GB/T 386-2010 Determination of cetane number of diesel fuel

Summary page. This page is a compiled excerpt/summary of the standard — it is not the full standard text and does not replace it. Verify every value against the official standard and the product certificate before use.

GB/T 386-2010 specifies the determination of the cetane number of diesel fuel in a standardized single-cylinder compression-ignition engine, and this page summarizes its version boundary, scope, principle, equipment, reference fuels, operating parameters, calculation and precision.

Evidence note: historical study material for the 2010 edition; the official record shows it abolished and replaced by the 2021 edition. Compiled only from the 38-page original in hand, not merged with the new edition; no equivalence, product applicability or basis for current operation is inferred. Technical review is pending; normative and informative annexes are listed separately, and complex figures and complete controlled safety operations have not been reconstructed.

Version, source and historical boundary: Original PDF pages 1–6; two SAMR service records. GB/T 386-2010 was published on 2011-01-10 and implemented on 2011-05-01; the 38 pages held include watermarked blank pages and a copyright end page, and the page count is not taken directly as technical acceptance. The original and the OCR are read-only. The foreword states modification adoption of ASTM D613-08, not equivalence. The official record shows the 2010 edition abolished and fully replaced by GB/T 386-2021; the two services both belong to SAMR and are not two technical originals. This card keeps the 2010 edition, and current contracts or tests should confirm the version separately.

What is measured and the scope boundary: Original PDF pages 5, 7, introduction/Chapter 1. The cetane number characterizes the ignition quality of diesel fuel in a specified compression-ignition test engine, on a scale of 0–100, with typical tests at 30–65. The original document includes non-conventional fuels, but the correlation with the full scale, with variable-speed variable-load engines and with the actual properties of non-conventional fuels is not fully clear; the scale is not used to infer applicability to all samples, nor is the precision table extrapolated to the full scale.

Determination chain and standard bracketing: Original PDF pages 8–10, Chapters 3–4. In a single-cylinder, four-stroke, variable compression ratio, indirect injection engine, at the specified flow rate/injection timing and ignition delay, the sample is bracketed by the handwheel readings of two standard fuels and interpolated. The cetane numbers of the two bracketing standard fuels differ by no more than 5.5 units; the relationship between the low/high standards and the sample reading must be checked, and extrapolation without bracketing evidence is not used.

Equipment and interferences: Original PDF pages 10–12, Chapters 5–6 and Table 1. Ultraviolet light, temperature, fuel flow properties, nozzle delivery and airborne soot can all affect the result; the engine photographs are not manufacturing, wiring or installation drawings. The maximum permissible volume error of the 400 or 500 mL volumetric blending measures is ±0.2%; use measures of the same batch at the same temperature. Annex C is a normative installation specification, not rebuilt item by item in this card, and installation is not carried out from this card.

Primary standards, secondary standards and check fuels: Original PDF pages 9, 12–13, Chapters 3/7. n-Hexadecane has a purity of ≥99.0% and CN 100; heptamethylnonane (HMN) has a purity of ≥98.0% and CN 15. CN_PRF = 100 × volume fraction of n-hexadecane + 15 × volume fraction of HMN, calculated by equation (1) to at least two decimal places; the old AMN = 0 must not be substituted into the HMN formulation. The approved value and certificate of each batch of T/U secondary standard fuels and check fuels must be verified in practice; a typical CN is not a batch value or a supply commitment for any product, and the physical and chemical properties in informative Annexes E/F are not public product master data.

Sampling, pre-treatment and safety: Original PDF page 13 Chapter 8, page 19 Clause 13.2, page 25 Annex B, pages 28–30 Annex D. Sample according to the referenced method, reducing exposure to light and ultraviolet radiation; the sample must be kept at room temperature, filtered if necessary, and the filtration reported. Dangerous fuels, flammable mists, high-pressure injection and hot surfaces all require controlled safety procedures. The informative warning in Annex B does not exhaust the safety requirements, and equipment must not be started or fuel blended directly from this learning card.

Independent definition of operating parameters: Original PDF pages 13–15, 18, Chapters 9/11. Speed 900 ± 9 r/min; injection pressure 10.30 ± 0.34 MPa, flow rate 13.0 ± 0.2 mL/min; intake air 66 ± 0.5 °C. The test injection advance angle and the ignition delay are both 13.0 ± 0.2°, but their definitions differ and they must not be used interchangeably. Cold/hot clearances, lubrication and cooling, and local atmospheric pressure conditions must be confirmed under control according to their own clauses; a complete operating window is not inferred from the few parameters in this section.

Correction and check fuel limits: Original PDF pages 16–17, Chapters 9–10. At the standard atmospheric pressure of 101.33 kPa the original compression pressure is 3275 ± 138 kPa; equation (2) corrects for local atmospheric pressure: compression pressure = 3275 × local atmospheric pressure / standard atmospheric pressure, the ratio requiring the same units. Equation (3) check fuel limit = CN_ARV ± 1.5 × s_ARV, where s_ARV is the standard deviation of the reference value tests; this is a check fuel verification and does not replace sample precision, 95% assurance or measurement uncertainty.

Test readings and averages: Original PDF pages 18–19, Chapters 11–12. Keep the same equilibrium reading conditions for the standards and the sample; equation (4) defines the variables as the means of three handwheel readings each for the sample/low standard/high standard, and the standard handwheel readings must bracket the sample. The rotation order of original Chapter 11 cannot by itself be used to assemble three readings each from the summary; how the three readings are actually obtained still requires controlled confirmation. The mean handwheel reading is kept to at least two decimal places; the one decimal place of the final CN must not be mistakenly applied to intermediate handwheel means. The complete switching and recording sequence requires the controlled original, and the summary here is not an operating procedure.

Cetane number calculation and reporting: Original PDF page 19, Clauses 12.2–13. Equation (4): CN = CN1 + (CN2 − CN1) × (a − a1)/(a2 − a1). CN1 is the CN of the low ignition quality standard, CN2 that of the high standard; a/a1/a2 are the arithmetic means of three handwheel readings for the sample/low standard/high standard respectively; the high and low definitions are not to be exchanged. The final CN is rounded to one decimal place, and the filtration treatment is reported. This number of digits is not a detection limit, accuracy or uncertainty, and this card does not publish a calculator that has not passed technical acceptance.

Precision of handwheel interpolation: Original PDF page 19, Clauses 14.1–14.2, Table 3. At the 95% confidence level, consecutive results obtained by the same person on the same instrument in the same laboratory are judged by repeatability r; single independent results from different laboratories by reproducibility R. Linear interpolation is permitted only between the tabulated mean CN values; no extrapolation to the typical range of 30–65 or to the 0–100 scale is made on one's own initiative. The original states that, because of the nature of the method definition, the test procedure has no bias; this does not mean that actual measurement has zero error or that equipment needs no calibration. Mean cetane number | Repeatability r | Reproducibility R 40 | 0.8 | 2.8 44 | 0.9 | 3.3 48 | 0.9 | 3.8 52 | 0.9 | 4.3 56 | 1.0 | 4.8

Installation, blending and the status of the annexes: Original PDF pages 20–32, Annexes A–F. Annex C is normative; A/B/D/E/F are informative; all annexes must not be labelled operating specifications indiscriminately, nor informative property tables be treated as product certificates. Complete engine assembly, calibration of measuring instruments, standard fuel blending and safety warnings are not reconstructed; the original figures/tables must be checked against controlled documentation for the specific equipment, and this textual version is not an installation or operating authorization.

Annex G compression ratio and typical curves: Original PDF pages 33–38, Annex G and the end page. Annex G is informative; the compression ratio equation (G.1) is calculated from the displacement Vs and the volumes of the main combustion chamber/vortex passage/sensor threaded hole and the pre-chamber; the constant 0.659 in (G.2) is limited to in³ units and is not converted into an SI volume constant. Equation (G.1): CR = (Vs + (Vcc + Vtp + Vpu) + Vpc)/((Vcc + Vtp + Vpu) + Vpc). Equation (G.2): CR = (Vs + Vpc + 0.659)/(Vpc + 0.659), in³ only; Vs is the swept volume of the piston, Vpc the pre-chamber, Vcc/Vtp/Vpu the main combustion chamber/vortex passage/sensor threaded hole, whose sum of 10.8 cm³ is 0.659 in³, and units must not be mixed. The typical sensitivity curves are not a numerical calibration table or measured curves of a current engine, and coordinates must not be guessed from the plotted lines. The annex figures/adjustment parameters are not an operating script for use without equipment conditions.

Review progress, gaps and use boundaries: Segmented visual evidence of the 38 pages held. The fixed queue for the 2010 edition is not replaced by the 2021 edition already on the website, and no unconfirmed product relationships, parameter master data or standard equivalence is added. This card is an original learning note, not the full standard text; Table A contains duplicated mappings and the wording on the number of standard samples in G.7.2 still requires interpretation; this card does not fully reproduce all tables and complex figures of Table A/Table 1 and Annexes D/E/F, and does not guess to fill gaps; the page-by-page numerical evidence is stored separately. Complete controlled procedures and independent technical acceptance remain to be done, and the currently cited version and sample applicability require separate confirmation.

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