1、Designation: C 1057 03Standard Practice forDetermination of Skin Contact Temperature from HeatedSurfaces Using a Mathematical Model andThermesthesiometer1This standard is issued under the fixed designation C 1057; the number immediately following the designation indicates the year oforiginal adoptio
2、n or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a procedure for evaluating the skincontact temperatur
3、e 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 and can be used
4、 only on operating systems.NOTE 1Both procedures listed herein are intended for use with GuideC 1055. 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 hazard measureme
5、nt is provided in the References atthe end of Guide C 1055. 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. The analysispr
6、ocedures 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 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the use
7、r of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C 680 Practice for Estimate of the Heat Gain or Loss andthe Surface Temperatures of Insulated Flat, Cylindrical,
8、and Spherical Systems by Use of Computer ProgramsC 1055 Guide for Heated System Surface Conditions ThatProduce Contact Burn Injuries3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 acceptable contact timethe limit of time of contactfor the heated surface and the exposed skin. P
9、ractice 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 wherethe intensity and duration is insufficient to cause completenecrosis of the epidermal layer. The normal response to thislevel of exposure
10、 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 sufficient to cause completenecrosis of the epidermis but no significant damage to thedermis. The normal response to this exposure is blisteri
11、ng ofthe epidermis.3.1.2.3 third degree burnsthe reaction to an exposurewhere significant dermal necrosis occurs. Significant dermalnecrosis has been defined in the literature as a 75 % destructionof the dermis thickness. The normal response to this exposureis open sores that leave permanent scar ti
12、ssue 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 layers. The thickness of this layer averages 0.08 mm.3.1.3.2 dermisthe second layer of skin tissue. This layercontains blood vessels and ne
13、rve 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 heatedsurfa
14、ce for a specified time.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 Oct. 1, 2003. Published October 2003. Originallyapproved in 1986. Last previous edition a
15、pproved in 1998 as C 105792 (Reap-proved 1998)e1.2The 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 Annual Book of ASTMStandards
16、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.3.1.5 thermesthesiometeran electromechanical device de-veloped by L. A. Marzetta at National Institut
17、e of Standardsand Technology to analogue the touch response of the humanskin when it contacts a heated surface. This measurementconcept holds U.S. Patent No. 3,878,728 dated April 22, 1975,and was assigned to the USA as represented by the Departmentof Health and Welfare. No known restriction exists
18、to limit thedevelopment of units based upon this principle.4. Summary of Practice4.1 This practice provides two procedures for evaluation ofthe skin contact temperature from heated surfaces. Either of thetwo methods, a mathematical model and a physical measure-ment, can be used depending upon the av
19、ailability 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 determine which procedure is to be used. Unlessthe system of interest is operating at design “worst case”conditions, such as high system t
20、emperatures and high ambienttemperature, the calculational procedure is recommended. Onthe other hand, if the question is safety at the presentconditions, the thermesthesiometer provides a quick measure-ment with no auxiliary calculations. Paragraphs 4.2 and 4.3outline the two alternative procedures
21、 available.4.2 Calculational Procedure, Method AFirst the surfacetemperature of the insulated system is determined by either adirect measurement, using either thermocouples, thermistors,or infrared noncontact techniques, or by modeling of thesystem using Practice C 680. Once the surface temperature
22、isknown, the designer uses the equation set to estimate themaximum epidermal contact temperature for the acceptablecontact time. This temperature is a function of surface tem-perature, time of contact, and composition of both the surfacematerial and substrate. The designer then refers to GuideC 1055
23、 to determine the burn hazard potential of the surface.4.3 Thermesthesiometer, Method BThe operator placesthe calibrated sensor probe face firmly against the heatedsurface for the acceptable contact time. The device directlyreads the contact temperature from the probe. The maximumtemperature is used
24、 in conjunction with the Guide C 1055 todetermine the burn hazard potential of the surface.5. Significance and Use5.1 The procedures in this practice support the determina-tion of the burn hazard potential for a heated surface. Theseprocedures provide an estimate of the maximum skin contacttemperatu
25、re and must be used in conjunction with GuideC 1055 to evaluate the surface hazard potential.5.2 The two procedures outlined herein are both based uponthe same heat transfer principles. Method A uses a mathemati-cal model to predict the contact temperature, while Method Buses a plastic rubber probe
26、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 skincontact temperatures which might occur for the “average”individual. Unusual conditions of exposure, incorrect designassumptions, s
27、ubject health conditions, or unforeseen operatingconditions may negate the validity of the estimations.5.4 These procedures are limited to direct contact exposureonly. Conditions of personal exposure to periods of highambient temperatures, direct flame exposure, or high radiantfluxes may cause human
28、 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 consensus criteria existsfor the destruction of skin cells by freezing. If, at some futuretime, such criteria are developed, extrapolat
29、ion 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 use when the system isbeing designed or, if for some reason, it cannot be operated atdesign conditions. The model approximates the
30、 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 definitions of system geometry andmaterials, the system operating conditions, and the allowabletime of exposure. After definition of the in
31、put values, theequation set yields an estimate of the skin contact temperatureneeded for the hazard evaluation. The user must realize that aswith all mathematical approximations, the estimate is only asgood as the input data. Where some input parameter is knownonly within some range of values, a sen
32、sitivity analysis aboutthat range is recommended.6.2 The first step in estimating the effective skin contacttemperature is to identify and record the following informationdescribing the system as input for the model:6.2.1 System DescriptionGeometry, location, accessibil-ity.6.2.2 Present/Design Oper
33、ating ConditionsDuty cycle,operating temperatures of equipment.6.2.3 System/Surface Data (as appropriate)Substrate (in-sulation) type and thickness, jacket type and thickness, surfaceproperties, such as emissivity and condition, shiny, painted,dirty, corroded.6.2.4 Ambient Conditions, including dry
34、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 used inthe selection of design conditions since the hazard design conditions aredifferent from the heat loss design conditions.6.3
35、 Using Practice C 680 or a compatible program and theinformation gathered in 6.2, calculate the maximum operatingsurface temperature. This temperature is an input to the modelfor the contact temperature.6.3.1 Where the system is operating at design conditions,direct measurement can be used to determ
36、ine the surfacetemperature. Thermocouples, resistance thermometers, or othermeans can be used; however, proper application techniques arerequired for accurate results. Caution must be observed sincethe surface temperature may be high and the surface couldconstitute a burn hazard.6.4 Calculate the ex
37、pected skin contact temperature versustime history using the procedure below based upon the hotsurface temperature, time of contact, and system properties.C1057032The development of the equations below is taken from Dussan(1). A more detailed derivation of the equation set used isincluded in the pap
38、ers 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 bedetermined 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.
39、 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! (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
40、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 constant, 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 materia
41、l, 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 contact, K,erfc(u) = complementary error function (a mathematicalfunction),ri= density of material i, kg/m3,Ki= conductivity of material
42、i, W/m K, 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 intervals fortimes up to the maximum contact time exposure expected.6.4.4 The maximum contact temperature used in the analy-sis of burn haz
43、ard (Guide C 1055) is the maximum contacttemperature calculated for the contact period in step 6.4.3.6.5 Typical Input DataTable 1 contains typical values forthe commonly used insulation and jacketing materials. Skinproperties are also included. Nonstandard insulations or jacketmaterial properties m
44、ay 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 equations listed in 6.4and the following input data parameters, the following resultswere obtained for a simulated burn condition.6.6.1 P
45、roblemAssume a heated system is to be insulatedwith light density fibrous glass. Jacketing material choicesavailable 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 qu
46、estion is: What would be the maximum expectedcontact skin temperature for each jacket material at the desiredFIG. 1 Schematic of Heat Transfer ModelC1057033depth 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 s
47、kin 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/temperaturehistories.7. Method BUse of the Thermethesiometer7.1 The thermesthesiometer approach is for use where thesystem is operating at the desired
48、design conditions or whenevaluation of an existing condition is desired. The thermesthe-siometer provides an electrical analogue of the fingers thermalresponse when placed against a heated surface. Since the use ofthis device requires some technique, the user should have someexperience on known syst
49、ems 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 analyzed:7.2.1 System DescriptionGeometry, location, accessibil-ity.7.2.2 Present Operational ConditionsDuty cycle, systemoperating temperatures.7.2
