ASTM F2732-23

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Designation: F2732 − 16 F2732 − 23
Standard Practice for
Determining the Temperature Ratings for Cold Weather
Protective Clothing
This standard is issued under the fixed designation F2732; 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
Manufacturers of cold weather protective clothing want consumers to be thermally comfortable
when wearing their products. Therefore, they want to indicate the amount of warmth (that is,
insulation) their products will provide to consumers at the point of sale. This is often expressed as a
temperature rating on product labels and in product descriptions in catalogs. A temperature rating is
commonly understood to mean the lowest air temperature at which the average adult person will have
an acceptable level of thermal comfort when wearing the product. Although it is not always stated on
labels or in catalogs, manufacturers are assuming that consumers will wear the appropriate amount of
clothing with the cold weather garments.
Heated manikins are used to measure the thermal resistance (insulation) and evaporative resistance
of clothing ensembles in accordance with Test Methods F1291 and F2370, respectively. The thermal
insulation value of a cold weather protective ensemble areis used in heat loss models to estimate the
thermal comfort of people in cold environments. This approach has already been is also used for
sleeping bags (see EN 13537).ISO 23537-1).
1. Scope
1.1 This standard practice covers the determination of the temperature rating of a cold weather protective clothing garment or
system of garments when worn with one of two base ensembles. It involves measuring the thermal resistance (insulation) value
of a clothing ensemble (base ensemble plus the garment or garment system being evaluated) with a heated manikin in accordance
with Test Method F1291 and using . The result is used in a heat loss model to predict the lowest environmental temperature for
comfort.
1.2 The predictive model used in this standard estimates the evaporative heat loss from a person wearing cold weather clothing
as opposed to measuring the evaporative resistance on a sweating manikin. If a person is active and gets overheated in a cold
environment, he/she is usually able to adjust the garments in order to dissipate excess heat.
1.3 The temperature ratings estimated by this standard practice are guidelines for thermal comfort that are designed to protect
people from hypothermia when wearing cold weather protectivecomfort, determined from a whole-body heat loss model (see
Annex A1garments. However,). Therefore, localized cooling, discomfort, and even frostbite could still occur at extremely low
temperatures because clothing insulation is not evenly distributed over the body surface. In addition, some body parts (for example,
ears, fingers, toes) have a high surface area relative to their mass, and consequently lose heat at a faster rate than other parts of
the body.
This practice is under the jurisdiction of ASTM Committee F23 on Personal Protective Clothing and Equipment and is the direct responsibility of Subcommittee F23.60
on Human Factors.
Current edition approved Oct. 1, 2016June 1, 2023. Published October 2916June 2023. Originally approved in 2009. Last previous edition approved in 20112016 as
F2732 - 11.F2732 – 16. DOI: 10.1520/F2732-16.10.1520/F2732-23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2732 − 23
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
F1291 Test Method for Measuring the Thermal Insulation of Clothing Using a Heated Manikin
F2370 Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin
2.2 Other Standards:
EN 13537ISO 23537-1 Requirements for Sleeping BagsBags—Part 1: Thermal, Mass and Dimensional Requirements for
Sleeping Bags Designed for Limit Temperatures of –20°C and Higher
ASHRAE 55-2013ASHRAE 55-2020 Thermal Environmental Conditions for Human Occupancy
3. Terminology
3.1 Definitions:
3.1.1 clo, n—a unit of thermal resistance (insulation) equal to 0.155 K-m°C·m /W.
3.1.1.1 Discussion—
The value of the clo was selected as roughly the insulation value of typical indoor clothing, which should keep a resting manperson
(producing heat at the rate of 58 W/m ) comfortable in an environment at 21°C,21 °C, air movement 0.1 m/s. When clo was
developed, typical indoor clothing consisted of a three-piece suit and light underclothes.
3.1.2 clothing area factor (f ), n—the ratio of the surface area of the clothed body to the surface area of the nude body.
cl
3.1.3 clothing ensemble, n—a group of garments worn together on the body at the same time.
3.1.4 temperature rating, n—the lowest environmental temperature at which a person can remain thermally neutral while wearing
a particular clothing ensemble.
3.1.5 thermal comfort, n—that condition of mind which expresses satisfaction with the thermal environment and is assessed by
subjective evaluation (see ASHRAE 55-2013).ASHRAE 55-2020).
3.1.6 thermal insulation, n—the resistance to dry heat transfer via conduction, convection, and radiation.
3.1.6.1 Discussion—The following insulation values can be determined with a thermal manikin using clo units:manikin:
I = thermal resistance (insulation) of the air layer on the surface of the nude manikin.
a
I = total thermal resistance (insulation) of the clothing and surface air layer around the manikin.
t
I = intrinsic thermal resistance (insulation) of the clothing.
cl
R = thermal resistance (insulation) of the air layer on the surface of the nude manikin,
a
R = total thermal resistance (insulation) of the clothing ensemble and surface air layer around the manikin, and
t
R = intrinsic thermal resistance (insulation) of the clothing ensemble.
cl
R ,R , and R are typically used for SI units, while I ,I , and I are typically used with clo units. Total insulation values are
a t cl a t cl
measured directly with a manikin. Intrinsic clothing insulation values are determined by subtracting the air layer resistance around
the clothed manikin from the total insulation value for the ensemble.
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA 30329,180 Technology
Parkway, Peachtree Corners, GA 30092, http://www.ashrae.org.
F2732 − 23
4. Significance and Use
4.1 This practice is used to measure the insulation provided by differenta cold weather clothing systems garment or garment
system using a heated manikin (see Test Method F1291) and to predict the temperature rating for comfort at two activity levels
using whole body whole-body heat loss models.
4.1.1 The temperature rating is for an ensemble—not an individual garment. However, manufacturers want to label cold weather
garments or garment systems with a temperature rating to help consumers select the product that will best meet their needs.
Therefore, the standard insulation of a garment or garment system is measured with a standard base ensemble. Furthermore, the
standard is limited to garments that cover a substantial amount of body surface area such as jackets, coats, and insulated pants,
coveralls, or snow suits. The temperature ratings of head wear, headwear, footwear, and hand wear handwear cannot be determined
with this practice.
4.1.2 The temperature predictions determined by this standard practice are for adults only. The physiology of children is
significantly different from that of adults, so a modified heat loss model needs to be used to predict the comfort of children wearing
outdoor clothing.
4.1.3 The temperature ratings determined by this standard practice and listed on garment labels are only guidelines for comfort
and will be affected by the garments consumers wear with them, their activity level during wear, and individual differences in the
physiological characteristics of people (for example, gender, age, body mass, etc.).
5. Calibration of Manikin
5.1 Manikin—Use a thermal manikin as described in Test Method F1291.
5.2 Calibration—Calibrate the manikin using the procedures in Test Method F1291.
5.2.1 The intrinsic clothing insulation value of the Test Method F1291 calibration ensemble (IR ) needs to be 0.79 clo, 610 %
cl
shall be within 610 % of the reference value before proceeding with this method.
6. Base Ensembles
6.1 Cold weather garments are A cold weather garment or garment system is typically worn with other garments as part of an
ensemble. Therefore, they need to be tested that way on the manikin in order garment or garment systems shall be tested with a
base ensemble to determine the temperature for comfort. All cold weather jackets, coveralls, and jacket/pant sets (where the
garments are designed to be jacket/pant sets are worn together) shall be tested with a lightweight base ensemble that represents
the minimum amount of clothing that a reasonable person might wear with the cold weather clothing (Base Ensemble #1). Cold
All cold weather pants shall be tested with a base jacket added to the base ensemble (Base Ensemble #2). The size of the garments
shall be selected based on the measurements of the manikin.
6.2 The garments used in Base Ensemble #1 are:
2 2
6.2.1 Shirt—Long-sleeve mock turtle neck shirt, interlock knit, 100 % cotton, turtleneck shirt, 214 g/m (6.3 (6.3 oz/yd ); ) 6
10 %; worn with shirttail over jeans.
2 2
6.2.2 Jeans—Denim 5-pocket jeans, 100 % cotton 397 g/m (11.7 (11.7 oz/yd ).) 6 10 %.
2 2
6.2.3 Men’s Underwear Briefs—Jersey knit briefs, 100 % cotton, 180 g/m (5.3 (5.3 oz/yd ); ) 6 10 %; jockey style that fits
snugly at the waist and legs (from (may use briefs from Test Method F1291). calibration ensemble).
6.2.4 Men’s Socks—Basic knit sock that covers foot and extends up the calf no more than 25.4 cm (10 in.) from the bottom of the
heel. Each individual sock shall be composed of at least 75 % cotton and shall weigh 33 6 5 g (from (may use socks from Test
Method F1291). calibration ensemble).
McCullough, ElizabethE. A., Eckels, Steve,S., and Harms, Craig. “DeterminingC., “Determining Temperature Ratings for Children’s Cold Weather Clothing Temperature
Ratings for Children’s Cold Weather Clothing,” ,” Applied Ergonomics, Vol.Vol 40, 2009, pp. 870-877.–877.
F2732 − 23
6.2.5 Athletic Shoes—Fabric/soft leather and soft sole.
6.2.6 Gloves or Mittens—Insulated knitted fleece gloves or mittens, 100% polyester, all layers 454 g/m (13.4 oz/yd (13.4
oz ⁄yd ); ) 6 10 %; cuffs worn under jacket sleeves.
2 2
6.2.7 Hat—Knitted fleece hat, 100 % polyester 129 g/m (3.8 (3.8 oz/yd ); ) 6 10 %; worn pulled down to eye brows.eyebrows.
6.2.8 The intrinsic thermal resistance (insulation) value (IR ) of Base Ensemble #1 needs to shall be measured according to Test
cl
Method F1291be 0.80 and the value shall be 0.124 °C·m clo, 610 %./W (0.80 clo) 6 10 %.
6.2.8.1 The insulation thermal resistance value of the cold weather ensembles would be higher (and the predicted temperature
ratings lower) if a thicker base ensemble was used. However, many people will not wear more clothing with the cold weather
garments, and some people might not wear gloves, or a hat, or both. Consequently, this standard practice is specifying a lightweight
base ensemble only. It is acceptable for other garments such as thermal underwear to be substituted for the knit shirt and jeans as
long as if the intrinsic insulation thermal resistance value is 0.800.124 °C·m clo, 610 % /W (0.80 clo) 6 10 % and the head,
hands, and feet are covered in the same way.
6.3 The garments used in Base Ensemble #2 are:
6.3.1 All of the garments in Base Ensemble #1.
6.3.2 Jacket—A quilted fiberfill jacket, 100 % nylon shell and lining, 100 % jacket with 100 % polyester fiberfill insulation, all
2 2
layers 339 g/m (10.0 (10.0 oz/yd ). The stow-away ) 6 10 %. The jacket shall not have a hood, or it shall have a hood that is
either detachable or a stow-away hood. A stow-away hood shall not be placed on the head during the test; it needs to be stowed
in the collar. A detachable hood shall be removed from the jacket for the test.
6.3.2.1 Only the jacket used for Base Ensemble #2 shall be tested with the hood stowed or removed. Other garments or garment
systems shall be tested with the hood up (see 8.5).
6.3.3 The intrinsic thermal resistance (insulation) value (IR ) of Base Ensemble #2 needs to shall be measured according to Test
cl
Method F1291be 1.35 and the value shall be 0.209 °C·m clo, 610 %./W (1.35 clo) 6 10 %.
7. Sampling and Test Specimens
7.1 Sampling—It is acceptable to test one sample (that is, specimen) of each garment type. However, there will be some variability
in garments made of fiberfill or down insulations, so it is recommended to test two or three specimens and average their insulation
values prior to modeling.modeling so that sample variability will be reflected in the test results.
7.2 Specimen Size and Fit—Select the size of garments that will fit the manikin appropriately (that is, the way the manufacturer
designed them to be worn on the human body during their intended end use).
8. Manikin Procedure
8.1 Environmental Test Conditions—The test conditions given below shall be standard for all tests unless otherwise stated.
8.1.1 Air Temperature—The air temperature shall be at least 12°C12 °C lower than the mankin’smanikin’s mean surface
temperature (that is 23°C)is, 23 °C) during a test. When emsemblesensembles with high insulation values are tested (for example,
cold weather clothing), the air temperature shall be lowered so the that a minimum average heat flux of 20 W/m formfrom the
manikin’s segementssegments is maintained. A temperature around 20–23°C will 20 to 23 °C may be needed for the nude test and
the base ensemble test. A lower air temperature (for example, 5°C)5 °C) will be needed for heavy cold weather ensembles.
8.1.2 Air Velocity—The air velocity shall be 0.4 6 0.1 m/s during a test.
8.1.3 Relative Humidity—Select a level between 30 and 80 % relative humidity 65 %, 6 5 %, preferably 50 %. The relative
humidity has no effect on measurements of insulation under steady-state conditions.
F2732 − 23
8.1.4 If it is necessary to test the cold weather ensembles in different environmental conditions (air temperature, air velocity, or
relative humidity), the conditions shall be clearly defined and reported.
8.2 Mean Surface (Skin) Temperature of Manikin—The manikin’s surface temperature shall be maintained at 35 6 0.5°C0.5 °C
for all tests. The mean surface temperature shall not be allowed to drift more than 6 0.2°C 60.2 °C during a 30 min test.
8.3 Nude Test—Measure the thermal resistance (insulation) (IR ) provided by the air layer surrounding the nude manikin by
a
conducting a test using the same procedures given for the cold weather ensemble tests (see 8.5).
8.3.1 A new nude test shall be conducted for every series of cold weather clothing tests since this value (IR ) is used to calculate
a
the standardized total thermal resistance of each clothing ensemble.
8.4 Base Ensemble Test—Measure the total thermal resistance (insulation) (IR ) provided by Base Ensemble #1 (and Base
t
Ensemble #2 if cold weather pants will be evaluated) by conducting a test using the same procedures given for the cold weather
ensemble tests (see 8.5).
8.4.1 The base ensemble tests shall be conducted periodically to document that the intrinsic thermal resistance values for these
ensembles meet the requirements given in the standard within 610 % (see 6.2 and 6.3).
8.5 Cold Weather Ensemble Test—Dress the standing manikin in Base Ensemble #1 or #2 the appropriate base ensemble and the
cold weather garment (such as a jacket, coverall, or pants) or garments garment system (such as a work jacket and pants set) to
be tested. Garments Garment test items with a hood need to shall be tested with the hood drawn up over the hat and tightened
around the face. Position the manikin so that it is hanging vertically a few inches off the floor with its arms at its sides. Take a
photograph of the ensemble on the manikin for the report (optional).
8.5.1 Conduct the test in accordance with procedures given in Test Method F1291.
8.5.2 Replication of Tests—Conduct three replications of the test, with at least 15 minutesmin in between test periods. If more than
one samplespecimen is available of each garment type, test each separately one time.
9. Insulation Calculations
9.1 The parallel method of calculating the total thermal resistance (insulation) of the clothing ensemble shall be used, where the
area-weighted temperatures of all body segments are summed and averaged, the power levels to all body segments are summed,
and the areas are summed before the total resistance is calculated. Calculate the total thermal insulation of the clothing ensemble
(used. First the total thermal resistance for each single zone isI ) to the nearest 0.01 clo, calculated using Eq 1: (6.45 is a units
t
constant).
I 5 ~T 2 T ! A·6.45/H (1)
t s a
R 5 T 2 T A ⁄H (1)
~ !
i i a i i
where:
I = total thermal resistance (insulation) of the clothing and surface air layer around the mankin (clo),
t
R = total thermal resistance (insulation) of the clothing and surface air layer around a single zone of the manikin (°C·m /W),
i
A = manikin’s surface area (m ),
A = surface area of a single zone of the manikin (m ),
i
T = mankin’s surface temperature (°C),
s
T = surface temperature of a single zone of the manikin (°C),
i
T = air temperature (°C), and
a
H = power required to heat a single zone of the manikin (W).
i
9.1.1 It is not valid to use only the zones of the manikin covered by the cold weather garment in the calculation of insulation. The
total thermal resistance value for the whole body is used to determine the temperature ratings for comfort.
9.2 Then calculate the parallel weighted average for the multi-zone sections of the manikin using Eq 2:
F2732 − 23
R 5 A ⁄Σ A ⁄ R (2)
~ !
t tot i i
where:
R = total thermal resistance (insulation) of the clothing on the manikin zone grouping (°C·m /W), and
t
A = total surface area of manikin zone grouping (m ).
tot
9.2.1 It is not valid to use only the zones of the manikin covered by the cold weather garment in the calculation of thermal
resistance used to determine the temperature ratings for comfort. The total thermal resistance value for the whole body shall be
used to determine the temperature ratings.
9.3 Determine the average total insulation thermal resistance value (IR ) of the ensemble to the nearest 0.001 °C·m /W (or nearest
t
0.01 clo) by averaging the values from the three replications of the test.
9.4 Determine the average intrinsic insulation thermal resistance value of the clothing alone (IR ) to the nearest 0.001 °C·m 0.01
cl
clo,/W (or nearest 0.01 clo) using the mean IR value and Eq 23:
t
I 5 I 2 ~I /f ! (2)
cl t a cl
where:
I = intrinsic thermal resistance (insulation) of the clothing (clo),
cl
I = total thermal resistance (insulation) of the clothing and surface air layer around the manikin (clo),
t
I = thermal resistance (insulation) of the air layer on the surface of the nude manikin (clo), and
a
f = clothing area factor (dimensionless).
cl
R 5 R 2 R ⁄ f (3)
~ !
cl t a cl
where:
R = intrinsic thermal resistance (insulation) of the clothing (°C·m /W),
cl
R = total thermal resistance (insulation) of the clothing and surface air layer around the manikin (°C·m /W),
t
R = thermal resistance (insulation) of the air layer on the surface of the nude manikin (°C·m /W), and
a
f = clothing area factor (dimensionless).
cl
9.4.1 Use the value of 1.25 for the f of Base Ensemble #1.
cl
9.4.2 Use the value of 1.30 for the f of Base Ensemble #2.
cl
9.4.3 Use the value of 1.35 for the f of a cold weather clothing ensembles. ensemble (that is, the garment or garment system worn
cl
with the base ensemble). It is possible to determine the f value for each ensemble using a photographic method, but it is very time
cl
consuming. Therefore, an average value for cold weather clothing ensembles is used here.
9.5 Calculate the standardized total insulation thermal resistance value (IR ) of the cold weather clothing ensembles to the nearest
t,s
2 2
0.001 °C·m 0.01 clo,/W (or nearest 0.01 clo) using a standard air layer resistance of 0.50.078 °C·m clo /W (0.50 clo) in Eq 34:
I 5 I 1 I /f (3)
~ !
t,s cl a,s cl
where:
I = intrinsic thermal resistance (insulation) of the clothing (clo),
cl
I = standardized total thermal resistance (insulation) of the clothing and surface air layer around the manikin (clo),
t,s
I = standard thermal resistance (insulat
...