1、Designation:F186809 Designation: F1868 12Standard Test Method forThermal and Evaporative Resistance of Clothing MaterialsUsing a Sweating Hot Plate1This standard is issued under the fixed designation F1868; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case of revision, 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
3、 the skin to theenvironment. 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
4、 selecting materialsfor different clothing applications.1. Scope1.1 This test method covers the measurement of the thermal resistance and the evaporative resistance, under steady-stateconditions, of fabrics, films, coatings, foams, and leathers, including multi-layer assemblies, for use in clothing
5、systems.1.2 The range of this measurement technique for intrinsic thermal resistance is from 0.002 to 0.5 Km2/W and for intrinsicevaporative 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 the safety
6、concerns, if any, associated with its use. It is the responsibilityof the user of this standard to consult and establish appropriate safety and health practices and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C177 Test Method for Stead
7、y-State Heat Flux Measurements and Thermal Transmission Properties by Means of theGuarded-Hot-Plate ApparatusD1518 Test Method for Thermal Resistance of Batting Systems Using a Hot PlateE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlab
8、oratory Study to Determine the Precision of a Test MethodF1291 Test Method for Measuring the Thermal Insulation of Clothing Using a Heated ManikinF1494 Terminology Relating to Protective ClothingF2370 Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin2.2 Other
9、Standards:ISO 11092 TextilesPhysiological EffectsMeasurement of Thermal and Water-Vapour Resistance Under Steady-StateConditions (Sweating Guarded-Hotplate Test)33. Terminology3.1 Definitions:3.1.1 clo, na unit of thermal resistance (insulation) equal to 0.155 Km2/W.3.1.1.1 DiscussionThe value of th
10、e clo was selected as roughly the insulation value of typical indoor clothing, which shouldkeep a resting man (producing heat at the rate of 58 W/m2) comfortable in an environment at 21C, air movement 0.1 m/s.1This test method is under the jurisdiction of ASTM Committee F23 on Personal Protective Cl
11、othing and Equipment and is the direct responsibility of SubcommitteeF23.60 on Human Factors.Current edition approved Feb. 15, 2009. Published March 2009. Originally approved in 1998. Last previous edition approved in 2002 as F1868-02. DOI:10.1520/F1868-09.Current edition approved June 1, 2012. Publ
12、ished June 2012. Originally approved in 1998. Last previous edition approved in 2009 as F1868 - 09. DOI: 10.1520/F1868-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, re
13、fer to the standards Document Summary page on the ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indica
14、tion of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be con
15、sidered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2 evaporative resistance, nThe resistance to the flow of moisture vapor from a saturated surface (high vapor pressure) toan environment with a lower vap
16、or pressure.3.1.2.1 Discussion The evaporative resistance in units of kPam2/W can be calculated for several different cases.RefA= apparent total evaporative resistance of the fabric test specimen only, when evaluated non-isothermally. The term apparentis used as a modifier for total evaporative resi
17、stance to reflect the fact that condensation may occur within the specimen.RetA= apparent total evaporative resistance of the fabric test specimen, liquid barrier, and surface air layer when evaluatednon-isothermally. The term apparent is used as a modifier for total evaporative resistance to reflec
18、t the fact that condensation mayoccur within the specimen.Rebp= evaporative resistance of the air layer on the surface of the liquid barrier without a fabric test specimen (that is, bare plate).This property reflects the instrument constant and the resistance of the liquid barrier, and in conjunctio
19、n with Ret, is used in thecalculation of Ref.Ref= intrinsic evaporative resistance of the fabric test specimen only. In the calculation of this value, the assumption is made thatthe boundary layers of the bare plate and the boundary layers of the fabric are equal.Ret= total evaporative resistance of
20、 the fabric test specimen, the liquid barrier, and the surface air layer.3.1.3 permeability index (im), nthe efficiency of evaporative heat transport in a clothing system.3.1.3.1 DiscussionAn imof zero indicates that the clothing system allows no evaporative heat transfer. An imof one indicatesthat
21、the clothing system achieves the theoretical maximum evaporative heat transfer allowed by its insulation. The permeabilityindex is calculated one of two ways.im= permeability index calculated using the total thermal resistance and the total evaporative resistance of a material. The U.S.military uses
22、 this value in their databases on fabrics and clothing systems.imf= permeability index calculated using the intrinsic thermal resistance and the intrinsic evaporative resistance of a material.ISO 11092 uses this value.3.1.4 thermal resistance, nthe resistance to the flow of heat from a heated surfac
23、e to a cooler environment.3.1.4.1 DiscussionThermal resistance in units of Km2/W can 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
24、 units.Rcbp= thermal resistance of the air layer on the surface of the plate without a fabric test specimen (that is, bare plate). This propertyreflects the instrument constant and is used to standardize the plate, and in conjunction with Rct, is used in the calculation of Rcf.Rcf= intrinsic thermal
25、 resistance of the fabric test specimen only. In the calculation of this value, the assumption is made that theboundary layers of the bare plate and the boundary layers of the fabric test specimen are equal.Rct= total thermal resistance of the test specimen and the air layer.3.1.5 total heat loss, n
26、the amount of heat transferred through a material or a composite by the combined dry and evaporativeheat exchanges under specified conditions expressed in watts per square meter,3.1.5.1 DiscussionThis single criterion for comparing fabric assemblies was developed as a special case by the National Fi
27、reProtection Assoc. The specific conditions used by NFPA are a 35C fully sweating hot plate surface in a 25C, 65 % RHenvironment.3.2 For definitions of other terms related to protective clothing used in this test method, refer to Terminology F1494.4. Significance and Use4.1 The thermal resistance an
28、d evaporative resistance provided by fabrics, films, coatings, foams, and leathers, includingmulti-layer assemblies, is of considerable importance in determining their suitability for use in fabricating protective clothingsystems.4.2 The thermal interchange between people and their environment is, h
29、owever, an extremely complicated subject that involvesmany factors in addition to the steady-state resistance values of fabrics, films, coatings, foams, and leathers, including multi-layerassemblies. Therefore, thermal resistance values and evaporative resistance values measured on a hot plate may o
30、r may not indicaterelative merit of a particular material or system for a given clothing application. While a possible indicator of clothing performance,measurements produced by the testing of fabrics have no proven correlation to the performance of clothing systems worn bypeople. Clothing weight, d
31、rape, tightness of fit, and so forth, can minimize or even neutralize the apparent differences betweenfabrics or fabric assemblies measured by this test method.4.3 The thermal resistance and evaporative resistance of clothing systems can be measured with a heated manikin in anenvironmental chamber i
32、n accordance with Test Methods F1291 and F2370.5. Interferences5.1 Departures from the instructions of this test method may lead to significantly different test results. Technical knowledgeconcerning the theory of heat flow, temperature measurement, and testing practices is needed to evaluate which
33、departures fromthe instructions are significant. Standardization of the method reduces, but does not eliminate the need for such technicalknowledge. Report any departures from the instructions of Test Method F1868 with the results.6. Apparatus6.1 Hot PlateThe guarded flat plate shall be composed of
34、a test plate, guard section, and bottom plate, each electricallyF1868 122maintained at a constant temperature in the range of human skin temperature (33 to 36C). The guard section shall be designedto prevent lateral loss of heat from the test plate. The guard section shall be wide enough to minimize
35、 heat loss and moisturetransport through the edges of the test specimen under the conditions of the test. The bottom plate shall prevent downward lossof heat from the test plate and guard section. A system for feeding water to the surface of the test plate and guard section is alsoneeded for testing
36、 Parts B and C. See Test Methods D1518, C177, and ISO 11092 for additional information on hot plates.6.2 Temperature ControlSeparate independent temperature control is required for the three sections of the hot plate (test plate,guard section, and bottom plate). Temperature control may be achieved b
37、y independent adjustments to the voltage or current, orboth, supplied to the heaters using solid state power supplies, solid-state relays (proportional time on), adjustable transformers,variable impedances, or intermittent heating cycles. The test plate, guard, and bottom plate sections shall be con
38、trolled to measurethe same temperature to within 60.1C of each other.6.3 Power Measuring Instruments Power to the hot plate test section shall be measured to provide an accurate average overthe period of the test. If time proportioning or phase proportioning is used for the power control, then devic
39、es that are capable ofaveraging over the control cycle are required. Integrating devices (watt-hour transducers) are preferred over instantaneous devices(watt meters). Overall accuracy of the power monitoring equipment must be within 62 % of the reading for the average powerfor the test period.6.4 T
40、emperature SensorsTemperature sensors shall be thermistors, thermocouples, resistance temperature devices (RTDs), orequivalent sensors. The test plate, guard section, and bottom plate shall each contain one or more temperature sensors that aremounted flush with the hot plate surface and in such a ma
41、nner that they measure the surface temperature within 60.1C.6.5 Controlled Atmosphere ChamberThe hot plate shall be housed in an environmental chamber that can be maintained atselected temperatures between 20 and 35C. The test chamber wall temperature shall be 60.5C of the air in the chamber. Therel
42、ative humidity shall be maintained as specified in the individual procedure section.6.6 Measuring Environmental ParametersThe air temperature, relative humidity, and air velocity shall be measured asfollows:6.6.1 Relative Humidity Measuring EquipmentEither a wet-and-dry bulb psychrometer, a dew poin
43、t hygrometer, or otherelectronic humidity measuring device shall be used to measure the relative humidity and calculate the dew point temperature insidethe chamber. The relative humidity sensing devices shall have an overall accuracy of at least 64%.6.6.2 Air Temperature SensorsShielded air temperat
44、ure sensors shall be used.Any sensor with an overall accuracy of 60.1Cis acceptable. The sensor shall have a time constant not exceeding 1 min. The sensor(s) is suspended with the measuring pointexposed to air inside the chamber at a point in the air stream such that the air temperature sensor is no
45、t influenced by the platetemperature.6.6.3 Air Velocity IndicatorAir velocity shall be measured with an accuracy of 60.1 m/s using a hot wire anemometer. Airvelocity is measured at a point 15 mm (nominal) from the plate surface or from the top of the test specimen surface to the bottomof the anemome
46、ter sensing element. The air velocity shall be measured at three positions located along a horizontal lineperpendicular to the airflow, including a point at the center of the plate and at points at the centers of the guard section on bothsides of the plate. Spatial variations in air velocity shall n
47、ot exceed 610 % of the mean value.NOTE 1The air velocity is to be measured 15 mm above the plate surface for bare plate measurements. The air velocity is to be measured 15 mmabove the test specimen surface when testing fabric or systems. The 15 mm distance is to be the distance from the plate or tes
48、t specimen to the anemometersensing element (wire)not to the bottom of the sensing element housing.6.6.4 Air Temperature Variations Air temperature variations during testing shall not exceed 60.1C6.6.5 Relative Humidity VariationsRelative humidity variations during testing shall not exceed 64%.6.6.6
49、 Air Velocity VariationsAir velocity variations shall not exceed 610 % of the mean value for data averaged over 5 min.7. Materials7.1 WaterFor the evaporative resistance measurements in Parts B and C distilled, de-ionized, or reverse osmosis-treated watershall be used to wet the test plate surface.7.2 Liquid BarrierFor the evaporative resistance measurements in Parts B and C, a liquid barrier shall be used to cover thetest plate so that water does not contact the test specimen. The permeability index of the liquid barrier shall be greater t
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