1、Designation: G 201 09Standard Practice forConducting Exposures in Outdoor Glass-Covered ExposureApparatus with Air Circulation1This standard is issued under the fixed designation G 201; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 covers the basic principles and operatingprocedures for using outdoor glass-covered expos
3、ure apparatuswith air circulation. This practice is limited to the proceduresfor obtaining, measuring and controlling conditions of expo-sure. A number of exposure procedures are listed in AppendixX1; however, this practice does not specify the exposureconditions best suited for the material to be t
4、ested.1.2 For direct weathering exposures, refer to Practice G7.For exposures behind glass without air circulation, refer toPractice G24.1.3 Test specimens are exposed to solar radiation filteredthrough glass under partially controlled environmental testconditions. Different glass types and operatin
5、g parameters aredescribed.1.4 Specimen preparation and evaluation of the results arecovered in ASTM methods or specifications for specificmaterials. More specific information for determining thechange in properties after exposure and reporting these resultsis described in Practices D5870, D2244 and
6、Test MethodD523.1.5 The values stated in SI units are to be regarded asstandard.1.6 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 det
7、ermine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D523 Test Method for Specular GlossD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD5870 Practice for Calculating Property
8、Retention Index ofPlasticsE903 Test Method for Solar Absorptance, Reflectance, andTransmittance of Materials Using Integrating Spheres3E1084 Test Method for Solar Transmittance (Terrestrial) ofSheet Materials Using SunlightG7 Practice for Atmospheric Environmental Exposure Test-ing of Nonmetallic Ma
9、terialsG24 Practice for Conducting Exposures to Daylight FilteredThrough GlassG113 Terminology Relating to Natural andArtificial Weath-ering Tests of Nonmetallic MaterialsG141 Guide for Addressing Variability in Exposure Testingof Nonmetallic MaterialsG173 Tables for Reference Solar Spectral Irradia
10、nces: Di-rect Normal and Hemispherical on 37 Tilted SurfaceG177 Tables for Reference Solar Ultraviolet Spectral Dis-tributions: Hemispherical on 37 Tilted SurfaceG179 Specification for Metal Black Panel and White PanelTemperature Devices for Natural Weathering TestsG183 Practice for Field Use of Pyr
11、anometers, Pyrheliom-eters and UV Radiometers2.2 Other Document:4WMO No. 8 Guide to Meteorological Instruments andMethods of Observation, Fifth Edition2.3 ISO Standard:5ISO 9060 Solar energy Specification and classification ofinstruments for measuring hemispherical solar and directsolar radiation3.
12、Terminology3.1 The definitions given in Terminology G113 are appli-cable to this practice.1This practice is under the jurisdiction of ASTM Committee G03 on Weatheringand Durability and is the direct responsibility of Subcommittee G03.02 on Naturaland Environmental Exposure Tests.Current edition appr
13、oved Dec. 1, 2009. Published May 2010. DOI: 10.1520/G020109.2For 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 Document Summary page onthe ASTM website.3
14、Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4Available from World Meteorological Organization (WMO), 7bis, avenue de laPaix, Case postale 2300, CH-1211 Geneva 2, Switzerland, http:/www.wmo.int.5Available from International Organization for Standardiz
15、ation (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 Other Definitions:3.2.1 limit temperature, nFor enclosures operated in tem-p
16、erature control mode, the specified black panel temperature atwhich the circulating fan switches on in order to prevent orminimize black panel temperature readings above the settemperature.4. Summary of Practices4.1 Specimens are exposed to light, moisture (in the form ofhumidity) and heat in an out
17、door glass-covered enclosure withair circulation.4.2 The exposure conditions may be varied by selection of:4.2.1 Glass Type:4.2.2 Operation of the circulating fan (whether constantlyon during daylight hours or only on when a specific limittemperature is reached).4.2.3 Temperature level at which the
18、fan operates.4.2.4 Orientation of the test fixture.5. Significance and Use5.1 As with any accelerated test, the increase in rate ofweathering compared to in-service exposure is material depen-dent. Results from exposures conducted to this practice mayprovide good rank correlation to results from act
19、ual useconditions for one type of material or product. It should not beassumed that this will be true for other materials or products. Itis always best to verify the ability of an accelerated exposuretest to properly rank the durability of materials with actual useconditions. Guide G141 provides inf
20、ormation about using rankcorrelation.5.2 Variation in results may be expected when operatingconditions are varied within the accepted limits of this practice.Therefore, no reference shall be made to results from the use ofthis practice unless accompanied by a report detailing thespecific operating c
21、onditions in conformance with ReportSection 8.5.3 The durability of materials in outdoor use can be verydifferent depending on the location of the exposure because ofdifferences in solar radiation, moisture, heat, pollutants, andother factors. Therefore, it cannot be assumed that results fromexposur
22、e in a single location will be useful for determiningdurability ranking of materials in a different location.5.4 It is strongly recommended that at least one controlmaterial be exposed with each test. The control material shouldbe of similar composition and construction and be chosen sothat its fail
23、ure modes are the same as that of the material beingtested. It is preferable to use two control materials, one withrelatively good durability, and one with relatively poor dura-bility. If control materials are included as part of the test, theyshall be used for the purpose of comparing the performan
24、ce ofthe test materials relative to the controls.6. Apparatus6.1 Enclosure:6.1.1 Exposures shall be conducted in a glass-coveredenclosure of any convenient size (see Fig. 1). The enclosureshall be constructed of a corrosion-resistant metal, such asanodized aluminum or stainless steel, and be designe
25、d toprevent outside air from circulating over specimens. Option-ally, vents covered with air filter material may be installed inthe bottom of the test fixture if required to limit the black paneltemperature to a specified maximum.6.1.2 The enclosure shall be located where it will receivesolar radiat
26、ion throughout the day with no shadow on anyspecimen when the suns angle of elevation is greater than 20degrees. When the enclosure is installed over grass, thedistance between the bottom of the enclosure and the groundshall be sufficient to prevent contact with plant growth, or tominimize damage th
27、at might occur during maintenance.6.1.3 The enclosure shall be equipped with a rack whichsupports the specimens in a plane parallel to the glass.Alternately, the specimens can be mounted in an in-serviceposition. Unless otherwise specified, the distance between theexposed surface of flat specimens s
28、hall be 75 6 25 mm fromthe back surface of the glass cover.6.1.4 Formed specimens with irregular dimensions mayrequire custom mounting with varying distances from the glasscover. In such cases, mount the test specimen surface of majorinterest parallel to the glass cover at a distance of 75 6 25 mmfr
29、om the glass cover. The mounting frame or plate shall beconstructed of a material that is compatible with the testspecimens. In order to minimize shadowing from the top andsides of the enclosure, the usable exposure area under the glassshall be limited to that of the glass cover reduced by twice the
30、distance from the cover to the specimens as shown in Fig. 2.The effective width of the specimen mounting area is L-4X andthe effective height of the mounting area is W-4X, where L isthe width of the glass cover, W is the height of the glass cover,and X is the distance between the glass cover and the
31、specimens.FIG. 1 Diagram of Typical Enclosure with Air CirculationG2010926.1.5 The enclosure shall be capable of being oriented in amanner mutually agreed upon between interested parties. Thetest report shall contain the orientation used. Possible exposureorientations are:6.1.5.1 Fixed tilt angle, t
32、ypically in the range of 5 to 45degrees, with cabinet facing equator.6.1.5.2 Fixed tilt angle, typically 51 degrees, with trackingin rotation (azimuth).6.1.5.3 Tracking azimuth and elevation in order to maintainthe exposure plane normal to the suns direct beam.6.1.5.4 Any other angle that is mutuall
33、y agreed on by allinterested parties may be used. In some instances, exposuresfacing directly away from the equator or some other specificdirection may be desired.6.2 Glass Cover:6.2.1 The glass cover shall be flat glass of one of thefollowing types:6.2.1.1 Clear Tempered GlassThe glass cover shall
34、benon-laminated, tempered, clear flat glass having a nominalthickness of 3 to 4 mm. The glass thickness used shall beincluded in the test report.6.2.1.2 Clear Laminated GlassThe glass cover shall belaminated, clear flat glass having a nominal thickness of 5.8mm and containing a PVB (polyvinyl butyra
35、l) inner layer withan approximate thickness of 0.76 mm (.030 in.). This type ofglass is typically used in automotive applications.6.2.1.3 Any other glass type as agreed upon between inter-ested parties.6.2.2 Wash the exterior and interior surfaces of the glasscover every month (or more frequently, i
36、f required) to removedust particles and other undesirable material.6.2.3 It is recommended that the spectral transmittance ofrepresentative glass samples be measured. If transmittance ismeasured, report the average for at least three representativepieces of the lot of glass being used. Follow the in
37、structions ofthe UV-visible spectrophotometer used for measurement of theglass. If a spectrophotometer with an integrating sphere is used,the measurements shall be performed in accordance with TestMethod E903.6.3 Black Panel Thermometer:6.3.1 For enclosures with a temperature-controlled circulat-ing
38、 fan, one of the following black panel thermometer typesshall be installed in the enclosure:6.3.1.1 Automotive Black PanelThe black panel ther-mometer shall be constructed of 0.60 6 0.06 mm (24 gauge)sheet steel with dimensions of approximately 100 by 125 mm(4 by 5 in.). The exposed surface of the b
39、lack panel shall beprimed and painted with black high heat spray paint.6.3.1.2 Specification G179 Black PanelThe black panelthermometer shall be constructed in accordance with therequirements of Specification G179 with dimensions of ap-proximately 100 by 125 mm (4 by 5 in.).6.3.1.3 The type of black
40、 panel thermometer used shall bedescribed in the test report. Regardless of which type of blackpanel is used, the black panel is exposed parallel to the glass atthe same respective depth from the surface of the glass as theexposed surface of the test specimen. The panel must bemounted on 13 mm (12 i
41、n.) thick plywood, painted black,whose dimensions are at least 110 by 135 mm (438 by 538 in.)with a machined recess to allow space for the temperaturesensor, thermocouple and their respective lead wires attachedto the back of the black panel. The black panel must befastened to the plywood with small
42、 screws near the corners ofthe panel. The black panel assembly shall be mounted in theplane of the test samples near the top edge of the samplemounting area no closer than 200 mm from the left or rightedge of the glass cover as shown in Fig. 3.6.4 Circulating Fan:6.4.1 The test enclosure shall be eq
43、uipped with a circulatingfan which directs air between the top surface of specimens andthe glass cover. This fan can be set to operate continuouslyduring daylight hours, or based on the temperature readingfrom a black panel thermometer. Unless otherwise specified,when the circulating fan is switched
44、 off and on based on thetemperature of a black panel thermometer, set the controller toturn on at the desired limit temperature and off at a temperaturethat is 3C less than the limit temperature.6.5 Over Temperature Protection:6.5.1 Unless otherwise specified, test enclosures shall beequipped with o
45、ver temperature protection to prevent specimenLegend: L = length of glass cover; W = width of glass cover; X = distance between glass cover and specimensFIG. 2 Sample Exposure Area DiagramG201093overheating in the event of a fan failure. The over temperatureprotection shall be set to operate at a te
46、mperature no greaterthan 6C above the limit temperature. The over temperatureprotection shall cover the test enclosure or change the enclo-sure orientation in order to prevent damage to specimens beingexposed.6.6 Climatological Instruments:6.6.1 Within 1000 m of test enclosures shall be an areadesig
47、nated for measuring climatological conditions such asambient temperature, relative humidity, and solar radiation.6.6.2 Optionally, ambient air temperature and relative hu-midity can be measured in a shielded, elevated location.6.6.3 Solar Radiation:6.6.3.1 Instrumental means of measuring full-spectr
48、um so-lar radiant exposure shall consist of a pyranometer connectedto an integrating device to indicate the total energy receivedover a given period. The pyranometer shall be sensitive to solarradiation received at a geometry similar to that over whichsolar radiation is received by the test specimen
49、s. The pyranom-eter shall meet the requirements of an ISO 9060 Second Classinstrument or better. The pyranometer shall be calibrated andoperated in accordance with requirements in Practice G183.6.6.3.2 Instrumental means of measuring solar radiant ex-posure in specific wavelength regions (such as all or a portionof the ultraviolet spectrum) shall consist of a wavelength-bandspecific global irradiance radiometer connected to an integrat-ing device to indicate the energy received in a specifiedwavelength band over a given period (optional). The radiom-eter shall be ca
