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GB/T 259-1988 English PDF (GBT259-1988)

GB/T 259-1988 English PDF (GBT259-1988)

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GB/T 259-1988: [Renamed from GB 259-1988] Petroleum products. Determination of water-soluble acids and alkalis

This method is suitable for the determination of the water-soluble acids and alkalis of the liquid petroleum products, additives, greases, paraffin waxes, ceresin waxes, wax-containing components. The water-soluble acid or alkali in the specimen is extracted by distilled water or ethanol aqueous solution, then the color change of the extract is checked by the methyl orange or phenolphthalein indicator, respectively, or otherwise the pH of the extract is determined by a pH meter, to determine whether or not there is a water-soluble acids or alkalis.
GB 259-1988
UDC 665.52
Replacing GB 259-1977
Petroleum products -
Determination of water-soluble acids and alkalis
Issued by. China Petrochemical Corporation
Table of Contents
Foreword ... Error! Bookmark not defined.
1 Summary of methods ... 3
2 Instruments ... 3
3 Reagents and materials ... 3
4 Preparation ... 4
5 Test steps ... 4
6 Precision ... 6
7 Report ... 6
3.1.2 Phenolphthalein. Prepare it into a 1% phenolphthalein ethanol solution. 3.1.3 95% ethanol. Analytically pure.
3.2 Materials
3.2.1 Filter paper. Industrial filter paper.
3.2.2 Solvent oil. It meets the NY-120 requirements in GB 1922 ?€?Solvent oil?€?. 3.2.3 Distilled water. It meets the requirements for the grade III water in GB 6682 ?€?Water for laboratory use - Specifications?€?.
4 Preparation
4.1 Preparation of specimen.
4.1.1 Place the specimen in a glass bottle, no more than three-quarters of its volume. Shake if for 5 min. Viscous or paraffin specimen shall be preheated to 50 ~ 60 ??C before being shaken.
4.1.2 When the specimen is grease, use a blade to scrape off the surface layer (3 ~ 5 mm) of the specimen. Then at least three places not close to the wall of the container, take about the same amount of specimen. Place it into the porcelain evaporating dish. Use a glass rod to carefully stir it uniformly. 4.2 The 95% ethanol can only be used after checking by the use of methyl orange and phenolphthalein indicator, or pH meter to confirm that it is neutral. 5 Test steps
5.1 When testing the liquid petroleum products, place 50 mL of specimen and 50 mL of distilled water in a separatory funnel. Heat it to 50 ~ 60 ??C. Light petroleum products such as gasoline and solvent oil do not need heating. For the petroleum products which has a kinematic viscosity greater than 75 mm2/s at 50 ??C, first mix it with 50 mL of gasoline at room temperature. Then add 50 mL of distilled water which is heated to 50 ~ 60 ??C.
Gently shake the test solution in the separatory funnel for 5 min. It is not allowed for emulsification. Discharge the lower aqueous layer after clarification. Use filter paper to filter it into a conical flask.
5.2 When testing the grease, paraffin waxes, ceresin waxes, wax-containing components, take 50 g of pre-melted specimen, weight it to 0.01 g. Place it in a porcelain evaporating dish or conical flask. Then inject 50 mL of distilled water. test tube which contains the same volume of distilled water and methyl orange solution. If the extract is rosy, it means that there are water-soluble acids in the petroleum product tested.
In the second tube which contains the extract, add 3 drops of phenolphthalein solution. If the solution is rosy or red, it indicates the presence of water-soluble alkalis.
When the extract uses the methyl orange or phenolphthalein as an indicator and it does not exhibit rosy or red color, it is considered that there is no water- soluble acids or alkalis.
5.5.3 When there is an inconsistency in the quality evaluation of petroleum products, the arbitration test of water-soluble acids or alkalis is carried out according to 5.5.1.
6 Precision
6.1 The provisions on the precision applies only to the pH meter method. 6.2 The difference between the two results proposed by the same operator shall not be greater than 0.05 pH.
7 Report
Take the arithmetic mean of the two pH values from repeated determination as the test result.
Additional information.
This standard shall be under the technical jurisdiction of the Petrochemical Science Institute.
This standard was drafted by the Petrochemical Science Institute.
This standard refers to and adopts the Soviet national standard TOCT 6307-75

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