ASTM D613-25 PDF

Full title and description

ASTM D613-25 — Standard Test Method for Cetane Number of Diesel Fuel Oil. This standard specifies a laboratory engine procedure to determine the cetane number (an index of ignition quality) of diesel fuel oils using a standard single‑cylinder, four‑stroke, variable compression ratio, indirect‑injection diesel engine test method.

Abstract

This test method describes the determination of a fuel’s cetane number on an established cetane scale (0–100) by measuring engine performance under defined operating conditions. It is used to assess ignition quality for diesel fuels and related candidate fuels, and includes requirements for reference fuels, engine operation, measurement procedures, and reporting. The 2025 edition consolidates prior revisions and reflects current precision and applicability guidance.

General information

• Status: Active (current ASTM edition D613-25 available through ASTM International).
• Publication date: April 1, 2025 (D613-25 edition; related research report and revision activity documented in 2024–2025).
• Publisher: ASTM International.
• ICS / categories: 75.160.20 (Liquid fuels).
• Edition / version: D613-25 (2025 edition).
• Number of pages: 24 pages (D613-25 main document).

Scope

The standard covers the determination of a diesel fuel’s rating on the cetane number scale using a standard single‑cylinder, four‑stroke, variable compression ratio, indirect‑injection test engine. Typical test results lie in the range of about 30 to 85 cetane number; SI units are given as standard, with inch‑pound units retained for certain engine measurements. The method addresses engine operation, calibration with reference fuels, sample handling, and reporting, while noting limitations for unconventional fuels where full‑scale engine correlations may be uncertain.

Key topics and requirements

• Measurement of cetane number using a single‑cylinder, variable compression ratio, precombustion‑chamber diesel test engine.
• Reference and secondary reference fuels and procedures for calibration and scale maintenance.
• Operating conditions, instrumentation, and reporting requirements (including units and correction factors).
• Precision, bias, and interlaboratory considerations; recent revision activity has clarified precision equations and the effect of cetane‑meter type on precision.
• Notes on applicability to unconventional fuels (e.g., synthetics, vegetable oils) and limitations in predicting full‑scale engine performance.

Typical use and users

Used by engine manufacturers, petroleum refiners and marketers, fuel testing laboratories, regulatory bodies, and research institutions to characterize ignition quality of diesel fuels for specification, quality control, fuel matching to engines, and research. Proficiency testing and interlaboratory studies are commonly used alongside the method to demonstrate laboratory competence.

Related standards

Standards commonly used with or referenced by D613 include methods for derived cetane and related measurements such as ASTM D6890 (derived cetane by ignition quality tester), D7668 (derived cetane from CVCC), density and distillation methods (D4052, D86), flash point (D93), hydrocarbon type (D1319), sulfur methods (D2622, D5453, D7039), and viscosity (D445/D455). Earlier and adjacent D613 editions/amendments (for example D613‑24, D613‑24a) and related ASTM research reports and work items document method validation and revision history.

Keywords

cetane number; cetane index; diesel fuel; ignition quality; precombustion chamber engine; reference fuels; precision; interlaboratory; fuel specification; D613-25.

FAQ

Q: What is this standard?

A: ASTM D613-25 is the 2025 edition of the Standard Test Method for Cetane Number of Diesel Fuel Oil, a laboratory engine method to determine cetane number as a measure of diesel fuel ignition quality.

Q: What does it cover?

A: It covers engine test procedures, calibration with reference fuels, operating conditions, measurement and reporting requirements, and guidance on precision, applicability, and limitations (including notes on unconventional fuels).

Q: Who typically uses it?

A: Engine and vehicle manufacturers, petroleum refiners and marketers, commercial and accreditation laboratories, and regulatory or standards bodies use D613 for fuel specification, quality control, research, and equipment/fuel matching.

Q: Is it current or superseded?

A: The 2025 edition (D613-25) is the current ASTM edition as published in 2025; ASTM continues to maintain and ballot revisions and amendments (work items and research reports related to D613 were active in 2024–2026), so users should confirm the very latest status and any amendments with ASTM International.

Q: Is it part of a series?

A: D613 is part of a family of diesel fuel and ignition quality methods and is frequently used alongside derived‑cetane and fuel characterization standards (for example D6890, D7668 and various physical/chemical test methods). There are historical and amendment versions of D613 (multiple earlier editions and redline/‑a amendments).

Q: What are the key keywords?

A: Cetane number, ignition quality, diesel fuel, reference fuels, precombustion chamber engine, precision, interlaboratory testing, fuel specification.