ISO 17492:2019

Overview

ISO 17492:2019 - "Clothing for protection against heat and flame - Determination of heat transmission on exposure to both flame and radiant heat" specifies a laboratory test method to measure heat transmitted through horizontally mounted flame‑resistant textile materials when exposed to a controlled mixture of convective and radiant heat. The method establishes exposure conditions approximating a 50/50 split of convective and radiant heat at a total heat flux of 84 kW/m². Results help characterize material insulation performance and predict potential onset of skin burn injury under combined heat sources.

Key topics and technical requirements

• Scope and applicability: Applies only to flame‑resistant sheet materials used as single layers or multilayer constructions; it does not apply to non‑flame‑resistant materials or to radiant‑only or flame‑contact‑only exposures.
• Test principle: Measurement of accumulated thermal energy transferred through the specimen to a sensor; two analysis approaches are defined:
  • Thermal Protection Index (TPI) - estimates time/energy to the onset of a second‑degree burn (Stoll curve).
  • Heat Transfer Index (HTI) - measures energy required to raise a copper sensor by specified temperatures (e.g., 12 °C and 24 °C), indicating insulation capacity and thermal mass.
• Exposure configuration: Horizontal mounting, with options for contact or spaced sensor configurations to simulate direct contact or an air gap between fabric and protected surface.
• Apparatus and calibration: Detailed requirements for burner alignment, radiant lamp settings, sensor care, and initial calibration to achieve the 50/50 convective/radiant balance at 84 kW/m².
• Sampling, conditioning and reporting: Specimen dimensions, number of specimens, conditioning/testing atmospheres (per ISO 139), data processing and required test report content are specified.
• Limitations and notes: Results are from small‑scale, controlled tests and are not a full fire‑hazard appraisal. Some textiles may ignite and continue burning under the test.

Practical applications

• Material selection and R&D for protective clothing, firefighting apparel, industrial PPE, and multilayer assemblies.
• Performance benchmarking of flame‑resistant textiles for insulation and thermal capacity under combined heat exposure.
• Input data for product development, compliance verification, procurement specifications, and partial fire‑risk assessments.

Who should use ISO 17492:2019

• PPE and textile manufacturers developing heat‑resistant garments
• Accredited test laboratories performing thermal protection testing
• Safety engineers, procurement officers, and standards specialists specifying protective clothing
• Regulatory and certification bodies needing standardized small‑scale test data

Related standards

• ISO 6942 - radiant‑only heat exposure testing
• ISO 9151 - flame‑contact‑only exposure testing
• ISO 139 - conditioning and testing atmospheres

Keywords: ISO 17492:2019, heat transmission, flame and radiant heat, thermal protection index (TPI), heat transfer index (HTI), flame‑resistant textile materials, protective clothing, 50/50 convective radiant, 84 kW/m².