ISO 17492:2019

• Abstract:

  This document specifies a test method for measuring the heat transferred through horizontally mounted flame-resistant textile materials when exposed to a combination of convective and radiant heat. The exposure conditions are adjusted to be approximately a 50/50 mixture of pure convective heat and pure radiant heat. The total exposure heat flux is 84 kW/m2. This test method is applicable to any type of sheet material used either as a single layer or in a multilayer construction when all structures or sub-assemblies are made of flame-resistant materials. It does not apply to materials that are not flame resistant. This test method does not apply to the evaluation of materials exposed to any other type of thermal energy sources, such as radiant heat only or flame contact only. ISO 6942 is applicable when evaluating materials for exposure to radiant heat only. ISO 9151 is applicable when evaluating materials due to flame contact only. NOTE Some, but not all, textiles materials can ignite and continue to burn after exposure to the convective and radiant heat produced by this test method.

• Status: Published
• Publication Date: 07-Oct-2019
• ICS: 13.340.10 - Protective clothing
• Technical Committee: ISO/TC 94/SC 13 - Protective clothing
• Drafting Committee: ISO/TC 94/SC 13/WG 2 - Protective clothing against heat and flame
• Current Stage: 9092 - International Standard to be revised
• Start Date: 08-Sep-2026
• Completion Date: 12-Sep-2026

• Revises: ISO 17492:2003 - Clothing for protection against heat and flame — Determination of heat transmission on exposure to both flame and radiant heat
• Effective Date: 11-Feb-2012

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.