1、Designation: C1057 03 (Reapproved 2010)Standard Practice forDetermination of Skin Contact Temperature from HeatedSurfaces Using a Mathematical Model andThermesthesiometer1This standard is issued under the fixed designation C1057; the number immediately following the designation indicates the year of
2、original adoption or, in 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.1. Scope1.1 This practice covers a procedure for evaluating the skincon
3、tact temperature for heated surfaces. Two complimentaryprocedures are presented. The first is a purely mathematicalapproximation that can be used during design or for worst caseevaluation. The second method describes the thermesthesiom-eter, an instrument that analogues the human sensory mecha-nism
4、and can be used only on operating systems.NOTE 1Both procedures listed herein are intended for use with GuideC1055. When used in conjunction with that guide, these procedures candetermine the burn hazard potential for a heated surface.1.2 A bibliography of human burn evaluation studies andsurface ha
5、zard measurement is provided in the References atthe end of Guide C1055. Thermesthesiometer and mathemati-cal modeling references are provided in the References at theend of this practice (1-5).21.3 This practice addresses the skin contact temperaturedetermination for passive heated surfaces only. T
6、he analysisprocedures contained herein are not applicable to chemical,electrical, or other similar hazards that provide a heat genera-tion source at the location of contact.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5
7、 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Docu
8、ments2.1 ASTM Standards:3C680 Practice for Estimate of the Heat Gain or Loss and theSurface Temperatures of Insulated Flat, Cylindrical, andSpherical Systems by Use of Computer ProgramsC1055 Guide for Heated System Surface Conditions thatProduce Contact Burn Injuries3. Terminology3.1 Definitions of
9、Terms Specific to This Standard:3.1.1 acceptable contact timethe limit of time of contactfor the heated surface and the exposed skin. Practice hassuggested limits of 5 s for industrial processes and up to 60 sfor consumer items.3.1.2 burns:3.1.2.1 first degree burnthe reaction to an exposure whereth
10、e intensity and duration is insufficient to cause completenecrosis of the epidermal layer. The normal response to thislevel of exposure is dilation of the superficial blood vessels(reddening of the skin).3.1.2.2 second degree burnthe reaction to an exposurewhere the intensity and duration is suffici
11、ent to cause completenecrosis of the epidermis but no significant damage to thedermis. The normal response to this exposure is blistering ofthe epidermis.3.1.2.3 third degree burnsthe reaction to an exposurewhere significant dermal necrosis occurs. Significant dermalnecrosis has been defined in the
12、literature as a 75 % destructionof the dermis thickness. The normal response to this exposureis open sores that leave permanent scar tissue upon healing.3.1.3 skin:3.1.3.1 epidermisthe outermost layer of skin cells. Thislayer contains no vascular or nerve cells and acts to protect theouter skin laye
13、rs.The thickness of this layer averages 0.08 mm.1This practice is under the jurisdiction of ASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved May 1, 2010. Published August 2010. Originallyapproved in 1986. L
14、ast previous edition approved in 2003 as C105703. DOI:10.1520/C1057-03R10.2The boldface numbers in parentheses refer to the list of references at the end ofthis practice.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annu
15、al Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.3.2 dermisthe second layer of skin tissue. This layercontains blood vess
16、els and nerve endings. The thickness of thislayer is about 2 mm.3.1.3.3 necrosislocalized death of living cells. This is aclinical term that defines when damage to the skin layer hasoccurred.3.1.4 skin contact temperaturethe temperature of the skinat a depth of 0.08 mm reached after contact with a h
17、eatedsurface for a specified time.3.1.5 thermesthesiometeran electromechanical device de-veloped by L. A. Marzetta at National Institute of Standardsand Technology to analogue the touch response of the humanskin when it contacts a heated surface. This measurementconcept holds U.S. Patent No. 3,878,7
18、28 dated April 22, 1975,and was assigned to the USAas represented by the Departmentof Health and Welfare. No known restriction exists to limit thedevelopment of units based upon this principle.4. Summary of Practice4.1 This practice provides two procedures for evaluation ofthe skin contact temperatu
19、re from heated surfaces. Either of thetwo methods, a mathematical model and a physical measure-ment, can be used depending upon the availability of thesystem (that is, is it built and operating or is it in the designstate) and the operating conditions. The first step in using thispractice is to dete
20、rmine which procedure is to be used. Unlessthe system of interest is operating at design “worst case”conditions, such as high system temperatures and high ambienttemperature, the calculational procedure is recommended. Onthe other hand, if the question is safety at the presentconditions, the thermes
21、thesiometer provides a quick measure-ment with no auxiliary calculations. Paragraphs 4.2 and 4.3outline the two alternative procedures available.4.2 Calculational Procedure, Method AFirst the surfacetemperature of the insulated system is determined by either adirect measurement, using either thermoc
22、ouples, thermistors,or infrared noncontact techniques, or by modeling of thesystem using Practice C680. Once the surface temperature isknown, the designer uses the equation set to estimate themaximum epidermal contact temperature for the acceptablecontact time. This temperature is a function of surf
23、ace tem-perature, time of contact, and composition of both the surfacematerial and substrate. The designer then refers to GuideC1055 to determine the burn hazard potential of the surface.4.3 Thermesthesiometer, Method BThe operator placesthe calibrated sensor probe face firmly against the heatedsurf
24、ace for the acceptable contact time. The device directlyreads the contact temperature from the probe. The maximumtemperature is used in conjunction with the Guide C1055 todetermine the burn hazard potential of the surface.5. Significance and Use5.1 The procedures in this practice support the determi
25、na-tion of the burn hazard potential for a heated surface. Theseprocedures provide an estimate of the maximum skin contacttemperature and must be used in conjunction with GuideC1055 to evaluate the surface hazard potential.5.2 The two procedures outlined herein are both based uponthe same heat trans
26、fer principles. Method A uses a mathemati-cal model to predict the contact temperature, while Method Buses a plastic rubber probe having similar heat transfercharacteristics to the human finger to “measure” the contacttemperature on real systems.5.3 These procedures serve as an estimate for the skin
27、contact temperatures which might occur for the “average”individual. Unusual conditions of exposure, incorrect designassumptions, subject health conditions, or unforeseen operatingconditions may negate the validity of the estimations.5.4 These procedures are limited to direct contact exposureonly. Co
28、nditions of personal exposure to periods of highambient temperatures, direct flame exposure, or high radiantfluxes may cause human injury in periods other than deter-mined herein. Evaluation of exposures other than direct contactare beyond the scope of this practice.5.5 Cold Surface ExposureNo conse
29、nsus criteria existsfor the destruction of skin cells by freezing. If, at some futuretime, such criteria are developed, extrapolation of the tech-niques presented here will serve as a basis for cold surfaceexposure evaluation.6. Method AUse of the Mathematical Model6.1 This modeling approach is for
30、use when the system isbeing designed or, if for some reason, it cannot be operated atdesign conditions. The model approximates the transient heatflow phenomena of the skin contacting a hot surface using theequation set described by Dussan (1) and Wu (5). The user isrequired to make certain definitio
31、ns of system geometry andmaterials, the system operating conditions, and the allowabletime of exposure. After definition of the input values, theequation set yields an estimate of the skin contact temperatureneeded for the hazard evaluation. The user must realize that aswith all mathematical approxi
32、mations, the estimate is only asgood as the input data. Where some input parameter is knownonly within some range of values, a sensitivity analysis aboutthat range is recommended.6.2 The first step in estimating the effective skin contacttemperature is to identify and record the following informatio
33、ndescribing the system as input for the model:6.2.1 System DescriptionGeometry, location, accessibil-ity.6.2.2 Present/Design Operating ConditionsDuty cycle,operating temperatures of equipment.6.2.3 System/Surface Data (as appropriate)Substrate (in-sulation) type and thickness, jacket type and thick
34、ness, surfaceproperties, such as emissivity and condition, shiny, painted,dirty, corroded.6.2.4 Ambient Conditions, including dry bulb temperatureand local wind velocity.NOTE 2The design temperatures should be at the worst case (gener-ally high operating and high ambient) conditions. Care should be
35、used inthe selection of design conditions since the hazard design conditions aredifferent from the heat loss design conditions.6.3 Using Practice C680 or a compatible program and theinformation gathered in 6.2, calculate the maximum operatingsurface temperature. This temperature is an input to the m
36、odelfor the contact temperature.C1057 03 (2010)26.3.1 Where the system is operating at design conditions,direct measurement can be used to determine the surfacetemperature. Thermocouples, resistance thermometers, or othermeans can be used; however, proper application techniques arerequired for accur
37、ate results. Caution must be observed sincethe surface temperature may be high and the surface couldconstitute a burn hazard.6.4 Calculate the expected skin contact temperature versustime history using the procedure below based upon the hotsurface temperature, time of contact, and system properties.
38、The development of the equations below is taken from Dussan(1). A more detailed derivation of the equation set used isincluded in the papers by Dussan (1) and Wu (5). See Fig. 1.6.4.1 Calculate the initial parameter constants, using Eq4-11.6.4.2 The contact temperature for the skin can now bedetermi
39、ned using Eq 1, Eq 2, and Eq 3 together for the systemin question. Note that the solution to this equation is a sum ofan infinite series. The solution, however, converges quickly(five or six terms) and can be easily handled manually or by asmall computer.Tc5 T01 A(N 5 0INerfc uN! 1 B(N 5 0INerfc u8N
40、! (1)and:uN5X1/=a11 2Nl/=a22=t(2)u8N5X1/=a11 2 N 1 1! l /=a22=t(3)I 5P22 P3!P22 P1!P21 P3! P21 P1!(4)A 5Ti2 T0!P2P21 P1(5)B 5Ti2 T0! P32 P2!P2P21 P3!P21 P1!(6)P15 r1C1K1!1/2(7)P25 r2C2K2!1/2(8)P35 r3C3K3!1/2(9)a15 K1/r1C1(10)a25 K2/r2 C2(11)where:T0= initial tissue temperature, C,N = integral consta
41、nt, 1 ,X1= depth of tissue of interest, normally 8.0 3 105m,ai= thermal diffusivity of layer i,m2/s,l = layer thickness of jacket material, m,P = layer thermal inertia; Wm2K1=s,t = time of contact, s,Ti= initial hot surface temperature, K,Tc= contact skin temperature at depth X and at time(t) after
42、contact, K,erfc(u) = complementary error function (a mathematicalfunction),ri= density of material i, kg/m3,Ki= conductivity of material i,W/mK,andCi= specific heat of material i,J/kgK.6.4.3 To obtain the skin contact temperature versus contacttime history, repeat the calculation at one second inter
43、vals fortimes up to the maximum contact time exposure expected.6.4.4 The maximum contact temperature used in the analy-sis of burn hazard (Guide C1055) is the maximum contacttemperature calculated for the contact period in step 6.4.3.6.5 Typical Input DataTable 1 contains typical values forthe commo
44、nly used insulation and jacketing materials. Skinproperties are also included. Nonstandard insulations or jacketmaterial properties may be substituted for the table values inthe calculation if they are known.NOTE 3Eq 1-11 work with any system of consistent units.6.6 Example CalculationUsing the equa
45、tions listed in 6.4and the following input data parameters, the following resultswere obtained for a simulated burn condition.FIG. 1 Schematic of Heat Transfer ModelC1057 03 (2010)36.6.1 ProblemAssume a heated system is to be insulatedwith light density fibrous glass. Jacketing material choicesavail
46、able include: (1) aluminum at 0.4 mm thickness and (2)glass cloth at 1.0 mm thickness. Also assume that the skindepth of interest is 0.008 cm and the initial skin temperature is33C. The question is: What would be the maximum expectedcontact skin temperature for each jacket material at the desireddep
47、th for an exposure of 10 s, if the operating jacket surfacetemperature is 150C?6.6.2 ResultIn 10 s of exposure the equations abovepredict a skin temperature at 0.008 cm of approximately50.2C for the aluminum jacket and approximately 40.3C forthe glass cloth jacket. See Fig. 2 for the time/temperatur
48、ehistories.7. Method BUse of the Thermethesiometer7.1 The thermesthesiometer approach is for use where thesystem is operating at the desired design conditions or whenevaluation of an existing condition is desired. The thermesthe-siometer provides an electrical analogue of the fingers thermalresponse
49、 when placed against a heated surface. Since the use ofthis device requires some technique, the user should have someexperience on known systems as practice before examiningunknown surfaces. Repeating a procedure similar to the cali-bration on other surface geometries is one method of obtainingthis needed training.7.2 The initial step in the measurement of the effective skincontact temperature using the thermesthesiometer is to identifyand record the following information describing the system tobe analyze
