ISO 18640-2:2018

Overview - ISO 18640-2:2018 (Protective clothing for firefighters)

ISO 18640-2:2018 defines a laboratory method to evaluate the thermo‑physiological impact of protective fabric ensembles and, optionally, full protective clothing ensembles worn by firefighters. It uses a Sweating Torso coupled with a validated physiological model (a Thermal Human Simulator - THS) to simulate activity, measure heat and moisture transfer, and predict physiological responses. The standard is intended for characterization and comparison of ensembles under defined, relevant scenarios - not for predicting heat stress in actual fire conditions. Results are used to calculate the Maximum Allowable Work Duration (MAWD) for defined tasks and environments.

Key topics and technical requirements

• Scope and purpose: Evaluate physiological heat load caused by protective clothing during simulated activity; default testing on fabric samples, optional tests on readymade garments or ensembles including underwear and air layers.
• Test apparatus and coupling: Uses the sweating torso (per ISO 18640-1) coupled with a physiological model (THS) to transform physical measurements into predicted physiological parameters.
• Measured and computed parameters:
  • Heat flux and evaporative heat loss
  • Skin diffusion (E_sk) and wicking layer correction
  • Mean skin temperature (T_m,sk) and core body temperature (T_co) predictions
  • Sweat rate, heart rate, heat storage and MAWD
• Test procedure elements: Defined firefighting scenarios, apparatus and software requirements, sampling and specimen preparation, measurement control and data exchange with the physiological model.
• Reporting: Test reports must include specimen identification, measurement conditions, THS results and predicted physiological parameters.
• Normative references: ISO 18640-1 (sweating torso) and ISO 11092 (sweating guarded‑hotplate) are directly referenced.
• Validation note: Current evaluation methods are validated for structural firefighting garments only.

Applications - who uses ISO 18640-2 and why

• PPE manufacturers and designers: Compare materials, garment constructions and design features (pockets, reflective strips) for thermo‑physiological performance and to guide design improvements.
• Test laboratories and certification bodies: Standardized method for generating comparable thermo‑physiological data using the THS protocol.
• Procurement and safety managers: Support evidence‑based selection of firefighter protective clothing by comparing MAWD and predicted thermal burden under defined tasks.
• Occupational health researchers: Quantify how ensembles impact heat strain and work duration in simulated scenarios to inform operational limits and training.

Related standards

• ISO 18640-1 - Measurement of coupled heat and mass transfer with the sweating torso (required for THS inputs).
• ISO 11092 - Sweating guarded‑hotplate test for thermal and water‑vapour resistance.

Keywords: ISO 18640-2:2018, protective clothing firefighters, thermo-physiological impact, Thermal Human Simulator, sweating torso, MAWD, physiological heat load, heat stress testing.