ISO 9773:2024

Overview

ISO 9773:2024 specifies a small-scale laboratory screening procedure for assessing the burning behaviour of thin, flexible, vertically oriented plastic specimens when exposed to a low‑energy small flame ignition source. The method measures afterflame and afterglow times to compare relative flammability of materials that cannot be tested with IEC 60695-11-10 method B because they distort or shrink away from the flame. The standard is primarily intended for quality control and preselection of component materials; classifications apply only to the tested material formulation.

Key topics and requirements

• Test objective: Determine afterflame and afterglow times of vertically mounted, nearly cylindrical specimens exposed to two successive 50 W diffusion burner applications.
• Specimen dimensions: Standard specimens are 200 mm ±5 mm long, 50 mm ±2 mm wide and a maximum thickness of 0.25 mm (thicker flexible specimens may be tested if they behave like thin nonrigid samples).
• Apparatus essentials:
  • Test chamber or fume hood with internal volume ≥ 0.5 m3, dark interior (light level < 20 lux facing rear).
  • 50 W diffusion laboratory burner per ISO 10093:2020 and IEC 60695 series.
  • Methane gas supply (technical grade, ≥ 98% purity) or equivalent with heat content ~37 MJ/m3.
  • Timing device (accuracy 0.5 s per hour), micrometer (0.01 mm), mandrel (13 mm ±0.5 mm), wire (0.2–0.5 mm), cotton wool conditioned in desiccator.
• Conditioning: Ambient conditioning at 23 °C ±2 °C / 50% ±10% RH. Oven conditioning recommended (preferred: 7 days at 70 °C) to assess changes in burning behaviour.
• Performance limits and notes:
  • Results depend on specimen shape, orientation, additives (pigments, fillers, flame retardants), density and thickness.
  • Test is not a full fire-hazard assessment - it is for comparative screening only.
• Classification: Annex A provides a classification system for quality control and material preselection.

Applications and users

ISO 9773:2024 is used by:

• Material manufacturers and R&D teams for evaluating new polymer formulations and additive effects.
• Quality assurance and production control for batch-to-batch consistency.
• Component and product designers selecting materials for low‑energy ignition environments.
• Independent test laboratories conducting comparative flame tests.
• Regulatory and procurement professionals seeking material-level flammability data for preselection.

Keywords: ISO 9773:2024, plastics burning behaviour, thin flexible specimens, small flame ignition, afterflame afterglow, flame test, laboratory screening.

Related standards

• ISO 10093:2020 (standard ignition sources)
• ISO 13943:2023 (fire safety vocabulary)
• ISO 845 (density of cellular plastics)
• IEC 60695 series (test flames and needle/50 W flame methods)