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1.1 This test method, known as the guarded hot box method, covers the measurement of the steady-state thermal transfer properties of panels. In distinction to Test Method C177, which is primarily applicable to homogeneous samples, the guarded hot box method provides for the evaluation of thermal performance of building assemblies. This test method is suitable for building construction assemblies, building panels, and other applications of nono-homogeneous specimens at similar temperature ranges. It may also be used for homogeneous specimens. 1.2 This test method may be applied to any building construction for which it is possible to build a reasonably representative specimen of size appropriate for the apparatus. Note 1-A calibrated hot box, Test Method C976, may also be used for the described measurements and may prove more satisfactory for testing assemblies under dynamic conditions (nonsteady-state) and to evaluate the effects of water migration and air infiltration. The choice between the calibrated or the guarded hot box should be made only after careful consideration of the contemplated use. 1.3 In applying this test method, the general principles outlined must be followed; however, the details of the apparatus and procedures may be varied as needed. 1.3.1 The intent of this test method is to give the essential principles and the general arrangement of the apparatus. Any test using this apparatus must follow those principles. The details of the apparatus and the suggested procedures that follow are given not as mandatory requirements but as examples of this test method and precautions that have been found useful to satisfy the essential principles. 1.3.2 Persons applying this test method shall be trained in the methods of temperature measurement, shall possess a knowledge of the theory of heat flow, and shall understand the general requirements of testing practice. 1.3.3 This standard does not purport to address all of the safety problems, 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. Note 2-While various units may be found for thermal properties, the International System of units is used exclusively in this test method. For conversion factors to inch-pound and kilogram-calorie systems, see Table 1.

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4.1 This test method details the calibration and testing procedures and necessary additional temperature instrumentation required in applying Test Method C1363 to measure the thermal transmittance of fenestration systems mounted vertically in the thermal chamber. 4.2 The thermal transmittance of a test specimen is affected by its size and three-dimensional geometry. Care must be exercised when extrapolating to product sizes smaller or larger than the test specimen. Therefore, it is recommended that fenestration systems be tested at the recommended sizes specified in Practice E1423 or NFRC 100. 4.3 Since both temperature and surface heat transfer coefficient conditions affect results, use of recommended conditions will assist in reducing confusion caused by comparing results of tests performed under dissimilar conditions. Standardized test conditions for determining the thermal transmittance of fenestration systems are specified in Practice E1423 and Section 6.2. The performance of a test specimen measured at standardized test conditions is potentially different than the performance of the same fenestration product when installed in the wall of a building located outdoors. Standardized test conditions often represent extreme summer or winter design conditions, which are potentially different than the average conditions typically experienced by a fenestration product installed in an exterior wall. For the purpose of comparison, it is essential to calibrate with surface heat transfer coefficients on the Calibration Transfer Standard (CTS) which are as close as possible to the conventionally accepted values for building design; however, this procedure can be used at other conditions for research purposes or product development. 4.4 Similarly, it would be desirable to have a surround panel that closely duplicates the actual wall where the fenestration system would be installed. Since there are such a wide variety of fenestration system openings in North American residential, commercial and industrial buildings, it is not feasible to select a typical surround panel construction for installing the fenestration system test specimen. Furthermore, for high resistance fenestration systems installed in fenestration opening designs and constructions that have thermal bridges, the large relative amount of heat transfer through the thermal bridge will cause the relatively small amount of heat transfer through the fenestration system to have a larger than desirable error. For this reason, the Calibration Transfer Standard and test specimen are installed in a homogeneous surround panel constructed from materials having a relatively high thermal resistance. Installing the test specimen in a relatively high thermal resistance surround panel places the focus of the test on the fenestration system thermal performance alone. Therefore, it is important to recognize that the thermal transmittance results obtained from this test method are for ideal laboratory conditions, and should only be used for fenestration product comparisons unless the thermal bridge effects that have the potential to occur due to the specific design and construction of the fenestration system opening are included in the analysis. 4.5 This test method does not include procedures to determine the heat flow due to either air movement through the specimen or solar radiation effects. As a consequence, the thermal transmittance results obtained do not reflect performances that are expected from field installations. It is possible to use the results from this test method as input to annual energy performance analyses which include solar, and air leakage effects to get a better estimate of how the test specimen would perform when installed in an actual building. To determine the Solar Heat Gain Coefficient of fenestration products, refer to NFRC 200. To determine air leakage for windows and doors, refer to Test Methods E283 and E783. 4.6 It is important to recognize that the thermal transmittance, US, value determined in Section 8 is the only true experimental measurement result of this test method. The “standardized” thermal transmittance value, UST, obtained by either the Calibration Transfer Standard (CTS) or Area Weighting (AW) methods described in Section 8 include adjustments to the thermal transmittance value bases on results from calibration runs described in Section 6. The standardized thermal transmittance is useful for two reasons; it facilitates comparison of test results between different laboratories with different thermal chamber geometries and configurations, and it improves the comparison between test results and computer simulation results. Due to the differences in size, geometry, and climate chamber air flow permitted by this test method, Test Method C1363, and Practice E1423, there can be significant variations in the local surface heat transfer coefficients on the same test specimen installed in different laboratories even though these laboratories measured identical surface heat transfer coefficients on their Calibration Transfer Standards. Inter-Laboratory Comparisons conducted by the NFRC have shown that the effect of this variation is reduced if the standardized thermal transmittance is used for comparison instead of the thermal transmittance. The standardized thermal transmittance is also a useful tool for the evaluation and comparison of experimental results of fenestration systems with computer calculations of the thermal transmittance. that are made because the current Historically, computer calculation methods (NFRC 100) for determining the thermal transmittance were not capable of applying the actual surface heat transfer coefficients that exist on the test specimen while testing at standardized conditions. These current computer calculation methods assumed that uniform standardized surface heat transfer coefficients exist on the indoor and outdoor fenestration product surfaces. Although the next generation of computer simulation programs includes improved radiation heat transfer algorithms, which generate non-uniform surface heat transfer coefficients, the standardized thermal transmittance remains to be a useful tool when comparing test results to computer modeling results. 4.6.1 It is important to recognize that due to radiation effects, the room side or weather side temperature (th and tc, respectively), has the potential to differ from the respective room side or weather side baffle temperatures (tb1 and tb2, respectively). If there is a difference of more than ±1 °C (±2 °F), either on the room side or weather side, the radiation effects shall be accounted for as described in Sections 6 and 9 to maintain accuracy in the calculated surface heat transfer coefficients. Calculating the radiation exchange for highly conductive test specimens or projecting fenestration products as described in Annex A2 is not a trivial task. 4.6.2 The calculation of the standardized thermal transmittance assumes that only the surface heat transfer coefficients change from the calibrated standardized values for the conditions of the test. This assumption is possibly not valid if the surface temperature differentials for the standardized calibration conditions are different from the surface temperature differential that exists on the test specimen during the test. Currently, specifications for the Calibration Transfer Standard give it a thermal transmittance of 1.7 W/(m2·K) [0.3 Btu/(hr·ft2·°F)]. Accordingly, the calculation of the standardized thermal transmittance produces the least error when performed on test specimens with a similar thermal transmittance. 4.6.3 It is important to note that the standardized surface heat transfer coefficients, hh and hc, as calibrated prior to testing a fenestration product using an appropriately sized Calibration Transfer Standard (CTS) have the potential to differ from the surface heat transfer coefficients that exist during a hot box test on a specific test specimen. Fenestration systems usually have frame and sash surfaces that introduce two- and three-dimensional convective heat transfer effects which result in variable surface heat transfer coefficients, which differ from the uniform standardized values. As a result of this, the test specimen surface heat transfer coefficients will differ from those obtained with the non-framed, essentially flat Calibration Transfer Standard tested under the same conditions. In this standardizing procedure, it is assumed that the differences are small enough so that the calibration surface heat transfer coefficients can be used to calculate equivalent test specimen average surfaces temperatures, t1 and t2, in order to estimate the actual test specimen surface heat transfer coefficients. It is important to recognize that this assumption will not be accurate for all fenestration products, especially for high thermal transmittance products where the surface heat transfer coefficients are a major portion of the overall thermal resistance and also for fenestration products with significant surface projections (for example, skylights, roof windows, garden windows) where the surface heat transfer coefficients are quite different from the standardized values. 4.6.4 In these situations, it is important to attempt to measure the test specimen surface temperature distributions and then calculate directly the test specimen average area weighted surfaces temperatures, t1 and t2. This area weighting (AW) method also has problems in that the placement of temperature sensors to get an accurate area weighting is not known, especially on high conductivity horizontal surfaces that act as heat transfer extended surfaces (that is, fins). In addition, the placement of many temperature sensors on the test specimen surfaces will affect the velocity fields in the vicinity of these surfaces which will affect the surface temperatures and surface heat transfer coefficients. 1.1 This test method covers requirements and guidelines and specifies calibration procedures required for the measurement of the steady-state thermal transmittance of fenestration systems installed vertically in the test chamber. This test method specifies the necessary measurements to be made using measurement systems conforming to Test Method C1363 for determination of fenestration system thermal transmittance. Note 1: This test method allows the testing of projecting fenestration products (that is, garden windows, skylights, and roof windows) installed vertically in a surround panel. Current research on skylights, roof windows, and projecting products hopefully will provide additional information that can be added to the next version of this test method so that skylight and roof windows can be tested horizontally or at some angle typical of a sloping roof. 1.2 This test method refers to the thermal transmittance, U of a fenestration system installed vertically in the absence of solar radiation and air leakage effects. Note 2: The methods described in this document may also be adapted for use in determining the thermal transmittance of sections of building wall, and roof and floor assemblies containing thermal anomalies, which are smaller than the hot box metering area. 1.3 This test method describes how to determine the thermal transmittance, US of a fenestration product (also called test specimen) at well-defined environmental conditions. The thermal transmittance is also a reported test result from Test Method C1363. If only the thermal transmittance is reported using this test method, the test report must also include a detailed description of the environmental conditions in the thermal chamber during the test as outlined in 10.1.14. 1.4 For rating purposes, this test method also describes how to calculate a standardized thermal transmittance, UST, which can be used to compare test results from laboratories with vastly different thermal chamber configurations, and facilitates the comparison to results from computer programs that use standard heat transfer coefficients to determine the thermal transmittance of fenestration products. Although this test method specifies two methods of calculating the standardized thermal transmittance, only the standardized thermal transmittance result from one method is reported for each test. One standardized thermal transmittance calculation procedure is the Calibration Transfer Standard (CTS) Method and another is the Area Weighting (AW) Method (see Section 9 for further descriptions of these two methods). The Area Weighting method requires that the surface temperatures on both sides of the test specimen be directly measured as specified in Practice E1423 in order to determine the surface heat transfer coefficients on the fenestration product during the test. The CTS Method does not use the measured surface temperatures on the test specimen and instead utilizes the calculation of equivalent surface temperatures from calibration data to determine the test specimen surface heat transfer coefficients. The AW shall be used whenever the thermal transmittance, US, is greater than 3.4 W/(m2·K) [0.6 Btu/(hr·ft 2·°F)], or when the ratio of test specimen projected surface area to wetted (that is, total heat transfer or developed) surface area on either side of the test specimen is less than 0.80. Otherwise the CTS Method shall be used to standardize the thermal transmittance results. 1.5 A discussion of the terminology and underlying assumptions for measuring the thermal transmittance are included. 1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only. 1.7 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 This test method provides a rapid means of determining the steady-state thermal transmission properties of thermal insulations and other materials with a high level of accuracy when the apparatus has been calibrated appropriately.4.2 Proper calibration of the heat flow meter apparatus requires that it be calibrated using specimen(s) having thermal transmission properties determined previously by Test Methods C177, or C1114.NOTE 1: Calibration of the apparatus typically requires specimens that are similar to the types of materials, thermal conductances, thicknesses, mean temperatures, and temperature gradients as expected for the test specimens.4.3 The thermal transmission properties of specimens of a given material or product may vary due to variability of the composition of the material; be affected by moisture or other conditions; change with time; change with mean temperature and temperature difference; and depend upon the prior thermal history. It must be recognized, therefore, that the selection of typical values of thermal transmission properties representative of a material in a particular application should be based on a consideration of these factors and will not apply necessarily without modification to all service conditions.4.3.1 As an example, this test method provides that the thermal properties shall be obtained on specimens that do not contain any free moisture although in service such conditions may not be realized. Even more basic is the dependence of the thermal properties on variables, such as mean temperature and temperature difference. These dependencies should be measured or the test made at conditions typical of use.4.4 Special care shall be taken in the measurement procedure for specimens exhibiting appreciable inhomogeneities, anisotropies, rigidity, or especially high or low resistance to heat flow (see Practice C1045). The use of a heat flow meter apparatus when there are thermal bridges present in the specimen may yield very unreliable results. If the thermal bridge is present and parallel to the heat flow the results obtained may well have no meaning. Special considerations also are necessary when the measurements are conducted at either high or low temperatures, in ambient pressures above or below atmospheric pressure, or in special ambient gases that are inert or hazardous.4.5 The determination of the accuracy of the method for any given test is a function of the apparatus design, of the related instrumentation, and of the type of specimens under test (see Section 10), but this test method is capable of determining thermal transmission properties within ± 2 % of those determined by Test Method C177 when the ambient temperature is near the mean temperature of the test (T (ambient) = T (mean) ± 1°C), and in the range of 10 to 40°C. In all cases the accuracy of the heat flow meter apparatus can never be better than the accuracy of the primary standards used to calibrate the apparatus.4.5.1 When this test method is to be used for certification testing of products, the apparatus shall have the capabilities required in A1.7 and one of the following procedures shall be followed:4.5.1.1 The apparatus shall have its calibration checked within 24 h before or after a certification test using either secondary transfer standards traceable to, or calibration standards whose values have been established by, a recognized national standards laboratory not more than five years prior to the certification date. The average of two calibrations shall be used as the calibration factor and the specimen(s) certified with this average value. When the change in calibration factor is greater than 1 %, the standard specimen shall be retested and a new average calculated. If the change in calibration factor is still greater than 1 % the apparatus shall be calibrated using the procedure in Section 6.4.5.1.2 Where both the short and long term stability of the apparatus have been proven to be better than 1 % of the reading (see Section 10), the apparatus may be calibrated at less frequent intervals, not exceeding 30 days. The specimens so tested cannot be certified until after the calibration test following the test and then only if the change in calibration factor from the previous calibration test is less than 1 %. When the change in calibration is greater than 1 %, test results from this interval shall be considered void and the tests repeated in accordance with 4.5.1.1.4.5.2 The precision (repeatability) of measurements made by the heat flow meter apparatus calibrated as in Section 6.6 normally are much better than ±1 % of the mean value. This precision is required to identify changes in calibration and is desirable in quality control applications.1.1 This test method covers the measurement of steady state thermal transmission through flat slab specimens using a heat flow meter apparatus.1.2 The heat flow meter apparatus is used widely because it is relatively simple in concept, rapid, and applicable to a wide range of test specimens. The precision and bias of the heat flow meter apparatus can be excellent provided calibration is carried out within the range of heat flows expected. This means calibration shall be carried out with similar types of materials, of similar thermal conductances, at similar thicknesses, mean temperatures, and temperature gradients, as expected for the test specimens.1.3 This a comparative, or secondary, method of measurement since specimens of known thermal transmission properties shall be used to calibrate the apparatus. Properties of the calibration specimens must be traceable to an absolute measurement method. The calibration specimens should be obtained from a recognized national standards laboratory.1.4 The heat flow meter apparatus establishes steady state one-dimensional heat flux through a test specimen between two parallel plates at constant but different temperatures. By appropriate calibration of the heat flux transducer(s) with calibration standards and by measurement of the plate temperatures and plate separation. Fourier’s law of heat conduction is used to calculate thermal conductivity, and thermal resistivity or thermal resistance and thermal conductance.1.5 This test method shall be used in conjunction with Practice C1045. Many advances have been made in thermal technology, both in measurement techniques and in improved understanding of the principles of heat flow through materials. These advances have prompted revisions in the conceptual approaches to the measurement of the thermal transmission properties (1-4).2 All users of this test method should be aware of these concepts.1.6 This test method is applicable to the measurement of thermal transmission through a wide range of specimen properties and environmental conditions. The method has been used at ambient conditions of 10 to 40°C with thicknesses up to approximately 250 mm, and with plate temperatures from –195°C to 540°C at 25-mm thickness (5, 6).1.7 This test method may be used to characterize material properties, which may or may not be representative of actual conditions of use. Other test methods, such as Test Methods C236 or C976 should be used if needed.1.8 To meet the requirements of this test method the thermal resistance of the test specimen shall be greater than 0.10 m2·K/W in the direction of the heat flow and edge heat losses shall be controlled, using edge insulation, or a guard heater, or both.1.9 It is not practical in a test method of this type to try to establish details of construction and procedures to cover all contingencies that might offer difficulties to a person without pertinent technical knowledge. Thus users of this test method shall have sufficient knowledge to satisfactorily fulfill their needs. For example, knowledge of heat transfer principles, low level electrical measurements, and general test procedures is required.1.10 The user of this method must be familiar with and understand the Annex. The Annex is critically important in addressing equipment design and error analysis.1.11 Standardization of this test method is not intended to restrict in any way the future development of improved or new methods or procedures by research workers.1.12 Since the design of a heat flow meter apparatus is not a simple matter, a procedure for proving the performance of an apparatus is given in Appendix X3.1.13 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.14 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.15 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 Thermal conductivity measurements on small insulation specimens are important during new product development processes or when larger specimens cannot be collected during forensic investigation (that is, failure analysis) (1, 2).5.2 Numerous research projects have recently been initiated to develop insulation materials that have very high thermal resistivities (greater than 83 (m K)/W). Projects ranging from coatings to improve the thermal performance of single pane/layer glazing systems to the development of novel insulation products for building envelopes are being undertaken (1-4). All these projects have struggled in the development of new material technologies due to the difficulty associated with the measurement of thermal conductivity of small sections (approximately 0.025 m by 0.025 m) of high thermal resistance materials. As new materials are being developed, the size of each test specimen impacts the cost of development. Most of the existing test equipment and the methods do not align with the researcher’s need; the equipment requires a large specimen size is time consuming, and expensive to produce.5.3 This practice provides a standardized procedure to enable the thermal characterization of small specimens of insulation materials. Accurate, and reliable thermal metrology to assess thermal properties of new insulation materials, such as novel very low thermal conductivity (< 0.01 W/ (m K)) nanomaterials or bio-based foam insulations, in small material sample sections, and minimal data analysis requirements is the desired outcome of this practice.5.4 The ratio of the area of the specimen and the heat flux transducer has a significant impact on the uncertainty of the results obtained from this practice. As the specimen area decreases this ratio decreases, a smaller percentage of the total heat flow is associated with the unknown specimen. Information from the literature (4) shows that some heat-flow-meter apparatus, generally not available commercially and used by the research laboratories only, can be modified to change out the heat flux transducer so that transducers of varying sizes can be deployed. The observations presented in Fig. 2 were obtained from the measurements done by such a heat-flow-meter apparatus that was modified to change out the heat flux transducer. Fig. 2 demonstrates the significance of the ratio of the area of the specimen and the heat flux transducer on the accuracy of the thermal conductivity measurement using this Practice. This exercise is not a required part of this Practice and Fig. 2 is for information only.FIG. 2 Example of a data set obtained from 0.010 m2 (that is, 0.10 m × 0.10 m) heat flux transducer (heat flow) exploring the uncertainty (that is, difference between full size XPS specimen and smaller XPS specimen placed inside the mask) of varying thicknesses, 0.005 m, 0.010 m, and 0.020 m1.1 This practice covers the measurement of steady state thermal transmission properties of the small flat slab thermal insulation specimen using a heat-flow-meter apparatus.1.2 This practice provides a supplemental procedure for use in conjunction with Test Method C518 for testing a small specimen. This practice is limited to only small specimens and, in all other particulars, the requirements of Test Method C518 apply.1.3 This practice characterizes small specimens having lateral dimensions less than the lateral dimensions of the heat flux transducer used to measure the heat flow. The procedure in Test Method C518 shall be used for specimens having lateral dimensions equal to or larger than the lateral dimensions of the heat flux transducer.NOTE 1: The lower limit for specimen size is typically determined by the user for their particular material. As an example, Ref. (1)2 established a lower limit for specimen dimensions of 0.1 m by 0.1 m for several different thermal insulation materials for a 0.3 m by 0.3 m heat-flow-meter apparatus having a heat flux transducer 0.15 m by 0.15 m.1.4 This practice is intended only for research purposes, in particular, when larger specimens are unavailable. This practice shall not be used in conjunction with Test Method C518 for certification testing of products; compliance with ASTM Specifications; or compliance with regulatory or building code requirements.1.5 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this practice.1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 Factors that may influence the thermal-transmission properties of a specimen of material are described in Practice C1045 and the Precision and Bias section of Test Method C177.5.2 Because of the required test conditions prescribed by this test method, it shall be recognized that the thermal properties obtained will not necessarily apply without modification to all conditions of service. As an example, this test method normally provides that the thermal properties shall be obtained on specimens that do not contain moisture, although in service such conditions may not be realized. Even more basic is the dependence of the thermal properties on variables such as mean temperature and temperature difference.5.3 When a new or modified design of apparatus is evolved, tests shall be made on at least two sets of differing material of known long-term thermal stability. Tests shall be made for each material at a minimum of two different mean temperatures within the operating range of each. Any differences in results should be carefully studied to determine the cause and then be removed by appropriate action. Only after a successful verification study on materials having known thermal properties traceable to a recognized national standards laboratory shall test results obtained with this apparatus be considered to conform with this test method. Periodic checks of apparatus performance are recommended.5.4 The thermal transmission properties of many materials depend upon the prior thermal history. Care must be exercised when testing such specimens at a number of conditions so that tests are performed in a sequence that limits such effects on the results.5.5 Typical uses for the thin-heater apparatus include the following:5.5.1 Product development and quality control applications.5.5.2 Measurement of thermal conductivity at desired mean temperatures.5.5.3 Thermal properties of specimens that are moist or close to melting point or other critical temperature (see Note 1).NOTE 1: Apparatus of the type covered by this test method apply to the study of thermal properties of specimens containing moisture because of the use of small temperature differences and the low thermal capacity of the heat source.5.5.4 Determination of thermal properties of relatively high R value insulation samples with large apparatuses. In the case of the metal-screen heater apparatus, samples with thicknesses up to 15 cm can be measured.1.1 This test method covers the determination of the steady-state thermal transmission properties of flat-slab specimens of thermal insulation using a thin heater of uniform power density having low lateral heat flow. A thin heater with low lateral thermal conductance can reduce unwanted lateral heat flow and avoid the need for active-edge guarding.1.2 This primary test method of thermal-transmission measurement describes a principle, rather than a particular apparatus. The principle involves determination of the thermal flux across a specimen of known thickness and the temperatures of the hot and cold faces of the specimen.1.3 Considerable latitude is given to the designer of the apparatus in this test method; since a variety of designs is possible, a procedure for qualifying an apparatus is given in 5.3.1.4 The specimens must meet the following conditions if thermal resistance or thermal conductance of the specimen is to be determined by this test method2:1.4.1 The portion of the specimen over the isothermal area of the heater must accurately represent the whole specimen.1.4.2 The remainder of the specimen should not distort the heat flow in that part of the specimen defined in 1.4.1.1.4.3 The specimen shall be thermally homogeneous such that the thermal conductivity is not a function of the position within the sample, but rather may be a function of direction, time, and temperature. The specimen shall be free of holes, of high-density volumes, and of thermal bridges between the test surfaces or the specimen edges.1.4.4 Test Method C177 describes tests that can help ascertain whether conditions of 1.4 are satisfied. For the purposes of this test method, differences in the measurements of less than 2 % may be considered insignificant, and the requirements fulfilled.1.5 The specimens shall meet one of the following requirements, in addition to those of 1.4.1.5.1 If homogeneous materials as defined in Terminology C168 are tested, then the thermal resistivity and thermal conductivity can be determined by this test method.1.5.2 If materials which are layered or otherwise thermally inhomogeneous are tested, thermal resistance and thermal conductance can be determined by this test method.1.6 Two versions of thin-heater apparatus using the same principle of the standard are described in Annex A1 and Annex A2. They are similar in concept but differ in size and construction, and hence warrant separate descriptions for each design. This test method in no way limits the size of the thin-heater element. One of the units described uses a thin metal foil, while the other uses a metal screen as the heat source. The smaller, foil apparatus is designed to make rapid measurements of heat transmission through specimens as thin as 0.5 cm and as thick as 2 cm; however, an apparatus using a foil heater could be designed to measure much thicker materials, if desired. The larger, screen apparatus is designed to measure specimens with thicknesses between 3 and 15 cm, where the exact limits depend on the thermal resistance of the specimens. Both apparatuses use thermocouples for measuring temperature, but other temperature-sensing systems can be used.1.7 This test method covers the theory and principles of the measurement technique. It does not provide details of construction other than those required to illustrate two devices which meet the prescribed requirements. Detailed information is available in References (1-23)3 and the Adjunct.1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.9 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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This method provides for the determination of the steady state thermal resistance of a fabric or layers of fabrics and for the determination of the temperature regulating factor (TRF) as defined below. This test method is considered satisfactory for acceptance testing of commercial shipments because the round robin testing shows high precision and no bias for testing of textile fabrics and foams.5.1.1 If there are differences of practical significance between reported test results for two laboratories (or more), comparative test should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, use the samples for such a comparative test that are as homogeneous as possible, drawn from the same lot of material as the samples that resulted in disparate results during initial testing and randomly assigned in equal numbers to each laboratory. The test results from the laboratories involved should be compared using a statistical test for unpaired data, a probability level chosen prior to the testing series. If bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.This test method is useful in quality and cost control during manufacture. It can be used to establish criteria for establishing thermal and comfort parameters for textiles particularly used in the clothing industry.1.1 This test method covers the determination of the overall thermal transmission coefficient due to conduction for dry specimens of textile fabrics, battings, and other materials and the determination of the temperature regulating factor (TRF) defined below.1.2 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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4.1 This practice details the test specimen sizes and test conditions, namely, the room-side and weather-side air temperatures, and the surface heat transfer coefficients for both sides of the test specimen, when testing fenestration products in accordance with Test Method C1199.4.2 The thermal transmittance and conductance of a specimen are affected by its size and three-dimensional geometry. Tests should therefore be conducted using the specimen sizes recommended in 5.1. Should the specimen size differ from those given in 5.1, the actual size shall be reported in the test report.4.3 Many factors can affect the thermal performance of a fenestration system, including deflections of sealed glazing units. Care should be exercised to maintain the original physical condition of the fenestration system and while installing it in the surround panel.4.4 The thermal transmittance and conductance results obtained do not, and are not intended, to reflect performances expected from field installations since they do not account for solar radiation and air leakage effects. The thermal transmittance and conductance results are taken from specified laboratory conditions and are to be used only for fenestration product comparisons and as input to thermal performance analyses that also include solar and air leakage effects.1.1 This practice covers standard test specimen sizes and test conditions as well as the calculation and presentation of the thermal transmittance and conductance data measured in accordance with Test Method C1199. The standard sizes and conditions are to be used for fenestration product comparison purposes. The specifier may choose other sizes and conditions for product development or research purposes.1.2 This practice deals with the determination of the thermal properties of a fenestration system installed vertically without the influences of solar heat gain and air leakage effects.NOTE 1: To determine air leakage effects of fenestration systems, Test Method E283/E283M or E1424 should be referenced.NOTE 2: See Appendix X1 regarding garage doors and rolling doors.1.3 This practice specifies the procedure for determining the standardized thermal transmittance of a fenestration test specimen using specified values of the room-side and weather-side surface heat transfer coefficients, hh and hc, respectively.1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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