SH/T 0694-2000 Calculation of Cetane Index of Middle Distillate Fuels (Four-Variable Equation Method)

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Card type: Test method

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

• Standard number: SH/T 0694—2000
• Chinese full title: Calculation of Cetane Index of Middle Distillate Fuels (Four-Variable Equation Method)
• English name: Calculation of cetane index of middle-distillate fuels by the four-variable equation
• Replacement relationship: not provided in the available source (the foreword only states equivalent adoption of ISO 4264:1995, and does not mention replacement of an old standard)
• Adoption relationship: equivalent adoption of the international standard ISO 4264:1995 "Petroleum products—Calculation of cetane index of middle-distillate fuels—Four-variable equation method"
• Publication/implementation: published on 2000-09-11, implemented on 2001-01-01; issued by the State Bureau of Petroleum and Chemical Industry
• Responsible body: Sinopec Research Institute of Petroleum Processing
• Drafting organization: Sinopec Research Institute of Petroleum Processing
• Main drafters: Yang Tingting, Chen Jie

2. Scope of application and non-applicability

• 1.1 specifies the calculation method for the cetane index of petroleum middle distillate fuels; the term "cetane index" denotes the "four-variable equation method cetane index".
• 1.2 applies to petroleum middle distillate fuels and fuels containing non-petroleum distillates derived from oil sands and oil shale.
• Not applicable to: fuels containing cetane number improvers; pure hydrocarbons; distillate fuels produced from coal.
• Note 1: This standard was mainly developed through research on a large number of middle distillate fuels, some of which contain non-petroleum distillates derived from oil sands and oil shale; other cetane index calculation equations that have been developed may be more applicable to oil sand products.
• Note 2: The cetane index cannot serve as a substitute value for the cetane number; it is an auxiliary characterization value with certain usage limitations. When the cetane number of a diesel fuel cannot be directly determined by engine testing or when the engine test sample is insufficient, the cetane index may be used for estimation; when the fuel cetane number is known and the source and production method remain unchanged, the cetane index may also be used to verify the cetane number of successive similar fuel samples.
• 1.3 Recommended application range (fuel property | recommended range):
  • Cetane number: 32.5~56.5
  • Density (15 °C), kg/m³: 805.0~895.0
  • 10% recovery temperature, °C: 171~259
  • 50% recovery temperature, °C: 212~308
  • 90% recovery temperature, °C: 251~363
• Note: For cetane numbers within the recommended range (32.5~56.5), the results calculated by the four-variable cetane index calculation equation for the 65% distillate fuels that have been tested have an error of no more than ±2 cetane numbers; outside the recommended range, the error between the calculated cetane index and the cetane number of the fuel will be larger.

3. Method principle

Determine the 15 °C density of the test sample and the 10%, 50% and 90% recovery temperatures in accordance with standard test methods. Using the measured test data, calculate the cetane index of the test sample according to the given equation.

4. Reagents and materials (purity / preparation)

Not provided in the available source.

5. Apparatus and equipment

Not provided in the available source (the standard is a calculation method; the apparatus required for testing is specified by the referenced methods).

6. Recommended operating conditions

Not provided in the available source (there is no independent operating conditions section; the determination conditions are specified by the referenced methods).

7. Sampling and sample preparation

Not provided in the available source.

8. Analysis procedure

• 4.1 In accordance with the operating procedures of GB/T 1884 or SH/T 0604, and the GB/T 1885 method, determine the 15 °C density of the test sample, accurate to 0.1 kg/m³ (the source source-text extraction has "kg/in'", requires confirmation against the source standard (source-text extraction)).
• 4.2 In accordance with the operating procedures of GB/T 6536, determine the 10%, 50% and 90% recovery temperatures of the test sample at standard atmospheric pressure, accurate to 1 °C.

9. Qualitative and quantitative determination and calculation equation

• 5.1 In accordance with the procedure of 5.1.1 or 5.1.2, calculate the cetane index of the test sample.
• 5.1.1 Substitute the test data obtained from 4.1 and 4.2 into equation (1) to calculate the cetane index CI of the test sample:
  • CI = 45.2 + 0.089 2T₁₀ + (0.131 − 0.901B)T₅₀ + (0.052 3 − 0.42B)T₉₀ + 0.000 49(T₁₀² − T₉₀²) + 107B + 60B²
  • Where:
    • T₁₀ = t₁₀ − 215
    • T₅₀ = t₅₀ − 260
    • T₉₀ = t₉₀ − 310
    • t₁₀ — the 10% recovery temperature of the test sample, °C
    • t₅₀ — the 50% recovery temperature of the test sample, °C
    • t₉₀ — the 90% recovery temperature of the test sample, °C
    • B = [exp(−0.003 5D)] − 1
    • D = d − 850
    • d — the 15 °C density of the test sample, kg/m³
  • Note: In the source equation, the symbols and subscripts of T₁₀, T₅₀, T₉₀ contain source-text extraction noise (such as "T0", "Tso", "Too", "TBN", etc.); the above is the result organized according to context, requires confirmation against the source standard (source-text extraction).
• 5.1.2 Graphical method (using Figure 1, Figure 2, Figure 3):
  • a) Using the 15 °C density and 50% recovery temperature of the test sample obtained from 4.1 and 4.2, according to Figure 1, obtain the estimated cetane index of the test sample.
  • b) Using the 15 °C density and 90% recovery temperature of the test sample obtained from 4.1 and 4.2, according to Figure 2, obtain the first correction coefficient for the deviation of the cetane index of the test sample from the average value.
  • c) Using the 10% and 90% recovery temperatures of the test sample obtained from 4.2, according to Figure 3, obtain the second correction coefficient for the deviation of the cetane index of the test sample from the average value.
  • d) Add the correction coefficients obtained from Figure 2 and Figure 3 to the estimated cetane index obtained from Figure 1, and finally obtain the cetane index of the test sample.
• 5.2 Example of use of the graphical method (the cetane number of this fuel is 46.8):
  • 5.2.1 Measured fuel properties:
    • Density (15 °C), kg/m³: 860.0
    • 10% recovery temperature, °C: 220
    • 50% recovery temperature, °C: 290
    • 90% recovery temperature, °C: 340
  • 5.2.2 Calculate cetane index CI:
    • Estimated cetane index obtained from Figure 1: 44.1
    • First correction coefficient obtained from Figure 2: +0.4
    • Second correction coefficient obtained from Figure 3: +1.5
    • CI = 46.0
  • Note: In the source example, "+15" is suspected to be "+1.5", requires confirmation against the source standard (source-text extraction).

10. Precision

• 6.1 The cetane index calculated from the measured 15 °C density and the 10%, 50% and 90% recovery temperatures of the test sample is exact.
• 6.2 The precision of the cetane index calculation method depends on the precision of the determination results of the density and the temperatures corresponding to the recovery percentages involved in the calculation. The precision of these determination results has been specified in methods GB/T 1884, SH/T 0604 and GB/T 6536.
• Note: In the source 6.2, "GB/T 188", "SH/T 0504", "CB/T 6535" are source-text extraction noise; according to the referenced standard clauses they should be GB/T 1884, SH/T 0604, GB/T 6536, requires confirmation against the source standard (source-text extraction).

11. Report

Report the calculated cetane index result of the test sample, accurate to 0.1.

12. Referenced documents

• GB/T 1884 Standard test method for density of crude petroleum and liquid petroleum products (hydrometer method)
• GB/T 1885 Petroleum measurement tables
• GB/T 6536 Standard test method for distillation of petroleum products
• SH/T 0604 Standard test method for density of crude petroleum and petroleum products (U-shaped vibrating tube method)
• Note: The provisions of the following standards, through reference, constitute a part of this standard. Unless otherwise expressly specified in this standard, the following referenced standards shall all be currently effective standards.

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