ASTM C1130-90(2001)
(Practice)Standard Practice for Calibrating Thin Heat Flux Transducers
Standard Practice for Calibrating Thin Heat Flux Transducers
SCOPE
1.1 This practice establishes an experimental procedure for determining the sensitivity of heat flux transducers (HFTs) that are relatively thin. The term sensitivity in this practice refers to the ratio of HFT electrical output to heat flux through the HFT.
1.1.1 For the purpose of this standard, the thickness of the HFT shall be less than 15 % of the narrowest planar dimension of the HFT.
1.2 This practice discusses two methods for determining HFT sensitivity. The first method is the calibration of the HFT in unperturbed heat flow normal to the surface of the HFT, while the second method is the sensitivity of the HFT in actual use, or the HFT conversion factor.
1.3 This practice should be used in conjunction with Practice C1041 when measuring in-situ heat flux and temperature on industrial insulation systems, and with Practice C1046 when performing in-situ measurements of heat flux on opaque building components.
1.4 This practice is not intended to determine the sensitivity of HFTs that are components of heat flow meter apparatus, as in Test Method C518. Refer to Practice C1132 for this purpose.
1.5 The following safety caveat pertains only to the Specimen Preparation and Procedure portions, Sections and , of this practice: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:C1130–90(Reapproved2001)
Standard Practice for
Calibrating Thin Heat Flux Transducers
This standard is issued under the fixed designation C 1130; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope C 236 Test Method for Steady-State Thermal Performance
of Building Assemblies by Means of a Guarded Hot Box
1.1 This practice establishes an experimental procedure for
C 335 Test Method for Steady-State Heat Transfer Proper-
determining the sensitivity of heat flux transducers (HFTs) that
ties of Horizontal Pipe Insulation
are relatively thin. The term sensitivity in this practice refers to
C 518 Test Method for Steady-State Thermal Transmission
the ratio of HFT electrical output to heat flux through the HFT.
Properties by Means of the Heat Flow Meter Apparatus
1.1.1 For the purpose of this standard, the thickness of the
C 976 Test Method for Thermal Performance of Building
HFT shall be less than 15 % of the narrowest planar dimension
Assemblies by Means of a Calibrated Hot Box
of the HFT.
C 1041 Practice for In-Situ Measurements of Heat Flux in
1.2 This practice discusses two methods for determining
Industrial Thermal Insulation Using Heat Flux Transduc-
HFT sensitivity. The first method is the calibration of the HFT
ers
in unperturbed heat flow normal to the surface of the HFT,
C 1044 PracticeforUsingtheGuarded-Hot-PlateApparatus
while the second method is the sensitivity of the HFT in actual
or Thin-Heater Apparatus in the Single-Sided Mode
use, or the HFT conversion factor.
C 1046 Practice for In-Situ Measurement of Heat Flux and
1.3 This practice should be used in conjunction with Prac-
Temperature on Building Envelope Components
tice C 1041 when measuring in-situ heat flux and temperature
C 1114 TestMethodforSteady-StateThermalTransmission
on industrial insulation systems, and with Practice C 1046
Properties by Means of the Thin-Heater Apparatus
when performing in-situ measurements of heat flux on opaque
C 1132 Practice for Calibration of the Heat Flow Meter
building components.
Apparatus
1.4 This practice is not intended to determine the sensitivity
of HFTs that are components of heat flow meter apparatus, as
3. Terminology
in Test Method C 518. Refer to Practice C 1132 for this
3.1 Definitions—For definitions of terms relating to thermal
purpose.
insulating materials, see Definitions C 168.
1.5 The following safety caveat pertains only to the Speci-
3.2 Definitions of Terms Specific to This Standard:
men Preparation and Procedure portions, Sections 5 and 6, of
3.2.1 heat flux transducer—a device containing a thermo-
this practice: This standard does not purport to address all of
pile (or equivalent) that produces an output which is a function
the safety concerns, if any, associated with its use. It is the
of the heat flux passing through the HFT.
responsibility of the user of this standard to establish appro-
3.2.2 sensitivity—the ratio of the electrical output of the
priate safety and health practices and determine the applica-
heat flux transducer to the heat flux passing through the HFT.
bility of regulatory limitations prior to use.
The sensitivity of the HFT will be a function of the HFT
2. Referenced Documents temperature, the HFT construction, its curvature, and the
method with which it is applied to the building component.
2.1 ASTM Standards:
3.2.3 heat flux transducer calibration factor—the sensitiv-
C 168 Terminology Relating to Thermal Insulating
ityoftheheatfluxtransducerwhenmeasuredinanundisturbed
C 177 Test Method for Steady-State Heat Flux Measure-
one-dimensional temperature field.
ments and Thermal Transmission Properties by Means of
3.2.4 heat flux transducer conversion factor—thesensitivity
the Guarded-Hot-Plate Apparatus
of the heat flux transducer for the thermal conditions surround-
ing the HFT in actual use.
This practice is under the jurisdiction of ASTM Committee C16 on Thermal
3.2.4.1 The relationship between the heat flux transducer
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
calibration and conversion factors is indicative of the magni-
Measurement.
tude of the heat flux distortion created by the application of the
Current edition approved June 29, 1990. Published August 1990. Originally
HFT.
published as C 1130 – 89. Last previous edition C 1130 – 89.
Annual Book of ASTM Standards, Vol 04.06.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1130
3.2.5 temperature field—a set of temperatures, where each HFT sensitivity. The two most widely used application tech-
temperatureisassociatedwithapointorsmalldomainofspace niques are to surface-mount the HFT or to embed the HFT in
in a region of interest. An example is the distribution of the insulation system.
temperatures within a slab of insulation.
5. Specimen Preparation
3.2.6 test stack—a layer or a series of layers of material put
5.1 Preparation of the HFT depends on which type of
together to comprise a test sample (for example, a roof system
sensitivity is desired and the method of HFT application to be
containing a membrane, an insulation, and a roof deck).
employed.
3.3 Symbols:
5.1.1 Three separate cases are discussed: the determination
ofthecalibrationfactorandthemeasurementoftheconversion
2 2
q = heat flux, W/m [Btu/h·ft ].
factor for embedded and surface-mounted HFTs.
V = measured output voltage of the HFT, V .
5.2 The HFT for which sensitivity is determined will
2 2
S = sensitivity of the HFT, V/(W/m ) [V/(Btu/hr·ft )].
measure the heat flux at the position of the HFT in the test
stack. It is recommended that the HFT be installed near the
4. Significance and Use
metering side of the test instrument and in a relatively thin
4.1 The use of heat flux transducers on industrial equipment
stack assembly to reduce the impact of edge effects. The
or building envelope components provides the user with a
thickness and thermal resistance of the test stack should be
relatively simple means for performing in-situ heat flux mea-
selected after considering its impact on the accuracy of the
surements. Accurate translation of the heat flux transducer
chosen test method.
output requires a complete understanding of the factors affect-
5.3 Calibration factor—The HFT shall be embedded in a
ing its output, and a standardized method for determining the
stack of materials and surrounded with a framing material or
HFT sensitivity for the application of interest.
mask. Guarded-hot-plate and heat flow meter apparatuses (Test
4.2 The placement of an HFT in a temperature field (see
Method C 177 and C 518, respectively) have been successfully
3.2.5) will probably disturb that field. If a disturbance in the
used for this purpose.
temperature field occurs when the HFT is applied, the user
5.3.1 The sample stack used to determine the calibration
must account for that disturbance when determining the
factor of HFTs shall consist of a sandwich of the HFT/masking
sensitivity of an HFT.
layer between two layers of a compressible homogeneous
4.3 There are several methods for determining the sensitiv-
material, such as high-density fiberglass insulation board, to
ity of HFTs (see 6.1). The selection of the best procedure will
assuregoodthermalcontactbetweentheplatesofthetesterand
dependontherequiredaccuracyandthephysicallimitationsof
the HFT/masking layer. The use of a thermally conductive gel
available equipment.
is another technique to improve good thermal contact.
4.4 The presence of a heat flux transducer is likely to alter
5.3.2 The mask used in determining the HFT calibration
the heat flux that is being measured. This disturbance is
factor must have the same thickness and thermal resistance as
difficult to predict without sufficient knowledge of the con-
the HFT.The matching of the mask and HFTis sensitive to the
struction of the HFT and the thermal conductivities of both the
HFT size and on whether the HFT incorporates an intrinsic
HFT components and its surroundings. With such knowledge,
mask surrounding its active sensing area.An effective masking
analytical (1, 2) and numerical (3, 4, 5) methods have been
technique that has been employed for small sensors is to utilize
used to account for the disturbance in heat flux caused by the
other identical sensors as a mask.
presence of an HFT.
5.4 Conversion factor, embedded—The HFT shall be
4.5 If an HFT calibration factor is sought, the user of this
placed, in a fashion identical to its end use application, in a
standardmustassurethatparallelheatflow,normaltotheHFT,
stack of materials duplicating the building construction to be
is achieved. If the user wishes to obtain a conversion factor,
evaluated. The instruments listed in 5.3 along with the thin-
then the user must account for the end-use conditions of the
heater apparatus (see Test Method C 1114) have been used for
HFT, either by using an acceptable and verifiable mathematical
this analysis.
technique to correct the calibration factor, or by performing a
5.5 Conversion factor, surface mounted—The HFT shall be
series of experiments that adequately simulates the conditions
applied in a manner identical to that of actual use to a
of use to obtain the conversion factor empirically (6, 7, 8).
homogeneous test panel or pipe insulation of similar thermal
4.6 This practice describes techniques to establish uniform
resistance, surface-layer thermal conductance, and orientation.
heat flow normal to the heat flux transducer for the determi-
Pipe tester (Test Method C 335), guarded-hot-box (Test
nation of the HFT calibration factor, or how to establish
Method C 236), and calibrated-hot-box (Test Method C 976)
conditions that simulate those that the HFT will encounter
apparatuses have been used to perform these procedures.
when in use.
5.5.1 The sample stack for use in determining HFT conver-
4.7 The method o
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