1、Designation: F1868 14F1868 17Standard 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, in the case o
2、f 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 the skin to
3、 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 selecting m
4、aterialsfor 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 systems.1.2
5、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. No other units of measurement are included in this standard.1.4 This standa
6、rd does not purport to address all of the safety 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.1.5 This internation
7、al standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.
8、2. Referenced Documents2.1 ASTM Standards:2C177 Test Method for Steady-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
9、and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory 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
10、Evaporative Resistance of Clothing Using a Sweating Manikin2.2 Other Standards:ISO 11092 TextilesPhysiological EffectsMeasurement Textiles Physiological Effects Measurement of Thermal andWater-Vapour Resistance Under Steady-State Conditions (Sweating Guarded-Hotplate Test)31 This test method is unde
11、r the jurisdiction of ASTM Committee F23 on Personal Protective Clothing and Equipment and is the direct responsibility of SubcommitteeF23.60 onHuman Factors.Current edition approved Feb. 1, 2014June 1, 2017. Published February 2014June 2017. Originally approved in 1998. Last previous edition approv
12、ed in 20122014 asF1868 - 12.F1868 14. DOI: 10.1520/F1868-14.10.1520/F1868-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on t
13、he ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the prev
14、ious 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 considered the official document.Copyright ASTM In
15、ternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 clo, na unit of thermal resistance (insulation) equal to 0.155 KmKm2/W.3.1.1.1 DiscussionThe value of the clo was selected as roughly the insulation value of typical i
16、ndoor clothing, which should keep a resting man(producing heat at the rate of 58 58 WW/mm2) comfortable in an environment at 21C,21 C, air movement 0.1 m/s.3.1.2 evaporative resistance, nThe resistance to the flow of moisture vapor from a saturated surface (high vapor pressure) toan environment with
17、 a lower vapor pressure.3.1.2.1 DiscussionThe evaporative resistance in units of kPamkPam2/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
18、evaporative resistance 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 res
19、istance to reflect 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,
20、 and in conjunction 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 evapo
21、rative resistance of 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 im of zero indicates that the clothing system allows no evaporative heat transfer.An im o
22、f one indicates that the clothing systemachieves the theoretical maximum evaporative heat transfer allowed by its insulation. The permeability index is calculated one oftwo ways.im = permeability index calculated using the total thermal resistance and the total evaporative resistance of a material.
23、The U.S.military uses 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 hea
24、t from a heated surface to a cooler environment.3.1.4.1 DiscussionThermal resistance in units of KmKm2/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 speci
25、men only, expressed in clo 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
26、 Rcf.Rcf = intrinsic thermal 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 l
27、ayer.3.1.5 total heat loss, nthe 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 metre.3.1.5.1 DiscussionThis single criterion for comparing fabric assemblies was developed as a sp
28、ecial case by the National Fire Protection Assoc. Thespecific conditions used by NFPA are a 35C35 C fully sweating hot plate surface in a 25C,25 C, 65 % RH environment.F1868 1723.2 For definitions of other terms related to protective clothing used in this test method, refer to Terminology F1494.4. S
29、ignificance and Use4.1 The thermal resistance and 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 interc
30、hange between people and their environment is, however, 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
31、 resistance values measured on a hot plate may or 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 clo
32、thing systems worn bypeople. Clothing weight, drape, 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 wit
33、h a heated manikin in anenvironmental chamber in 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
34、 testing practices is needed to evaluate which 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 Pl
35、ateThe guarded flat plate shall be composed of a test plate, guard section, and bottom plate, each electricallymaintained at a constant temperature in the range of human skin temperature (33 to 36C).36 C). The guard section shall bedesigned to prevent lateral loss of heat from the test plate. The gu
36、ard section shall be wide enough to minimize heat loss andmoisture transport through the edges of the test specimen under the conditions of the test. The bottom plate shall prevent downwardloss of heat from the test plate and guard section. A system for feeding water to the surface of the test plate
37、 and guard section isalso needed for testing 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
38、plate). Temperature control may be achieved by independent adjustments to the voltage or current, orboth, supplied to the heaters using solid state solid-state power supplies, solid-state relays (proportional time on), adjustabletransformers, variable impedances, or intermittent heating cycles. The
39、test plate, guard, and bottom plate sections shall becontrolled to measure the same temperature to within 60.1C60.1 C of each other.6.3 Power Measuring Power-Measuring InstrumentsPower to the hot plate test section shall be measured to provide anaccurate average over the period of the test. If time
40、proportioning or phase proportioning is used for the power control, then devicesthat are capable of averaging over the control cycle are required. Integrating devices (watt-hour transducers) are preferred overinstantaneous devices (watt metres). Overall accuracy of the power monitoring power-monitor
41、ing equipment must be within 62 %of the reading for the average power for the test period.6.4 Temperature SensorsTemperature sensors shall be thermistors, thermocouples, resistance temperature devices (RTDs), orequivalent sensors. The test plate, guard section, and bottom plate shall each contain on
42、e or more temperature sensors that aremounted flush with the hot plate surface and in such a manner that they measure the surface temperature within 60.1C.60.1 C.6.5 Controlled Atmosphere ChamberThe hot plate shall be housed in an environmental chamber that can be maintained atselected temperatures
43、between 20 and 35C.35 C. The test chamber wall temperature shall be 60.5C60.5 C of the air in thechamber. The relative 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
44、 measured asfollows:6.6.1 Relative Humidity Measuring EquipmentEither a wet-and-dry bulb psychrometer, a dew point hygrometer, or otherelectronic humidity measuring humidity-measuring device shall be used to measure the relative humidity and calculate the dewpoint temperature inside the chamber. The
45、 relative humidity sensing humidity-sensing devices shall have an overall accuracy ofat least 64 %.6.6.2 Air Temperature SensorsShielded air temperature sensors shall be used. Any sensor with an overall accuracy of60.1C60.1 C is acceptable. The sensor shall have a time constant not exceeding 1 min.
46、The sensor(s) is suspended with themeasuring point exposed to air inside the chamber at a point in the air stream such that the air temperature sensor is not influencedby the plate temperature.F1868 1736.6.3 Air Velocity IndicatorAir velocity shall be measured with an accuracy of 60.1 m/s using a ho
47、t 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 anemometer sensing element. The air velocity shall be measured at three positions located along a horizontal line oneposition perpendicular to
48、 the airflow, including a point at the center of the plate and at points at the centers of the guard sectionon both sides of the plate. Spatial variations in air velocity shall not exceed 610 % of the mean value.plate.NOTE 1The air velocity is to be measured 15 mm above the plate surface for bare pl
49、ate 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 test specimen to the anemometersensing element (wire)not to the bottom of the sensing element housing.6.6.3.1 The air velocity is to be measured 15 mm above the plate surface for bare plate measurements. The air velocity is tobe measured 15 mm above the test specimen surface when testing fabric or systems. The 15-mm distance is to be the distance f
