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JJG 631-2013Verification Regulation of Ammonia-Nitrogen Automatic Analyzers (English PDF)

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Issued by

General Administration of Quality Supervision, Inspection and Quarantine Verification Regulation of

Level / Type

National · Mandatory

Issue date

August 15, 2013

Implementation date

February 15, 2013

Scope

JJG 631-2013 (Verification Regulation of Ammonia-Nitrogen Automatic Analyzers) is available as an English-translated PDF.

JJG 631-2013 is the Chinese standard "Verification Regulation of Ammonia-Nitrogen Automatic Analyzers". Its scope clause reads: 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.

Its clauses include overview; measuring performance requirements; appearance; indicated value error /(% or mg/l); repeatability /%; stability /%; response time/min; insulation resistance/momega; insulation strength; leakage current/ma; appearance; indicated value error /(% or mg/l); repeatability /%; stability /%; response time/min; insulation resistance/momega; insulation strength; leakage current/ma.

It was issued by the General Administration of Quality Supervision, Inspection and Quarantine Verification Regulation of on 2013-08-15 and took effect on 2013-02-15.

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Document preview — JJG 631-2013

National Standard of the People's Republic of China

Issued by: General Administration of Quality Supervision, Inspection and Quarantine Verification Regulation of

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

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/Mohm

7 Insulation strength

8 Leakage Current/mA

(Blank)

C.3 Conclusion pages of verification certificate