current-limit of 5 mA. Maintain for 1 min. Observe if there is arcing and
C.2 Conclusion pages of verification certificate
Certificate Number xxxxxx - xxxx
Verification Result
Tested items and verification result.
Instrument category. Class A Class B
S/N Verification item Verification result
1 Appearance
2 Indicated value error /(% or mg/L)
3 Repeatability /%
4 Stability /%
5 Response time/min
6 Insulation resistance/MΩ
7 Insulation strength
8 Leakage Current/mA
(Blank)
C.3 Conclusion pages of verification certificate
Certificate Number xxxxxx - xxxx
Verification Result
Tested items and verification result.
Instrument category. Class A Class B
S/N Verification item Verification result
1 Appearance
2 Indicated value error /(% or mg/L)
3 Repeatability /%
4 Stability /%
5 Response time/min
6 Insulation resistance/MΩ
7 Insulation strength
8 Leakage Current/mA
Unqualified item of verification result.
(Blank)
......
| Standard ID | JJG 631-2013 (JJG631-2013) | | Description (Translated English) | Verification Regulation of Ammonia-Nitrogen Automatic Analyzers | | Sector / Industry | Metrology & Measurement Industry Standard | | Classification of Chinese Standard | A61 | | Classification of International Standard | 17.020 | | Word Count Estimation | 17,144 | | Older Standard (superseded by this standard) | JJG 631-2004 | | Drafting Organization | Shanghai Institute of Measurement and Testing | | Administrative Organization | National Technical Committee on Environment stoichiometric | | Regulation (derived from) | AQSIQ Announcement No. 114, 2013 | | Issuing agency(ies) | State Administration of Quality Supervision, Inspection and Quarantine | | Summary | This standard applies to: electrode method and spectrophotometry automatic monitor on -line ammonia initial verification, testing and use of the follow-up examination. |
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