SH/T 0021-1990 Determination of naphthenic acid soap content in jet fuel

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

1. Method number / full title / English name / replacement relationship

• Standard number: SH/T 0021-90
• Chinese title: Determination of naphthenic acid soap content in jet fuel
• English title: not provided in the available source
• Replacement relationship: not provided in the available source (the source text marks "(2〕confirmed in an old year)", suspected to be source-text extraction noise from "confirmed in 19XX", requires confirmation against the source standard (source-text extraction))
• Approval/implementation: approved by China Petrochemical Corporation 1991-03-27, implemented on 1992-04-01
• Technical committee: technically administered by the Research Institute of Petroleum Processing
• Drafting organization: Lanzhou Refining and Chemical Complex
• Main drafters: Qian Funan, Sun Fengying

2. Applicable scope and non-applicable scope

• This standard specifies a reaction-extraction method for determining the naphthenic acid soap content in jet fuel.
• Applicable to jet fuel with a naphthenic acid soap content of 0.003～0.01 % (m/m).
• Non-applicable scope: not provided in the available source.

3. Method principle

The sample is mixed and reacted with a standard hydrochloric acid titrant, then extracted twice with boiling water. The collected aqueous phase solution is concentrated, then a standard sodium hydroxide titrant is added, with phenolphthalein as indicator; after further concentration, it is titrated with the standard hydrochloric acid titrant until the pink color disappears.

4. Reagents and materials (purity / preparation)

• 5.1 Sodium hydroxide: analytical reagent, prepared as 0.01 mol/L standard titrant.
• 5.2 Hydrochloric acid: analytical reagent, prepared as 0.01 mol/L standard titrant.
  • Note: The concentrations of the two titrants should be as close as possible.
• 5.3 Phenolphthalein indicator: prepared as an ethanol indicator solution with a concentration of 10 g/L.
• 5.4 Distilled water: meets the grade three specification requirements in GB/T 6682.
  • Note: The distilled water used in this standard must be tested before use. Test method: take 100 mL water, concentrate to 10 mL, add 1 drops of phenolphthalein indicator solution while hot; if colorless, it may be used. (The volume unit source-text extraction here in the source text is ".L", suspected to be mL, requires confirmation against the source standard (source-text extraction))

5. Instruments and equipment

• 4.1 Pipette: 10 mL
• 4.2 Microburette: 2 mL, graduation 0.01 mL
• 4.3 Conical flask: 250 mL
• 4.4 Beaker: 250 mL
• 4.5 Graduated cylinder: 100, 500 mL
• 4.6 Separatory funnel: 500 mL
• 4.7 Electric furnace or electric heating plate

6. Recommended operating conditions

not provided in the available source (no recommended conditions such as chromatography or temperature programs; only operations such as boiling and concentrating to 5～10 mL are involved, see Section 8).

7. Sampling and sample preparation

• 6.1 Use a 500 mL graduated cylinder to measure 300 mL of sample and pour it into a separatory funnel, then extract with 100 mL water for 5 min. Place the aqueous phase solution into a conical flask, boil and concentrate to 5～10 mL, then add 1～2 drops of phenolphthalein indicator solution, titrate with standard hydrochloric acid titrant (5.2) until colorless, and record the volume of standard hydrochloric acid titrant consumed V₁. If the solution is colorless after adding phenolphthalein indicator solution, the water-soluble alkali of the sample is zero.
• 6.2 Determine the density of the sample at the test temperature according to GB/T 1884 and GB/T 1885.

8. Analytical procedure

• 7.1 Use a 100 mL graduated cylinder to measure 100 mL of sample, pour it into a separatory funnel, then use a pipette to accurately measure 10 mL of standard hydrochloric acid titrant, place it into the same separatory funnel, shake for 5 min and allow to stand for layer separation. Place the aqueous phase solution into a conical flask. Then repeat extraction twice with 30～40 mL of boiling water while hot. Combine the two aqueous phase solutions in the same conical flask, then place on an electric furnace or electric heating plate to boil and concentrate.
• 7.2 When the volume of the aqueous solution in the conical flask is 5～10 mL, remove the conical flask, accurately add 10 mL of standard sodium hydroxide titrant (5.1) into the conical flask with a pipette, shake well, add 1～2 drops of phenolphthalein indicator solution, and concentrate again to 5～10 mL (must be less than 10 mL).
• 7.3 Remove the conical flask, titrate while hot with standard hydrochloric acid titrant (5.2) until the pink color disappears, and record the volume of standard hydrochloric acid titrant consumed V₂.

9. Qualitative/quantitative determination and calculation formula

The naphthenic acid soap content in jet fuel X[% (m/m)] is calculated according to the following formula:

X = [ c × (V₂ − 1/3 V₁) × M/1000 ] / (V × ρ) × 100

Where:

• c —— actual concentration of the standard hydrochloric acid titrant, mol/L;
• V₂ —— volume of standard hydrochloric acid titrant consumed during titration, mL;
• V₁ —— volume of standard hydrochloric acid titrant consumed when determining water-soluble alkali, mL;
• V —— volume of the sample, mL;
• ρ —— density of the sample at the test temperature, g/mL;
• M/1000 —— mass of naphthenic acid soap, expressed in grams, equivalent to 1.00 mL of standard hydrochloric acid titrant [c(HCl) = 1.000 mol/L];
• M —— average molecular weight of naphthenic acid soap. When the density of the sample is 0.775～0.800 g/mL, M takes the value 240; when the density is greater than 0.800 g/mL, M takes the value 270.

(Note: The formula layout in the source text is extracted as source-text extraction, and the fraction structure is suspected to be misaligned, requires confirmation against the source standard (source-text extraction); the coefficient "1/3 V₁" and the term "M/1000" in the formula are subject to the source text.)

10. Precision

Precision (provisional), the reliability of test results is judged according to the following provisions (95% confidence level):

• 9.1 Repeatability (r): the difference between two results obtained by repeated determination by the same operator shall not exceed the value listed in the table below.
• 9.2 Reproducibility (R): the difference between two results submitted by different laboratories shall not exceed the value listed in the table below.

Precision table % (m/m)

(Note: The table source-text extraction in the source text is garbled in layout, and the correspondence between r and R values requires confirmation against the source standard (source-text extraction).)

11. Report

Take the arithmetic mean of two results from repeated determination as the naphthenic acid soap content of the sample, and report the test result to the fourth decimal place.

12. Referenced documents

• GB/T 1884 Standard test method for density of crude petroleum and liquid petroleum products by laboratory determination (hydrometer method)
• GB/T 1885 Petroleum measurement tables
• GB/T 6682 Specifications and test methods for water used in analytical laboratories

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Q&A