GB/T 503-2016 Motor octane number of gasoline

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Card type: Test method

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

• Standard number: GB/T 503—2016
• Chinese name: Determination of gasoline octane number — Motor method (inferred from the file name; the body title source-text extraction is garbled, requires confirmation against the source standard (source-text extraction))
• English name: Determination of the gasoline octane number—Test method for motor octane number (the English title is garbled in the source transcription; verify the official title against the original standard)
• Replacement relationship: replaces GB/T 503—1995; previous versions are GB/T 503—1965, GB/T 503—1985, GB/T 503—1995
• Publication/implementation: published on 2016-06-14, implemented on 2017-01-01
• Adoption relationship: the original text states that the consistency degree of this part with ASTM D2700—12 "Determination of octane number of spark-ignition engine fuels — Motor method" is modified adoption (the original expression source-text extraction is garbled, requires confirmation against the source standard (source-text extraction))

2. Scope of application and non-applicability

• Applicable: specifies the test method for determining gasoline octane number (Motor method) using the CFR engine (the original expression source-text extraction is garbled, requires confirmation against the source standard (source-text extraction)).
• Applicable objects: determination of octane number of spark-ignition engine fuels, also applicable to other volatile distillate oils (the original expression source-text extraction is garbled, requires confirmation against the source standard (source-text extraction)).
• Octane number range: 0～120; the applicable gasoline octane number range of this method is 40～120. The applicable octane number range for leaded gasoline is 80～90; the applicable octane number range for unleaded gasoline is 98～102. Outside this range, this method may be referenced, but the precision may not be applicable.
• Units: this method uses the SI system of units; values in parentheses are in imperial units and are for reference only.
• Not applicable: the original text does not explicitly list non-applicable objects.

3. Method principle

• Under standard operating conditions, the sample is compared with reference fuels of known octane number in the CFR engine; by adjusting the compression ratio, the sample and the reference fuel are made to produce the same knock intensity, and the octane number of the sample is determined from the octane number of the reference fuel (the original expression source-text extraction is garbled, requires confirmation against the source standard (source-text extraction)).
• Definitions (3.1): including reference fuel, check fuel, cylinder height, knock meter (analog/digital), knock sensor, knock intensity, dynamic oil level, equilibrium oil level, ignition, maximum knock intensity fuel-air ratio, guide plate, knock, knockmeter (analog/digital), Motor method, Motor octane number, octane number, oxygenate, primary reference fuel, reference fuel, primary reference fuel (above/below 100), repeatability conditions, reproducibility conditions, expanded uncertainty, standard knock intensity (analog/digital), toluene standardization fuel, etc. (original text 3.1.1～3.1.30).
• Symbols (3.2): ARV, CFR, C.R., IAT, K.I., MIXT, OA, O.N., PRF, RTD, TSF.

4. Reagents and materials (purity / preparation)

• 8.3 Reference fuels (toluene, isooctane, n-heptane, etc.):
  • Isooctane (2,2,4-trimethylpentane): purity ≥99.75% (mass fraction), n-heptane ≤0.10% (mass fraction) (determined according to GB/T 8120), lead content ≤0.5 mg/L.
  • n-Heptane: purity ≥99.75% (mass fraction), isooctane ≤0.10% (mass fraction) (determined according to GB/T 8120), lead content ≤0.5 mg/L.
  • Reference fuel No. 80: prepared from isooctane and n-heptane, octane number 80, isooctane 80% (mass fraction) ±0.1% (mass fraction).
  • Reference fuels below No. 80: prepared according to Appendix C.
• 8.4 Toluene standardization fuel (TEL fuel): 70% (mass fraction) toluene + 30% (mass fraction) n-heptane; density 18.23% (volume fraction) ±0.05% (volume fraction) toluene, 15.6/15.6℃ density 0.957～0.967; composition is shown in Table 2 (isooctane 10.6%, n-heptane 52.5%, toluene 17.8%, others 0.87%).
• 8.5 Toluene: purity ≥99.5% (mass fraction) (determined according to GB/T 3144), sulfur content ≤5 mg/kg (determined according to SH/T 0176), total sulfur ≤200 mg/kg (determined according to GB/T 11133).
• 8.6 Diluent: solvent oil or white oil meeting the requirements (the original expression source-text extraction is garbled, requires confirmation against the source standard (source-text extraction)).
• 8.1 Coolant: 50% water + 50% ethylene glycol (volume ratio) or other equivalent coolant, freezing point ≤-100℃±1.5℃ (212℉±3℉) (the original expression source-text extraction is garbled, requires confirmation against the source standard (source-text extraction)).
• 8.2 Lubricating oil: meets API SAE 30 or equivalent specification, 100℃ kinematic viscosity 9.3 mm²/s～12.5 mm²/s, viscosity index ≥85.

5. Instruments and equipment

• CFR Engine (7.1): single cylinder, variable compression ratio, carburetor or electronic fuel injection, ignition system, knock measurement system, etc. (the original 7.1 expression source-text extraction is garbled, requires confirmation against the source standard (source-text extraction)).
• Knock measurement system (7.3): knock sensor, knock meter (analog/digital), knockmeter, etc.
• Cylinder height measuring device (7.3.2): micrometer, etc., range 200 mL～500 mL, accuracy ±0.2%.
• Temperature measurement: intake air temperature, mixture temperature, coolant temperature, oil temperature, etc.
• 10.3 Equipment related to operating conditions: compression ratio adjustment, ignition advance angle, carburetor/electronic fuel injection, intake air temperature, coolant temperature, oil temperature, etc.
• Appendix A (normative appendix): list of instruments, equipment, and materials (A.2, A.3, A.4, A.5).
• Appendix B (normative appendix): engine operating conditions (B.1, B.2).
• Appendix D (normative appendix): knock meter calibration (D.1～D.10).

6. Recommended operating conditions

• 10.2 Engine operating conditions:
  • Speed: 900 r/min ±9 r/min; ignition advance angle adjusted according to 10.2.3 (before top dead center 10.0°±2.5° or 34°, etc.; the original expression source-text extraction is garbled, requires confirmation against the source standard (source-text extraction)).
  • Intake air temperature: controlled according to 10.3.5 100℃±1.5℃ (212℉±3℉).
  • Coolant temperature: 100℃±1.5℃ (212℉±3℉).
  • Oil temperature: 57℃±8℃ (135℉±15℉).
  • Mixture temperature: 38℃±2.8℃ (100℉±5℉).
  • Carburetor/electronic fuel injection: controlled according to 10.3.7 149℃±1℃ (300℉±2℉).
  • Compression ratio: controlled according to 10.3.8 3.56 g/kg～7.12 g/kg (the original unit source-text extraction is garbled, requires confirmation against the source standard (source-text extraction)).
  • Ignition advance angle: adjusted according to 10.3.16 (26°, etc.).
  • Knock intensity: controlled according to 10.3.21 20～80.
• 10.3 Detailed parameters of operating conditions: including compression ratio, ignition advance angle, carburetor/electronic fuel injection, intake air temperature, coolant temperature, oil temperature, mixture temperature, knock intensity, etc. (original text 10.3.1～10.3.22).
• Table 3: carburetor/electronic fuel injection parameters at different intake air temperatures (0～500 m, 500～1000 m, 1000 m and above).
• Table 4: knock meter calibration parameters (R-fR< 264～1145, 4f 0.825～0.200 in, knockmeter 26～14).

7. Sampling and sample preparation

• 7.2 Sampling: carried out according to GB/T 4756 or SY/T 5317 (the original 9.1 states that sampling is carried out according to GB/T 4756 and SY/T 5317).
• 7.3 Sample preparation:
  • 7.3.1 Reference fuel: prepared according to GB/T 8120 or SH/T 0176.
  • 7.3.2 Primary reference fuel: prepared according to 7.3.2.1～7.3.2.6.
  • 7.3.3 Toluene standardization fuel: prepared according to 7.3.3.
  • 7.3.4 Calibration of reference fuel: carried out according to 7.3.4.
• 7.4 Sample treatment: carried out according to 7.4.1, 7.4.2.
• 9.2 Sample temperature: sample temperature is controlled at 2℃～10℃.
• 9.3 Sample storage: stored according to the requirements of 9.3.

8. Analysis procedure

• 8.1 Engine startup: carried out according to 8.1.
• 8.2 Engine operation: carried out according to 8.2.
• 8.3 Reference fuel preparation: carried out according to 8.3.1～8.3.4.
• 8.4 Toluene standardization fuel preparation: carried out according to 8.4.1～8.4.4.
• 8.5 Toluene: carried out according to 8.5.1, 8.5.2.
• 8.6 Diluent: carried out according to 8.6.
• 10.1 Engine operation: carried out according to 10.1.1, 10.1.2.
• 10.2 Engine operating conditions: proceed according to 10.2.1 to 10.2.6.
• 10.3 Operating conditions: proceed according to 10.3.1 to 10.3.22.
• 11.1 Engine start: proceed according to 11.1.1, 11.1.2.
• 11.2 Sample introduction: proceed according to 11.2.1 to 11.2.5.
• 11.3 79.6 to 94.7 Octane number range: proceed according to 11.3.1 to 11.3.5.
• 11.4 Below 79.6 or above 94.7 octane number range: proceed according to 11.4.1 to 11.4.5.
• 11.5 Calibration of reference fuels: proceed according to 11.5.1 to 11.5.5.
• 12.1 Knock meter reading: proceed according to 12.1.
• 12.2 Knock meter reading correction: proceed according to 12.2.1 to 12.2.3.
• 12.3 Sample determination: proceed according to 12.3.1 to 12.3.5.
• 12.4 Knock intensity: proceed according to 12.4.1 to 12.4.5.
• 13 Annex A (normative annex): Preparation of reference fuel (toluene standardization fuel).
• 14 Annex B (normative annex): Preparation of toluene standardization fuel.
• 15 Annex C (normative annex): Calibration of toluene standardization fuel.
• 16 Annex D (normative annex): Calibration of toluene standardization fuel (OA).
• 17 Octane number calculation: proceed according to 17.1, 17.2.
• 18 Precision: proceed according to 18.1 to 18.3.
• 19 Report: proceed according to 19.1, 19.2.

9. Qualitative and quantitative and calculation formulas

• 17.1 Calculate the octane number from the knock intensity of the test fuel and reference fuels.
• 17.2 Calculate according to formula (4):
  • X = (b - c)/(b - a) × (A - B) + B
  • Where: X— sample octane number; A— octane number of the high-octane reference fuel; B— octane number of the low-octane reference fuel; a— knock intensity of the high-octane reference fuel; b— knock intensity of the low-octane reference fuel; c— knock intensity of the sample.
• Example: sample octane number = 88.0 + (60 - 51)/(60 - 38) × (90.0 - 88.0) = 88.0 + 0.409 × 2.0 = 88.82.
• 18.1 Precision: proceed according to 18.1.1 to 18.1.3.
• 18.2 Reproducibility: proceed according to 18.2.
• 18.3 Report: proceed according to 18.3.
• 19.1 Report content: proceed according to 19.1.1 to 19.1.4.
• 19.2 Report format: proceed according to 19.2.1 to 19.2.6.
• Table 10: Repeatability and reproducibility for different octane number ranges (0.0 to 0.8, etc.).

10. Precision

• 18.1.1 Repeatability (r): as specified in Table 9, repeatability differs for different octane number ranges (below 80, 80 to 90, 90 to 102, 102 to 103, above 103).
• 18.1.2 Reproducibility (R): as specified in Table 9.
• 18.1.3 Report: proceed according to 18.1.3.
• 18.2 Reproducibility: proceed according to 18.2.
• 18.3 Report: proceed according to 18.3.
• Table 9: Repeatability and reproducibility (below 80, 80 to 90, 90 to 102, 102 to 103, above 103).
• Table 10: Repeatability and reproducibility for different octane number ranges (0.0 to 0.8, etc.).

11. Report

• 19.1 Report content:
  • 19.1.1 Round the numerical value according to GB/T 8170.
  • 19.1.2 Report the octane number of the sample.
  • 19.1.3 Report the environmental conditions during the test.
  • 19.1.4 Report the test date.
• 19.2 Report format:
  • 19.2.1 Report the octane number of the sample.
  • 19.2.2 Report the environmental conditions during the test.
  • 19.2.3 Report the test date.
  • 19.2.4 Report the standard number of the test method.
  • 19.2.5 Report the test results.
  • 19.2.6 Report the test personnel.

12. Normative references

• GB/T 3144 Determination of hydrocarbon impurities in toluene
• GB/T 4756 Manual sampling of petroleum liquids (GB/T 4756—1998, eqv ISO 3170:1988)
• GB/T 6682—2008 Specifications and test methods for water for analytical laboratory use (ISO 3696:1987 MOD)
• GB/T 8120 Determination of lead content in gasoline (atomic absorption spectrometry)
• GB/T 8170 Rules for rounding off numerical values and expression and judgment of limiting values
• GB/T 11133 Determination of water content in petroleum products - Distillation method
• SH/T 0176 Determination of mercaptan sulfur in jet fuels
• SH/T 0521 Determination of pour point of petroleum products
• SY/T 5317 Automatic sampling of petroleum liquids in pipelines (SY/T 5317—2006, ISO 3171:1988, IDT)
• ASTM D2700—12 Determination of octane number of spark-ignition engine fuels - Motor method
• ASTM D614 Determination of gasoline octane number (motor method)
• ASTM D357 Determination of gasoline octane number (research method)
• ASTM E1—13 Standard specification for liquid-in-glass thermometers
• ASTM E1—86 Standard specification for liquid-in-glass thermometers
• ASTM D02—1208, ASTM D02—1354, ASTM D02—69, etc. (original citation)

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 for questions and answers