1、Designation: C1057 12C1057 17Standard 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 oforiginal a
2、doption 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 skin contact temp
3、erature for heated surfaces. Two complimentaryprocedures are presented. The first is a purely mathematical approximation that can be used during design or for worst caseevaluation. The second method describes the thermesthesiometer, an instrument that analogues the human sensory mechanism andcan be
4、used only on operating systems.NOTE 1Both procedures listed herein are intended for use with Guide C1055. 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 and surface hazard meas
5、urement is provided in the References at the endof Guide C1055. Thermesthesiometer and mathematical modeling references are provided in the References at the end of thispractice (1-5).21.3 This practice addresses the skin contact temperature determination for passive heated surfaces only. The analys
6、is procedurescontained herein are not applicable to chemical, electrical, or other similar hazards that provide a heat generation source at thelocation of contact.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This st
7、andard 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 establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.6 This international stand
8、ard 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.2. Refer
9、enced Documents2.1 ASTM Standards:3C168 Terminology Relating to Thermal InsulationC680 Practice for Estimate of the Heat Gain or Loss and the Surface Temperatures of Insulated Flat, Cylindrical, and SphericalSystems by Use of Computer ProgramsC1055 Guide for Heated System Surface Conditions that Pro
10、duce Contact Burn Injuries3. Terminology3.1 DefinitionsTerminology C168 shall be considered as applicable to the terms used in this standard.3.2 Definitions of Terms Specific to This Standard:3.2.1 acceptable contact timethe limit of time of contact for the heated surface and the exposed skin. Pract
11、ice has suggestedlimits of 5 s for industrial processes and up to 60 s for consumer items.1 This practice is under the jurisdiction ofASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal Measurement.Current edition approved Oct. 1, 2012May 1, 20
12、17. Published August 2013.June 2017. Originally approved in 1986. Last previous edition approved in 20102012 asC105703(2010).C1057 12. DOI: 10.1520/C1057-12. 10.1520/C1057-17.2 The boldface numbers in parentheses refer to the list of references at the end of this practice.3 For referencedASTM standa
13、rds, 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 the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an AST
14、M standard an indication 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
15、by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.2 burns:3.2.2.1 first degree burnthe reaction to an exposure where the intensity and duration is insufficient to cause complete necr
16、osisof the epidermal layer. The normal response to this level of exposure is dilation of the superficial blood vessels (reddening of theskin).3.2.2.2 second degree burnthe reaction to an exposure where the intensity and duration is sufficient to cause complete necrosisof the epidermis but no signifi
17、cant damage to the dermis. The normal response to this exposure is blistering of the epidermis.3.2.2.3 third degree burnsthe reaction to an exposure where significant dermal necrosis occurs. Significant dermal necrosishas been defined in the literature as a 75 % destruction of the dermis thickness.
18、The normal response to this exposure is open soresthat leave permanent scar tissue upon healing.3.2.3 skin:3.2.3.1 epidermisthe outermost layer of skin cells. This layer contains no vascular or nerve cells and acts to protect the outerskin layers. The thickness of this layer averages 0.08 mm.3.2.3.2
19、 dermisthe second layer of skin tissue. This layer contains blood vessels and nerve endings. The thickness of this layeris about 2 mm.3.2.3.3 necrosislocalized death of living cells. This is a clinical term that defines when damage to the skin layer has occurred.3.2.4 skin contact temperaturethe tem
20、perature of the skin at a depth of 0.08 mm reached after contact with a heated surfacefor a specified time.3.2.5 thermal inertiaa measure of the responsiveness of a material to variations in temperature. This property is also knownas thermal effusivity.3.2.6 thermesthesiometeran electromechanical de
21、vice developed by L. A. Marzetta at National Institute of Standards andTechnology to analogue the touch response of the human skin when it contacts a heated surface. This measurement concept holdsU.S. Patent No. 3,878,728 dated April 22, 1975, and was assigned to the USA as represented by the Depart
22、ment of Health andWelfare. No known restriction exists to limit the development of units based upon this principle.4. Summary of Practice4.1 This practice provides two procedures for evaluation of the skin contact temperature from heated surfaces. Either of the twomethods, a mathematical model and a
23、 physical measurement, can be used depending upon the availability of the system (that is,is it built and operating or is it in the design state) and the operating conditions. The first step in using this practice is to determinewhich procedure is to be used. Unless the system of interest is operati
24、ng at design “worst case” conditions, such as high systemtemperatures and high ambient temperature, the calculational procedure is recommended. On the other hand, if the question issafety at the present conditions, the thermesthesiometer provides a quick measurement with no auxiliary calculations. P
25、aragraphs4.2 and 4.3 outline the two alternative procedures available.4.2 Calculational Procedure, Method AFirst the surface temperature of the insulated system is determined by either a directmeasurement, using either thermocouples, thermistors, or infrared noncontact techniques, or by modeling of
26、the system usingPractice C680. Once the surface temperature is known, the designer uses the equation set to estimate the maximum epidermalcontact temperature for the acceptable contact time. This temperature is a function of surface temperature, time of contact, andcomposition of both the surface ma
27、terial and substrate. The designer then refers to Guide C1055 to determine the burn hazardpotential of the surface.4.3 Thermesthesiometer, Method BThe operator places the calibrated sensor probe face firmly against the heated surface forthe acceptable contact time. The device directly reads the cont
28、act temperature from the probe. The maximum temperature is usedin conjunction with the Guide C1055 to determine the burn hazard potential of the surface.5. Significance and Use5.1 The procedures in this practice support the determination of the burn hazard potential for a heated surface. These proce
29、duresprovide an estimate of the maximum skin contact temperature and must be used in conjunction with Guide C1055 to evaluate thesurface hazard potential.5.2 The two procedures outlined herein are both based upon the same heat transfer principles. Method A uses a mathematicalmodel to predict the con
30、tact temperature, while Method B uses a plastic rubber probe having similar heat transfer characteristicsto the human finger to “measure” the contact temperature on real systems.5.3 These procedures serve as an estimate for the skin contact temperatures which might occur for the “average” individual
31、.Unusual conditions of exposure, incorrect design assumptions, subject health conditions, or unforeseen operating conditions maynegate the validity of the estimations.5.4 These procedures are limited to direct contact exposure only. Conditions of personal exposure to periods of high ambienttemperatu
32、res, direct flame exposure, or high radiant fluxes may cause human injury in periods other than determined herein.Evaluation of exposures other than direct contact are beyond the scope of this practice.C1057 1725.5 Cold Surface ExposureNo consensus criteria exists for the destruction of skin cells b
33、y freezing. If, at some future time,such criteria are developed, extrapolation of the techniques presented here will serve as a basis for cold surface exposureevaluation.6. Method AUse of the Mathematical Model6.1 This modeling approach is for use when the system is being designed or, if for some re
34、ason, it cannot be operated at designconditions. The model approximates the transient heat flow phenomena of the skin contacting a hot surface using the equation setdescribed by Dussan and Weiner (1) and Wu (5). The user is required to make certain definitions of system geometry and materials,the sy
35、stem operating conditions, and the allowable time of exposure. After definition of the input values, the equation set yieldsan estimate of the skin contact temperature needed for the hazard evaluation. The user must realize that as with all mathematicalapproximations, the estimate is only as good as
36、 the input data. Where some input parameter is known only within some range ofvalues, a sensitivity analysis about that range is recommended.6.2 The first step in estimating the effective skin contact temperature is to identify and record the following informationdescribing the system as input for t
37、he model:6.2.1 System DescriptionGeometry, location, accessibility.6.2.2 Present/Design Operating ConditionsDuty cycle, operating temperatures of equipment.6.2.3 System/Surface Data (as appropriate)Substrate (insulation) type and thickness, jacket type and thickness, surfaceproperties, such as emiss
38、ivity and condition, shiny, painted, dirty, corroded.6.2.4 Ambient Conditions, including dry bulb temperature and local wind velocity.NOTE 2The design temperatures should be at the worst case (generally high operating and high ambient) conditions. Care should be used in theselection of design condit
39、ions since the hazard design conditions are different from the heat loss design conditions.6.3 Using Practice C680 or a compatible program and the information gathered in 6.2, calculate the maximum operating surfacetemperature. This temperature is an input to the model for the contact temperature.6.
40、3.1 Where the system is operating at design conditions, direct measurement can be used to determine the surface temperature.Thermocouples, resistance thermometers, or other means can be used; however, proper application techniques are required foraccurate results. Caution must be observed since the
41、surface temperature may be high and the surface could constitute a burnhazard.6.4 Calculate the expected skin contact temperature versus time history using the procedure below based upon the hot surfacetemperature, time of contact, and system properties. The development of the equations below is tak
42、en from Dussan and Weiner(1). A more detailed derivation of the equation set used is included in the papers by Dussan and Weiner (1) and Wu (5). See Fig.1.6.4.1 Calculate the initial parameter constants, using Eq 4-11.6.4.2 The contact temperature for the skin can now be determined using Eq 1, Eq 2,
43、 and Eq 3 together for the system in question.Note that the solution to this equation is a sum of an infinite series. The solution, however, converges quickly (five or six terms)and can be easily handled manually or by a small computer.Tc 5T01A (N50I N erfc N!1B (N50IN erfc N! (1)FIG. 1 Schematic of
44、 Heat Transfer ModelC1057 173and:N 5X1/=112Nl/=22=t(2)N 5X1/=112N11!l/=22=t(3)I 5P22P3!P22P1!P21P3!P21P1!(4)A 5Ti2T0!P2P21P1(5)B 5Ti2T0!P32P2!P2P21P3!P21P1!(6)P151C1K1!1/2 (7)P252C2K2!1/2 (8)P353C3K3!1/2 (9)15K1/1C1 (10)25K2/2C2 (11)where:T0 = initial tissue temperature, K,T0 = initial tissue temper
45、ature, C,N = integral constant, 1 ,X1 = depth of tissue of interest, normally 8.0 105 m,i = thermal diffusivity of layer i, m2/s,l = layer thickness of jacket material, m,P = layer thermal inertia;Wm22K21=s,t = time of contact, s,Ti = initial hot surface temperature, K,Ti = initial hot surface tempe
46、rature, C,Tc = contact skin temperature at depth X and at time (t) after contact, C,erfc() = complementary error function (a mathematical function),i = density of material i, kg/m3,Ki = conductivity of material i, W/m K, andCi = specific heat of material i, J/kg K.6.4.3 To obtain the skin contact te
47、mperature versus contact time history, repeat the calculation at one second intervals for timesup to the maximum contact time exposure expected.6.4.4 The maximum contact temperature used in the analysis of burn hazard (Guide C1055) is the maximum contacttemperature calculated for the contact period
48、in step 6.4.3.6.5 Typical Input DataTable 1 contains typical values for the commonly used insulation and jacketing materials. Skinproperties are also included. Nonstandard insulations or jacket material properties may be substituted for the table values in thecalculation if they are known. Table 2 c
49、ontains calculated values of Thermal Inertia and Thermal Diffusivity for the 25 materialslisted in Table 1 using Eq. 7 and Eq. 10 respectively.NOTE 3Eq 1-11 work with any system of consistent units.6.6 Example CalculationUsing the equations listed in 6.4 and the following input data parameters, the following results wereobtained for a simulated burn condition.6.6.1 ProblemAssume a heated system is to be insulated with light density fibrous glass. Jacketing material choices availableincl
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