Overview
ISO 4589-1:2017 specifies the general requirements for the determination of burning behaviour of plastics by the oxygen index (OI) test. It defines the scope, terminology and essential test principles that are implemented in the companion methods:
- ISO 4589-2 – ambient-temperature OI test (minimum oxygen volume fraction at 23 °C ± 2 °C that just supports flaming combustion);
- ISO 4589-3 – elevated-temperature OI test (range typically 25 °C to 150 °C, with capability up to 400 °C).
ISO 4589-1 frames specimen preparation, apparatus expectations, calibration and operating conditions so results from ISO 4589-2 and ISO 4589-3 are consistent and reproducible.
Key topics
- Definitions and terminology – including OI / LOI (limiting oxygen index) as the minimum oxygen volume fraction supporting flaming combustion.
- Test principles – specimen in a vertical transparent column with upward laminar flow of oxygen/nitrogen; ignition procedures include top-surface, propagating-ignition and thin-film methods.
- Specimen preparation – clean, flaw‑free surfaces and correct conditioning; dimensional and orientation dependence highlighted.
- Apparatus requirements – column design (preferred diameter 75–100 mm for ambient tests; ≥75 mm for heated columns), sample holders for rigid/flexible specimens, measuring devices (flow meters or oxygen analysers).
- Operating conditions and calibration – calibration schedules, use of reference material (e.g., PMMA per ISO 7823-1) and leak checks; flame application time limits (top-surface flame application up to 30 s with periodic removal), gas-flow control and elevated-temperature preheating (specimen preheat ≈240 s ± 10 s).
- Limitations and interpretation – sensitivity to specimen size, shape and orientation; small-scale laboratory test for material comparisons, R&D and quality control, not a standalone assessment of real-world fire hazard.
Applications
ISO 4589-1 (and Parts 2 & 3) are used for:
- Quality control of plastics and verification of flame-retardant formulations.
- Research and development to compare material burning characteristics across temperatures.
- Inclusion of OI values in material data sheets and product specifications.
Primary users include plastics manufacturers, cable and wire producers, flame-retardant suppliers, testing laboratories and R&D teams.
Related standards
Note: ISO 4589 results are valuable for material selection and process control but should be combined with other fire tests for comprehensive fire-safety assessment.
Open preview (PDF)Plastics — Determination of burning behaviour by oxygen index — Part 1: General requirements
