ASTM F3426-20

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3426 − 20
Standard Test Method for
Measuring the Thermal Insulation of Clothing Items Using
Heated Manikin Body Forms
This standard is issued under the fixed designation F3426; 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.
INTRODUCTION
Thetypeofclothingwornbypeopledirectlyaffectstheheatexchangebetweenthehumanbodyand
the environment. The heat transfer is both sensible (conduction, convection, and radiation) and latent
(evaporation). The thermal resistance (insulation) and evaporative resistance provided by a clothing
ensemble are measured on full-body, life-size manikins according to Test Methods F1291 and F2370,
respectively. These standards also discuss measuring the local total resistance values of garments by
using only a few body parts (zones) covered by the clothing. However, more detailed data can be
obtained from a body part manikin with several zones than from a full-body manikin where only one
or two zones are used to take measurements. This detailed information about extremities is important,
as they are often vulnerable to thermal injury. The resistance values measured are dependent upon the
designs and materials used in the component garments, the amount of body surface area covered by
clothing, distribution of the fabric layers over the body, looseness or tightness of fit, and the increased
surfaceareaforheatloss.Insulationmeasurementsmadeonfabricsalonedonottakethesefactorsinto
account.
1. Scope SI, shall be identified clearly and consistency of units shall be
maintained throughout reporting process.
1.1 This test method covers the determination of the insu-
lation value of clothing items that cover only the head (Option
1.4 This standard does not purport to address all of the
1), a hand (Option 2), or a foot (Option 3). It describes the
safety concerns, if any, associated with its use. It is the
measurement of the resistance to dry heat transfer from a
responsibility of the user of this standard to establish appro-
heated manikin form to a relatively calm, cool environment.
priate safety, health, and environmental practices and deter-
1.1.1 This is a static test that provides a baseline clothing
mine the applicability of regulatory limitations prior to use.
measurement on a stationary head manikin form (Option 1),
1.5 This international standard was developed in accor-
hand manikin form (Option 2), or foot manikin form (Option
dance with internationally recognized principles on standard-
3).
ization established in the Decision on Principles for the
1.1.2 The effects of body form position, movement, and
Development of International Standards, Guides and Recom-
contact with other surfaces are not addressed in this test
mendations issued by the World Trade Organization Technical
method.
Barriers to Trade (TBT) Committee.
1.2 The insulation values obtained apply only to the par-
ticular clothing item evaluated and for the specified environ-
2. Referenced Documents
mental conditions of each test, particularly with respect to air
2.1 ASTM Standards:
movement.
F1291 Test Method for Measuring the Thermal Insulation of
1.3 The values stated in either clo or SI units are to be
Clothing Using a Heated Manikin
regarded separately as standard. Each system shall be used
F2370 Test Method for Measuring the Evaporative Resis-
independently of the other. The thermal resistance units, clo or
tance of Clothing Using a Sweating Manikin
ThistestmethodisunderthejurisdictionofASTMCommitteeF23onPersonal
Protective Clothing and Equipment and is the direct responsibility of Subcommittee For referenced ASTM standards, visit the ASTM website, www.astm.org, or
F23.60 on Human Factors. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved July 15, 2020. Published August 2020. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
F3426-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3426 − 20
2.2 ASHRAE Standard: establish details sufficient to cover all contingencies. Depar-
ASHRAE55 ThermalEnvironmentalConditionsforHuman turesfromtheinstructionsinthistestmethodhavethepotential
Occupancy to lead to significantly different test results. Technical knowl-
edge concerning the theory of heat transfer, temperature,
2.3 ISO Standard:
humidity and air motion measurement, and testing practices is
ISO 9920 Ergonomics of the Thermal Environment—
needed to evaluate which departures from the instructions
Estimation of the Thermal Insulation and Evaporation
given in this test method are significant. Standardization of the
Resistance of a Clothing Ensemble
method reduces, but does not eliminate, the need for such
3. Terminology
technical knowledge. Report any departures with the results.
3.1 Definitions:
4.3 Report the insulation values in SI units or clo units as
3.1.1 clo, n—unit of thermal resistance defined as the
standard procedure.
insulationrequiredtokeeparestingman(producingheatatthe
rate of 58 W⁄m ) comfortable in an environment at 21 °C, air
5. Apparatus
movement 0.1 m⁄s, or roughly the insulation value of typical
5.1 Manikin Body Forms:
indoor clothing.
5.1.1 Option 1 – Head Manikin:
3.1.1.1 Discussion—Numerically, one clo is equal to
5.1.1.1 Manikin—Use a manikin head form that is the size
0.155 °C·m /W.
and shape of an adult human and heated to a constant, average
3.1.2 clothing ensemble, n—a group of garments worn
surface temperature.
together on the body at the same time.
5.1.1.2 Size and Shape—The manikin head shall be con-
3.1.3 clothing item, n—a garment or product worn as part of
structed to simulate the head of a human being; that is, it shall
the clothing ensemble or separately.
consist of a head, chin, and nose. Ear protrusions are not
3.1.3.1 Discussion—This standard only addresses clothing
required. Total surface area shall be 0.134 m 6 15 %.
items worn on the head, a hand, or a foot. However, this is not
5.1.1.3 Manikin Zones—Construct the manikin head form
limited to a single item. For example, some handwear systems
with no less than four independent temperature-controlled
consist of multiple gloves, mittens, or both, and may be
zones.At a minimum the top of the head, the back of the head,
evaluated using this test method.
the eye/forehead area, and the mouth area shall be independent
3.1.4 thermal insulation, n—the resistance to dry heat trans- zones.
fer by way of conduction, convection, and radiation. 5.1.1.4 Guard Zone—Construct the manikin head form with
3.1.4.1 Discussion—The following insulation values can be
a guard zone butting up against the terminus of the head/neck
determined in this method: (where the head form would connect to the rest of a body if it
were a full-body manikin). Heat this zone to the same constant
R = thermal resistance (insulation) of the air layer on the
a
temperature as all other zones to prevent unwanted heat loss
surface of the nude manikin body form,
from the manikin head form into the apparatus or environment.
R = total thermal resistance (insulation) of the clothing
t
This zone shall not be included as one of the four required
item and surface air layer around the manikin body
manikin zones.
form, and
5.1.2 Option 2 – Hand Manikin:
R = intrinsic thermal resistance (insulation) of the clothing
cl
5.1.2.1 Manikin—Use a hand manikin form that is the size
item.
and shape of an adult human’s left or right hand and heated to
R , R, and R are typically used for SI units while I , I,
a t cl a t
a constant, average surface temperature.
and I are typically used with clo units.
cl
5.1.2.2 Size and Shape—The hand manikin shall be con-
structed to simulate the hand and wrist/forearm of an adult
4. Significance and Use
human being; that is, it shall consist of a wrist/forearm, palm
4.1 This test method can be used to quantify and compare
and back of hand, four finger digits, and a thumb digit with
the insulation provided by different clothing items as long as
fingers extended to allow gloves to be worn. Total surface area
each test is conducted using the same experimental procedures
of form shall be 0.069 m 6 15 %.
and test conditions. For example, variations in the design and
NOTE 1—Based on the specified manikin dimensions, use appropriately
fabric used in gloves can be evaluated. The effects of layering,
sized glove specimens approximately size 8 to 10 (medium to large).
closures, and fit can be measured for clothing items.
5.1.2.3 Manikin Zones—Construct the manikin hand form
4.2 The measurement of the insulation provided by clothing
with no less than four independent temperature-controlled
is complex and dependent upon the apparatus and techniques
zones. At a minimum the palm, the fingers, the back of the
used. It is not practical in a test method of this scope to
hand, and the wrist shall be independent zones.
5.1.2.4 Guard Zone—Construct the manikin hand form with
a guard zone butting up against the terminus of the wrist/
Available from American Society of Heating, Refrigerating, and Air-
Conditioning Engineers, Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA
forearm (where the hand form would connect to the rest of a
30329, http://www.ashrae.org.
bodyifitwereafull-bodymanikin).Heatthiszonetothesame
Available from International Organization for Standardization (ISO), ISO
constant temperature as all other zones to prevent unwanted
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
Geneva, Switzerland, http://www.iso.org. heat loss from the manikin hand form into the apparatus or
F3426 − 20
environment.This zone shall not be included as one of the four lent sensors. They shall be no more than 2 mm thick and shall
required manikin zones. be well bonded, both mechanically and thermally, to the
manikin’sbodyformsurface.Leadwiresshallbebondedtothe
5.1.3 Option 3 – Foot Manikin:
surface or pass through the interior of the manikin, or both.
5.1.3.1 Manikin—Use a foot manikin form that is the size
Each sensor temperature shall be area-weighted when calcu-
and shape of an adult human’s left or right foot and heated to
lating the mean surface temperature for the body form. If point
a constant, average surface temperature.
sensors are used, apply at least one point sensor in each zone
5.1.3.2 Size and Shape—The foot manikin shall be con-
of the manikin body form.
structed to simulate the foot and ankle/lower leg of an adult
5.4.2 Distributed Sensors—If distributed sensors are used
human being; that is, it shall consist of an ankle/lower leg and
(for example, resistance wire), then the sensors must be
an approximate foot form.The foot must have an overall shape
distributed over the surface so that all areas are equally
that is representative of a human foot; however, it is not
weighted. If several such sensors are used to measure the
necessary for the manikin to have individual toe digits. Total
temperature of different zones of the manikin, then their
surface area of the foot form shall be 0.096 m 6 15 %.
respective temperatures shall be area-weighted when calculat-
NOTE 2—Based on the specified manikin dimensions, use appropriately
ing the mean surface temperature. Distributed sensors shall be
sized shoe specimens approximately size US 9M to US 10.5M (EU 43 to
less than 1 mm in diameter and firmly attached to the manikin
44).
surface at all points.
5.1.3.3 Manikin Zones—Construct the manikin foot form
5.5 Controlled Environmental Chamber—The manikin shall
with no less than four independent temperature-controlled
be placed in a chamber that can provide uniform conditions,
zones. At a minimum the bottom of the foot, the toes, the top
both spatially and temporally.
of the foot, and the ankle/leg area shall be independent zones.
5.5.1 Spatial Variations—Spatial variations shall not exceed
5.1.3.4 Guard Zone—Construct the manikin foot form with
a guard zone butting up against the terminus of the lower leg the following: air temperature 61.0 °C, relative humidity
65 %, and air velocity 650 % of the mean value. In addition,
(where the foot form would connect to the rest of a body if it
were a full-body manikin). Heat this zone to the same constant the mean radiant temperature shall not be more than 1.0 °C
different from the mean air temperature.The spatial uniformity
temperature as all other zones to prevent unwanted heat loss
fromthemanikinhandformintotheapparatusorenvironment. shall be verified at least annually or after any significant
modificationsaremadetothechamber.Spatialuniformityshall
This zone shall not be included as one of the four required
manikin zones. be verified by recording values for the conditions stated above
at two distinct heights. Take the measurements, at the two
5.2 Surface Temperature—The manikin body form shall be
locations occupied by the manikin form, 50 mm 6 10 mm
constructed so as to maintain a uniform temperature distribu-
below the top of the manikin form and 50 mm 6 10 mm above
tionoverthenudebodysurface,withnolocalhotorcoldspots.
the bottom of the manikin form.
The mean surface (skin) temperature of the manikin body form
5.5.2 Temporal Variations—Temporal variations shall not
shall be 35 °C. Local deviations from the mean skin tempera-
exceed the following: air temperature 60.5 °C, mean radiant
ture shall not exceed 60.3 °C. Temperature uniformity of the
temperature 60.5 °C, relative humidity 65 %, air velocity
nude manikin body form shall be evaluated at least once
625 % of the mean value for data averaged over 5 min (see
annually or after repairs or alterations are completed that could
5.5.5).
affect temperature uniformity, for example, replacement of a
5.5.3 Relative Humidity Measuring Equipment—Any hu-
heating element. D
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