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GB/T 18856.14-2002Test methods for quality of coal water mixture -- Part 14: Determination for pH value of coal water mixture (English PDF)

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Issued by

General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China Rep

Level / Type

National · Recommended

Issue date

October 18, 2002

Implementation date

April 1, 2003

Scope

GB/T 18856.14-2002 (Test methods for quality of coal water mixture -- Part 14: Determination for pH value of coal water mixture) is available as an English-translated PDF.

GB/T 18856.14-2002 is the Chinese standard "Test methods for quality of coal water mixture -- Part 14: Determination for pH value of coal water mixture". Its scope clause reads: This Part of GB/T 18856 specifies the method overview, apparatuses, test procedures, result expression, and precision for determining the pH value of coal water mixture.

This Part is applicable to various types of coal water mixture. Its clauses include method overview; reagents; apparatuses; specimen; test procedures. It was issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China Rep on 2002-10-18 and took effect on 2003-04-01.

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Document preview — GB/T 18856.14-2002

National Standard of the People's Republic of China

ICS: 75.160
Classification: D 21

Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China Rep

Foreword...3
1 Scope...4
2 Method Overview...4
3 Reagents...4
4 Apparatuses...5
5 Specimen...5
6 Test Procedures...5
7 Result Expression...6
8 Precision of the Method...6

1 Scope

This Part of GB/T 18856 specifies the method overview, apparatuses, test procedures, result expression, and precision for determining the pH value of coal water mixture.

This Part is applicable to various types of coal water mixture.

2 Method Overview

The glass electrode and calomel electrode of the pH meter are immersed in the coal water mixture, creating a potential difference between the two electrodes, thereby providing the pH value of the coal water mixture.

3 Reagents

3.1 Water

Distilled water or water of equivalent purity shall be freshly boiled and cooled to room temperature before use.

3.2 Buffer solutions with standard pH values

3.2.1 Neutral phosphate solution. pH around 7.

Weigh 3.40 g of potassium dihydrogen phosphate (GB 6853) and 3.55 g of disodium hydrogen phosphate (GB 6854); dissolve in carbon dioxide-free water; and dilute to 1000 mL. Potassium dihydrogen phosphate and disodium hydrogen phosphate shall be pre-dried at (120±10)°C for

2 h.

3.2.2 Potassium hydrogen phthalate standard solution. pH around 4.

Weigh 10.21 g of potassium hydrogen phthalate (GB 6857) dried at 110°C for 1 h; dissolve in carbon dioxide-free water; and dilute to 1000 mL.

3.2.3 Borate standard solution. pH 9 ~ 9.5.

Weigh 3.81 g of sodium tetraborate (GB 6856); dissolve in carbon dioxide-free water and dilute to 1000 mL. Prevent carbon dioxide from entering during storage.

The above three standard solutions must be prepared using pH standard substances. The pH values of each standard solution at different temperatures are shown in Table 1.

3.2.4 Standard pH value buffer solutions can also be prepared according to the instructions in the pH standard substance certificate.

4 Apparatuses

4.1 pH measuring device, capable of measuring to 0.1 unit. It shall be calibrated by standard pH value buffer solutions at the specified test temperature.

4.2 Wide-mouth plastic bottle or 50 mL beaker.

4.3 Mercury thermometer. 0°C~50°C, with graduation of 0.2°C.

5 Specimen

Water coal mixture specimen used for pH determination shall be sealed and placed at room temperature for at least 2 h before test.

6 Test Procedures

6.1 pH meter calibration

Select two standard pH value buffer solutions (close to or covering the pH of the water coal mixture being tested). Immerse the measuring part of the pH meter into one of the standard solutions and adjust the indicating part until the displayed pH value matches that of the standard buffer solution. Then immerse the measuring part into the other standard buffer solution. If the

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 6 pages — is available in the English PDF.

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