ISO 4589-2:2017

Overview

ISO 4589-2:2017 - "Plastics - Determination of burning behaviour by oxygen index - Part 2: Ambient‑temperature test" - specifies laboratory methods to determine the oxygen index (OI): the minimum volume fraction of oxygen in a nitrogen/oxygen mixture that will support combustion of small vertical plastic specimens under defined ambient‑temperature conditions. The standard covers self‑supporting bars and sheets (up to 10.5 mm thick), many cellular materials (typically ≥100 kg/m³), and supported flexible films/sheets. A short procedure is included to determine whether a material’s OI exceeds a specified minimum.

Key topics and technical requirements

• Test principle: Vertical specimen in a transparent chimney with controlled oxygen/nitrogen flow; ignite top end and observe burning behaviour to estimate OI.
• Specimen types & limits: Solid, laminated or cellular materials self‑supporting as vertical bars/sheets ≤10.5 mm; some low‑density cellular materials may be applicable; flexible films tested while supported vertically.
• Apparatus essentials: heat‑resistant glass chimney (recommended 450–500 mm height; 75–100 mm inside diameter), restricted outlet/cap (example 40 mm outlet), gas supply and flow control, oxygen analyser, flame igniter, timing and fume extraction.
• Flow & exhaust: exhaust velocity at chimney outlet of at least 90 mm/s; even gas distribution at base.
• Ignition procedures: Procedure A (top surface ignition) and Procedure B (propagating ignition); marking and conditioning of specimens required.
• Calibration & quality: equipment calibration, specimen conditioning per ISO 291, calculation of OI and statistical treatment (k factor, standard deviation, precision) described; normative annexes provide calibration and calculation methods.
• Limitations: Results depend on specimen shape, thickness, orientation and ignition conditions - not a direct measure of real fire hazard unless used within a full risk assessment.

Practical applications and users

ISO 4589-2 is used for:

• Material selection & specification - comparing flammability of polymers and formulations.
• Quality control - batch acceptance testing and process control in plastics manufacturing.
• Product safety & compliance - input to fire safety assessments for consumer goods, electrical enclosures, construction components (as part of broader testing programs).
• R&D and formulation development - evaluating flame‑retardant additives and composite constructions. Primary users: testing laboratories, polymer manufacturers, product safety engineers, regulatory bodies, and compliance teams.

Related standards

• ISO 4589‑1 - General requirements for oxygen index testing.
• ISO 3582 - Methods for cellular materials of density < 100 kg/m³.
• ISO 291 - Conditioning of plastics for testing.
• ISO 5725‑2 - Measurement precision and reproducibility.
• ISO 13943 - Fire safety vocabulary.

Keywords: ISO 4589-2, oxygen index (OI), plastics flammability testing, ambient-temperature test, test chimney, oxygen analyser, material qualification, fire safety testing.