1、Designation: G151 10Standard Practice forExposing Nonmetallic Materials in Accelerated Test Devicesthat Use Laboratory Light Sources1This standard is issued under the fixed designation G151; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, 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 acceler
3、ated 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 car
4、bon arc, xenon arcand fluorescent UV light source are found in Practices G152,G153, G154, and G155 respectively.NOTE 1Carbon-arc, xenon arc, and fluorescent UV exposures werealso described in Practices G23, G26, and G53 which referred to veryspecific equipment designs. Practices G152, G153, and G154
5、, and G155are performance based standards that replace Practices G23, G26, andG53.1.2 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 laboratory accel
6、erated 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 method used to me
7、asure each prop-erty. Information regarding the reporting of results fromexposure testing of plastic materials is described in PracticeD5870.NOTE 2Guide G141 provides information for addressing variabilityin exposure testing of nonmetallic materials. Guide G169 providesinformation for application of
8、 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-priate safety and he
9、alth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD3924 Specification for Environment for Conditioning andTesting Paint, Varnish, Lacquer, and Related MaterialsD5870 Pra
10、ctice for Calculating Property Retention Index ofPlasticsE41 Terminology Relating To ConditioningE171 Specification for Atmospheres for Conditioning andTesting Flexible Barrier MaterialsE644 Test Methods for Testing Industrial Resistance Ther-mometersE691 Practice for Conducting an Interlaboratory S
11、tudy toDetermine the Precision of a Test MethodE772 Terminology Relating to Solar Energy ConversionE839 Test Methods for Sheathed Thermocouples andSheathed Thermocouple MaterialG23 Practice for Operating Light-Exposure Apparatus(Carbon-Arc Type) Wigh and Without Water for Exposureof Nonmetallic Mate
12、rials3G26 Practice for Operating Light-Exposure Apparatus(Xenon-Arc Type) With and Without Water for Exposureof Nonmetallic Materials3G53 Practice of Operating Light-and Water-Exposure Ap-paratus (Fluorescent UV-Condensation Type) for Exposureof Nonmetallic Materials3G113 Terminology Relating to Nat
13、ural andArtificial Weath-ering Tests of Nonmetallic MaterialsG130 Test Method for Calibration of Narrow- and Broad-Band Ultraviolet Radiometers Using a SpectroradiometerG141 Guide for Addressing Variability in Exposure Testingof Nonmetallic Materials1This practice is under the jurisdiction of ASTM C
14、ommittee G03 on Weatheringand Durability and is the direct responsibility of Subcommittee G03.03 onSimulated and Controlled Exposure Tests.Current edition approved April 1, 2010. Published May 2010. Originallyapproved in 1997. Last previous edition approved in 2009 as G151 09. DOI:10.1520/G0151-10.2
15、For 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 Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical stand
16、ard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.G147 Practice for Conditioning and Handling of Nonmetal-lic Materials for Natural and Artificial Weathering TestsG152 Practice for Operating Open Flame
17、Carbon Arc LightApparatus for Exposure of Nonmetallic MaterialsG153 Practice for Operating Enclosed Carbon Arc LightApparatus for Exposure of Nonmetallic MaterialsG154 Practice for Operating Fluorescent Light Apparatusfor UV Exposure of Nonmetallic MaterialsG155 Practice for Operating XenonArc Light
18、Apparatus forExposure of Non-Metallic MaterialsG156 Practice for Selecting and Characterizing WeatheringReference MaterialsG169 Guide for Application of Basic Statistical Methods toWeathering TestsG177 Tables for Reference Solar Ultraviolet Spectral Dis-tributions: Hemispherical on 37 Tilted Surface
19、2.2 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 ReportSolarSpectral Ir
20、radiance52.4 ASTM Adjuncts:SMARTS2, Simple Model for Atmospheric Transmission ofSunshine63. Terminology3.1 DefinitionsThe definitions given in TerminologiesE41, E772, and G113 are applicable to this practice.4. Significance and Use4.1 Significance:4.1.1 When conducting exposures in devices that use
21、labo-ratory light sources, it is important to consider how well 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 accelerat
22、ed test and outdoorexposures when setting up exposure experiments 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 accelerat
23、ed exposurescan be considered as representative of actual use 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
24、in different locationsbecause of differences in UV radiation, 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 ma
25、terials exposed in aparticular exterior environment, it cannot 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 radiantexpo
26、sure in a laboratory accelerated test to y months or yearsof 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
27、same material.4.1.3.2 Variability in the rate of degradation 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 sol
28、ar radia-tion, even when identical bandpasses are used, do not 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 desir
29、ed in spite of thewarnings given in this practice, such acceleration 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 anal
30、yzed usingstatistical methods. An example of a statistical analysis using multiplelaboratory and exterior exposures to calculate an acceleration factor isdescribed by J.A. Simms (1).74.1.4 There are a number of factors that may decrease thedegree of correlation between accelerated tests using labora
31、-tory light sources and exterior exposures. More specific infor-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 thos
32、e experienced inactual use conditions.4.1.4.3 Test conditions 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 unrealis
33、tic tem-perature differences between light and dark colored specimens.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 moistu
34、re.4.1.4.8 Absence of biological agents or pollutants.4.2 Use of Accelerated Tests with Laboratory Light Sources:4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5Available from the Commission Internationale de LEclairage,
35、 CIE, CentralBureau, Kegelgasse 27, A-1030 Vienna, Austria or the U.S. National Committee forCIE, National Institute for Science and Technology, Gaithersburg, MD.6Available from ASTM International Headquarters. Order Adjunct No.ADJG173CD. Original adjunct produced in 2005.7The boldface numbers in pa
36、rentheses refer to the list of references at the end ofthis standard.G151 1024.2.1 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 qualit
37、y of different batchesdoes 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. Resultscan be expressed by comparing the exposure time or radiantexposure necessary to change a characteris
38、tic 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 terms of performance ranking compared to othermaterials or to a control;8,9therefore, exposure of a similarmaterial of known perfor
39、mance (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 of the operating conditions inan exposure test.4.2.3 Reference materials, for example, blue wool testfabric, also may be used fo
40、r 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 change in property of the reference material. The testmaterial then is evaluated. In some cases, the results for the testmaterial
41、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 thetest material or when the reference material is very sensitive toan exposure stress that has very little effect on the test
42、material.NOTE 5Definitions for control and reference material that are appro-priate to weathering tests are found in Terminology G113.NOTE 6Practice G156 describes procedures for selecting and charac-terizing weathering reference materials used to establish consistency ofoperating conditions in a la
43、boratory accelerated test.NOTE 7Results from accelerated exposure tests should only be usedto establish a pass/fail approval of materials after a specific time ofexposure to a prescribed set of conditions when the variability in theexposure and property measurement procedure has been quantified so t
44、hatstatistically 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 placement ofspecimens and any designated sensing devices in positionswhich provide uniform irradiance by the light source.NOTE 8In
45、some devices, several individual light sources are usedsimultaneously. In these devices, the term light source refers to thecombination of individual light sources being used.5.1.2 Manufacturers of exposure devices shall assure thatthe irradiance at any location in the area used for specimenexposure
46、s 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 irradiance uniformity in exposure devices canbe affected by several factors, such as deposits, which can develop on theoptical system and c
47、hamber walls. Irradiance uniformity also can beaffected by the type and number of specimens being exposed. Theirradiance uniformity as assured by the manufacturer is valid for newequipment and well defined measuring conditions.5.1.3 Periodic repositioning of the specimens during expo-sure is not nec
48、essary 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 in the area used forspecimen exposure is between 70 and 90 % of the maximumirradiance, specimens shall be periodically repositione
49、d toreduce variability in radiant exposure. The repositioning sched-ule shall be agreed upon by all interested parties. Appendix X2describes some possible specimen placement 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 manufacturer
