1、Designation: G 153 04Standard Practice forOperating Enclosed Carbon Arc Light Apparatus forExposure of Nonmetallic Materials1This standard is issued under the fixed designation G 153; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the basic principles and operatingprocedures for using enclosed carbon-arc light an
3、d waterapparatus intended to reproduce the weathering effects thatoccur when materials are exposed to sunlight (either direct orthrough window glass) and moisture as rain or dew in actualuse. This practice is limited to the procedures for obtaining,measuring, and controlling conditions of exposure.
4、A numberof exposure procedures are listed in an appendix; however, thispractice does not specify the exposure conditions best suitedfor the material to be tested.NOTE 1Practice G 151 describes performance criteria for all exposuredevices that use laboratory light sources. This practice replaces Prac
5、ticeG23, which describes very specific designs for devices used for carbon-arc exposures. The apparatus described in Practice G23is covered by thispractice.1.2 Test specimens are exposed to enclosed carbon arc lightunder controlled environmental conditions.1.3 Specimen preparation and evaluation of
6、the results arecovered in various methods or specifications for specificmaterials. General guidance is given in Practice G 151 and ISO4892-1. More specific information about methods for deter-mining the change in properties after exposure and reportingthese results is described in ISO 4582.1.4 The v
7、alues stated in SI units are to be regarded as thestandard.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-bi
8、lity of regulatory limitations prior to use.1.5.1 Should any ozone be generated from the operation ofthe light source, it shall be carried away from the testspecimens and operating personnel by an exhaust system.2. Referenced Documents2.1 ASTM Standards:2D 3980 Practice for Interlaboratory Testing o
9、f Paint andRelated MaterialsE 691 Practice for Conducting Interlaboratory Study toDetermine the Precision of a Test MethodG23 Practice for Operating Light-Exposure Apparatus(Carbon-Arc Type) With and Without Water for Exposureof Nonmetallic MaterialsG113 Terminology Relating to Natural and Artificia
10、lWeathering Tests of Nonmetallic MaterialsG 151 Practice for Exposing Nonmetallic Materials in Ac-celerated Test Devices that Use Laboratory Light Sources2.2 ISO Standards:ISO 4582, PlasticsDetermination of the Changes of Co-lour and Variations in Properties After Exposure to Day-light Under Glass,
11、Natural Weathering or Artificial Light3ISO 4892-1, PlasticsMethods of Exposure to LaboratoryLight Sources, Part 1, General Guidance3ISO 4892-4, PlasticsMethods of Exposure to LaboratoryLight Sources, Part 4, Open-Flame Carbon Arc Lamp32.3 CIE Standards:CIE-Publ. No. 85: Recommendations for the Integ
12、ratedIrradiance and the Spectral Distribution of SimulatedSolar Radiation for Testing Purposes43. Terminology3.1 DefinitionsThe definitions that are applicable to thispractice are provided in Terminology G113.3.1.1 As used in this practice, the term sunlight is identicalto the terms daylight and sol
13、ar irradiance, global as they aredefined in Terminology G113.1This practice is under the jurisdiction of ASTM Committee G03 on Weatheringand Durability and is the direct responsibility of Subcommittee G03.03 onSimulated and Controlled Exposure Tests.Current edition approved Oct. 1, 2004. Published D
14、ecember 2004. Originallyapproved in 1997. Last previous edition approved in 2000 as G 153 00ae1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Docume
15、nt Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Available from Secretary, U.S. National Committee, CIE, National Institute ofStandards and Technology, Gaithersburg, MD 20899.1Copyright ASTM International,
16、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Practice4.1 Specimens are exposed to repetitive cycles of light andmoisture under controlled environmental conditions. Moistureusually is produced by spraying the test specimen withdemineralized/deioniz
17、ed water or by condensation of watervapor onto the specimen.4.2 The exposure condition may be varied by selection ofthe following:4.2.1 Filter,4.2.2 The type of moisture exposure,4.2.3 The timing of the light and moisture exposure,4.2.4 The temperature of light exposure, and4.2.5 The timing of a lig
18、ht/dark cycle.4.3 Comparison of results obtained from specimens exposedin same model of apparatus should not be made unlessreproducibility has been established among devices for thematerial to be tested.4.4 Comparison of results obtained from specimens exposedin different models of apparatus should
19、not be made unlesscorrelation has been established among devices for the materialto be tested.5. Significance and Use5.1 The use of this apparatus is intended to induce propertychanges associated with the end use conditions, including theeffects of sunlight, moisture, and heat. These exposures mayin
20、clude a means to introduce moisture to the test specimen.Exposures are not intended to simulate the deterioration causedby localized weather phenomena, such as atmospheric pollu-tion, biological attack, and saltwater exposure. Alternatively,the exposure may simulate the effects of sunlight throughwi
21、ndow glass. Typically, these exposures would include mois-ture in the form of humidity.5.2 CautionsRefer to Practice G 151 for full cautionaryguidance applicable to all laboratory weathering devices.5.2.1 Variation in results may be expected when operatingconditions are varied within the accepted li
22、mits of this practice.Therefore, no reference shall be made to results from the use ofthis practice unless accompanied by a report detailing thespecific operating conditions in conformance with Section 10.5.2.2 It is recommended that a similar material of knownperformance, a control, be exposed simu
23、ltaneously with thetest specimen to provide a standard for comparative purposes.It is recommended that at least three replicates of each materialevaluated be exposed in each test to allow for statisticalevaluation of results.6. Apparatus6.1 Laboratory Light SourceEnclosed carbon arc lightsources typ
24、ically use carbon rods which contain a mixture ofmetal salts. An electric current is passed between the carbonrods which burn and give off ultraviolet, visible, and infraredradiation. Use carbon rods recommended by the device manu-facturer.6.1.1 FilterThe most commonly used filters are borosili-cate
25、 glass globes which fit around the carbon burners. Otherfilters may be used by mutual agreement by the interestedparties as long as the filter type is reported in conformance withthe report section in Practice G 151.6.1.2 The emission spectra of the enclosed carbon arc showsstrong emission in the lo
26、ng wavelength ultraviolet region.Emissions in the visible, infrared, and short wavelength ultra-violet below 350 nm generally are weaker than in sunlight (seeTable 1).6.1.3 The following factors can affect the spectral powerdistribution of enclosed carbon arc light sources:6.1.3.1 Differences in the
27、 composition and thickness offilters can have large effects on the amount of short wavelengthUV radiation transmitted.6.1.3.2 Aging (solarization) of filters can result in changesin filter transmission. The aging properties of filters can beinfluenced by the composition. Aging of filters can result
28、in asignificant reduction in the short wavelength UV emission of aburner.6.1.3.3 Accumulation of dirt or other residue on filters canaffect filter transmission.6.1.3.4 Differences in chemical composition of carbons.6.1.4 Spectral Irradiance for Enclosed Carbon with Day-light FiltersThe data in Table
29、 1 are representative of thespectral irradiance received by a test specimen mounted in thespecimen plane.6.2 Test ChamberThe design of the test chamber mayvary, but it should be constructed from corrosion resistantmaterial, and in addition to the radiant source, may provide formeans of controlling t
30、emperature and relative humidity. Whenrequired, provision shall be made for the spraying of water onthe test specimen or for the formation of condensate on theexposed face of the specimen.TABLE 1 Typical Relative Spectral Power Distribution forEnclosed Carbon-Arc with Daylight FiltersA,BSpectral Ban
31、dpassWavelength l in nmTypicalPercentCBenchmark SolarRadiation PercentD,E,Fl 290 0.0290 # l # 320 0.1 5.8320 l # 360 19.9 40.0360 l # 400 80.1 54.2AData in Table 1 are the irradiance in the given bandpass expressed as apercentage of the total irradiance from 290 to 400 nm. Annex A1 states how todete
32、rmine relative spectral irradiance.BThe data in Table 1 is representative and is based on the rectangularintegration of the spectral power distributions enclosed carbon arcs with daylightfilters. There is not enough data available to establish a meaningful specification.CFor any individual spectral
33、power distribution, the calculated percentage forthe bandpasses in Table 1 will sum to 100 %. Test results can be expected to differbetween exposures using enclosed carbon arc devices in which the spectral powerdistributions differ by as much as that allowed by the tolerances typical for daylightfil
34、ters. Contact the manufacturer of the enclosed carbon-arc devices for specificspectral power distribution data for the enclosed carbon-arc and filters used.DThe benchmark solar radiation data is defined in ASTM G 177 and is foratmospheric conditions and altitude chosen to maximize the short waveleng
35、th UVfraction of solar UV. While this data is provided for comparison purposes only, it isdesirable for a laboratory accelerated light source with daylight filters to provide aspectrum that is a close match to this solar spectrum.EPrevious versions of this standard used solar radiation data from Tab
36、le 4 ofCIE Publication Number 85. See Appendix X2 for more information comparing thesolar radiation data used in this standard with that for CIE 85 Table 4.FFor the benchmark solar spectrum, the UV irradiance (290 to 400 nm) is 9.8 %and the visible irradiance (400 to 800 nm) is 90.2 % expressed as a
37、 percentage ofthe total irradiance from 290 to 800 nm. The percentages of UV and visibleirradiances on samples exposed in enclosed carbon-arc devices may vary due tothe number and reflectance properties of specimens being exposed. This is basedon measurements in xenon-arc devices but similar measure
38、ments have not beenmade in enclosed carbon-arc devices.G1530426.2.1 The radiant source(s) shall be located with respect tothe specimens such that the irradiance at the specimen facecomplies with the requirements in Practice G 151.6.3 Instrument CalibrationTo ensure standardization andaccuracy, the i
39、nstruments associated with the exposure appa-ratus, for example, timers, thermometers, wet bulb sensors, drybulb sensors, humidity sensors, UV sensors and radiometers,require periodic calibration to ensure repeatability of testresults. Whenever possible, calibration should be traceable tonational or
40、 international standards. Calibration schedule andprocedure should be in accordance with manufacturers in-structions.6.4 ThermometerEither insulated or uninsulated black orwhite panel thermometers may be used. Thermometers shallconform to the descriptions found in Practice G 151. The typeof thermome
41、ter used, the method of mounting on specimenholder, and the exposure temperature shall be stated in the testreport.6.4.1 Some specifications may require chamber air tempera-ture control. Positioning and calibration of chamber air tem-perature sensors shall be in accordance with the descriptionsfound
42、 in Practice G 151.NOTE 2Typically, these devices control by black panel temperatureonly.6.4.2 The thermometer shall be mounted on the specimenrack so that its surface is in the relative position and subjectedto the same influences as the test specimens.6.5 MoistureThe test specimens may be exposed
43、to mois-ture in the form of water spray, condensation, or high humidity.6.5.1 Water SprayThe test chamber may be equipped witha means to introduce intermittent water spray onto the testspecimens under specified conditions. The spray shall beapplied so that the specimens are uniformly wetted. The spr
44、aysystem shall be made from corrosion resistant materials that donot contaminate the water used.6.5.1.1 Quality of Water for SpraysSpray water must havea conductivity below 5 S/cm, contain less than 1-ppm solids,and leave no observable stains or deposits on the specimens.Very low levels of silica in
45、 spray water can cause significantdeposits on the surface of test specimens. Care should be takento keep silica levels below 0.1 ppm. In addition to distillation,a combination of deionization and reverse osmosis can effec-tively produce water of the required quality. The pH of thewater used should b
46、e reported. See Practice G 151 for detailedwater quality instructions.6.5.1.2 A spray system designed to cool the specimen byspraying the back surface of the specimen or specimensubstrate may be required when the exposure program specifiesperiods of condensation.6.5.2 Relative HumidityThe test chamb
47、er may beequipped with a means to measure and control the relativehumidity. Such instruments shall be shielded from the lightsource.6.6 Specimen HoldersHolders for test specimens shall bemade from corrosion resistant materials that will not affect thetest results. Corrosion resistant alloys of alumi
48、num or stainlesssteel have been found acceptable. Brass, steel, or copper shallnot be used in the vicinity of the test specimens.6.6.1 The specimen holders typically, but not necessarily,are mounted on a revolving cylindrical rack, which is rotatedaround the light source at a speed dependent on the
49、type ofequipment, and which is centered both horizontally and verti-cally with respect to the exposure area in the specimen holders.6.6.2 Specimen holders may be in the form of an openframe, leaving the back of the specimen exposed, or they mayprovide the specimen with a solid backing. Any backing usedmay affect test results and shall be agreed upon in advancebetween the interested parties.6.7 Apparatus to Assess Changes in PropertiesUse theapparatus required by the ASTM or other standard thatdescribes determination of the property or properties beingmonitored.7.
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