1、Designation: D7990 15Standard Test Method forUsing Reflectance Spectra to Produce an Index ofTemperature Rise in Polymeric Siding1This standard is issued under the fixed designation D7990; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, 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 uses reflectance spectra from theultraviolet, visible, and near infrared region to
3、produce anindex of the temperature rise of polymeric siding aboveambient temperature that occurs due to absorption of the sunsenergy.1.2 The test method determines the intensity factor of asample color. The intensity factor is a function of the samplesreflectance spectra and the energy output of the
4、 heat lamp usedin the test method Test Method D4803.1.3 Appendix X1 provides a method for using the intensityfactor to determine the maximum temperature rise of a sampleunder severe solar exposure.1.3.1 A correlation between intensity factor and heatbuildup (temperature rise) as predicted by Test Me
5、thod D4803exists.1.3.2 The heat buildup (temperature rise) for a polymericbuilding product specimen is determined from its reflectancespectra and the correlations regression equation.1.4 UnitsThe values stated in SI units are to be regardedas standard. No other units of measurement are included in t
6、hisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.
7、Referenced Documents2.1 ASTM Standards:D2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD4803 Test Method for Predicting Heat Buildup in PVCBuilding ProductsE903 Test Method for Solar Absorptance, Reflectance, andTransmittance of Ma
8、terials Using Integrating SpheresE1331 Test Method for Reflectance Factor and Color bySpectrophotometry Using Hemispherical Geometry3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 fractional absorptanceone minus FractionalReflectance,1R.3.1.2 fractional reflectancethe percenta
9、ge of energy re-flected by a sample at a given wavelength, divided by 100.3.1.3 intensity factoran indicator of a specimens heatbuildup based on its reflectance spectrum and the energy outputof the IR lamp used in Test Method D4803.3.1.3.1 DiscussionThe intensity factor is a summationproduct of the
10、heat lamps relative intensity and the specimensfractional absorptance at 20 nm intervals between 200 and2,500 nm.3.1.4 heat buildupthe temperature rise above that ofambient air due to the amount of energy absorbed from the sunby a specimen.3.1.5 relative intensity (of heat lamp)the lamps spectralout
11、put across the range of 200 nm to 2500 nm, normalized toa value of 100 at the lamps maximum output.4. Summary of Test Method4.1 The specimens size must cover the spectrophotometersmeasurement port, typically 25.4 mm in diameter. Typicalsample dimensions are 102 by 102 by 1.3 mm.4.2 Ablack backer car
12、d or plaque is used directly behind thespecimen to absorb any radiant energy transmitted through thespecimen.4.3 The spectral reflectance curve of the test specimen ismeasured to determine the amount of energy the specimenabsorbs at each wavelength.4.4 The intensity factor of the test specimen is th
13、e result ofa series summation for the specimens spectral absorptance andthe relative intensity of the IR lamp used in Test MethodD4803. The product of the specimens spectral absorptance andrelative intensity is determined for the spectral region of 200 2,500 nm at an interval of 20 nm1This test meth
14、od is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.24 on Plastic BuildingProducts.Current edition approved Dec. 1, 2015. Published December 2015. DOI:10.1520/D799015Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
15、Conshohocken, PA 19428-2959. United States14.5 Appendix X1 provides a method for using the intensityfactor to determine the maximum temperature rise of a sampleunder severe solar exposure.4.5.1 A correlation of intensity factors and heat buildup(temperature rise) results from Test Method D4803 for a
16、number of specimens was determined to derive an equationexpressing a specimens temperature rise as a function of itsreflectance.4.5.2 Aspecimens heat buildup is determined by measuringits reflectance in the UV, VIS, and NIR spectral region and thecorrelations regression equation.5. Significance and
17、Use5.1 Heat buildup of polymeric building products due toabsorption of energy from the sun may lead to distortionproblems. Test Method Test Method D4803 was developed topredict a building products heat buildup (temperature rise). Itcompares the relative temperature changes of a pigmentedPVC product
18、and a PVC panel containing carbon black whenexposed to an infrared heat lamp. Based on experimentalresults that determined the maximum temperature for this blackpanel under both solar exposure and in the laboratory test, amethod for determining the exterior temperature rise and heatbuildup for a tes
19、t panel was developed. This test has shown tobe useful and reliable but is time consuming and requirescontrolled conditions to minimize sources of variation.5.2 This test method uses a spectrophotometer to measure aspecimens reflectance in the ultraviolet, visible, and nearinfrared region and uses t
20、he spectral power distribution of theheat lamp specified in Test Method D4803 to determine anintensity factor, which is an index of the relative spectralenergy absorption by the specimen.5.2.1 The temperature rise that would occur under an TestMethod D4803 test is proportional to this intensity fact
21、or. Anequation has been derived from the correlation of the intensityfactor and temperature rise data obtained from Test MethodD4803 testing of samples with a wide range of color andlightness. A total of 99 samples were studied and representsamples with the lowest to highest temperature rise. Linear
22、regression analysis yields a R2 correlation coefficient of 0.98.5.2.2 The procedure in Appendix X1 allows prediction oftemperature rise that would result from testing of the samesample under Test Method D4803.5.2.3 As this procedure is a correlation to results obtainedby Test Method D4803, it is a m
23、ethod that yields a relativetemperature rise compared to black under certain definedsevere conditions, but does not predict actual field applicationtemperatures of the product. These product temperatures areinfluenced by incident angle of the sun, clouds, wind speed,insulation, installation behind g
24、lass, etc.5.3 The intensity factor itself is a dimensionless index of therelative energy absorption of the specimen, without conversionto a temperature rise. It can be used to compare the heatbuildup characteristics of different colors, or different candi-date formulations for the same color. It can
25、 also be used tocategorize color into ranges of intensity factor, to be used as abasis for testing of full siding products for resistance to thermaldistortion.6. Apparatus6.1 UV/VIS/NIR SpectrophotometerThe spectral reflec-tance data are obtained using a spectrophotometer equippedwith a PTFE-coated
26、integrating sphere detector, capable ofreading spectral reflectance across the range of 200 nm to 2500nm.7. Sampling and Test Specimens7.1 Samples shall be representative of the color or pigmentsystem under study.7.2 Test specimens shall consist of the actual product ormaterial in which the color is
27、 used, in a thickness typical of theactual product.7.3 An opaque black backing material is placed behind thespecimen. The backer shall be a card, plaque or other rigid orsemi-rigid material. The black color shall cover the entiresurface.7.3.1 Measure the color of the backer in accordance withTest Me
28、thod E1331. Calculate the CIE 1976 L*a*b* units inaccordance with the “CIE 1976 L* a* b* Uniform Color Spaceand Color-Difference Equation” in Practice D2244.7.3.2 The backer shall have L* not greater than 30.0, andboth a* and b* shall not exceed 63.0.7.4 The specimen and backer shall be large enough
29、 to coverthe instruments sample port and fit inside the instrumentsmeasurement compartment.8. Procedure8.1 Allow the spectrophotometer instrument to warm up andstabilize according to manufacturers instructions.8.2 Acquire a baseline correction according to manufactur-ers instructions.8.3 Acquire spe
30、ctral data between 200 and 2,500 nm.8.4 Check the spectrophotometers readiness by testing aknown standard.8.5 Once the instruments readiness is confirmed, proceedwith the analysis.8.6 Place the test specimen and black backer on the mea-surement port with the side to be tested facing and covering the
31、instruments measurement port.8.7 Acquire the test specimens spectral reflectance data 200 2,500 nm following the procedures in Test Method E903.D7990 1529. Calculation9.1 Determine the test specimens Intensity Factor:IF 5(n511161 2 R520n1180!*L520n1180(1)where:IF = Intensity Factor,R= Fractional Ref
32、lectance of the test specimen at specifiedwavelength,L= Relative Intensity of the IR heat lamp used in TestMethod D4803 at specified wavelength and reported inTable 1.TABLE 1 Relative Intensity of IR Heat Lamp Used in Test Method D4803| L|L|L|L|L|200 0 680 41 1160 100 1640 61 2120 33220 0 700 45 118
33、0 99 1660 59 2140 32240 0 720 50 1200 99 1680 58 2160 31260 0 740 56 1220 98 1700 56 2180 30280 0 760 60 1240 97 1720 55 2200 29300 0 780 63 1260 96 1740 53 2220 28320 0 800 67 1280 95 1760 52 2240 27340 0 820 70 1300 94 1780 51 2260 26360 0 840 73 1320 94 1800 50 2280 25380 2 860 77 1340 93 1820 49
34、 2300 24400 3 880 80 1360 92 1840 48 2320 23420 4 900 83 1380 90 1860 47 2340 22440 5 920 85 1400 88 1880 46 2360 21460 6 940 88 1420 86 1900 45 2380 20480 8 960 91 1440 84 1920 44 2400 19500 10 980 94 1460 82 1940 43 2420 18520 13 1000 95 1480 80 1960 42 2440 17540 18 1020 96 1500 78 1980 41 2460 1
35、6560 21 1040 97 1520 76 2000 40 2480 15580 25 1060 98 1540 74 2020 39 2500 14600 28 1080 99 1560 72 2040 38620 32 1100 100 1580 70 2060 37640 35 1120 100 1600 68 2080 36660 38 1140 100 1620 65 2100 3510. Precision and Bias10.1 The precision and bias of this test method for measur-ing spectral reflec
36、tance are essentially as specified in TestMethod E903.11. Keywords11.1 heat build; intensity factor; polymeric siding; siding;spectral reflectance; temperature riseAPPENDIXX1. DETERMINING MAXIMUM TEMPERATURE RISE(Nonmandatory Information)X1.1 The intensity factor can be used to calculate anestimated
37、 maximum temperature rise for the sample underhigh-intensity solar exposure. The temperature rise for thesample in a vertical position can be calculated separately fromthat in a horizontal position.X1.1.1 The temperature rise predicted by this method hasbeen found to closely match the “heat buildup”
38、 temperaturerise determined for the same sample using Test MethodD4803.2X1.2 Use the specimens intensity factor, determined in 9.1,in the following equations to calculate the predicted tempera-ture rise, in C.X1.2.1 Vertical sample orientation:T C! 5 0.00501*IF114.2 (0)X1.2.2 Horizontal sample orien
39、tation:T C! 5 0.00611*IF117.3 (0)X1.3 The maximum temperature the specimen is likely toreach outdoors due to natural, non-reflected sunlight under themost severe conditions (clear sky, no wind, sun is perpendicu-lar to the specimen) is estimated by adding the predictedtemperature rise to the ambient
40、 outdoor temperature.2T. Sullivan and G. Peake, Journal of Vinyl Technology, “Use of ReflectanceSpectra to Predict Heat Buildup of Pigmented PVC Panels,” Vol. 15, No. 4, p232-236, December 1993.D7990 153ASTM International takes no position respecting the validity of any patent rights asserted in con
41、nection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the respon
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