ASTM G151-2009 Standard Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources.pdf

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1、Designation: G 151 09Standard Practice forExposing Nonmetallic Materials in Accelerated Test Devicesthat Use Laboratory Light Sources1This standard is issued under the fixed designation G 151; the number immediately following the designation indicates the year oforiginal adoption or, in the case of

2、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 practice provides general procedures to be usedwhen exposing nonmetallic materials in accel

3、erated test de-vices that use laboratory light sources. Detailed informationregarding procedures to be used for specific devices are foundin standards describing the particular device being used. Forexample, detailed information covering exposures in devicesthat use open flame carbon arc, enclosed c

4、arbon arc, xenon arcand fluorescent UV light source are found in Practices G 152,G 153, and G 154, and G 155 respectively.NOTE 1Carbon-arc, xenon arc, and fluorescent UV exposures werealso described in Practices 23, G26, and G53which referred to veryspecific equipment designs. Practices G 152, G 153

5、, and G 154, and G 155are performance based standards that replace Practices G23, G26, andG 53.1.2 This practice also describes general performance re-quirements for devices used for exposing nonmetallic materialsto laboratory light sources. This information is intendedprimarily for producers of lab

6、oratory accelerated exposuredevices.1.3 This practice provides information on the use andinterpretation of data from accelerated exposure tests. Specificinformation about methods for determining the property of anonmetallic material before and after exposure are found instandards describing the meth

7、od used to measure each prop-erty. Information regarding the reporting of results fromexposure testing of plastic materials is described in PracticeD 5870.NOTE 2Guide G 141 provides information for addressing variabilityin exposure testing of nonmetallic materials. Guide G 169 providesinformation fo

8、r application of statistics to exposure test resultsNOTE 3This standard is technically equivalent to ISO 4892, Part 1.1.4 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-pria

9、te safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 3924 Specification for Environment for Conditioning andTesting Paint, Varnish, Lacquer, and Related

10、MaterialsD 5870 Practice for Calculating Property Retention Indexof PlasticsE41 Terminology Relating To ConditioningE 171 Specification for Atmospheres for Conditioning andTesting Flexible Barrier MaterialsE 644 Test Methods for Testing Industrial Resistance Ther-mometersE 691 Practice for Conductin

11、g an Interlaboratory Study toDetermine the Precision of a Test MethodE 772 Terminology Relating to Solar Energy ConversionE 839 Test Methods for Sheathed Thermocouples andSheathed Thermocouple MaterialG23 Practice for Operating Light-Exposure Apparatus(Carbon-Arc Type) With and Without Water for Exp

12、osureof Nonmetallic Materials3G26 Practice for Operating Light-Exposure Apparatus(Xenon-Arc Type) With and Without Water for Exposureof Nonmetallic Materials3G53 Practice for Operating Light- and Water-ExposureApparatus (Fluorescent UV-Condensation Type) for Expo-sure of Nonmetallic Materials3G113 T

13、erminology Relating to Natural and ArtificialWeathering Tests of Nonmetallic MaterialsG 130 Test Method for Calibration of Narrow- and Broad-Band Ultraviolet Radiometers Using a SpectroradiometerG 141 Guide forAddressing Variability in Exposure Testingof Nonmetallic MaterialsG 147 Practice for Condi

14、tioning and Handling of Nonme-tallic Materials for Natural and Artificial Weathering TestsG 152 Practice for Operating Open Flame CarbonArc LightApparatus for Exposure of Nonmetallic Materials1This practice is under the jurisdiction of ASTM Committee G03 on Weatheringand Durability and is the direct

15、 responsibility of Subcommittee G03.03 onSimulated and Controlled Exposure Tests.Current edition approved July 1, 2009. Published August 2009. Originallyapproved in 1997. Last previous edition approved in 2006 as G 151 06.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac

16、t ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3“Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.”1Copyright ASTM International, 100 Barr Ha

17、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.G 153 Practice for Operating Enclosed Carbon Arc LightApparatus for Exposure of Nonmetallic MaterialsG 154 Practice for Operating Fluorescent Light Apparatusfor UV Exposure of Nonmetallic MaterialsG 155 Practice for Operating X

18、enon Arc Light Apparatusfor Exposure of Non-Metallic MaterialsG 156 Practice for Selecting and Characterizing WeatheringReference MaterialsG 169 Guide forApplication of Basic Statistical Methods toWeathering TestsG 177 Tables for Reference Solar Ultraviolet Spectral Dis-tributions: Hemispherical on

19、37 Tilted Surface2.2 ISO Standards:ISO 4892, Part 1 Plastics: Exposure to laboratory LightSourcesGeneral Guidance4ISO 9370 Plastics: Instrumental Determination of RadiantExposure in Weathering TestsGeneral Guidance andBasic Test Method42.3 CIE Document:CIE Publication Number 85: 1989, Technical Repo

20、rtSolar Spectral Irradiance53. Terminology3.1 DefinitionsThe definitions given in TerminologiesE41, E 772, and G113are applicable to this practice.4. Significance and Use4.1 Significance:4.1.1 When conducting exposures in devices that use labo-ratory light sources, it is important to consider how we

21、ll theaccelerated test conditions will reproduce property changes andfailure modes associated with end-use environments for thematerials being tested. In addition, it is essential to consider theeffects of variability in both the accelerated test and outdoorexposures when setting up exposure experim

22、ents and wheninterpreting the results from accelerated exposure tests.4.1.2 No laboratory exposure test can be specified as a totalsimulation of actual use conditions in outdoor environments.Results obtained from these laboratory accelerated exposurescan be considered as representative of actual use

23、 exposuresonly when the degree of rank correlation has been establishedfor the specific materials being tested and when the type ofdegradation is the same. The relative durability of materials inactual use conditions can be very different in different locationsbecause of differences in UV radiation,

24、 time of wetness,relative humidity, temperature, pollutants, and other factors.Therefore, even if results from a specific exposure test con-ducted according to this practice are found to be useful forcomparing the relative durability of materials exposed in aparticular exterior environment, it canno

25、t be assumed that theywill be useful for determining relative durability of the samematerials for a different environment.4.1.3 Even though it is very tempting, calculation of anacceleration factor relating x h or megajoules of radiantexposure in a laboratory accelerated test to y months or yearsof

26、exterior exposure is not recommended. These accelerationfactors are not valid for several reasons.4.1.3.1 Acceleration factors are material dependent and canbe significantly different for each material and for differentformulations of the same material.4.1.3.2 Variability in the rate of degradation

27、in both actualuse and laboratory accelerated exposure test can have asignificant effect on the calculated acceleration factor.4.1.3.3 Acceleration factors calculated based on the ratio ofirradiance between a laboratory light source and solar radia-tion, even when identical bandpasses are used, do no

28、t take intoconsideration the effects on a material of irradiance, tempera-ture, moisture, and differences in spectral power distributionbetween the laboratory light source and solar radiation.NOTE 4If use of an acceleration factor is desired in spite of thewarnings given in this practice, such accel

29、eration factors for a particularmaterial are only valid if they are based on data from a sufficient numberof separate exterior and laboratory accelerated exposures so that resultsused to relate times to failure in each exposure can be analyzed usingstatistical methods. An example of a statistical an

30、alysis using multiplelaboratory and exterior exposures to calculate an acceleration factor isdescribed by J.A. Simms (1).64.1.4 There are a number of factors that may decrease thedegree of correlation between accelerated tests using labora-tory light sources and exterior exposures. More specific inf

31、or-mation on how each factor may alter stability ranking ofmaterials is given in Appendix X1.4.1.4.1 Differences in the spectral distribution between thelaboratory light source and solar radiation.4.1.4.2 Light intensities higher than those experienced inactual use conditions.4.1.4.3 Test conditions

32、 where specimens are exposed con-tinuously to light when actual use conditions provide alternateperiods of light and dark.4.1.4.4 Specimen temperatures higher than those in actualconditions.4.1.4.5 Exposure conditions that produce unrealistic tem-perature differences between light and dark colored s

33、pecimens.4.1.4.6 Exposure conditions that do not have any tempera-ture cycling or that produce temperature cycling, or thermalshock, or both, that is not representative of use conditions.4.1.4.7 Unrealistically high or low levels of moisture.4.1.4.8 Absence of biological agents or pollutants.4.2 Use

34、 of Accelerated Tests with Laboratory Light Sources:4.2.1 Results from accelerated exposure tests conductedaccording to this standard are best used to compare the relativeperformance of materials. A common application is conductinga test to establish that the level of quality of different batchesdoe

35、s not vary from a control material with known performance.Comparisons between materials are best made when they aretested at the same time in the same exposure device. Results4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.or

36、g.5Available from the Commission Internationale de LEclairage, CIE, CentralBureau, Kegelgasse 27, A-1030 Vienna, Austria or the U.S. National Committee forCIE, National Institute for Science and Technology, Gaithersburg, MD.6The boldface numbers in parentheses refer to the list of references at the

37、end ofthis standard.G151092can be expressed by comparing the exposure time or radiantexposure necessary to change a characteristic property to somespecified level.4.2.1.1 Reproducibility of test results between laboratorieshas been shown to be good when the stability of materials isevaluated in term

38、s of performance ranking compared to othermaterials or to a control7,8; therefore, exposure of a similarmaterial of known performance (a control) at the same time asthe test materials is strongly recommended.4.2.2 In some applications, weathering reference materialsare used to establish consistency

39、of the operating conditions inan exposure test.4.2.3 Reference materials, for example, blue wool testfabric, also may be used for the purpose of timing exposures.In some cases, a reference material is exposed at the same timeas a test material and the exposure is conducted until there is adefined ch

40、ange in property of the reference material. The testmaterial then is evaluated. In some cases, the results for the testmaterial are compared to those for the reference material.These are inappropriate uses of reference materials when theyare not sensitive to exposure stresses that produce failure in

41、 thetest material or when the reference material is very sensitive toan exposure stress that has very little effect on the test material.NOTE 5Definitions for control and reference material that are appro-priate to weathering tests are found in Terminology G 113.NOTE 6Practice G 156 describes proced

42、ures for selecting and char-acterizing weathering reference materials used to establish consistency ofoperating conditions in a laboratory accelerated test.NOTE 7Results from accelerated exposure tests should only be usedto establish a pass/fail approval of materials after a specific time ofexposure

43、 to a prescribed set of conditions when the variability in theexposure and property measurement procedure has been quantified so thatstatistically significant pass/fail judgments can be made.5. Requirements for Laboratory Exposure Devices5.1 Light Source:5.1.1 The exposure device shall provide for p

44、lacement ofspecimens and any designated sensing devices in positionswhich provide uniform irradiance by the light source.NOTE 8In some devices, several individual light sources are usedsimultaneously. In these devices, the term light source refers to thecombination of individual light sources being

45、used.5.1.2 Manufacturers of exposure devices shall assure thatthe irradiance at any location in the area used for specimenexposures is at least 70 % of the maximum irradiance mea-sured in this area. Procedures for measuring irradiance unifor-mity are found in Annex A1.NOTE 9During use, the irradianc

46、e uniformity in exposure devices canbe affected by several factors, such as deposits, which can develop on theoptical system and chamber walls. Irradiance uniformity also can beaffected by the type and number of specimens being exposed. Theirradiance uniformity as assured by the manufacturer is vali

47、d for newequipment and well defined measuring conditions.5.1.3 Periodic repositioning of the specimens during expo-sure is not necessary if the irradiance at positions farthest fromthe point of maximum irradiance is at least 90 % of themaximum measured irradiance.5.1.4 If irradiance at any position

48、in the area used forspecimen exposure is between 70 and 90 % of the maximumirradiance, specimens shall be periodically repositioned toreduce variability in radiant exposure. The repositioning sched-ule shall be agreed upon by all interested parties. Appendix X2describes some possible specimen placem

49、ent and repositioningplans and frequencies.NOTE 10While not required in devices meeting the irradiance unifor-mity requirements of 5.1.3, periodic specimen repositioning is a goodpractice to reduce the variability in exposure stresses experienced duringthe test interval.5.1.5 Replace lamps and filters according to the schedulerecommended by the device manufacturer. Follow the appara-tus manufacturers instructions for lamp and filter replacementand for pre-aging of lamps or filters, or both.5.1.6 ASTM G 177 describes a standard solar ultravioletspectrum that can be u