GB/T 11048-2018 English PDF (GBT11048-2018)

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GB/T 11048-2018: Textiles -- Physiological effects -- Measurement of thermal and water-vapour resistance under steady-state conditions (sweating guarded-hotplate test)
GB/T 11048-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.080.30
W 04
Replacing GB/T 11048-2008
Textiles - Physiological Effects - Measurement of Thermal
and Water-vapor Resistance under Steady-state Conditions
(sweating guarded-hotplate test)
(ISO 11092.2014, MOD)
ISSUED ON. MARCH 15, 2018
IMPLEMENTED ON. OCTOBER 1, 2018
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People’s Republic of China;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword... 3
Introduction... 5
1 Scope... 6
2 Terms and Definitions... 6
3 Symbols... 7
4 Principle... 8
5 Instruments... 9
6 Specimens... 12
7 Test... 13
8 Result Accuracy... 16
9 Test Report... 17
Appendix A (normative) Preparation of Specimens Containing Loose Fillings and
Uneven Thickness... 18
Appendix B (normative) Determination of Correction Value for Heating Power... 19
Appendix C (normative) Instrument Verification... 21
Appendix D (informative) The Placement of Specimens Prone to Expansion... 22
Textiles - Physiological Effects - Measurement of Thermal
and Water-vapor Resistance under Steady-state Conditions
(sweating guarded-hotplate test)
1 Scope
This Standard specifies the determination methods for thermal and water-vapor resistance of
physiological effects of textiles under steady-state conditions.
This Standard is applicable to all types of textile fabrics and their products. Coated fabrics,
leather and multi-layer composite materials may take this as a reference.
NOTE 1.the application of determination techniques of this Standard is affected by the maximum
determination ranges of thermal and water-vapor resistance. The two maximum values
depend on the size and structural properties of the instrument (for example, the thermal
and water-vapor resistance determination ranges of the instrument applicable to this
Standard are generally not less than 2 m2  K/W and 700 m2  Pa/W).
NOTE 2.the test environment used in this Standard does not represent a specific comfort
environment, nor does it provide the performance requirements for comfort.
2 Terms and Definitions
The following term and definitions are applicable to this document.
2.1 thermal resistance
Rct
The ratio of the temperature difference on both sides of the specimen to the heat flow per unit
area vertically passing through the specimen.
NOTE 1.the dry heat flow may include one or multiple forms of conduction, convection and
radiation.
NOTE 2.thermal resistance Rct is expressed in the unit of (m2  K/W).
2.2 water-vapor resistance
Ret
The ratio of the water vapor pressure difference on both sides of the specimen to the evaporative
heat flow per unit area vertically passing through the specimen.
imt. water-vapor permeability index, dimensionless.
Rct0.an instrument constant determined for the determination of thermal resistance Rct,
expressed in m2  K/W.
Ret0.an instrument constant determined for the determination of water-vapor resistance Ret,
expressed in m2  Pa/W.
Wd. water-vapor permeability, expressed in g/(m2  h  Pa).
Tm. latent heat of saturated water vapor when the surface temperature of the test plate is Tm,
expressed in W  h/g.
A. area of the test plate, expressed in m2.
Ta. air temperature in the climate chamber, expressed in C.
Tm. temperature of the test plate, expressed in C.
Ts. temperature of the thermal retainer, expressed in C.
pa. water vapor pressure (when the temperature in the climate chamber is Ta), expressed in Pa.
pm. saturated water vapor pressure (when the surface temperature of the test plate is Tm),
expressed in Pa.
va. flow velocity of the air above the surface of the specimen under test, expressed in m/s.
sv. standard deviation of air flow velocity va, expressed in m/s.
R.H.. relative humidity, expressed in %.
H. heating power provided to the test plate, expressed in W.
Hc. correction amount of heating power in thermal resistance determination.
He. correction amount of heating power in water-vapor resistance determination.
. slope of the correction amount curve for the calculated result of Hc.
. slope of the correction amount curve for the calculated result of He.
4 Principle
Use the specimen to cover the test plate. The test plate, the surrounding thermal retainer, and
the protective plate at the bottom can maintain a constant temperature, so that the heat of the
test plate can only be dissipated through the specimen, and the air can flow parallel to the upper
surface of the specimen. After the test conditions stabilize, determine the heat flow through the
specimen, so as to calculate the thermal resistance of the specimen.
The method described in this Standard is to obtain the thermal resistance value Rct of the
determined material by subtracting the thermal resistance value of the air layer from the thermal
resistance value of the determined specimen plus the air layer. Both determinations are
performed under identical conditions.
For the determination of water-vapor resistance, the porous test plate needs to be covered with
a breathable but water-impermeable film. The water entering the test plate evaporates, then,
passes through the film in the form of water vapor, so no liquid water contacts the specimen.
After the specimen is placed on the film, determine the heat flow required to maintain a constant
temperature of the test plate under a certain water evaporation rate, and calculate the water-
vapor resistance of the specimen together with the water vapor pressure passing through the
specimen.
The method described in this Standard is to obtain the water-vapor resistance value Ret of the
determined material by subtracting the water-vapor resistance value of the air layer from the
water-vapor resistance value of the determined specimen plus the air layer. Both determinations
are performed under identical conditions.
5 Instruments
5.1 Test Part with Temperature and Feed Water Control
The test plate consists of a metal plate with a thickness of about 3 mm and an area of at least
0.04 m2 (for example, a square with a side length of 200 mm) fixed on a conductive metal
component containing a heating wire (see Figure 1).
For the determination of water-vapor resistance, the test plate shall be porous, which shall be
surrounded by a thermal retainer located within the specimen platform.
In an environment of 20 C, by using a beam with a wavelength range of 8 m ~ 14 m to
vertically irradiate on the surface of the metal plate and in the mode of hemispheric reflection,
determine the radiation emissivity of the metal plate surface, which shall be higher than 0.35.
The surface of the electric heating wire metal component in contact with the porous plate is a
groove, so that the water provided by the quantitative water supply device can enter the test
plate.
The position of the test plate relative to the specimen platform shall be adjustable, so that the
upper surface of the specimen placed on it can remain flush with the specimen platform.
The heat loss in the test plate or temperature test device shall be minimized, for example, by
routing the traces along the inner surface of the thermal retainer as much as possible.
The temperature controller, including the temperature sensor of the test plate, shall maintain the
resistance is lower than 100 m2  Pa/W, the accuracy can be controlled at  0.5 C; th...