ISO 3795:1989

Overview

ISO 3795:1989 specifies a laboratory test method for determining the horizontal burning rate of interior materials used in the occupant compartment of road vehicles, tractors and machinery for agriculture and forestry. The procedure exposes samples or parts (up to 13 mm thickness) to a small, defined flame in a controlled combustion chamber and records whether the flame self‑extinguishes or how fast it propagates. The method is intended for production lot testing and quality control, not as a full simulation of in‑vehicle fire scenarios.

Key topics and technical requirements

• Purpose: Measure burning behaviour (burnt distance and time) to calculate burning rate in mm/min.
• Test specimen limits: Samples up to 13 mm thickness; typical sample lengths 356 mm (width 3–60 mm) or 138 mm (width 60–100 mm). Samples narrower than 3 mm or shorter than specified cannot be tested.
• Conditioning: Samples conditioned 24 hours to 7 days at 23 °C ±2 °C and 50 % ±5 % relative humidity before testing.
• Apparatus essentials:
  • Combustion chamber with specified ventilation (vent holes and slot), observation window and drip pan.
  • Sample holder: U‑shaped frames with pins/holes for repeatable placement; heat‑resistant support wires (0.25 mm dia.) spaced at 25 mm.
  • Gas burner: Bunsen-type burner with 9.5 mm nominal inside nozzle; flame adjusted to 38 mm height and applied for 15 s.
  • Additional accessories: Comb for nap/tuft preparation, metal comb for pretest treatment, stopwatch accurate to 0.5 s.
• Procedure highlights: Flame applied to free end of horizontally mounted sample for 15 s; start timing when flame foot passes the first measuring point; measure burnt distance or note self‑extinguishing.
• Reporting: Test report must include sample identification, dimensions, preparation, burnt distance/time, calculated burning rates (individual, max/min), special conditions (fume cupboard, ventilation), and observations (self‑extinguishing, melt‑drip).

Applications and users

ISO 3795 is used by:

• Vehicle and agricultural/forestry machinery manufacturers for component qualification and production lot consistency.
• Interior materials and trim suppliers for material selection and supplier compliance.
• Testing laboratories performing fire performance testing of upholstery, headliners, carpets, foams and composite assemblies within the thickness limit.
• Regulatory bodies and safety engineers referencing objective test data during standards development or conformity assessment. Practical applications include quality control, supplier acceptance testing, safety audits, and pre‑compliance screening during material development.

Related standards

• The standard references normative tolerances and laboratory practices (see the normative references listed in ISO 3795:1989). The test procedure was developed with consideration of existing methods (for example, US FMVSS 302) and international vehicle safety requirements.

Keywords: ISO 3795, burning behaviour, horizontal burning rate, interior materials, vehicle interior fire test, occupant compartment, combustion chamber, FMVSS 302, sample conditioning.