HJ/T 97-2003The technical requirement for water quality automatic analyzer of electroconductivity (English PDF)

2.1 Sample

The surface water, industrial wastewater and municipal wastewater that is led into

automatic analyzer.

2.2 Zero drift

The percentage of the change of an automatic analyzer's indication value over a given

period TO its measurement-range, when the zero correction solution specified in the

technical requirement is employed to give continuous test to sample.

2.3 Span drift

The percentage of the change of an automatic analyzer's indication value over a given

period TO its measurement-range, when the measurement-range correction solution

specified in the technical requirement is employed to give continuous test to sample.

2.4 Mean Time between Failures

The ratio of total hours (h) to failures (number) of an automatic analyzer during its

inspection period, expressed as "MTBF", in h/times.

2.5 Response Time (T90)

The time required for the indication value of an electrode system to reach 90% of the

standard electroconductivity value of measurement-range correction solution, when the

electrode system is moved from zero correction solution to measurement-range correction

solution.

7.1.6 Electroconductivity standard solution temperature

(25.0 ± 0.5)°C.

7.2 Reagent

7.2.1 Pure Water

Let distilled water pass through an ion exchange column. The electroconductivity shall be

less than 0.1mS/m.

7.2.2 Zero-point Correction Solution

Adopt the pure water as specified in 8.2.1.

7.2.3 Measurement-Range Correction Solution

Adopt the solution of 80% measurement-range value.

7.2.4 0.0100mol/L KCl Standard Solution

Weigh 0.7456g of potassium chloride (KCl) that has been dried at 105°C for 2h and

cooled down. Dissolve it in pure water and dilute to 1000ml at 25°C. The

electroconductivity of this solution (0.0100mol/L KCl) is 141.3mS/m at 25°C.

7.3 Test Preparation and Correction

7.3.1 Test Preparation

Connect the electrode to the signal converter. Switch on the power. Preheat the automatic

analyzer for more than 30min before starting the test, so as to make the function of all

parts and the displaying records unit to be stable. In case the electrode is polluted, it shall

be washed with detergents or 0.01 mol/L hydrochloric acid or the like. Then clean up with

running water, and dry-clean it.

7.3.2 Correction

7.3.2.1 Dip the electrode into the zero correction solution. Adjust the indication value to be

zero.

7.3.2.2 Dip the electrode into the measurement-range correction solution. Adjust the

indication value to be the electroconductivity value of 0.0300mol/L KCl standard solution.

7.3.2.3 Adjustment

Alternate the operation of 7.3.2.1 and 7.3.2.2.Adjust the analyzer until the difference

between the measured value and the standard value of the standard solution falls within

±1%.

8.5 Power supply category and capacity.

8.6 Manufacturer name.

8.7 Manufacturing date and batch number.

8.8 Signal output class (if necessary).

9.1 Selection of installation site.

9.2 Sample flow rate.

9.3 Piping and wiring.

9.4 Preheating time.

9.5 Use methods.

9.5.1 Measurement preparation and correction method.

9.5.2 Preparation method of correction solution.

9.5.3 Operating method of determination.

9.5.4 Handling when measurement is stopped.

9.6 Maintenance inspection.

9.6.1 Daily routine inspection methods.

9.6.2 Regular inspection methods.

9.6.3 Electrode system cleaning.

9.6.4 Countermeasures for failures.

9.7 Other considerations for use.

10.1 Routine calibration

For reproducibility, drift and response time, the calibrating period is at least once a month,

either by automatic or manual calibration.

10.2 Calibration under Supervision

The installed continuous monitoring system shall be calibrated regularly. And the regular

calibration results shall be reported to relevant administrative department of

environmental protection. Regular calibration shall be undertaken by qualified monitoring

agencies.

According to environmental monitoring technical specification, regular calibration mainly

includes on-site contrast test, review and examination of operation data and daily

operation records etc.

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