ASTM_C_1363_-_11.pdf

Designation:C136311Standard Test Method forThermal Performance of Building Materials and EnvelopeAssemblies by Means of a Hot Box Apparatus1This standard is issued under the fixed designation C1363;the number immediately following the designation indicates the year oforiginal 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 test method establishes the principles for the designof a hot box apparatus and the minimum requirements for thedetermination of the steady state thermal performance ofbuilding assemblies when exposed to controlled laboratoryconditions.This method is also used to measure the thermalperformance of a building material at standardized test condi-tions such as those required in material Specifications C739,C764,C1224 and Practice C1373.1.2 This test method is used for large homogeneous ornon-homogeneous specimens.This test method applies tobuilding structures or composite assemblies of building mate-rials for which it is possible to build a representative specimenthat fits the test apparatus.The dimensions of specimenprojections or recesses are controlled by the design of the hotbox apparatus.Some hot boxes are limited to planar or nearlyplanar specimens.However,larger hot boxes have been used tocharacterize projecting skylights and attic sections.See 3.2 fora definition of the test specimen and other terms specific to thismethod.NOTE1This test method replaces Test Methods C236,the GuardedHot Box,and C976,the Calibrated Hot Box which have been withdrawn.Test apparatus designed and operated previously under Test MethodsC236 and C976 will require slight modifications to the calibration andoperational procedures to meet the requirements of Test Method C1363.21.3 A properly designed and operated hot box apparatus isdirectly analogous to the Test Method C177 guarded hot platefor testing large specimens exposed to air induced temperaturedifferences.The operation of a hot box apparatus requires asignificantnumberoffundamentalmeasurementsoftemperatures,areas and power.The equipment performingthese measurements requires calibration to ensure that the dataare accurate.During initial setup and periodic verificationtesting,each measurement system and sensor is calibratedagainst a standard traceable to a national standards laboratory.If the hot box apparatus has been designed,constructed andoperated in the ideal manner,no further calibration or adjust-ment would be necessary.As such,the hot box is considered aprimary method and the uncertainty of the result is analyzed bydirect evaluation of the component measurement uncertaintiesof the instrumentation used in making the measurements.1.3.1 In an ideal hotbox test of a homogenous material thereis no temperature difference on either the warm or coldspecimen faces to drive a flanking heat flow.In addition,therewould be no temperature differences that would drive heatacross the boundary of the metering chamber walls.However,experience has demonstrated that maintaining a perfect guard/metering chamber balance is not possible and small correctionsare needed to accurately characterize all the heat flow pathsfrom the metering chamber.To gain this final confidence in thetest result,it is necessary to benchmark the overall result of thehot box apparatus by performing measurements on specimenshaving known heat transfer values and comparing those resultsto the expected values.1.3.2 The benchmarking specimens are homogeneous pan-els whose thermal properties are uniform and predictable.These panels,or representative sections of the panels,have hadtheir thermal performance measured on other devices that aredirectly traceable or have been favorably compared to anational standards laboratory.For example,a Test MethodC177 Hot Plate,a Test Method C518 Heat Meter or anotherTest Method C1363 Hot Box will provide adequate specimens.Note that the use of Test Method C518 or similar apparatuscreates additional uncertainty since those devices are calibratedusing transfer standards or standard reference materials.Byperforming this benchmarking process,the hot box operator isable to develop the additional equations that predict themagnitude of the corrections to the net heat flow through thespecimen that account for any hot box wall loss and flankingloss.This benchmarking provides substantial confidence thatany extraneous heat flows can be eliminated or quantified withsufficient accuracy to be a minor factor of the overall uncer-tainty.1.4 In order to ensure an acceptable level of resultuncertainty,persons applying this test method must possess aknowledge of the requirements of thermal measurements and1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved May 15,2011.Publi