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EN 590
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 | This article relies largely or entirely on a single source. (March 2018) |
EN 590 is a standard published by the European Committee for Standardization that describes the physical and chemical properties that all automotive diesel fuel must meet if it is to be sold in the European Union and several other European countries.
Based on 98/70/EG it allows the blending of up to 7% fatty acid methyl ester biodiesel with 'conventional' diesel - a 7:93 mix.
History
[edit]The EN 590 had been introduced along with the European emission standards. With each of its revisions the EN 590 had been adapted to lower the sulphur content of diesel fuel – since 2007 this is called ultra-low-sulphur diesel as the former function of sulphur as a lubricant is absent (and needs to be replaced by additives).
| emission standard | at latest | sulphur content | cetane number |
|---|---|---|---|
| Euro 1 | 1 January 1993 | max. 0.200% | min. 49 |
| Euro 2 | 1 January 1996 | max. 0.050% | min. 49 |
| Euro 3 | 1 January 2001 | max. 0.035% | min. 51 |
| Euro 4 | 1 January 2006 | max. 0.005% | min. 51 |
| Euro 5 | 1 January 2009 | max. 0.001% | min. 51 |
| Euro 6 | 1 January 2014 |
Generally applicable requirements and test methods
[edit]| Property | Unit | lower limit | upper limit | Test-Method |
|---|---|---|---|---|
| Cetane index | 46.0 | - | EN ISO 4264 | |
| Cetane number | 51.0 | - | EN ISO 5165 | |
| Density at 15°C | kg/m³ | 820 | 845 | EN ISO 3675, EN ISO 12185 |
| Polycyclic aromatic hydrocarbons | %(m/m) | - | 11 | EN ISO 12916 |
| Sulphur content | mg/kg | - | 350 (until 2004-12-31) or 50.0 | EN ISO 20846, EN ISO 20847, EN ISO 20884 |
| 10.0 (on the 01-01-2009) | EN ISO 20846, EN ISO 20884 | |||
| Flash point | °C | Above 55 | - | EN ISO 2719 |
| Carbon residue (on 10% distillation residue) | %m/m | - | 0.30 | EN ISO 10370 |
| Ash content | % (m/m) | - | 0.01 | EN ISO 6245 |
| Water content | mg/kg | - | 200 | EN ISO 12937 |
| Total contamination | mg/kg | - | 24 | EN ISO 12662 |
| Copper strip corrosion (3 hours at 50 °C) | rating | Class 1 | Class 1 | EN ISO 2160 |
| Oxidation Stability | g/m3 | - | 25 | EN ISO 12205 |
| Lubricity, corrected wear scar diameter (wsd 1.4) at 60 °C | μm | - | 460 | EN ISO 12156-1 |
| Viscosity at 40 °C | mm2/s | 2.00 | 4.50 | EN ISO 3104, ISO 23581 |
| Distillation recovered at 250 °C, 350 °C | %V/V | 85 | <65 | EN ISO 3405 |
| 95%(V/V) recovered at | °C | - | 360 | |
| Fatty acid methyl ester content | % (V/V) | - | 7 | EN 14078 |
GOST R 32511-2013
[edit]| Property | Unit | Value |
|---|---|---|
| Cetane index | 46.0 | |
| Cetane number | 51.0 | |
| Density at 15°C | kg/m³ | 820-845 |
| Polycyclic aromatic hydrocarbons | %(m/m) | 8.0 |
| Sulphur content - type K3 | mg/kg | 350 |
| Sulphur content - type K4 | mg/kg | 50 |
| Sulphur content - type K5 | mg/kg | 10 |
| Flash point | °C | 55 |
| Carbon residue (on 10% distillation residue) | %m/m | 0.30 |
| Ash content | % (m/m) | 0.01 |
| Water content | mg/kg | 200 |
| Total contamination | mg/kg | 24 |
| Copper strip corrosion (3 hours at 50 °C) | rating | Class 1 |
| Stability no more than | g/m3 | 25 |
| Lubricity, corrected wear scar diameter (wsd 1,4) at 60 °C | μm | 460 |
| Viscosity at 40 °C | mm2/s | 2.00-4.50 |
| Distillation recovered at 250 °C, 350 °C | %V/V | 65.85 |
| 95%(V/V) recovered at | °C | 360 |
| Fatty acid methyl ester content no more than | % (V/V) | 7.0 |
Winter Diesel
[edit]The standard EN 590 puts diesel fuel into two groups destined for specific climatic environments. For the "temperate" climatic zones the standard defines six classes from A to F. For the "arctic" climatic zones the standard defines five classes from 0 to 4.[1]
| Characteristics | Class A | Class B | Class C | Class D | Class E | Class F | Units |
|---|---|---|---|---|---|---|---|
| CFPP | +5 | 0 | -5 | -10 | -15 | -20 | °C |
| Density at 15 °C | 820 - 860 | 820 - 860 | 820 - 860 | 820 - 860 | 820 - 860 | 820 - 860 | kg/m³ |
| Viscosity at 40 °C | 2 - 4.5 | 2 - 4.5 | 2 - 4.5 | 2 - 4.5 | 2 - 4.5 | 2 - 4.5 | mm²/s |
| Cetane index | 46 | 46 | 46 | 46 | 46 | 46 | |
| Cetane number | 49 | 49 | 49 | 49 | 49 | 49 |
| Characteristics | Class 0 | Class 1 | Class 2 | Class 3 | Class 4 | Unit |
|---|---|---|---|---|---|---|
| CFPP | -20 | -26 | -32 | -38 | -44 | °C |
| Cloud point | -10 | -16 | -22 | -28 | -34 | °C |
| Density at 15 °C | 800 - 845 | 800 - 845 | 800 - 845 | 800 - 840 | 800 - 840 | kg/m³ |
| Viscosity at 40 °C | 1.5 - 4.0 | 1.5 - 4.0 | 1.5 - 4.0 | 1.4 - 4.0 | 1.2 - 4.0 | mm²/s |
| Cetane index | 46 | 46 | 45 | 43 | 43 | |
| Cetane number | 47 | 47 | 46 | 45 | 45 |
Many countries in Europe require diesel fuel to meet a specific class in winter times. In Central and Western Europe the Winter Diesel (Winterdiesel, diesel d'hiver) must meet Class F conditions at least from the beginning of December to the end of February. During a transitional period (mostly October and April) a lower Class must be met. In the Scandinavian countries the Winter Diesel (Vinterdiesel) must meet Class 2 conditions. Some mineral groups offer both types commonly known as Winter Diesel (Winterdiesel, diesel d'hiver) and Arctic Diesel (Polardiesel, diesel polaires).
See also
[edit]- EN 14214
- European emission standards
- Hydrogenated vegetable oil
- Ultra-low-sulfur diesel
- EN 15940 paraffinic diesel fuel standard
References
[edit]External links
[edit]- Standard Archived 2007-04-30 at the Wayback Machine.
- First Texas Energy Corporation
- National D2 Diesel
 | This standards- or measurement-related article is a stub. You can help Wikipedia by expanding it. |
EN 590
View on Grokipediafrom Grokipedia
| Property | Unit | Minimum | Maximum | Notes |
|---|---|---|---|---|
| Cetane Number | - | 51 | - | Measures ignition delay; higher values improve cold starts and efficiency.[1] |
| Sulfur Content | mg/kg | - | 10 | Ultra-low to enable advanced exhaust aftertreatment systems.[1] |
| Fatty Acid Methyl Ester (FAME) | % (V/V) | - | 7 | Biodiesel blend limit; up to 10% permitted under EN 14078 for certified fuels.[1][3] |
| Polycyclic Aromatic Hydrocarbons | % (m/m) | - | 8 | Reduced to lower soot emissions.[1] |
| Density at 15°C | kg/m³ | 815 | 845 | Minimum 815 for classes A, B, C (summer, transition, winter); ensures proper injection and combustion; varies by climatic class.[2][8] |
| Distillation (95% recovered) | °C | - | 360 | Controls volatility for engine performance.[1] |
| Lubricity (wear scar diameter) | µm | - | 460 | Prevents fuel system wear, especially with low sulfur.[5] |
| Abrasive Particles (≥4 μm) | counts/ml | - | 10,000 | New limit in 2025 edition to enhance fuel cleanliness and reduce engine wear (IP 630 method).[9] |
Introduction
Scope and Applicability
EN 590:2025 is the current edition of the European standard specifying the requirements and test methods for automotive diesel fuel marketed and delivered for use in compression-ignition engines. Published by the European Committee for Standardization (CEN), it defines the physico-chemical properties that ensure fuel quality, performance, and compatibility with modern diesel engine technologies.[8] The standard applies primarily to diesel fuel for road vehicles, including cars, trucks, and buses equipped with compression-ignition engines, as well as to non-road mobile machinery where national regulations specify its use, such as in construction and agricultural equipment. It accommodates biodiesel blends containing up to 7% (V/V) fatty acid methyl ester (FAME), enabling compatibility with renewable components while maintaining engine performance and emissions control.[1][10] Geographically, EN 590 is mandatory in all European Union (EU) member states under the Fuel Quality Directive (Directive 98/70/EC, as amended), which enforces its specifications for road transport diesel and gasoil for non-road mobile machinery. It also applies in European Free Trade Association (EFTA) countries that are part of the European Economic Area (EEA)—Iceland, Liechtenstein, and Norway—due to their adoption of EU legislation, and Switzerland, which adopts the standard voluntarily but observes it in practice. In the United Kingdom, following Brexit, the standard has been retained as BS EN 590 and remains mandatory for road diesel, ensuring continuity in fuel quality. While voluntary outside these regions, EN 590 exerts significant global influence, with many fuel suppliers adopting its specifications to facilitate international trade and harmonize quality benchmarks.[10][1][2][11] EN 590 explicitly excludes fuels intended for marine propulsion, aviation, or stationary engines, which are governed by separate standards such as ISO 8217 for marine distillate fuels and ASTM D1655 for aviation kerosene.[1]Key Objectives
The EN 590 standard primarily aims to protect engine durability by specifying fuel properties that prevent wear and deposits, while minimizing emissions through strict limits on pollutants such as sulfur, which reduces sulfur oxides (SOx) and particulate matter from combustion.[1] It also ensures compatibility with modern exhaust aftertreatment systems, including diesel particulate filters (DPF), by maintaining ultra-low sulfur levels to avoid poisoning catalysts and filters.[1] These objectives are driven by environmental imperatives, aligning with EU directives on air quality, notably Directive 98/70/EC, which seeks to reduce atmospheric pollution from road transport vehicles by harmonizing fuel specifications and progressively lowering pollutant levels.[12] This supports compliance with evolving Euro emission standards, facilitating reductions in nitrogen oxides, hydrocarbons, and particulates to safeguard human health and the environment.[1] In terms of performance, EN 590 maintains ignition quality through requirements for the cetane number and index and ensures reliable operation in varying climates via cold-flow properties, enabling consistent engine starting and efficiency across Europe.[1] Economically, the standard promotes harmonization of diesel fuel quality to eliminate trade barriers within the EU, fostering supply chain consistency and supporting the competitiveness of the refining and automotive industries through uniform specifications observed by all suppliers.[12][1]Historical Development
Initial Establishment
The EN 590 standard was first published in 1993 by the European Committee for Standardization (CEN) as EN 590:1993, marking the initial effort to establish a unified specification for automotive diesel fuel across European member states.[13] This development followed a 1988 mandate from the European Union to CEN to create harmonized fuel standards, addressing the need for consistent quality amid varying national regulations.[14] The primary driver for this initial establishment was the completion of the European single market in 1992, which necessitated reducing cross-border discrepancies in diesel fuel specifications to facilitate free movement of goods and vehicles.[1] It directly supported the implementation of Council Directive 93/12/EEC, which aimed to approximate the laws of member states regarding the sulfur content of certain liquid fuels, including diesel, to curb emissions and promote environmental consistency. By standardizing requirements, EN 590:1993 enabled seamless trade and compatibility with emerging emission controls without imposing biodiesel blends. Key parameters in the 1993 version included a maximum sulfur content of 0.2% (2000 ppm) to limit pollutants, a minimum cetane number of 49 to ensure ignition quality, and a density range of 820-845 kg/m³ at 15°C to maintain fuel performance across climates.[1] These limits applied to both on-road and off-road applications, focusing solely on conventional petroleum-derived diesel fuels with no provisions for renewable additives.[14]Major Revisions and Updates
The EN 590 standard has undergone several key revisions since its initial adoption in 1993, primarily driven by the need to reduce emissions, improve fuel quality, and accommodate advancements in engine technology and renewable energy integration. These updates have progressively tightened specifications for sulfur content, biodiesel blending, and other parameters to align with evolving European environmental regulations.[1] In 1996, the first major revision (EN 590:1996) reduced the maximum sulfur content to 500 ppm from the previous 2,000 ppm, supporting the introduction of Euro 2 emission standards and enabling better performance of catalytic systems in diesel engines.[1] This change marked an initial step toward lower-emission fuels while maintaining the cetane number at 49.[1] By 1999, EN 590:1999 further lowered sulfur to a maximum of 350 ppm in response to Directive 98/70/EC, preparing for Euro 3 standards effective in 2001, and raised the minimum cetane number to 51.[15][1] The EN 590:2004 revision then reduced the sulfur limit to 50 ppm effective January 2005 for Euro 4 compliance under Directive 2003/17/EC, with a further reduction to 10 ppm effective January 2009 for Euro 5. The 2009 revision (EN 590:2009) confirmed the mandatory ultra-low sulfur diesel (ULSD) limit of 10 ppm, aligning with Euro 5 emission requirements and enhancing compatibility with advanced exhaust aftertreatment systems like diesel particulate filters.[16] This sulfur reduction also raised the FAME (fatty acid methyl ester) biodiesel limit to 7% v/v from 5% in the 2004 version, promoting biofuel integration without compromising fuel stability.[1] Subsequent revisions in 2014 and 2022 maintained the 7% v/v FAME allowance while emphasizing compatibility with paraffinic diesels, with the introduction of EN 15940 around 2016 specifying requirements for hydrotreated vegetable oil (HVO) and other paraffinic fuels that can blend up to 7% FAME, offering lower lifecycle emissions and high cetane numbers.[1] The 2022 update (EN 590:2022) reaffirmed these parameters amid ongoing biofuel adoption.[17] The most recent 2025 revision (EN 590:2025), effective July 31, 2025, reduces the minimum density for summer grades (A, B, C) from 820 kg/m³ to 815 kg/m³ to facilitate higher blending of renewable, lower-density fuels, and introduces the first explicit limit on abrasive particles measured via the IP 630 method to protect modern high-pressure fuel injection systems.[8][6] These revisions reflect a broader trend of alignment with the EU Fuel Quality Directive 2009/30/EC, which mandates progressive greenhouse gas emission reductions from fuels, and supports EU decarbonization goals by enabling greater use of low-carbon alternatives like biofuels and paraffinic diesels.[18][19]Technical Specifications
Physico-Chemical Properties
The physico-chemical properties defined in EN 590 ensure that automotive diesel fuel exhibits consistent performance, combustion efficiency, and compatibility with modern engine systems across Europe. These properties encompass key metrics such as density, ignition quality via cetane parameters, flow characteristics through viscosity, thermal behavior via distillation, resistance to degradation through oxidative stability, limits on harmful aromatics, and biodiesel blending constraints. Compliance with these specifications is mandatory for fuels marketed in the European Union and associated countries, promoting environmental and operational reliability.[1] Density, measured at 15°C, is specified to balance energy content and fuel injection performance. For standard temperate grades (A, B, C), it ranges from a minimum of 815 kg/m³ to a maximum of 845 kg/m³, ensuring adequate volumetric energy density without excessive heaviness that could impair cold-weather flow. Winter and arctic grades feature a lower minimum density of 800 kg/m³ to improve low-temperature fluidity while maintaining the upper limit at 845 kg/m³.[1][2][8] The cetane index, an estimated measure of ignition delay, must be at least 46 for temperate grades, serving as a proxy when direct cetane number testing is not performed. The cetane number, determined through engine testing, requires a minimum of 51, indicating rapid and reliable ignition to minimize engine knock and emissions. The cetane index is calculated using a formula that incorporates fuel density at 15°C and distillation temperatures at 10%, 50%, and 90% recovery volumes, providing a reliable approximation of ignition quality based on these physical attributes; a simplified estimation begins with a base of 45.2 adjusted by density and boiling range factors, though full derivation involves multivariate correlations for precision. For arctic classes 3 and 4, the cetane index minimum is 43, while the cetane number remains ≥51 for EU compliance. Lower limits apply to severe winter grades in non-EU contexts.[1][20] Kinematic viscosity at 40°C is limited to 2.0–4.5 mm²/s for most grades, ensuring proper fuel atomization and lubrication in high-pressure injection systems without causing excessive drag or filter clogging. Arctic grades may extend the lower limit to 1.2 mm²/s to accommodate lighter formulations for cold starts. This range supports efficient fuel delivery across varying operational temperatures.[1][2] Distillation characteristics define the boiling range, critical for vaporization and combustion completeness. At least 65% by volume must recover by 250°C to prevent light ends that could lead to vapor lock, while 95% recovery is capped at 360°C to avoid heavy residues that increase particulate emissions and engine deposits. An additional constraint limits recovery to no more than 10% at 180°C for severe winter options, promoting a narrower profile suited to low temperatures. These parameters ensure the fuel evaporates progressively during combustion.[1][20] Oxidative stability is mandated to prevent fuel degradation during storage and use, with fuels containing 0–2% fatty acid methyl ester (FAME) limited to a maximum of 25 g/m³ insoluble surfactants after accelerated oxidation testing. For blends with 2–7% FAME, an induction period of at least 20 hours is required, reflecting enhanced susceptibility to oxidation in biodiesel components and ensuring shelf life exceeds typical distribution periods.[1][2] Polycyclic aromatic hydrocarbons (PAH), which contribute to soot formation and potential carcinogenicity, are restricted to a maximum of 8% by mass. This limit reduces exhaust particulates and supports compliance with emission standards by minimizing incomplete combustion precursors.[1][20] Fatty acid methyl ester (FAME) content, representing biodiesel incorporation, is capped at 7% by volume to integrate renewable components without compromising fuel stability or engine compatibility. This allowance aligns with sustainability goals while imposing the aforementioned oxidative stability requirements for higher FAME levels to mitigate rancidity risks. Recent directives permit up to 10% in certain contexts, but EN 590 maintains the 7% threshold for standard automotive use.[1][2]| Property | Limit (Temperate Grades) | Unit | Notes |
|---|---|---|---|
| Density at 15°C | 815–845 (min–max) | kg/m³ | Lower min (800) for winter/arctic |
| Cetane Number | ≥51 | - | Engine-tested ignition quality |
| Cetane Index | ≥46 | - | Calculated from density and distillation |
| Viscosity at 40°C | 2.0–4.5 | mm²/s | Ensures flow and lubrication |
| Distillation: 95% Recovery | ≤360 | °C | Controls heavy fractions |
| Oxidative Stability (0–2% FAME) | ≤25 | g/m³ | Insolubles after oxidation |
| Oxidative Stability (2–7% FAME) | ≥20 | hours | Induction period |
| PAH | ≤8 | % m/m | Limits aromatics for emissions |
| FAME Content | ≤7 | % v/v | Biodiesel blend maximum |
Composition and Additive Limits
EN 590 establishes strict limits on the chemical composition of automotive diesel fuel to minimize impurities that could harm engine components, exhaust aftertreatment systems, or fuel system integrity. The maximum sulfur content is set at 10 mg/kg to reduce emissions of sulfur oxides and protect catalytic converters from poisoning. Water content is limited to 200 mg/kg to prevent corrosion, microbial growth, and phase separation in the fuel. Ash content must not exceed 0.01% by mass, ensuring minimal inorganic residues that could cause abrasive wear in engines. Total contamination, including particulates and sediments, is capped at 24 mg/kg to avoid filter clogging and injector fouling. Particle number concentration for particles ≥4 μm is limited to 10,000 per ml to further control abrasive contaminants (EN 590:2025, IP 630).[1][21] Additives are permitted to enhance fuel performance but are subject to specific constraints to ensure compatibility with engine materials and aftertreatment devices. Detergents are allowed to maintain injector cleanliness, lubricity improvers must achieve a high-frequency reciprocating rig (HFRR) wear scar diameter of ≤460 µm at 60°C to compensate for reduced natural lubricity in low-sulfur fuels, and antifoam agents are used to improve handling. No additives are mandatory, but phosphorus content is limited to ≤10 mg/kg to avoid poisoning of diesel oxidation catalysts and particulate filters.[1] Biodiesel integration is facilitated through fatty acid methyl esters (FAME), which must comply with EN 14214 specifications for quality and purity. The FAME content in EN 590-compliant diesel is limited to a maximum of 7% by volume, resulting in a total oxygen content of ≤3.7% by mass to balance renewable energy incorporation with fuel stability and combustion characteristics. This allows for up to B7 blends while ensuring the overall fuel meets performance and emissions requirements.[22][1]| Parameter | Limit | Test Method | Purpose |
|---|---|---|---|
| Sulfur | ≤10 mg/kg | EN ISO 20846 or EN ISO 20884 | Emissions reduction and catalyst protection |
| Water | ≤200 mg/kg | EN ISO 12937 | Corrosion and microbial control |
| Ash | ≤0.01% m/m | EN ISO 6245 | Abrasive wear prevention |
| Total Contamination | ≤24 mg/kg | EN 12662 | Filter and injector protection |
| Particle Number (≥4 μm) | ≤10,000 /ml | IP 630 | Abrasive wear prevention |
| Phosphorus | ≤10 mg/kg | EN 16476 (ICP-OES) | Aftertreatment compatibility |
| Lubricity (HFRR wear scar) | ≤460 µm | ISO 12156-1 | Fuel system lubrication |
| FAME Content | ≤7% v/v (per EN 14214) | EN 14078 | Renewable integration with quality assurance |
| Total Oxygen | ≤3.7% m/m | Derived from FAME limit | Combustion stability |
Test Methods
Core Test Procedures
The core test procedures for EN 590 compliance focus on verifying essential physico-chemical properties of automotive diesel fuel through standardized methods, ensuring fuel quality, engine compatibility, and environmental adherence across the supply chain. These routine tests are performed to confirm limits on density, cetane index, sulfur content, kinematic viscosity, and water and total contamination levels, using precise laboratory techniques referenced in the European standard.[1] Density at 15°C is determined using the oscillating U-tube method per EN ISO 3675 or the vibrating tube method per EN ISO 12185, with acceptable values typically ranging from 820 to 845 kg/m³ to balance combustion efficiency and cold flow properties.[23] The cetane index, an indicator of ignition quality without direct engine testing, is calculated via the 4-variable equation method in EN ISO 4264, which incorporates density and distillation characteristics (e.g., 10%, 50%, and 90% recovery temperatures) to estimate a minimum value of 46, promoting reliable engine start-up and reduced emissions.[23][1] Sulfur content, critical for minimizing SOx emissions, is measured by ultraviolet fluorescence per EN ISO 20846 or energy-dispersive X-ray spectroscopy per EN ISO 20884, enforcing a maximum of 10 mg/kg to comply with ultra-low sulfur diesel requirements.[1] Kinematic viscosity at 40°C is assessed using a capillary viscometer according to EN ISO 3104, targeting 2.0 to 4.5 mm²/s to ensure proper fuel atomization and lubrication in injectors.[23] Water content is quantified via coulometric Karl Fischer titration in EN ISO 12937, limited to 200 mg/kg, while total contamination is determined using the gravimetric filtration method per EN 12662, limited to 24 mg/kg, to prevent filter clogging and corrosion.[23][1] These tests are mandated at key stages—production (refineries), import terminals, and retail outlets—under EU fuel quality monitoring directives to maintain consistent compliance, with annual reporting required from member states to the European Commission.[24] Particle limits for contamination were introduced in the 2025 revision of EN 590, with details covered in advanced assessments.[8]Advanced Quality Assessments
Advanced quality assessments in EN 590 address emerging challenges in diesel fuel performance, particularly related to contamination, stability, and compatibility with modern engine systems. These tests evaluate aspects such as particulate matter that could cause abrasive wear, oxidative degradation over time, and the influence of biodiesel components on fuel properties. Introduced or refined in recent revisions, these methods ensure fuel reliability in advanced diesel technologies, including high-pressure common-rail injection systems.[8] A key advancement in the EN 590:2025 standard is the assessment of abrasive particle contamination, aimed at mitigating wear in fuel pumps and injectors. This involves the IP 630 test method, which uses automatic particle counters (APCs) employing light obscuration to measure the concentration and size distribution of dispersed particles in diesel fuel. Specifically, procedure A of IP 630 quantifies particles ≥4 μm, with a mandatory limit of 10,000 particles per milliliter at the point of particle certification. Instruments such as the Seta AvCount laser particle counter are explicitly referenced for compliance, enabling precise detection in the range of 0.1 to 21.25 mg/L equivalent mass. This requirement addresses concerns over soft and hard particulates from biofuels and additives, which were not fully covered in prior versions.[25][21][26] Oxidative stability is evaluated using EN ISO 12205, the Rancimat method, which measures the induction period—the time until rapid oxidation occurs under accelerated conditions at 110°C with air bubbling. For diesel fuels containing up to 7% (V/V) fatty acid methyl ester (FAME), the minimum induction period is 20 hours, ensuring resistance to gum formation and deposit buildup during storage and use. This test is critical for fuels with biodiesel blends, as FAME accelerates peroxidation, and it builds on earlier specifications by maintaining this threshold amid increasing biofuel integration.[27][28] Lubricity testing employs EN ISO 12156-1, utilizing the high-frequency reciprocating rig (HFRR) to assess wear protection under boundary lubrication conditions. The method involves oscillating a steel ball against a disk immersed in the fuel at 60°C, measuring the wear scar diameter (WSD) on the ball. EN 590 requires a maximum WSD of 460 μm, a limit established to counteract reduced lubricity from ultra-low sulfur processing, often supplemented by additives like fatty acids. This ensures compatibility with precision-engineered components in modern engines.[2][29][28] For winter-grade diesels, the cold filter plugging point (CFPP) is determined per EN 116, simulating filterability under low temperatures by cooling the fuel and monitoring pressure drop through a standardized filter. Limits vary by climatic grade: for example, Grade D (winter) specifies a maximum CFPP of -10°C, while arctic Grade F allows -20°C, preventing wax crystallization that could block fuel systems in cold climates. These assessments are essential for seasonal formulations, distinct from basic viscosity tests.[1][2] Fatty acid methyl ester (FAME) content is quantified using EN 14078, a gas chromatography (GC) method that separates and detects FAME components via flame ionization detection after extraction or direct injection. EN 590 caps FAME at 7% (V/V) to balance renewable content with stability and performance, with the test ensuring no exceedance that could degrade cold flow or oxidation properties—historical limits were raised from 5% in earlier revisions to accommodate biodiesel mandates.[30][8] All advanced assessments require calibration and validation in laboratories accredited to ISO/IEC 17025, which mandates competence, traceability of measurements, and proficiency testing to guarantee reliable results. This accreditation ensures method validation, equipment maintenance, and inter-laboratory comparability, critical for regulatory compliance and trade in EN 590-compliant fuels.[31][32]Variations and Implementations
Seasonal and Climatic Grades
EN 590 accommodates varying climatic conditions by defining multiple grades of diesel fuel based on cold weather performance, ensuring the fuel remains fluid and filterable to prevent engine issues from wax crystallization. The primary metric is the cold filter plugging point (CFPP), which measures the lowest temperature at which the fuel can flow through a standardized filter. For temperate climates, the standard specifies six grades (A through F) with CFPP limits ranging from +5°C (grade A) to -20°C (grade F), allowing suppliers to select appropriate formulations for seasonal needs.[1] In mild regions, summer diesel corresponds to grades with higher CFPP tolerances, such as grade B (≤0°C) or grade C (≤-5°C), typically supplied during warmer periods to optimize storage and handling without excessive refinement. During colder months from October to March, winter diesel shifts to grades D, E, or F with CFPP limits from -10°C to -20°C, enabling reliable operation in sub-zero temperatures; these formulations often incorporate additives like pour point depressants to further lower the temperature at which the fuel gels.[1][33] For extreme cold in regions like Northern Europe, arctic diesel employs specialized grades with CFPP ≤-20°C, such as class 0 (-20°C) extending to class 4 (-44°C), designed for severe winter conditions where standard temperate grades would fail. These arctic formulations prioritize low-temperature fluidity, with permitted use of additives to enhance performance.[1] Cloud point (the temperature at which wax crystals first appear) is limited in arctic grades to ensure it does not exceed the CFPP by more than approximately 6-10°C, while pour point (the lowest temperature for fuel flow) is typically at least 12°C below the CFPP; these properties are controlled through base fuel composition and additives rather than strict limits in temperate grades.[1][33] The European Union employs a map-based regional zoning system to assign climatic classes, with Zone 1 covering mild winter areas requiring less stringent CFPP (e.g., grades B or C) and higher zones demanding winter or arctic grades. Transition periods for grade switching, often 1-2 months long (e.g., March to April in Germany), allow infrastructure adjustments and prevent supply disruptions.[1] The EN 590:2025 edition introduces a maximum limit of 10,000 particles per ml for abrasive particles (measured by IP 630 method) and reduces the minimum density for summer grades from 820 kg/m³ to 815 kg/m³ to facilitate higher renewable diesel content while maintaining performance.[6] Seasonal variations may also influence density specifications slightly, with winter grades often allowing lower minimum densities to facilitate better cold flow.[1]| Climatic Grade Type | Example Classes | CFPP Limit (°C) | Typical Usage |
|---|---|---|---|
| Summer (Temperate, Mild) | B, C | 0 to -5 | Warmer months in Zone 1 regions |
| Winter (Temperate) | D, E, F | -10 to -20 | October-March in colder temperate areas |
| Arctic (Extreme Cold) | 0 to 4 | -20 to -44 | Northern Europe severe winters |