ISO 14624-2:2023

Overview

ISO 14624-2:2023 - "Space systems - Safety and compatibility of materials - Part 2" defines standardized methods to assess the flammability of electrical-wire insulation and accessory materials used in spacecraft and related systems. The standard specifies two complementary test methods: Test A (static environment) and Test B (gas-flow environment). Both methods evaluate whether an insulated-wire assembly, when exposed to a defined ignition source, will self‑extinguish and avoid transfer of burning debris that could ignite adjacent materials.

Key topics and technical requirements

• Two test methods
  • Test A (static): Exposes a representative wire specimen to a chemical ignitor in a still atmosphere to determine burn length and transfer risk.
  • Test B (gas‑flow): Evaluates flammability under flowing-gas conditions to simulate pressurized or flowing environments.
• Pass/fail criteria
  • A specimen is considered self‑extinguishing if burn length does not exceed 150 mm on a standard specimen; failure of any single replicate constitutes failure of the material under that test condition.
  • Tests also check for transfer of burning debris (paper ignition under the specimen is a common indicator).
• Specimen definition and preparation
  • Standard test specimen: representative wire segment (document cites 1.2 m length with an active length of 300 mm); wire configuration and insulation thickness must represent worst‑case use.
• Environmental controls
  • Ambient conditions specified (e.g., oxygen concentration 20.9% ± 0.2%, pressure 101.4 kPa ± 5 kPa, temperature 23 °C ± 5 °C).
  • Worst‑case configurations (oxygen, pressure, temperature) should be considered when selecting test conditions.
• Ignition source and reproducibility
  • Use of a validated chemical ignitor (requirements and example preparation given; see Annex A).
  • Requirements for accuracy, test reporting, and Good Laboratory Practice (GLP) to ensure repeatability.

Practical applications and users

• Who uses it: aerospace and satellite manufacturers, harness and cable suppliers, materials engineers, test laboratories, regulatory and safety compliance teams.
• Why it matters:
  • Ensures spacecraft wiring systems meet safety and compatibility criteria for in‑flight environments.
  • Guides selection of insulation materials and accessory components to minimize fire risk, burn propagation, and risk of secondary ignition.
  • Supports procurement specifications, qualification testing, and design reviews for spacecraft electrical systems.

Related standards

• This document is part of the ISO 14624 series on space system material safety and references ISO 14624‑1:2023 terminology and related test definitions.
• Conforms with ISO/IEC editorial and development practices for consistency across electrotechnical and space-system standards.

Keywords: ISO 14624-2:2023, flammability testing, electrical‑wire insulation, space systems safety, wire insulation flammability test, test A static, test B gas‑flow, chemical ignitor, self‑extinguish, burn length.