ISO 4264:2018
Petroleum products — Calculation of cetane index of middle-distillate fuels by the four variable equation
Petroleum products — Calculation of cetane index of middle-distillate fuels by the four variable equation
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 9
- Дата публикации:
- 22 июня 2018 г.
- Издание:
- ISO IS 4264 edition 3 version 1
- ICS:
- 75.160.20
This document specifies a procedure for the calculation of the cetane index of middle-distillate fuels from petroleum-derived sources. The calculated value is termed the "cetane index by four-variable equation". Throughout the remaining text of this document, the term "cetane index" implies cetane index by four-variable equation. This document is applicable to fuels containing non-petroleum derivatives from tar sand and oil shale. It is not applicable to pure hydrocarbons, nor to distillate fuels derived from coal. Cetane index calculations do not take into account the effects from additives used to enhance the Cetane number. NOTE 1 This document was originally developed using a matrix of fuels, some of which contain non-petroleum derivatives from tar sands and oil shale. NOTE 2 The cetane index is not an alternative way to express the cetane number; it is a supplementary tool, to be used with due regard for its limitations. NOTE 3 The cetane index is used to estimate the cetane number of diesel fuel when a test engine is not available to determine this property directly, or when insufficient sample is available for an engine rating. The most suitable range of fuel properties for application of this document is as follows: Fuel property Range Cetane number 32,5 to 56,5 Density at 15 °C, kg/m3 805,0 to 895,0 10 % (V/V) distillation recovery temperature, °C 171 to 259 50 % (V/V) distillation recovery temperature, °C 212 to 308 90 % (V/V) distillation recovery temperature, °C 251 to 363 Within the range of cetane number (32,5 to 56,5), the expected error of the prediction via the cetane index equation will be less than ±2 cetane numbers for 65 % of the distillate fuels examined. Errors can be greater for fuels whose properties fall outside this range of application. As a consequence of sample-specific biases observed, the expected error can be greater even when the fuel's properties fall inside the recommended range of application. Therefore, users can assess the required degree of prediction agreement to determine the fitness-for-use of the prediction. NOTE 4 Sample specific biases were observed for distillate fuels containing FAME (fatty acid methyl ester).
Abstract
Overview
ISO 4264:2018 - Petroleum products - Calculation of cetane index of middle‑distillate fuels by the four‑variable equation - specifies a laboratory calculation method to estimate the cetane index of middle‑distillate (diesel) fuels. The standard defines the four‑variable equation approach using measured density at 15 °C and the 10 %, 50 % and 90 % (V/V) distillation recovery temperatures. The calculated value is termed the “cetane index by four‑variable equation” and is intended as a supplementary estimate of the cetane number when engine testing is unavailable or sample volume is limited.
Key topics and requirements
- Input variables: density at 15 °C (D) and distillation recovery temperatures T10, T50 and T90.
- Measurement methods: density by ISO 3675 (hydrometer) or ISO 12185 (oscillating U‑tube); distillation by ISO 3405 (atmospheric) or ISO 3924 (GC boiling‑range, with conversion to ISO 3405 equivalent data).
- Calculation: the cetane index is computed from the measured values using the four‑variable correlation (formula provided in Clause 6). A nomograph method (Annex A) offers an alternative for manual estimation; however the numeric formula is authoritative in case of dispute.
- Reporting: report the cetane index to the nearest 0.1.
- Applicability limits: suitable for middle‑distillate fuels with properties roughly in the ranges - cetane number 32.5–56.5; density 805–895 kg/m3 at 15 °C; T10 171–259 °C; T50 212–308 °C; T90 251–363 °C.
- Uncertainties and exclusions: the calculation does not account for cetane‑enhancing additives and is not applicable to pure hydrocarbons or coal‑derived distillates. Sample‑specific biases were observed (notably with fuels containing FAME - fatty acid methyl ester). Expected error: within the 32.5–56.5 cetane range, prediction error is <±2 cetane numbers for about 65 % of examined fuels.
Applications and users
- Refinery and fuel quality laboratories - routine quality control and reporting when engine tests (cetane number) are impractical.
- Fuel producers and blenders - estimating diesel ignition quality during production or formulation.
- Regulatory bodies and certification labs - preliminary assessment of middle‑distillate fuels.
- Research and development - comparative studies, fuel screening, and when only limited sample volumes are available.
This standard is a practical tool for estimating diesel ignition quality (cetane index) but should be used with awareness of its limitations and the effect of non‑petroleum components or additives.
Related standards
- ISO 3405 - Determination of distillation characteristics (atmospheric pressure)
- ISO 3924 - Boiling range distribution by gas chromatography (alternative distillation method)
- ISO 3675 - Density (hydrometer method)
- ISO 12185 - Density (oscillating U‑tube method)
- ISO 91 - Temperature and pressure volume correction factors
Keywords: ISO 4264, cetane index, four‑variable equation, middle‑distillate fuels, diesel fuel, distillation, density at 15 °C, ISO 3405, ISO 3924, FAME.
Технические детали
- Технический комитет
- ISO/TC 28 - Petroleum and related products, fuels and lubricants from natural or synthetic sources
- SKU
- ISO 4264:2018
Похожие стандарты
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