ASTM D1518-85(2003)
(Test Method)Standard Test Method for Thermal Transmittance of Textile Materials
Standard Test Method for Thermal Transmittance of Textile Materials
SCOPE
1.1 This test method covers the determination of the overall thermal transmission coefficients due to the combined action of conduction, convection, and radiation for dry specimens of textile fabrics, battings, and other materials within the limits specified in 1.2. It measures the time rate of heat transfer from a warm, dry, constant-temperature, horizontal flat-plate up through a layer of the test material to a relatively calm, cool atmosphere.
1.2 For practical purposes, this test method is limited to determinations on specimens of fabrics, layered fabric assemblies, and battings having thermal transmittances (U2, as defined in 3.1.2) within a range of 0.7 to 14 W/m2K and thicknesses not in excess of 50 mm.
1.3 The coefficients obtained apply strictly only to the particular specimens tested and for the specified thermal and environmental conditions of each test. This test method gives values that are valid for comparison under the same conditions of test, that is, with the specified air velocity, temperature difference between the warm plate and the cool air, and air gap for measuring cool air temperature.
1.4 The values stated in metric units are to be regarded as the standard. Conversion factors, for thermal conductance and conductivity and thermal resistance and resistivity, to other units in common use are given in 1-5
1.5 This standard does not purport to address the safety concerns associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D1518 – 85 (Reapproved 2003)
Standard Test Method for
Thermal Transmittance of Textile Materials
This standard is issued under the fixed designation D1518; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers the determination of the overall 3.1 Definitions:
thermaltransmissioncoefficientsduetothecombinedactionof 3.1.1 bulk density, n—apparent mass per unit volume.
conduction, convection, and radiation for dry specimens of 3.1.1.1 Discussion—In testing the thermal transmittance of
textile fabrics, battings, and other materials within the limits fabrics, bulk density is calculated from the fabric weight per
specified in 1.2. It measures the time rate of heat transfer from unit area and the thickness value used to calculate thermal
a warm, dry, constant-temperature, horizontal flat-plate up conductivity.
through a layer of the test material to a relatively calm, cool 3.1.2 clo, n—unit of thermal resistance defined as the
atmosphere. insulationrequiredtokeeparestingman(producingheatatthe
1.2 For practical purposes, this test method is limited to rate of 58 W/m ) comfortable in an environment at 21°C, air
determinations on specimens of fabrics, layered fabric assem- movement 0.1 m/s, or roughly the insulation value of typical
,
3 4
blies, and battings having thermal transmittances (U,as indoor clothing. (Syn. intrinsic clo).
defined in 3.1.2) within a range of 0.7 to 14 W/m ·K and 3.1.2.1 Discussion—Numerically the clo is equal to 0.155
thicknesses not in excess of 50 mm. K·m /W.
1.3 The coefficients obtained apply strictly only to the 3.1.3 heat transfer coeffıcient, n—see thermal transmit-
particular specimens tested and for the specified thermal and tance.
environmental conditions of each test. This test method gives 3.1.4 intrinsic clo, n—see clo.
values that are valid for comparison under the same conditions 3.1.5 specific clo, n—the specific thermal resistance in clo
of test, that is, with the specified air velocity, temperature units per unit thickness.
difference between the warm plate and the cool air, and air gap 3.1.6 thermal conductance, n—see thermal transmittance.
for measuring cool air temperature. 3.1.7 thermal conductivity, n—time rate of unidirectional
1.4 The values stated in metric units are to be regarded as heat transfer per unit area, in the steady-state, between parallel
the standard. Conversion factors, for thermal conductance and planes separated by unit distance, per unit difference of
conductivity and thermal resistance and resistivity, to other temperature of the planes.
units in common use are given in Tables 1-5 3.1.7.1 Discussion—Numerically, thermal conductivity
1.5 This standard does not purport to address the safety equals the product of the heat transfer coefficient and the
concerns associated with its use. It is the responsibility of distance separating the planes. Thus, k, the thermal conductiv-
whoever uses this standard to consult and establish appropri- ity of the fabric only, is the product of U and the fabric
ate safety and health practices and determine the applicability thickness. Units of thermal conductivity are W/m·K.
of regulatory limitations prior to use. 3.1.8 thermal resistance, n—reciprocal of thermal transmit-
tance.
2. Referenced Documents
3.1.9 thermal resistivity, n—reciprocal of thermal conduc-
2.1 ASTM Standards: tivity.
D123 Terminology Relating to Textiles
3.1.10 thermal transmittance, n—time rate of unidirectional
D1777 Test Method for Thickness of Textile Materials heat transfer per unit area, in the steady-state, between parallel
planes, per unit difference of temperature of the planes (Syn.
thermal conductance, heat transfer coefficient).
This test method is under the jurisdiction ofASTM Committee D13 onTextiles
3.1.10.1 Discussion—Thermaltransmittanceisexpressedas
and is the direct responsibility of Subcommittee D13.51 on Chemical Conditioning
watts per square metre of test specimen per kelvin difference
and Performance.
Current edition approved July 26, 1985. Published September 1985. Originally
between the hot plate and the cool atmosphere (W/m ·K).
published as D1518 – 57 T. Last previous edition D1518 – 77. DOI: 10.1520/
D1518-85R03.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM American Society of Heating, Refrigerating, and Air-Conditioning Engineers.
Standards volume information, refer to the standard’s Document Summary page on Gagge, A. P., Burton, A. C., Bazett, H. C., Science, Vol 94, Nov. 7, 1941, pp.
the ASTM website. 428–430.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1518 – 85 (2003)
A
TABLE 1 Conversion Factors for Thermal Conductivity
To Convert
Thermal Con- Multiply by
ductivity
From kg-cal·cm/ Btu·in/
B 2
W/m·K W·cm/m ·K W/cm·K cal/s·cm·K kg-cal/h·m·K Btu/h·ft·°F in/clo mm/clo
2 2
to h·m ·K h·ft ·°F
+2 −2 −3 −1 +1 −1 +2
W/m·K 1. 1. 3 10 1. 3 10 2.388 3 10 8.598 3 10 8.598 3 10 5.778 3 10 6.934 6.093 1.548 3 10
−2 −4 −5 −3 −1 −3 −2 −2
W·cm/ 1. 3 10 1. 1. 3 10 2.388 3 10 8.598 3 10 8.598 3 10 5.778 3 10 6.934 3 10 6.093 3 10 1.548
m ·K
+2 +4 −1 +1 +3 +1 +2 +2 +4
W/cm·K 1. 3 10 1. 3 10 1. 2.388 3 10 8.598 3 10 8.598 3 10 5.778 3 10 6.934 3 10 6.093 3 10 1.548 3 10
+2 +4 +2 +4 +2 +3 +3 +4
cal/s·cm·K 4.187 3 10 4.187 3 10 4.187 1. 3.6 3 10 3.6 3 10 2.419 3 10 2.903 3 10 2.551 3 10 6.480 3 10
kg-cal/
+2 −2 −3 +2 −1 +2
h·m·K 1.163 1.163 3 10 1.163 3 10 2.778 3 10 1. 1. 3 10 6.720 3 10 8.064 7.087 1.8 3 10
kg-cal·cm/
2 −2 −4 −5 −2 −3 −2 −2
h·m ·K 1.163 3 10 1.163 1.163 3 10 2.778 3 10 1. 3 10 1. 6.720 3 10 8.064 3 10 7.087 3 10 1.8
+2 −2 −3 +2 +1 +1 +2
Btu/h·ft·°F 1.731 1.731 3 10 1.731 3 10 4.134 3 10 1.488 1.488 3 10 1. 1.2 3 10 1.055 3 10 2.679 3 10
Btu·in/
2 −1 +1 −3 −4 −1 +1 −2 −1 +1
h·ft ·°F 1.442 3 10 1.442 3 10 1.442 3 10 3.445 3 10 1.240 3 10 1.240 3 10 8.333 3 10 1. 8.788 3 10 2.232 3 10
−1 +1 −3 −4 −1 −1 −2 +1
in/clo 1.641 3 10 1.641 3 10 1.641 3 10 3.920 3 10 1.411 3 10 1.411 3 10 9.482 3 10 1.138 1. 2.540 3 10
−3 −1 −5 −5 −3 −1 −3 −3 −2
mm/clo 6.461 3 10 6.461 3 10 6.461 3 10 1.543 3 10 5.556 3 10 5.556 3 10 3.733 3 10 4.480 3 10 3.937 3 10 1.
A
Units are given in terms of: (1) the absolute joule per second, or watt; (2) the calorie (International Table) = 4.1868 J; (3) the British thermal unit (International
Table) = 1055.06 J; and (4) the clo (unit of clothing resistance) = 0.155 K·m /W.
B
Recommended (SI) units.
A
TABLE 2 Conversion Factors for Thermal Transmittance
To Convert
Thermal Multiply by
Transmittance
From
2 B 2 2 2 2 −1
W/m ·K W/cm ·K cal/s·cm ·K kg-cal/h·m ·K Btu/h·ft ·°F clo
to
2 −4 −5 −1 −1 −1
W/m ·K 1. 1. 3 10 2.388 3 10 8.598 3 10 1.761 3 10 1.548 3 10
2 +4 −1 +3 +3 +3
W/cm ·K 1. 3 10 1. 2.388 3 10 8.598 3 10 1.761 3 10 1.548 3 10
2 +4 +4 +3 +3
cal/s·cm ·K 4.187 3 10 4.187 1. 3.6 3 10 7.373 3 10 6.480 3 10
2 −4 −5 −1 −1
kg-cal/h·m ·K 1.163 1.163 3 10 2.778 3 10 1. 2.048 3 10 1.8 3 10
2 −4 −4 −1
Btu/h·ft ·°F 5.678 5.678 3 10 1.356 3 10 4.882 1. 8.788 3 10
−1 −4 −4
clo 6.461 6.461 3 10 1.543 3 10 5.556 1.138 1.
A
Units are given in terms of: (1) the absolute joule per second, or watt; (2) the calorie (International Table) = 4.1868 J; (3) the British thermal unit (International
Table) = 1055.06 J; and (4) the clo (unit of clothing resistance) = 0.155 K·m /W.
B
Recommended (SI) units.
A
TABLE 3 Conversion Factors for Thermal Resistivity
To Convert
Thermal Multiply by
B
Resistivity
2 2
From m ·K·h/kg- ft ·°F·h/
B 2
m·K/W m ·K/W·cm cm·K/W cm·K·s/cal m·K·h/kg-cal ft·°F·h/Btu clo/in clo/mm
to cal·cm Btu·in
−2 +2 +2 −2 −1 −1 −3
m·K/W 1. 1. 3 10 1. 3 10 4.187 3 10 1.163 1.163 3 10 1.731 1.442 3 10 1.641 3 10 6.461 3 10
2 +2 +4 +4 +2 +2 +1 −1 −1
m ·K/W· 1. 3 10 1. 1. 3 10 4.187 3 10 1.163 3 10 1.163 1.731 3 10 1.442 3 10 1.641 3 10 6.461 3 10
cm
−2 −4 −2 −4 −2 −3 −3 −5
cm·K/W 1. 3 10 1. 3 10 1. 4.187 1.163 3 10 1.163 3 10 1.731 3 10 1.442 3 10 1.641 3 10 6.461 3 10
−3 −5 −1 −3 −5 −3 −4 −4 −5
cm·K·s/cal 2.388 3 10 2.388 3 10 2.388 3 10 1. 2.778 3 10 2.778 3 10 4.134 3 10 3.445 3 10 3.920 3 10 1.543 3 10
−1 −3 +1 +2 −2 −1 −1 −3
m·K·h/kg- 8.598 3 10 8.598 3 10 8.598 3 10 3.6 3 10 1. 1. 3 10 1.488 1.240 3 10 1.411 3 10 5.556 3 10
cal
2 +1 −1 +3 +4 +2 +2 +1 +1 −1
m ·K·h/kg- 8.598 3 10 8.598 3 10 8.598 3 10 3.6 3 10 1. 3 10 1. 1.488 3 10 1.240 3 10 1.411 3 10 5.556 3 10
cal·cm
−1 −3 +1 +2 −1 −3 −2 −2 −3
ft·°F·h/Btu 5.778 3 10 5.778 3 10 5.778 3 10 2.419 3 10 6.720 3 10 6.720 3 10 1. 8.333 3 10 9.482 3 10 3.733 3 10
2 −2 +2 +3 −2 +1 −3
ft ·°F·h/ 6.934 6.934 3 10 6.934 3 10 2.903 3 10 8.064 8.064 3 10 1.2 3 10 1. 1.138 4.480 3 10
Btu·in
−2 +2 +3 −2 +1 −1 −2
clo/in 6.093 6.093 3 10 6.093 3 10 2.551 3 10 7.087 7.087 3 10 1.055 3 10 8.788 3 10 1. 3.937 3 10
+2 +4 +4 +2 +2 +1 +1
clo/mm 1.548 3 10 1.548 1.548 3 10 6.480 3 10 1.8 3 10 1.8 2.679 3 10 2.232 3 10 2.540 3 10 1.
A
Units are given in terms of: (1) the absolute joule per second, or watt; (2) the calorie (International Table) = 4.1868 J; (3) the British thermal unit (International
Table) = 1055.06 J; and (4) the clo (unit of clothing resistance) = 0.155 K·m /W.
B
Recommended (SI) units.
D1518 – 85 (2003)
A
TABLE 4 Conversion Factors for Thermal Resistance
To Convert
Thermal Multiply by
Resistance
From
2 B 2 2 2 2
m ·K/W cm ·K/W cm ·K·s/cal m ·K·h/kg-cal ft ·°F·h/Btu clo
to
2 +4 +4
m ·K/W 1. 1. 3 10 4.187 3 10 1.163 5.678 6.461
2 −4 −4 −4 −4
cm ·K/W 1. 3 10 1. 4.187 1.163 3 10 5.678 3 10 6.461 3 10
2 −5 −1 −5 −4 −4
cm ·K·s/cal 2.388 3 10 2.388 3 10 1. 2.778 3 10 1.356 3 10 1.543 3 10
2 −1 +3 +4
m ·K·h/kg-cal 8.598 3 10 8.598 3 10 3.6 3 10 1. 4.882 5.556
2 −1 +3 +3 −1
ft ·°F·h/Btu 1.761 3 10 1.761 3 10 7.373 3 10 2.048 3 10 1. 1.138
−1 +3 +3 −1 −1
clo 1.548 3 10 1.548 3 10 6.480 3 10 1.8 3 10 8.788 3 10 1.
A
Units are given in terms of: (1) the absolute joule per second, or watt; (2) the calorie (International Table) = 4.1868 J; (3) the British thermal unit (International
Table) = 1055.06 J; and (4) the clo (unit of clothing resistance) = 0.155 K·m /W.
B
Recommended (SI) units.
TABLE 5 Miscellaneous Conversion Factors
thermal interchange between man and his environment is,
To Convert from however, an extremely complicated subject which involves
To a Value
Properties a Value Ex- Multiply by
many factors in addition to the equilibrium insulation values of
Expressed as
pressed as
fabrics and battings. Therefore, measured thermal transmit-
2 2
Mass per unit oz/yd g/m 33.91
tancecoefficientscanonlyindicaterelativemeritofaparticular
2 2
area mg/cm g/m 10.0
material.
Thickness in. mm 25.4
1/1000 in. (mil) mm 0.0254
4.2 The measurement of heat transfer coefficients is a very
3 3
Bulk density lb/ft kg/m 16.02
2 3 difficult and highly technical field, and it is not practical in a
(oz/yd )/in kg/m 1.335
2 3
(g/m )/mm kg/m 1.0
test method of this scope to establish details sufficient to cover
all contingencies. Departures from the instructions of Test
Method D1518 may lead to significantly different test results.
Technical knowledge concerning the theory of heat flow,
Thermal transmittance for three different cases is deter-
temperature measurement, and testing practices is needed to
mined in this method:
evaluate which departures from the instructions are significant.
U = combinedthermaltransmittanceofthetestspecimen
Standardization of the method reduces, but does not eliminate
and air.
the need for such technical knowledge. Any significant depar-
U = thermal transmittance of the plate without fabric
bp
tures are to be reported with the results.
cover (“bare plate”). This property reflects the in-
4.3 Test Method D1518 for the determination of the thermal
strument constant and is used to standardize the
transmittance of textile materials is considered satisfactory for
plate, and, in conjunction with U , is used in the
acceptancetestingofcommercialshipmentsoftextilematerials
calculation of U .
because the test method has been used in the trade for
U = thermal transmittance of fabric only. This value
acceptancetesting.Anditisthebesttestmethodknownforthis
corresponds to the C value (W/m ·K) defined and
4 purpose.
used byASTM andASHRAE. In the calculation of
4.3.1 In case of a dispute arising from differences in
this value the assumption is made that the boundary
reported results when usingTest Method D1518 for acceptance
layers of the bare plate and the boundary layers of
testing of commercial shipments, the purchaser and the sup-
the fabric are equal. Experimental results indicate
plier should conduct comparative tests to determine if there is
that the U values are valid when tested within the
a statistical bias between their laboratories. Competent statis-
limits specified in Section 1.
tical assistance is recommended for the investigation of bias.
3.1.11 total clo, n—the intrinsic clo plus the thermal resis-
As a minimum, the two parties should take a group of test
tance from the air boundary.
specimens which are as homogeneous as possible and which
3.1.12 For definitions of other textile terms used in this
are from a lot of material of the type in question. The test
method, refer to Terminology D123.
specimens should then be sent to each laboratory for testing.
3.2 Definitions of Terms Specific to This Standard:
The average results from the two laboratories should be
3.2.1 effective insulation ratio, n—indicates the increase in
compared using Student’s t-test for paired data and an accept-
insulation afforded by the fabric in comparison to the uncov-
able probability level chosen by the two parties before testing
ered test plate under specified conditions of test.
is begun. If a bias is found, either its cause must be found and
3.2.2 mean temperature, n—the average of the hot plate
corrected or the purchaser and the supplier must agree to
temperature and the temperature of the calm, cool air that
interpret future test results with consideration to the known
prevailed during the test.
bias.
4. Significance and Use
5. Apparatus (Fig. 1, Fig. 2, and Fig. 3)
4.1 The thermal transmittance of a fabric or batting is of
considerableimportanceindeterminingitssuitabilityforusein
NOTE 1—The drawings and illustrations are intended as suggested
fabricating cold weather protective gear and clothing. The designs only. The final design of equipment, including necessary wiring,
...
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