Fuel Resistance — ISO 1817 / ASTM D471 / SAE J1681 · Rubber Testing

What Is Fuel Resistance?

Fuel resistance test is a test in which the sample is immersed in the reference fuel or liquid defined in the standard at a defined temperature and time; It is an experiment in which volume swelling, mass change, hardness and loss of mechanical properties are measured.

Purpose of Fuel Resistance

The aim is to verify that swelling and loss of properties of the elastomer in contact with the fuel system remain within acceptable limits.

Which Products Is Fuel Resistance Applied To?

Fuel hoses and gaskets
Fuel pump and injector elastomers
Tank and cover gaskets
Fuel system O-rings

In Which Sectors Is Fuel Resistance Used?

RubberAutomotiveMachinery

Standards Related to Fuel Resistance

ISO 1817
ASTM D471
SAE J1681 (reference fuels)
ISO 23529

Fuel Resistance Conditions

Reference liquid: Reference fuels defined in the standard (e.g. ISO 1817 liquids or SAE J1681 fuel mixtures)
Temperature: Defined in the specification; represents the service temperature
Time: Defined in the standard; typically 22, 70 or 168 hours
measured change: Volume change, mass change, hardness and tensile properties

Equipment for Fuel Resistance

Closed dipping vessels and temperature-controlled bath
Analytical balance and volume measurement setup
Tensile tester and durometer
Fume hood and flammable liquid storage

Sample Requirements for Fuel Resistance

Initial measurements should be recorded
Containers must be leak-proof; Loss of volatile component spoils the result
Reference fluid freshness and composition must be documented
The number of specimens is defined in the standard

Duration of Fuel Resistance

1–2 weeks depending on duration.

Fuel Resistance Procedure

1Samples are measured and weighed.
2The reference liquid is prepared and brought to temperature.
3Samples are immersed in a closed container for a defined period of time.
4Samples are removed and the surface is wiped according to the standard.
5Volume, mass and hardness are measured.
6Mechanical properties are measured and the change is calculated.

Fuel Resistance Acceptance Criteria

The acceptance criteria are the maximum volume swelling and property change limits given in the specification.

Evaluation of Results

The composition of the reference fuel (especially the aromatic and alcohol content) determines the swelling; Results obtained with different reference liquids cannot be compared. Biofuel and alcohol-containing fuels behave differently than traditional reference fuels and should be evaluated separately.

Fuel Resistance Report

Applied standard and reference fluid
Temperature and duration
Before/after measurements
Volume and mass change
Mechanical property change

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Automotive fuel system specifications

Rubber Testing — What Does This Testing Field Cover?

The section below describes the field that the Fuel Resistance test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Rubber testing determines the mechanical behaviour of an elastomer and its resistance to environmental effects. Elastomers are assessed with a different logic from metals and plastics: the real question is not strength but ELASTIC RECOVERY and ageing behaviour.

The function of an elastomer is usually to deform and return: a gasket is compressed and provides a seal, a mount absorbs vibration, a hose expands under pressure. What is measured in the field is therefore not "how many newtons does it withstand" but "how far does it recover after deformation, and how long does it keep doing so".

COMPRESSION SET is therefore the most decisive measurement in the field. If a gasket cannot recover after being held compressed for a long period, it has lost its sealing function even though it has not torn at all. This measurement is made together with temperature, because permanent set increases rapidly with temperature.

Hardness is the most common measurement in the field, using the Shore A and IRHD scales. It is fast and practical but does not define the material on its own: two different compounds of the same hardness can show completely different ageing and fluid resistance. Hardness is valuable in monitoring compound consistency.

On the environmental resistance side, hot air ageing, swelling in fluids, ozone cracking and low temperature behaviour are examined. FLUID RESISTANCE is particularly critical: the same elastomer behaves differently in fuel, oil, coolant and brake fluid — swelling in one, shrinking in another, hardening in a third. The material is therefore tested with the actual fluid it will contact and at the actual temperature.

Ozone cracking is a silent cause of failure in parts used outdoors. Low concentrations of ozone in the atmosphere create surface cracks in unsaturated elastomers under strain; the part cracks while appearing to carry no load at all. An ozone chamber accelerates and reveals this behaviour.

Low temperature behaviour is the second silent risk. As an elastomer approaches its glass transition temperature it loses elasticity and behaves like a rigid plastic; a gasket starts to leak in the cold. Low temperature recovery and brittleness tests establish this limit.

A change of compound is not a silent change in this family. When filler content, plasticiser or the vulcanisation system changes, mechanical properties and fluid resistance shift together; verification is repeated.

Method groups in this field

Mechanical
Tensile stress-strain properties, tear strength, abrasion (rotating drum and Pico), fatigue and tear propagation.
Hardness
Shore A and IRHD indentation hardness; a rapid indicator of compound consistency.
Permanent deformation
Compression set and stress relaxation; decisive for sealing components.
Fluid resistance
Swelling in fuel, oil, coolant and chemicals, change in mass and volume, loss of hardness and strength.
Ageing
Hot air ageing, ozone cracking, the effects of UV and humidity.
Low temperature
Low temperature recovery, brittleness temperature and flexibility measurements.

Commonly confused in this field

Hardness does not define the material; two compounds of the same hardness can show different ageing and fluid resistance.
Fluid resistance must be tested with the actual fluid and the actual temperature; a general claim of oil resistance is insufficient.
Without measuring compression set, no decision can be made about sealing life.
Ozone cracking occurs under strain; a test with an unstrained specimen does not show the real risk.
A change of compound requires verification to be repeated; a supplier may change its compound silently.
A gasket whose low temperature behaviour is not stated produces unexpected leaks in cold climates.

Which decisions these results support

Material selection for gaskets and sealing components
Automotive and industrial component approval
Verification of a compound change
Root cause analysis of field leaks and cracking
Declaration of the operating temperature range and fluid compatibility

Related Tests

Frequently Asked Questions About Fuel Resistance

Is the gasoline resistance report valid for fuel with ethanol additives?

No. Alcohol addition significantly changes the swelling behavior of the elastomer. Separate testing with a reference fluid representative of the target fuel is required.