BS ISO 20852:2020 pdf download.Textiles — Determination of the total heat transfer through textiles in simulated environments
1 Scope
This document specifies the test method for determining the amount of heat transferred through clothing fabrics by the combined dry and evaporative heat emission under simulated and specified conditions. This test method can be used for fabrics, films, coatings, foams and leathers including multilayer assemblies used in hot environment or in activities. The application of this measurement technique is restricted to a maximum amount of total heat transfer which depend on the dimensions and construction of the apparatus used (e.g. about 1 200 W/m 2 for the maximum specifications of the equipment according to ISO 11092).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 11092:2014, Textiles — Physiological effects — Measurement of thermal and water-vapour resistance under steady-state conditions (sweating guarded-hotplate test)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 dry heat emission
heat transferred by the temperature difference between the two faces of a material divided by the resultant heat flux per unit area in the direction of the gradient in dry state
Note 1 to entry: It is a quantity which determines the dry heat flux across a given area in response to a steady applied temperature gradient.
3.2 evaporative heat emission
heat transferred by the water-vapour pressure difference between the two faces of a material divided by the resultant evaporative heat flux per unit area in the direction of the gradient, when evaluated non-isothermally
Note 1 to entry: It is a quantity which determines the “latent” evaporative heat flux across a given area in response to a steady applied water-vapour pressure gradient. The evaporative heat flux may consist of condensation as well as diffusive and convective components.
3.3 total heat transfer
amount of heat transferred by the combined dry and evaporative heat exchanges under the specified conditions
Note 1 to entry: It is expressed in watts per square metre.
BS ISO 20852:2020 pdf download
