Masurement of thermal and water vapour resistance under steady-state conditions according to EN ISO 11092:2014

Sweating guarded-hotplate test
fire fighter
Testing lab
Physical lab
Legislation
PPE Regulation (EU) 2016/425
Testing standard

ISO 11092:2014

Principle

The method simulates human skin conditions using a guarded hotplate that:

  • Maintains a constant surface temperature.
  • Can be either dry (for thermal resistance) or sweating (for water vapour resistance).
  • Measures the amount of power needed to maintain that surface temperature while heat and/or moisture pass through the textile specimen.
Survey of our Thermo-physiological Comfort Tests
skinmodel

Key Concepts:

  • Thermal Resistance (Rct): The material's resistance to dry heat flow.
  • Water Vapour Resistance (Ret): The material's resistance to water vapour (simulating sweating or perspiration).

These are expressed as:

  • Rct (m²·K/W) = Thermal resistance.
  • Ret (m²·Pa/W) = Water vapour resistance.

Testing Procedures

Equipment Setup

Sweating guarded-hotplate (also called the "skin model"):

  • Heated plate simulating skin surface temperature (usually 35°C).
  • Surrounded by guard ring to minimize edge losses.
  • Placed in a climate-controlled chamber (typically 20°C, 65% RH, no air movement for standard testing).

Sample Preparation

  • Textile specimen is conditioned (usually for 24 h at standard atmosphere).
  • The sample is cut to appropriate size to fit over the measuring plate.

Measurement Steps

Thermal Resistance (Dry Test)

  1. the dry specimen is placed over the hotplate.
  2. The plate temperature is maintained at a steady 35°C.
  3. The electrical power required is measured to keep the plate at this temperature.
  4. The thermal resistance (Rct) is calculated

Water Vapour Resistance (Wet/Sweating Test)

  1. The hotplate is covered with a wet porous surface (simulating sweating skin).
  2. The textile sample is laid on top of this surface.
  3. The apparatus operates under isothermal conditions (same air and plate temperature).
  4. The power required to maintain 35°C with evaporation occurring is measured.
  5. The water vapor resistance Ret is calculated
sportswear

Applications of ISO 11092

  • Sportswear
  • Military clothing
  • Garments for industrial use
  • Protective garments
  • Bedding and sleepwear
  • Automotive and furniture textiles (in some cases).

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