What Is Flammability?
The automotive interior flammability test measures how fast materials used in the vehicle cabin burn when ignited in the horizontal position. The goal is not that the material does not burn at all, but that the burn rate stays below the limit; this aims to give occupants time to evacuate.
Purpose of Flammability
The purpose is to verify that interior trim materials do not lead to rapid flame spread in a fire, and to produce the evidence required for vehicle type approval.
Which Products Is Flammability Applied To?
- Seat fabrics and foams
- Headliner and door panels
- Carpet and floor mats
- Instrument-panel coverings
- Cable-protection materials and insulation parts
In Which Sectors Is Flammability Used?
Standards Related to Flammability
- ISO 3795
- FMVSS 302
- UNECE R118combustion behavior of internal materials test
- GB 8410
Flammability Conditions
- Specimen orientation
- Horizontal
- Flame application time
- 15 seconds
- Conditioning
- At least 24 hours at 23 °C ± 2 °C and 50% ± 5 relative humidity
- Measurement zone
- The burn rate is calculated over the distance between the marker lines
Equipment for Flammability
- Horizontal burn test chamber
- Bunsen-type gas burner
- Specimen holder and wire grid
- Stopwatch
- Conditioning chamber
Sample Requirements for Flammability
- Specimens cut to the dimensions prescribed by the standard
- Generally at least five specimens
- Layer structure must be preserved for composite materials
- The material's orientation and surface as used in the vehicle must be stated
Duration of Flammability
Conditioning takes at least 24 hours; the test itself takes a few minutes per specimen. Total duration is determined by conditioning.
Flammability Procedure
- 1Specimens are cut and marked per the standard.
- 2They are held in the conditioning chamber.
- 3The specimen is placed horizontally in the holder.
- 4The burner flame is applied for 15 seconds and withdrawn.
- 5The stopwatch starts when the flame reaches the first marker line.
- 6The time to reach the second marker line, or the point of extinguishment, is recorded.
- 7The burn rate is calculated and the results are reported.
Flammability Acceptance Criteria
The common acceptance criterion under FMVSS 302 and ISO 3795 is that the burn rate does not exceed 100 mm/minute. The material is deemed acceptable if the flame extinguishes before reaching the first marker line, or self-extinguishes under specified conditions. The exact criterion is determined by the applied standard's text and the OEM specification.
Evaluation of Results
The burn rate is calculated separately for each specimen; the worst-case result is used in the evaluation. Dripping and ignition of the dripping material are recorded separately.
Flammability Report
- Applied standard and revision
- Specimen description, thickness and construction
- Conditioning conditions
- Burn rate or extinguishment status for each specimen
- Dripping observations
- Assessment result
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 authorisationsRelated Regulations
- UNECE R118
- FMVSS 302
- Vehicle type-approval legislation
Otomotiv Testleri — What Does This Testing Field Cover?
The section below describes the field that the Flammability 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.
Automotive testing shows that a component keeps working under conditions representing the loads it will meet over the life of the vehicle. A vehicle is not a single product but an ENVIRONMENT: vibration, temperature cycling, salt water, stone impact, electrical transients and electromagnetic noise are all present at the same time and for years.
What distinguishes this family is that VEHICLE MANUFACTURER SPECIFICATIONS sit on top of the standards. ISO and SAE publications establish the common ground; but Volkswagen, BMW, Ford, Stellantis, Toyota and Renault define different severity levels, additional tests and different acceptance criteria in their own specifications. For a component, the phrase "complies with automotive standards" is not sufficient on its own; which manufacturer's specification, and which revision of it, must be answered.
The family carries three separate processes together and they are often confused. Homologation covers the type approvals a vehicle needs to enter traffic and runs under state authority. Supplier approval means passing the vehicle manufacturer's own quality and testing requirements and is a commercial relationship. The third is design verification: the engineering team demonstrating that its own design meets its targets.
At component level the test plan is built around the LOCATION OF USE. A module in the engine bay and a module in the boot do not go through the same temperature and vibration profile; a component inside a door and one in the roof console do not see the same water and dust exposure. The ISO 16750 series is the common framework for this location-based approach.
The shift to electric vehicles has reshaped the field. High-voltage safety, insulation coordination, battery safety, charging interface conformity and the electromagnetic behaviour of high-voltage components have been added to the classical automotive test set. In a quiet vehicle, acoustic and vibration expectations have changed too; sounds once masked by the combustion engine are now audible.
The quality system side cannot be separated from testing in this field. A manufacturer under IATF 16949 presents test results in the PPAP file; measurement system analysis, process capability study and the control plan stand around the test report. A single good result is not enough — the process must be shown to be able to repeat it.
Method groups in this field
Environmental and climatic
Temperature cycling, thermal shock, damp heat, salt spray, dust and water ingress (IP), solar radiation. Severity levels vary with the mounting location.
Mechanical
Sine and random vibration, shock, mechanical loads, fastener torque and durability cycles.
Electrical
Supply voltage variations, transients (ISO 7637), reverse polarity, overvoltage, short circuit and sleep current measurements.
EMC
Component emissions (CISPR 25), radiated and conducted immunity (ISO 11452 series), electrostatic discharge (ISO 10605).
Materials and emissions
Odour, fogging and VOC emissions from interior materials; flammability; UV ageing; coating durability and stone impact.
Functional safety and cyber security
Functional safety evidence under ISO 26262 and cyber security engineering under ISO/SAE 21434; these are tied to regulation through UNECE R155 and R156.
Commonly confused in this field
- An automotive report without a specification reference is not accepted in the supply chain; which OEM specification and revision was applied must be stated.
- Type approval and supplier approval are different processes. A component with E-Mark approval is not thereby considered to have passed the OEM's own acceptance tests.
- A result obtained on a prototype does not carry over to series production; PPAP is done with series production parts.
- On the EMC side, measuring emissions alone is incomplete; immunity is a separate body of work and is more critical in a vehicle.
- On electric vehicle components, high-voltage safety is a distinct competence; classical 12 V test infrastructure is not sufficient.
Which decisions these results support
- Supplier component approval and the PPAP file
- UNECE type approval and E-Mark marking
- Design verification and durability evidence
- Root cause analysis of field complaints and warranty returns
- Assessing the impact of a design or supplier change
Related Tests
Frequently Asked Questions About Flammability
Are FMVSS 302 and ISO 3795 the same test?
The test rig and logic are largely the same; ISO 3795 is international, while FMVSS 302 is a US federal regulation. Differences exist in specimen preparation and reporting details; which one applies is determined by the target market.
What is the difference from UNECE R118?
R118 defines a more comprehensive regime specifically for the interior materials of buses and large passenger-carrying vehicles; besides horizontal burn rate, it includes additional tests such as vertical burning behaviour, melting-material behaviour, and resistance to fuel droplets.