SH/T 0585-1994 Determination of oxidation stability of aviation fuels (potential residue method)

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Card type: Test method

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

• Standard number: SH/T 0585-94
• Chinese name: Determination of oxidation stability of aviation fuels (potential residue method)
• English name: not provided in the available source
• Replacement relationship: not provided in the available source
• Other: approved under 1994-03-10, implemented under 1994-10-01; (confirmed in the year 2004)
• Reference adoption: ASTM D873-88 "Test method for oxidation stability of aviation fuels (potential residue method)"

2. Scope of application and non-applicability

• Applicable to: fuels for piston aviation engines and aviation turbine engines.
• Not applicable to: determination of the stability of fuel components, especially fuel components with a high content of low-boiling unsaturated hydrocarbons.

3. Method principle

Under the specified test conditions, place the oxygen bomb containing the 100 mL test sample into the oxidation bath after filling with oxygen; after reaching the specified time, separately determine the masses of soluble gum, insoluble gum, and sediment formed by oxidation of the sample.

4. Reagents and materials (purity / preparation)

• Toluene: chemically pure.
• Acetone: chemically pure.
• Gum solvent: equal-volume mixture of toluene and acetone.
• Oxygen: purity not lower than 99.6%.
• Note (source text): Oxygen can cause explosion and fire under high temperature and high pressure. During operation, keep away from heat sources, sparks, and open flames, and eliminate all ignition sources, especially some non-explosion-proof electrical appliances and heaters.
• Note (source text): Gum solvent is flammable and toxic. Avoid prolonged inhalation of its vapor or prolonged contact with skin, and use it under good ventilation conditions.

5. Instruments and equipment

• Oxygen bomb, glass sample bottle and lid, pressure gauge, and related accessories: see GB/T 8018 Appendix A (source text is "Appendix Aa", requires confirmation against the source standard (source-text extraction)).
• Thermometer: see GB/T 8018 Appendix B (source text is "Appendix Bo", requires confirmation against the source standard (source-text extraction)).
• Oven: temperature range 100～150 ℃.
• Steel tongs: corrosion resistant.
• Oxidation bath: see GB/T 8018 oxidation bath; the temperature can be controlled at a constant temperature of 100 ℃±0.1 ℃ or maintained at its boiling point, and this boiling point should be between 99.5～100.5 ℃.
• Microporous sintered glass crucible: fine pores, pore diameter not greater than 5 μm (source text is "5ymo", requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Sample amount: 100 mL±1 mL.
• Temperature of oxygen bomb and fuel to be tested: 15～25 ℃.
• Oxygen filling pressure: gauge pressure 689～703 kPa (100～102 psi).
• Venting speed: not greater than 345 kPa/min (50 psi/min), with each release time not less than 15 s.
• Leak determination: if the pressure drop rate within 10 min does not exceed 13.8 kPa (2 psi), the system is considered leak-free.
• Oxidation bath temperature: constant-temperature control at 100 ℃±0.1 ℃; or boiling water oxidation bath maintained at 99.5～100.5 ℃.
• Oxidation period correction: if the boiling water oxidation bath temperature deviates from 100 ℃, correct the "X" hour oxidation period according to the correction factors in Table 1.
• Drying conditions: dry in an oven at 100～150 ℃ for 1 h; cool in a desiccator for at least 2 h.
• Weighing precision: accurate to 0.1 mg.

Table 1 Oxidation period correction factors (source text)

Note: To obtain the corrected oxidation period at the operating temperature, multiply the specified oxidation period of 100 ℃ by the correction factor.

7. Sampling and sample preparation

• Sample according to GB/T 4756.
• Preparation work:
  • Thoroughly clean the glass sample bottle and lid to remove trace adhering substances. Soak the glass sample bottle and lid in a cleaning solution containing detergent, remove them from the cleaning solution with steel tongs (and thereafter hold them only with steel tongs), first rinse thoroughly with tap water, then with distilled water, then place in an oven at 100～150 ℃ to dry for 1 h, place the glass sample bottle and lid in a desiccator, cool for at least 2 h, weigh the mass of the glass sample bottle, accurate to 0.1 mg.
  • Note ①: A qualified cleaning solution should have the same cleaning effect as chromic acid; the above comparison can be made by observing the appearance and the mass loss of the glassware after heating under the test conditions.
  • Note ②: When using chromic acid cleaning solution, soak the glass sample bottle and lid in freshly prepared chromic acid cleaning solution for 6 h, then rinse with distilled water and dry. Chromic acid is a recognized carcinogen, has strong oxidizing properties, can cause severe burns on contact with the human body, can cause fire on contact with organic matter, and is highly hygroscopic; therefore, during use, never touch the liquid with hands, and wear protective clothing and protective gloves.
  • Note ③: Experiments show that the insoluble gum of piston aviation engine fuel is negligible; therefore, when testing such fuels, after the glass sample bottle is washed with gum solvent, unless visible insoluble matter remains, the glass sample bottle does not need to be weighed. If the former situation occurs, the test must be repeated, and the mass of the glass sample bottle recorded.
  • Drain all fuel from the oxygen bomb, first wipe the inner surfaces of the oxygen bomb and bomb lid with a wet cloth soaked with gum solvent, then wipe with a dry cloth, remove the bomb rod from the bomb handle, similarly wipe the bomb handle, bomb rod, and needle valve with gum solvent to remove gum and fuel. Before each test begins, the oxygen bomb, valve, and all connecting lines must be thoroughly dried.
  • Note (source text): In the previous test, volatile peroxides that have formed may accumulate in the apparatus. If not thoroughly removed, potentially explosive conditions may be created.
  • If a constant-temperature controlled oxidation bath is used, the temperature should be controlled at 100 ℃±0.1 ℃, and this temperature range should be maintained throughout the test.
  • If a boiling water oxidation bath is used, control the temperature within 99.5～100.5 ℃ by adding water or a liquid with a higher boiling point such as ethylene glycol. If the temperature deviates from 100 ℃, correct the "X" hour oxidation period according to the correction factors given in Table 1.

8. Analysis procedure

• 10.1 Maintain the oxygen bomb and the fuel to be tested within the temperature range of 15～25 ℃, add 100 mL±1 mL of test sample to the weighed glass sample bottle, place it in the oxygen bomb, cover the bottle lid, tighten the oxygen bomb, introduce oxygen until the gauge pressure reaches 689～703 kPa (100～102 psi), adjust the needle valve to vent at a slow rate not greater than 345 kPa/min (50 psi/min); when releasing pressure, do so uniformly and slowly, with each release time not less than 15 s, then repeat the oxygen filling and venting steps again to drive out the original gas in the bomb. Finally, fill the oxygen bomb pressure to 689～703 kPa (100～102 psi), and observe whether there is leakage; the rapid pressure drop due to oxygen dissolving in the sample may be ignored (generally not exceeding 41.4 kPa, i.e., 6 psi). If the pressure drop rate within 10 min does not exceed 13.8 kPa (2 psi), the system is considered leak-free, and the test may be carried out without re-pressurizing.
• 10.2 Place the oxygen bomb containing the test sample into the oxidation bath; when placing it, be careful not to shake it, and record the starting time when the oxygen bomb is immersed in the oxidation bath; the oxygen bomb remains in the bath for the specified "X" hour oxidation period. If a boiling water oxidation bath is used and the temperature after the start of the test deviates from 100 ℃, correct the oxidation time "X" hours using the correction factors given in Table 1.
• 10.3 After oxidation is completed, remove the oxygen bomb from the oxidation bath, and with the inlet valve closed, rapidly cool it with water to room temperature. Adjust the needle valve to release the pressure in the oxygen bomb at a rate not greater than 345 kPa/min (50 psi/min) (the pressure release process should be slow and uniform, and the operation process should not be less than 15 s). Open the oxygen bomb and take out the glass sample bottle.
• 10.4 If no obvious sediment is seen in the glass sample bottle, or if the specification does not explicitly require determination of its amount, the oxidized sample may be transferred directly to a flask; wash the glass sample bottle twice with gum solvent to remove soluble gum, using 10 mL of gum solvent each time; mix the oxidized sample and the wash liquid thoroughly, and retain this mixed liquid for determination of soluble gum; then test the glass sample bottle according to the procedure described in clause 10.6. If sediment appears in the glass sample bottle and the specification requires determination of its amount, filter the oxidized sample through a microporous sintered glass crucible and save the filtrate. Wash the glass sample bottle twice with gum solvent to remove soluble gum and sediment, using 10 mL of gum solvent each time. Filter the wash liquid through the microporous sintered glass crucible, mix the two filtrates thoroughly, and retain the mixed liquid for determination of soluble gum.
  • Note: Before determining the sediment, weigh the microporous sintered glass crucible by the same weighing method as the glass sample bottle, record the initial mass of the microporous sintered glass crucible, and weigh accurate to 0.1 mg.
• 10.5 Place the microporous sintered glass crucible in an oven at 100～150 ℃ to dry for 1 h, cool in a desiccator near the balance for at least 2 h, then weigh, and record the increased mass as sediment (A).
• 10.6 Dry the glass sample bottle in an oven at 100～150 ℃ for 1 h, cool in a desiccator near the balance for at least 2 h, then weigh, and record the increase in mass as insoluble gum (B).
• 10.7 Divide the mixed liquid obtained in clause 10.4 into two equal portions (within an error of 2 mL) and determine the soluble gum therein according to the procedure and test conditions of GB/T 8019, except that the sample amount for each test is not the 50 mL specified in method GB/T 8019, but half of the entire mixed liquid; record the sum of the mass increases of the two beakers as soluble gum (C).

9. Qualitative and Quantitative and Calculation Formulas

• Term definitions (Chapter 3): The terms used in this standard are all expressed as the milligrams of the following items in a 100 mL sample after X hours of oxidation. X is the accelerated oxidation period of 100 ℃.
  • 3.1 Precipitate: sediment and suspended matter in the oxidized fuel, obtained by filtering the oxidized fuel and the washings from the glass sample container.
  • 3.2 Insoluble gum: deposit adhering to the glass sample container after removing the oxidized fuel, precipitate, and soluble gum; the insoluble gum is measured by the mass increase of the glass sample container.
  • 3.3 Soluble gum: deterioration products appearing at the end of the specified oxidation period. Part of these deterioration products dissolves in the oxidized fuel; part deposits on the wall of the glass sample container and is soluble in toluene-acetone solution. The nonvolatile residue obtained by evaporating the oxidized fuel together with the washings from washing the glass sample container is the soluble gum.
  • 3.4 Potential gum: the sum of soluble gum and insoluble gum.
  • 3.5 Total potential residue: the sum of potential gum and precipitate.
• Calculation (Chapter 12 Table 2):
  • Potential gum, mg/100mL = the sum of insoluble gum B and soluble gum C (B+C)
  • Precipitate, mg/100mL = precipitate A (determined when required)
  • Total potential residue, mg/100mL = the sum of precipitate A (determined when required), insoluble gum B, and soluble gum C (A+B+C)

Table 2 Oxidation properties (original text)

10. Precision

Judge the reliability of test results according to the following provisions (95% confidence level).

11.1 Repeatability: The difference between two results obtained by repeated determination by the same operator shall not exceed the following values.

Repeatability (oxidation 16h) (original text)

11.2 Reproducibility: The difference between test results submitted by different operators in two laboratories shall not exceed the following values.

Reproducibility (oxidation 16h) (original text)

11. Report

Combine the separately measured results according to the format of Table 2, calculate the result, and report the result as the oxidation property for "X" hours of this test method.

12. Referenced Documents

• GB/T 4756 Petroleum liquids—Manual sampling
• GB/T 8018 Determination of oxidation stability of gasoline (induction period method)
• GB/T 8019 Determination of actual gum in automotive gasoline and aviation fuels (jet evaporation method)

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 Reference Q&A