1、Designation: F 1868 09Standard Test Method forThermal and Evaporative Resistance of Clothing MaterialsUsing a Sweating Hot Plate1This standard is issued under the fixed designation F 1868; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONClothing is often made of materials that impede the flow of heat and moisture from the skin to theen
3、vironment. Consequently, people may suffer from heat stress or cold stress when wearing clothingin different environmental conditions. Therefore, it is important to quantify the thermal resistance andevaporative resistance of clothing materials and to consider these properties when selecting materia
4、lsfor different clothing applications.1. Scope1.1 This test method covers the measurement of the thermalresistance and the evaporative resistance, under steady-stateconditions, of fabrics, films, coatings, foams, and leathers,including multi-layer assemblies, for use in clothing systems.1.2 The rang
5、e of this measurement technique for intrinsicthermal resistance is from 0.002 to 0.5 Km2/W and forintrinsic evaporative resistance is from 0.0 to 1.0 kPam2/W.1.3 The values in SI units shall be regarded as standard.1.4 This standard does not purport to address all of thesafety concerns, if any, asso
6、ciated with its use. It is theresponsibility of the user of this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 177 Test Method for Steady-State Heat Flux Me
7、asure-ments and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate ApparatusD 1518 Test Method for Thermal Transmittance of Tex-tile MaterialsE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the
8、 Precision of a Test MethodF 1291 Test Method for Measuring the Thermal Insulationof Clothing Using a Heated ManikinF 1494 Terminology Relating to Protective ClothingF 2370 Test Method for Measuring the Evaporative Resis-tance of Clothing Using a Sweating Manikin2.2 Other Standards:ISO 11092 Textile
9、sPhysiological EffectsMeasurement ofThermal and Water-Vapour Resistance Under Steady-State Conditions (Sweating Guarded-Hotplate Test)33. Terminology3.1 Definitions:3.1.1 clo, na unit of thermal resistance (insulation) equalto 0.155 Km2/W.3.1.1.1 DiscussionThe value of the clo was selected asroughly
10、 the insulation value of typical indoor clothing, whichshould keep a resting man (producing heat at the rate of 58W/m2) comfortable in an environment at 21C, air movement0.1 m/s.3.1.2 evaporative resistance, nThe resistance to the flowof moisture vapor from a saturated surface (high vaporpressure) t
11、o an environment with a lower vapor pressure.3.1.2.1 Discussion The evaporative resistance in units ofkPam2/W can be calculated for several different cases.RefA= apparent total evaporative resistance of the fabric testspecimen only, when evaluated non-isothermally. The termapparent is used as a modi
12、fier for total evaporative resistance toreflect the fact that condensation may occur within the speci-men.RetA= apparent total evaporative resistance of the fabric testspecimen, liquid barrier, and surface air layer when evaluatednon-isothermally. The term apparent is used as a modifier for1This tes
13、t method is under the jurisdiction ofASTM Committee F23 on PersonalProtective Clothing and Equipment and is the direct responsibility of SubcommitteeF23.60 onHuman Factors.Current edition approved Feb. 15, 2009. Published March 2009. Originallyapproved in 1998. Last previous edition approved in 2002
14、 as F 1868 - 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards I
15、nstitute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.total evaporative resistance to reflect the fact that condensationmay occur within the specimen.Rebp= e
16、vaporative resistance of the air layer on the surface ofthe liquid barrier without a fabric test specimen (that is, bareplate). This property reflects the instrument constant and theresistance of the liquid barrier, and in conjunction with Ret,isused in the calculation of Ref.Ref= intrinsic evaporat
17、ive resistance of the fabric test specimenonly. In the calculation of this value, the assumption is madethat the boundary layers of the bare plate and the boundarylayers of the fabric are equal.Ret= total evaporative resistance of the fabric test specimen,the liquid barrier, and the surface air laye
18、r.3.1.3 permeability index (im), nthe efficiency of evapora-tive heat transport in a clothing system.3.1.3.1 DiscussionAn imof zero indicates that the cloth-ing system allows no evaporative heat transfer. An imof oneindicates that the clothing system achieves the theoreticalmaximum evaporative heat
19、transfer allowed by its insulation.The permeability index is calculated one of two ways.im= permeability index calculated using the total thermalresistance and the total evaporative resistance of a material.The U.S. military uses this value in their databases on fabricsand clothing systems.imf= perm
20、eability index calculated using the intrinsic thermalresistance and the intrinsic evaporative resistance of a material.ISO 11092 uses this value.3.1.4 thermal resistance, nthe resistance to the flow ofheat from a heated surface to a cooler environment.3.1.4.1 DiscussionThermal resistance in units of
21、 Km2/Wcan be calculated for several different cases.It= total insulation value of the test specimen and the air layer,expressed in clo units.If= intrinsic thermal resistance of the fabric test specimen only,expressed in clo units.Rcbp= thermal resistance of the air layer on the surface of theplate w
22、ithout a fabric test specimen (that is, bare plate). Thisproperty reflects the instrument constant and is used to stan-dardize the plate, and in conjunction with Rct, is used in thecalculation of Rcf.Rcf= intrinsic thermal resistance of the fabric test specimenonly. In the calculation of this value,
23、 the assumption is madethat the boundary layers of the bare plate and the boundarylayers of the fabric test specimen are equal.Rct= total thermal resistance of the test specimen and the airlayer.3.1.5 total heat loss, nthe amount of heat transferredthrough a material or a composite by the combined d
24、ry andevaporative heat exchanges under specified conditions ex-pressed in watts per square meter,3.1.5.1 DiscussionThis single criterion for comparingfabric assemblies was developed as a special case by theNational Fire ProtectionAssoc. The specific conditions used byNFPA are a 35C fully sweating ho
25、t plate surface in a 25C,65 % RH environment.3.2 For definitions of other terms related to protectiveclothing used in this test method, refer to Terminology F 1494.4. Significance and Use4.1 The thermal resistance and evaporative resistance pro-vided by fabrics, films, coatings, foams, and leathers,
26、 includingmulti-layer assemblies, is of considerable importance in deter-mining their suitability for use in fabricating protective cloth-ing systems.4.2 The thermal interchange between people and theirenvironment is, however, an extremely complicated subjectthat involves many factors in addition to
27、 the steady-stateresistance values of fabrics, films, coatings, foams, and leath-ers, including multi-layer assemblies. Therefore, thermal resis-tance values and evaporative resistance values measured on ahot plate may or may not indicate relative merit of a particularmaterial or system for a given
28、clothing application. While apossible indicator of clothing performance, measurementsproduced by the testing of fabrics have no proven correlation tothe performance of clothing systems worn by people. Clothingweight, drape, tightness of fit, and so forth, can minimize oreven neutralize the apparent
29、differences between fabrics orfabric assemblies measured by this test method.4.3 The thermal resistance and evaporative resistance ofclothing systems can be measured with a heated manikin in anenvironmental chamber in accordance with Test MethodsF 1291 and F 2370.5. Interferences5.1 Departures from
30、the instructions of this test method maylead to significantly different test results. Technical knowledgeconcerning the theory of heat flow, temperature measurement,and testing practices is needed to evaluate which departuresfrom the instructions are significant. Standardization of themethod reduces
31、, but does not eliminate the need for suchtechnical knowledge. Report any departures from the instruc-tions of Test Method F 1868 with the results.6. Apparatus6.1 Hot PlateThe guarded flat plate shall be composed ofa test plate, guard section, and bottom plate, each electricallymaintained at a const
32、ant temperature in the range of humanskin temperature (33 to 36C). The guard section shall bedesigned to prevent lateral loss of heat from the test plate. Theguard section shall be wide enough to minimize heat loss andmoisture transport through the edges of the test specimen underthe conditions of t
33、he test. The bottom plate shall preventdownward loss of heat from the test plate and guard section. Asystem for feeding water to the surface of the test plate andguard section is also needed for testing Parts B and C. See TestMethods D 1518, C 177, and ISO 11092 for additional infor-mation on hot pl
34、ates.6.2 Temperature ControlSeparate independent tempera-ture control is required for the three sections of the hot plate(test plate, guard section, and bottom plate). Temperaturecontrol may be achieved by independent adjustments to thevoltage or current, or both, supplied to the heaters using solid
35、state power supplies, solid-state relays (proportional time on),adjustable transformers, variable impedances, or intermittentheating cycles. The test plate, guard, and bottom plate sectionsshall be controlled to measure the same temperature to within60.1C of each other.F18680926.3 Power Measuring In
36、strumentsPower to the hot platetest section shall be measured to provide an accurate averageover the period of the test. If time proportioning or phaseproportioning is used for the power control, then devices thatare capable of averaging over the control cycle are required.Integrating devices (watt-
37、hour transducers) are preferred overinstantaneous devices (watt meters). Overall accuracy of thepower monitoring equipment must be within 62 % of thereading for the average power for the test period.6.4 Temperature SensorsTemperature sensors shall bethermistors, thermocouples, resistance temperature
38、 devices(RTDs), or equivalent sensors. The test plate, guard section,and bottom plate shall each contain one or more temperaturesensors that are mounted flush with the hot plate surface and insuch a manner that they measure the surface temperaturewithin 60.1C.6.5 Controlled Atmosphere ChamberThe hot
39、 plate shallbe housed in an environmental chamber that can be maintainedat selected temperatures between 20 and 35C. The testchamber wall temperature shall be 60.5C of the air in thechamber. The relative humidity shall be maintained as speci-fied in the individual procedure section.6.6 Measuring Env
40、ironmental ParametersThe air tem-perature, relative humidity, and air velocity shall be measuredas follows:6.6.1 Relative Humidity Measuring EquipmentEither awet-and-dry bulb psychrometer, a dew point hygrometer, orother electronic humidity measuring device shall be used tomeasure the relative humid
41、ity and calculate the dew pointtemperature inside the chamber. The relative humidity sensingdevices shall have an overall accuracy of at least 64%.6.6.2 Air Temperature SensorsShielded air temperaturesensors shall be used. Any sensor with an overall accuracy of60.1C is acceptable. The sensor shall h
42、ave a time constant notexceeding 1 min. The sensor(s) is suspended with the measur-ing point exposed to air inside the chamber at a point in the airstream such that the air temperature sensor is not influenced bythe plate temperature.6.6.3 Air Velocity IndicatorAir velocity shall be measuredwith an
43、accuracy of 60.1 m/s using a hot wire anemometer.Airvelocity is measured at a point 15 mm (nominal) from the platesurface or from the top of the test specimen surface to thebottom of the anemometer sensing element. The air velocityshall be measured at three positions located along a horizontalline p
44、erpendicular to the airflow, including a point at the centerof the plate and at points at the centers of the guard section onboth sides of the plate. Spatial variations in air velocity shallnot exceed 610 % of the mean value.NOTE 1The air velocity is to be measured 15 mm above the platesurface for b
45、are plate measurements. The air velocity is to be measured 15mm above the test specimen surface when testing fabric or systems. The15 mm distance is to be the distance from the plate or test specimen to theanemometer sensing element (wire)not to the bottom of the sensingelement housing.6.6.4 Air Tem
46、perature VariationsAir temperature varia-tions during testing shall not exceed 60.1C6.6.5 Relative Humidity VariationsRelative humidityvariations during testing shall not exceed 64%.6.6.6 Air Velocity VariationsAir velocity variations shallnot exceed 610 % of the mean value for data averaged over 5m
47、in.7. Materials7.1 WaterFor the evaporative resistance measurements inParts B and C distilled, de-ionized, or reverse osmosis-treatedwater shall be used to wet the test plate surface.7.2 Liquid BarrierFor the evaporative resistance mea-surements in Parts B and C, a liquid barrier shall be used tocov
48、er the test plate so that water does not contact the testspecimen. The permeability index of the liquid barrier shall begreater than 0.7, where im= .060 (Rcbp/Rebp). Examples includeuntreated cellophane film and microporous polytetraflouroeth-ylene film.7.3 Calibration Fabrics4A calibration fabric i
49、s requiredfor the calibration in Part C. The calibration fabric is 7.5oz/yd2, plain weave, yellow color with a fiber blend of 93 %meta-aramid, 5 % para-aramid, and 2 % anti-static with adurable water-repellent finish. Sources for the calibrationfabric are given in Footnote 8.8. Sampling and Preparation of Test Specimens8.1 SamplingTest three specimens from each laboratorysampling unit.8.2 Specimen PreparationUse test specimens largeenough to cover the surface of the hot plate test section and theguard section completely. Remove any undesir
