ASTM C1057-03(2010)
(Practice)Standard Practice for Determination of Skin Contact Temperature from Heated Surfaces Using A Mathematical Model and Thermesthesiometer
Standard Practice for Determination of Skin Contact Temperature from Heated Surfaces Using A Mathematical Model and Thermesthesiometer
SIGNIFICANCE AND USE
The procedures in this practice support the determination of the burn hazard potential for a heated surface. These procedures provide an estimate of the maximum skin contact temperature and must be used in conjunction with Guide C1055 to evaluate the surface hazard potential.
The two procedures outlined herein are both based upon the same heat transfer principles. Method A uses a mathematical model to predict the contact temperature, while Method B uses a plastic rubber probe having similar heat transfer characteristics to the human finger to “measure” the contact temperature on real systems.
These procedures serve as an estimate for the skin contact temperatures which might occur for the “average” individual. Unusual conditions of exposure, incorrect design assumptions, subject health conditions, or unforeseen operating conditions may negate the validity of the estimations.
These procedures are limited to direct contact exposure only. Conditions of personal exposure to periods of high ambient temperatures, 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.
Cold Surface Exposure—No consensus criteria exists for the destruction of skin cells by freezing. If, at some future time, such criteria are developed, extrapolation of the techniques presented here will serve as a basis for cold surface exposure evaluation.
SCOPE
1.1 This practice covers a procedure for evaluating the skin contact temperature for heated surfaces. Two complimentary procedures are presented. The first is a purely mathematical approximation that can be used during design or for worst case evaluation. The second method describes the thermesthesiometer, an instrument that analogues the human sensory mechanism and can be used only on operating systems.
Note 1—Both procedures listed herein are intended for use with Guide C1055. When used in conjunction with that guide, these procedures can determine the burn hazard potential for a heated surface.
1.2 A bibliography of human burn evaluation studies and surface hazard measurement is provided in the References at the end of Guide C1055. Thermesthesiometer and mathematical modeling references are provided in the References at the end of this practice (1-5).
1.3 This practice addresses the skin contact temperature determination for passive heated surfaces only. The analysis procedures contained herein are not applicable to chemical, electrical, or other similar hazards that provide a heat generation source at the location 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 standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C1057 − 03(Reapproved 2010)
Standard Practice for
Determination of Skin Contact Temperature from Heated
Surfaces Using a Mathematical Model and
Thermesthesiometer
This standard is issued under the fixed designation C1057; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice covers a procedure for evaluating the skin
C680Practice for Estimate of the Heat Gain or Loss and the
contact temperature for heated surfaces. Two complimentary
Surface Temperatures of Insulated Flat, Cylindrical, and
procedures are presented. The first is a purely mathematical
Spherical Systems by Use of Computer Programs
approximationthatcanbeusedduringdesignorforworstcase
C1055Guide for Heated System Surface Conditions that
evaluation. The second method describes the
Produce Contact Burn Injuries
thermesthesiometer, an instrument that analogues the human
sensorymechanismandcanbeusedonlyonoperatingsystems.
3. Terminology
NOTE 1—Both procedures listed herein are intended for use with Guide
3.1 Definitions of Terms Specific to This Standard:
C1055. When used in conjunction with that guide, these procedures can
3.1.1 acceptable contact time—the limit of time of contact
determine the burn hazard potential for a heated surface.
for the heated surface and the exposed skin. Practice has
1.2 A bibliography of human burn evaluation studies and
suggested limits of 5 s for industrial processes and up to 60 s
surface hazard measurement is provided in the References at
for consumer items.
the end of Guide C1055. Thermesthesiometer and mathemati-
3.1.2 burns:
cal modeling references are provided in the References at the
3.1.2.1 first degree burn—thereactiontoanexposurewhere
end of this practice (1-5).
the intensity and duration is insufficient to cause complete
1.3 This practice addresses the skin contact temperature
necrosis of the epidermal layer. The normal response to this
determination for passive heated surfaces only. The analysis
level of exposure is dilation of the superficial blood vessels
procedures contained herein are not applicable to chemical, (reddening of the skin).
electrical, or other similar hazards that provide a heat genera-
3.1.2.2 second degree burn—the reaction to an exposure
tion source at the location of contact. wheretheintensityanddurationissufficienttocausecomplete
necrosis of the epidermis but no significant damage to the
1.4 The values stated in SI units are to be regarded as
dermis. The normal response to this exposure is blistering of
standard. No other units of measurement are included in this
the epidermis.
standard.
3.1.2.3 third degree burns—the reaction to an exposure
1.5 This standard does not purport to address all of the
where significant dermal necrosis occurs. Significant dermal
safety concerns, if any, associated with its use. It is the necrosishasbeendefinedintheliteratureasa75%destruction
responsibility of the user of this standard to establish appro- of the dermis thickness. The normal response to this exposure
is open sores that leave permanent scar tissue upon healing.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
3.1.3 skin:
3.1.3.1 epidermis—the outermost layer of skin cells. This
layer contains no vascular or nerve cells and acts to protect the
outerskinlayers.Thethicknessofthislayeraverages0.08mm.
This practice is under the jurisdiction of ASTM Committee C16 on Thermal
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
Measurement.
Current edition approved May 1, 2010. Published August 2010. Originally
approved in 1986. Last previous edition approved in 2003 as C1057–03. DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/C1057-03R10. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof Standards volume information, refer to the standard’s Document Summary page on
this practice. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1057 − 03 (2010)
3.1.3.2 dermis—the second layer of skin tissue. This layer 5.2 Thetwoproceduresoutlinedhereinarebothbasedupon
containsbloodvesselsandnerveendings.Thethicknessofthis the same heat transfer principles. MethodAuses a mathemati-
layer is about 2 mm. cal model to predict the contact temperature, while Method B
3.1.3.3 necrosis—localized death of living cells. This is a uses a plastic rubber probe having similar heat transfer
clinical term that defines when damage to the skin layer has characteristics to the human finger to “measure” the contact
occurred. temperature on real systems.
3.1.4 skin contact temperature—the temperature of the skin
5.3 These procedures serve as an estimate for the skin
at a depth of 0.08 mm reached after contact with a heated
contact temperatures which might occur for the “average”
surface for a specified time.
individual. Unusual conditions of exposure, incorrect design
3.1.5 thermesthesiometer—an electromechanical device de-
assumptions,subjecthealthconditions,orunforeseenoperating
veloped by L. A. Marzetta at National Institute of Standards
conditions may negate the validity of the estimations.
and Technology to analogue the touch response of the human
5.4 These procedures are limited to direct contact exposure
skin when it contacts a heated surface. This measurement
only. Conditions of personal exposure to periods of high
concept holds U.S. Patent No. 3,878,728 datedApril 22, 1975,
ambient temperatures, direct flame exposure, or high radiant
andwasassignedtotheUSAasrepresentedbytheDepartment
fluxes may cause human injury in periods other than deter-
of Health andWelfare. No known restriction exists to limit the
minedherein.Evaluationofexposuresotherthandirectcontact
development of units based upon this principle.
are beyond the scope of this practice.
4. Summary of Practice
5.5 ColdSurfaceExposure—Noconsensuscriteriaexistsfor
thedestructionofskincellsbyfreezing.If,atsomefuturetime,
4.1 This practice provides two procedures for evaluation of
such criteria are developed, extrapolation of the techniques
theskincontacttemperaturefromheatedsurfaces.Eitherofthe
presented here will serve as a basis for cold surface exposure
two methods, a mathematical model and a physical
evaluation.
measurement, can be used depending upon the availability of
thesystem(thatis,isitbuiltandoperatingorisitinthedesign
6. Method A—Use of the Mathematical Model
state) and the operating conditions. The first step in using this
practice is to determine which procedure is to be used. Unless
6.1 This modeling approach is for use when the system is
the system of interest is operating at design “worst case”
being designed or, if for some reason, it cannot be operated at
conditions,suchashighsystemtemperaturesandhighambient
design conditions. The model approximates the transient heat
temperature, the calculational procedure is recommended. On
flow phenomena of the skin contacting a hot surface using the
the other hand, if the question is safety at the present
equation set described by Dussan (1) and Wu (5). The user is
conditions, the thermesthesiometer provides a quick measure-
required to make certain definitions of system geometry and
ment with no auxiliary calculations. Paragraphs 4.2 and 4.3
materials, the system operating conditions, and the allowable
outline the two alternative procedures available.
time of exposure. After definition of the input values, the
equation set yields an estimate of the skin contact temperature
4.2 Calculational Procedure, Method A—First the surface
needed for the hazard evaluation.The user must realize that as
temperature of the insulated system is determined by either a
with all mathematical approximations, the estimate is only as
direct measurement, using either thermocouples, thermistors,
good as the input data. Where some input parameter is known
or infrared noncontact techniques, or by modeling of the
only within some range of values, a sensitivity analysis about
system using Practice C680. Once the surface temperature is
that range is recommended.
known, the designer uses the equation set to estimate the
maximum epidermal contact temperature for the acceptable
6.2 The first step in estimating the effective skin contact
contact time. This temperature is a function of surface
temperatureistoidentifyandrecordthefollowinginformation
temperature, time of contact, and composition of both the
describing the system as input for the model:
surface material and substrate. The designer then refers to
6.2.1 System Description—Geometry, location, accessibil-
Guide C1055 to determine the burn hazard potential of the
ity.
surface.
6.2.2 Present/Design Operating Conditions—Duty cycle,
operating temperatures of equipment.
4.3 Thermesthesiometer, Method B—The operator places
6.2.3 System/Surface Data (as appropriate)—Substrate (in-
the calibrated sensor probe face firmly against the heated
sulation) type and thickness, jacket type and thickness, surface
surface for the acceptable contact time. The device directly
properties, such as emissivity and condition, shiny, painted,
reads the contact temperature from the probe. The maximum
dirty, corroded.
temperature is used in conjunction with the Guide C1055 to
6.2.4 Ambient Conditions, including dry bulb temperature
determine the burn hazard potential of the surface.
and local wind velocity.
5. Significance and Use
NOTE 2—The design temperatures should be at the worst case (gener-
5.1 The procedures in this practice support the determina-
ally high operating and high ambient) conditions. Care should be used in
the selection of design conditions since the hazard design conditions are
tion of the burn hazard potential for a heated surface. These
different from the heat loss design conditions.
procedures provide an estimate of the maximum skin contact
temperature and must be used in conjunction with Guide 6.3 Using Practice C680 or a compatible program and the
C1055 to evaluate the surface hazard potential. information gathered in 6.2, calculate the maximum operating
C1057 − 03 (2010)
1/2
surface temperature. This temperature is an input to the model P 5 ρ ·C ·K (7)
~ !
1 1 1 1
for the contact temperature. 1/2
P 5 ρ ·C ·K (8)
~ !
2 2 2 2
6.3.1 Where the system is operating at design conditions,
1/2
P 5 ρ ·C ·K (9)
~ !
3 3 3 3
direct measurement can be used to determine the surface
α 5 K /ρ ·C (10)
temperature.Thermocouples,resistancethermometers,orother
1 1 1 1
meanscanbeused;however,properapplicationtechniquesare
α 5 K /ρ ·C (11)
2 2 2 2
required for accurate results. Caution must be observed since
where:
the surface temperature may be high and the surface could
T = initial tissue temperature, °C,
constitute a burn hazard.
N = integral constant, 1 > ∞,
6.4 Calculate the expected skin contact temperature versus −5
X = depth of tissue of interest, normally 8.0×10 m,
time history using the procedure below based upon the hot 2
α = thermal diffusivity of layer i,m /s,
i
surface temperature, time of contact, and system properties.
l = layer thickness of jacket material, m,
The development of the equations below is taken from Dussan
22 21
P =
layer thermal inertia; W·m ·K ·=s,
(1). A more detailed derivation of the equation set used is
t = time of contact, s,
included in the papers by Dussan (1) and Wu (5). See Fig. 1.
T = initial hot surface temperature, K,
i
6.4.1 Calculate the initial parameter constants, using Eq
T = contact skin temperature at depth X and at time (t)
c
4-11.
after contact, K,
6.4.2 The contact temperature for the skin can now be
erfc(θ) = complementary error function (a mathematical
determined using Eq 1, Eq 2, and Eq 3 together for the system
function),
in question. Note that the solution to this equation is a sum of
ρ = density of material i, kg/m ,
i
K = conductivity of material i, W/m · K, and
an infinite series. The solution, however, converges quickly
i
C = specific heat of material i,J/kg·K.
(five or six terms) and can be easily handled manually or by a
i
small computer.
6.4.3 To obtain the skin contact temperature versus contact
` `
time history, repeat the calculation at one second intervals for
N N
T 5 T 1A I erfc θ 1B I erfc θ` (1)
~ ! ~ !
c 0 N N
( (
N50 N50 times up to the maximum contact time exposure expected.
6.4.4 The maximum contact temperature used in the analy-
and:
sis of burn hazard (Guide C1055) is the maximum contact
X /=α 12·N·l/=α
1 1 2
temperature calculated for the contact period in step 6.4.3.
θ 5 (2)
N
2=t
6.5 Typical Input Data—Table 1 contains typical values for
X /=α 12·~N11!·l/=α the commonly used insulation and jacketing materials. Skin
1 1 2
θ` 5 (3)
N
properties are also included. Nonstandard insulations or jacket
2=t
material properties may be substituted for the table values in
~P 2 P !·~P 2 P !
2 3 2 1
the calculation if they are known.
I 5 (4)
P 1P · P 1P
~ ! ~ !
2 3 2 1
NOTE 3—Eq 1-11 work with any system of consistent units.
~T 2 T !·P
i 0 2
A 5 (5)
P 1P
2 1 6.6 Example Calculation—Using the equations listed in 6.4
T 2 T · P 2 P ·P and the following input data parameters, the following results
~ ! ~ !
i 0 3 2 2
B 5 (6)
~P 1P !·~P 1P ! were obtained for a simulated burn condition.
2 3 2 1
FIG. 1 Schematic of Heat Transfer Model
C1057 − 03 (2010)
TABLE 1 Typical Properties (23°C)
Specific Conduc-
Density,
Heat, tivity,
Code Material kg/m ·
J/kg W/m·
K·10 K
1 steel 7.80 0.46 45.200
2 aluminum 2.70 0.96 154.800
3 brass 8.90 0.38 85.400
4 borosilicate glass 2.25 0.84 1.130
5 porcelain 2.20 0.84 1.210
6 concrete 2.47 0.92 2.430
7 brick 1.70 0.84 0.630
8 stone 2.30 0.84 0.920
9 plastics 1.28 1.55 0.250
10 phenolics 1.25 1.38 0.042
11 nylons 1.11 2.09 0.209
12 ABS resins 1.04 1.51 0.170
13 wood 0.66 1.72 0.130
14 paper 0.60 2.81 0.084
15 human tissue 0.90 4.60 0.544
16 water 1.00 4.19 0.602
17 cork 0.13 2.01 0.042
18 mineral wool 0.19 1.00 0.059
19 cal silicate 0.24 1.09 0.067
20 foam glass 0.13 0.76 0.071
21 organic foam 0.05 1.05 0.021
22 glass cloth 0.40 0.63 0.084
23 fiberglas-LD 0.10 1.00 0.046
24 TFE-fluorocarbon 2.15 1.05 0.243
25 masonite 1.00 1.67 0.173
6.6.1 Problem—Assume a heated system is to be insulated
with light density fibrous glass. Jacketing material choices
FIG. 2 Time-Contact Temperatur
...
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