SH/T 0175-2004 Oxidation Stability of Distillate Fuel Oil (Accelerated Method)

AI-translated method card — human verification pending. This is not an official translation of the standard. Check the original controlled standard before use.

Source limitations: The source card does not reproduce the apparatus figures or the Appendix A and Appendix B tables in full. The available PDF was visually checked for the precision root indices, two table entries, formula grouping, sample volume and inert-gas wording; these transcription checks await independent review. Exact membrane composition remains unverified. This page does not establish technical equivalence, current validity or product suitability.

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

• Method number: SH/T 0175-2004
• Full title: Oxidation Stability of Distillate Fuel Oil (Accelerated Method)
• English title: Standard test method for oxidation stability of distillate fuel oil (accelerated method)
• Replacement relationship recorded in the source card: replaces SH/T 0175-2002; previous editions: SH/T 0175-92, SH/T 0175-94 and SH/T 0175-2002. Current controlled status requires separate verification.
• Adoption relationship recorded in the source card: modified adoption of ASTM D2274-2001. This statement does not establish technical equivalence or interchangeability.
• Publication/implementation: published on 2004-04-09; implemented on 2004-09-01.
• Issuing body: National Development and Reform Commission of the People's Republic of China.

2. Scope and exclusions

• 1.1 Specifies an accelerated oxidation method for determining the inherent stability of middle-distillate fuel oils.
• Does not apply to fuel oils containing residual oil or synthetic fuel oils whose principal constituents are non-petroleum components.
• 5.1 Applies to evaluating the storage stability of middle-distillate fuel oils with a 90% recovery temperature below 370°C.
• 1.2 The standard does not address every safety issue associated with its use. Users must establish appropriate safety and protective measures and determine applicable restrictions before use.

3. Principle

Place a filtered 350mL test portion in an oxidation tube and pass oxygen through it at 50mL/min while oxidizing at 95°C for 16h. Cool the oxidized test portion to room temperature and filter it to obtain filterable insolubles. Wash adherent insolubles from the walls of the oxidation tube and oxygen-delivery tube with the three-solvent mixture, then evaporate the mixture to obtain the adherent insolubles. The sum of filterable and adherent insolubles is the total insolubles, expressed in mg/100mL.

4. Reagents and materials (purity / preparation)

• 8.1 Reagent purity: use analytical-reagent grade or higher-purity reagents.
• 8.2 Water purity: unless otherwise specified, meet the Grade III water requirements of GB/T 6682.
• 8.3 Isooctane: purity at least 99.75%. Prefilter through one membrane before use.
• 8.4 Oxygen: purity at least 99.5%. If supplied through a plant distribution line, install a filter upstream of the constant-temperature bath to prevent moisture and foreign matter from entering the oxidation tube, and fit a pressure regulator to maintain stable flow. Cylinders meeting the requirements may also be used. Note: oxygen supports combustion; do not use equipment with oily or greasy surfaces.
• 8.5 Three-solvent mixture: equal volumes of acetone, methanol and toluene. Note: use analytical-reagent grade or higher-purity reagents to prepare this mixture; otherwise the measured adherent insolubles may increase appreciably. The mixture is flammable and toxic.

5. Apparatus

• 7.1 Oxidation assembly: borosilicate glass, with dimensions as shown in Figure 1 of the source standard. Consists of an oxidation tube, condenser and oxygen-delivery tube. The source identifies it as the same oxidation tube used in GB/T 12581.
• 7.2 Heating bath: contains a liquid heating medium controlled at 95°C±0.2°C. Stirring maintains a uniform bath temperature. The bottom of each oxidation tube can be immersed approximately 350mm below the heating-medium surface. The arrangement must protect the test portion from light during oxidation.
• 7.3 Float flowmeter: 50mL/min±5mL/min; connect one flowmeter to each oxidation tube.
• 7.4 Membrane drying oven: for drying filterable insolubles, controlled at 80°C±2°C.
• 7.5 Glassware drying oven: for drying glassware, controlled at 105°C±5°C.
• 7.6 Filtration apparatus: as shown in Figure 2 of the source standard; capable of securing the membranes specified in 7.7.
• 7.7 Membranes: cellulose-based membranes (exact membrane composition remains unverified), 47mm in diameter, nominal pore size 0.8μm, free from surfactants. The source-card material wording requires confirmation against the controlled standard.
  • 7.7.1 Use one membrane for sample prefiltration.
  • 7.7.2 Use two mass-matched membranes, or membranes selected by prior weighing, to determine filterable insolubles.
• 7.8 Evaporation vessel: tall-form borosilicate glass beaker, 200mL.
• 7.9 Hotplate: capable of reaching 135°C, for heating solvent in the evaporation vessel.
• Note: calibrate the apparatus according to the manufacturer's instructions to ensure stable test results.

6. Operating conditions recorded in the source

• Oxidation temperature: 95°C±0.2°C.
• Oxygen flow rate: 50mL/min±5mL/min.
• Oxidation time: 16h±0.25h.
• Test-portion volume: 350mL±5mL.
• Membrane drying temperature: 80°C±2°C.
• Glassware drying temperature: 105°C±5°C.
• Hotplate evaporation temperature: 135°C.
• Evaporation temperature for the GB/T 8019 jet-evaporation method: 160°C.
• Filtration vacuum: approximately 80kPa.
• Note (11.2.3): the time in the heating bath may be extended appropriately, for example to 40h, but the precision values apply only to the 16h cycle.

7. Sampling and test-portion preparation

• 9.1 Sample in accordance with GB/T 4756 or another sampling standard to obtain a representative sample.
• 9.2 Analyze samples as soon as possible after receipt. If testing cannot be performed within one day, the source specifies an inert-gas blanket, listing oxygen-free nitrogen, argon or helium. The source-card text extraction rendered the middle gas name as "hydrogen"; the available PDF glyph was visually checked as argon, and independent review remains pending. Do not use the unverified extracted gas name as an operating instruction. Storage temperature must not exceed 10°C and must not be below the sample cloud point. Note: use a precleaned metal container or glass container protected from light; do not use plastic or soft-glass (soda-glass) containers. For No. 5 and No. 10 light diesel samples, the storage temperature may be raised to no more than 15°C.
• 9.3 Test sample: approximately 400mL per test. The source-card OCR flag for the fragment "<IOML" is retained; the available PDF was visually checked, while independent review remains pending. If the sample is in a large container, mix thoroughly by oscillating, shaking or another suitable means. Divide it into test samples by pouring, suction through tubing or another method. Wash tubing, sampling devices, pipettes, beakers and all items that contact the sample first with the three-solvent mixture and then rinse with a small amount of sample. Because storage temperature may be below 10°C, allow the sample to reach room temperature before mixing and subdivision.
• 11.1 Test-portion preparation: place one membrane on the support plate and clamp the membrane, funnel and support together. Connect the vacuum system, with a vacuum of approximately 80kPa, and filter approximately 400mL into a clean 500mL suction flask; discard the membrane. Prepare each test portion in this way. Do not reuse a membrane from a previous filtration.

8. Procedure

• 11.2 Oxidation of the test portion
  • 11.2.1 Place 350mL±5mL of filtered test portion in a clean oxidation tube. As soon as practicable, and within 1h, place the tube in the bath already maintained at 95°C±0.2°C. The test-portion surface must be below the heating-medium surface. Protect the tube from light during temporary storage.
  • 11.2.2 After placing the oxidation tube in the bath, fit the oxygen-delivery tube and condenser, connect cooling water and oxygen, and adjust oxygen flow to 50mL/min±5mL/min. Protect the test portion from light.
  • 11.2.3 Record when the first oxidation tube enters the bath; this is zero time.
• 11.3 Cooling the test portion
  • 11.3.1 At 16h±0.25h from zero time, remove the oxidation tubes in the order in which they were placed in the bath. Cover each opening with aluminum foil or plastic sheet of matching size. Record when the first tube is removed.
  • 11.3.2 Cool the tubes in a ventilated, dark location at room temperature, which must be above the sample cloud point, until close to room temperature. The standing time must not exceed 4h.
• 11.4 Determination of filterable insolubles
  • Place two mass-matched membranes on the support plate, assemble the filtration apparatus and apply a vacuum of approximately 80kPa. Pour in and filter the test portion after cooling to room temperature. Add isooctane rinse only after the entire test portion has been filtered. Rinse the oxidation tube and oxygen-delivery tube three times with 50mL±5mL of isooctane each time, passing all rinses through the apparatus under suction. After filtration, remove the upper funnel section and clean the membrane support and adjacent parts with a further 50mL±5mL of isooctane; discard the filtrate. Carefully remove both membranes, dry at 80°C±2°C for 30min, and cool for 30min. Weigh the upper membrane (sample) and lower membrane (blank) separately to 0.1mg. Calculate filterable insolubles (A).
  • Note: if severe membrane blockage prevents filtration from being completed within 2h, use another pair of membranes for the remaining test portion.
• 11.5 Determination of adherent insolubles
  • 11.5.1 Use 75mL±5mL of the three-solvent mixture in three portions to wash insolubles from the walls of the oxidation tube and oxygen-delivery tube.
  • 11.5.2 Inspect the tube surfaces for remaining insolubles or discoloration. If either remains, rinse again with 25mL of the three-solvent mixture.
  • 11.5.3 Evaporation of the three-solvent mixture: use either of the following procedures.
    • 11.5.3.1 Collect the rinses in a previously weighed 200mL tall-form beaker. Heat on a hotplate at 135°C in a fume hood to evaporate the solvent mixture. After evaporation, cool the beaker containing insolubles for 1h in a desiccator without desiccant, then weigh each beaker to 0.1mg.
    • 11.5.3.2 Alternatively, collect the rinses in 1 or 2 beakers of 100mL capacity specified in GB/T 8019 and evaporate the mixture at 160°C using the GB/T 8019 jet-evaporation procedure.
  • 11.5.4 Evaporate and test an equal volume of the three-solvent mixture as the adherent-insolubles blank to correct for impurities in the mixture.
• 10. Preparation of apparatus
  • 10.1 Glassware other than oxidation tubes: rinse all glassware with the three-solvent mixture, wash with water and a moderately alkaline or neutral laboratory detergent, rinse three times with distilled water, and finally wash with acetone to remove water. Dry before use.
  • 10.2 Oxidation tubes and accessories: fill the tube with aqueous detergent, fit the oxygen-delivery tube and condenser, and soak for at least 2h. Brush-clean, discard the wash solution, rinse 5 times with tap water, and then rinse three times with distilled water or water meeting the Grade III requirements of GB/T 6682. Wash with acetone to remove water, and dry before use.
  • 10.3 Evaporation vessels: dry the cleaned 200mL tall-form beakers, including blank-test beakers, at 105°C±5°C for 1h. Cool for 1h in a desiccator without desiccant and weigh each beaker to 0.1mg.

9. Determination and calculation

• 12.1 Calculate filterable insolubles A (mg/100mL) using equation (1): A = (m2 - m1) / 3.5 Where m1 is the mass of the lower (blank) membrane, mg; m2 is the mass of the upper (sample) membrane, mg.
• 12.2 Calculate adherent insolubles B (mg/100mL) using equation (2): B = [(m6 - m4) - (m5 - m3)] / 3.5 Where m3 is the mass of the blank-test beaker, mg; m4 is the mass of the sample-test beaker, mg; m5 is the total mass of the blank-test beaker and its contents after the test, mg; m6 is the total mass of the sample-test beaker and its contents after the test, mg. (Note: the source card flagged the numerator in equation (2) as incomplete in OCR. The grouping shown here follows the available PDF after visual inspection; independent technical review remains pending.)
• 12.3 Calculate total insolubles X (mg/100mL) using equation (3): X = A + B

10. Precision

• 14.1 Precision: established by statistical analysis of interlaboratory test results at the 95% confidence level.
• 14.1.1 Repeatability: the difference between two results on the same sample, obtained by the same operator using the same apparatus under identical operating conditions, must not exceed the value calculated using equation (4) or the corresponding value in Table 1. r = 0.54∜X [fourth root; the source card omitted the root index; visually checked against the available PDF, independent review pending] Where X is the mean of the two total-insolubles results, mg/100mL.
• 14.1.2 Reproducibility: the difference between two results on the same sample, obtained by different operators in different laboratories, must not exceed the value calculated using equation (5) or the corresponding value in Table 1. R = 1.06∜X [fourth root; the source card omitted the root index; visually checked against the available PDF, independent review pending] Where X is the mean of the two total-insolubles results, mg/100mL.
• Table 1 Typical repeatability and reproducibility values for total insolubles (mg/100mL):

• 14.2 Bias: not stated because no suitable reference sample is available for this standard.

11. Report

• 13.1 Report the arithmetic mean of the duplicate total-insolubles determinations as total insolubles X (mg/100mL), rounded to one decimal place.
• 13.2 Filterable insolubles A (mg/100mL) and adherent insolubles B (mg/100mL) may also be reported.

12. References

• GB/T 4756 Manual sampling of petroleum liquids (GB/T 4756-1998, ISO 3170:1988, EQV; relationship recorded in the source, not independently verified here).
• GB/T 6682 Water for analytical laboratory use: specification and test methods (GB/T 6682-92, ISO 3696:1987, MOD; relationship recorded in the source, not independently verified here).
• GB/T 8019 Determination of existent gum in motor gasoline and aviation fuels by jet evaporation (GB/T 8019-87, ISO 6246:1981, MOD; relationship recorded in the source, not independently verified here).
• GB/T 12581 Oxidation characteristics of inhibited mineral oils.
• SH/T 0690 Storage stability of distillate fuel oils at 43°C.

13. Source and verification notes

• Items flagged by the source card for OCR review: the sample-volume fragment "<IOML" in 9.3; the unclear Table 1 reproducibility fragment "0.[illegible]" at 0.1 and repeatability fragment "0.o" at 1.5; the numerator of equation (2) in 12.2; and substantial OCR noise in the Appendix A and Appendix B tables, which the card does not reproduce item by item. PDF transcription checks noted above do not replace independent technical review.

14. Quick-reference questions