The Importance of Flame Resistance in Automotive Interiors

The automotive industry is a highly regulated industry, and rightfully so. One critical aspect of this industry is ensuring the safety of passengers in vehicles. Flammability of interior materials in automotive vehicles is an essential safety feature that everyone in the industry must understand. With that being said, for most automotive applications the test protocol described in FMVSS 302 which is derived from title 49 Part 571.302 applies to this topic. For vehicles of categories M3, Classes II and III 1/, carrying more than 22 passengers are subject to the ECE Regulations 118. For Road vehicles, tractors and machinery for agriculture and forestry, BS AU 169a: 1992 (ISO 3795: 1989) applies. All these test standards and protocols have one thing in common and that is, they all determine the Horizontal burning rate of interior materials used in the occupant compartments of such vehicles.

In this blog post, we will dive into the world of flammability on interior materials used in automotive vehicles and the regulations and test methods that govern it.

The first method of test we will discuss is FMVSS 302 (49 Part 571.302) this is a US federal motor vehicle safety standard that requires interior materials to have a horizontal burn rate of less than 102 millimetres per minute. This test protocol applies to most automotive applications and is widely adopted by most car manufacturers, whom often reduce the burning rate requirement from 102 millimetres per minute to as low as 75 millimetres per minute for a much more stringent requirement for a wide range of interior materials, including seat cushions, seat belts, headliners, carpets, and dashboards, to name a few.

Similar to the FMVSS 302 test protocol is the BS AU 169a: 1992 and its international counterpart ISO 3795: 1989. This International Standard specifies a method for determining the horizontal burning rate of materials used in the occupant compartment of road vehicles (for example, passenger cars, lorries/trucks, estate cars, coaches), and of tractors and machinery for agriculture and forestry, after exposure to a small flame. This method permits testing of materials and parts of the vehicle interior equipment individually or in combination up to a thickness of 13 mm. It is used to judge the uniformity of production lots of such materials with respect to their burning behaviour. However, because of the many differences between the real world situation (application and orientation within vehicle interior, conditions of use, ignition source, etc.) and the precise test conditions specified in this International Standard, this method cannot be considered as suitable for evaluation of all true in-vehicle burning characteristics.

Lastly, we have ECE Regulation 118: This regulation applies to the horizontal, vertical burning and melting behaviour of interior materials used in vehicles of categories M3, Classes II and III 1/, carrying more than 22 passengers, not being designed for standing passengers and urban use (city buses). The test methods set out to assess the horizontal burning rate of “Annex 6” are very similar to those used to determine the horizontal burning rate in ISO 3795: 1989. The determination of the vertical burn rate given in “Annex 8” is very similar to that of the international test method of ISO 6941 – Measurement of Flame spread properties.

In conclusion, Flammability of Interior Materials is a critical safety feature that every automotive industry player must understand. The regulations, Methods of tests and Protocols governing this topic are in place to ensure that manufacturers compliantly integrate flame-resistant materials throughout their vehicles so we can all feel a little safer as we take to the roads. As a manufacturer or decision-maker in the automotive industry, understanding the importance of flame resistance and adhering to the regulations is of utmost importance.

Whatever your test requirement, please be assured at IFS Laboratories Ltd we are UKAS accredited to perform FMVSS 302 (49.571.302), BS AU 169a: 1992 (ISO 3795: 1989) and ECE Regulation 118: Annex’s 6, 7 and 8.

Simply get in touch at info@ifs-labs.com or Technical@ifs-labs.com or contact us on 0161 5050 650 and one of our experience Test Technician will be on hand to guide you through the process.