ASTM G151-97
(Practice)Standard Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
Standard Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
SCOPE
1.1 This practice provides general procedures to be used when exposing nonmetallic materials in accelerated test devices that use laboratory light sources. Detailed information regarding procedures to be used for specific devices are found in standards describing the particular device being used. For example, detailed information covering exposures in devices that use carbon-arc, xenon-arc, and fluorescent UV light sources are found in Practices G152, G153, and G154, and G154 respectively.
Note 1--Carbon-arc, xenono-arc, and fluorescent UV exposures are also described in Practices G23, G26, and G53 which described very specific equipment designs. Practices G152, G153, and G154, and G 154 are performance based standards that replace Practices G23, G26, and G53
1.2 This practice also describes general performance requirements for devices used for exposing nonmetallic materials to laboratory light sources. This information is intended primarily for producers of laboratory accelerated exposure devices.
1.3 This practice provides information on the use and interpretation of data from accelerated exposure tests. Specific information about methods for determining the property of a nonmetallic material before and after exposure are found in standards describing the method used to measure each property. Information regarding the reporting of results from exposure testing of plastic materials is described in Practice D5870.
Note 2--Guide G141 provides information for addressing variability in exposure testing of nonmetallic materials. ASTM Committee G3 is developing a standard guide for application of statistics to exposure test results.
Note 3--This standard is technically equivalent to ISO 4892, Part 1.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: G 151 – 97
Standard Practice for
Exposing Nonmetallic Materials in Accelerated Test Devices
that Use Laboratory Light Sources
This standard is issued under the fixed designation G 151; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope bility of regulatory limitations prior to use.
1.1 This practice provides general procedures to be used
2. Referenced Documents
when exposing nonmetallic materials in accelerated test de-
2.1 ASTM Standards:
vices that use laboratory light sources. Detailed information
D 618 Practice for Conditioning Plastics and Electrical
regarding procedures to be used for specific devices are found
Insulating Materials for Testing
in standards describing the particular device being used. For
D 3924 Specification for Standard Environment for Condi-
example, detailed information covering exposures in devices
tioning and Testing Paint, Varnish, Lacquer and Related
that use carbon-arc, xenon-arc, and fluorescent UV light
materials
sources are found in Practices G 23, G 26, and G 53, respec-
D 5870 Practice for Calculating Property Retention Index
tively.
of Plastics
NOTE 1—New performance based standards describing exposures in
E 41 Terminology Relating to Conditioning
carbon-arc, xenon-arc, and fluorescent UV exposures are being developed
E 171 Specification for Standard Atmospheres for Condi-
by Subcommittee G 03.03.
tioning and Testing Flexible Barrier Materials
1.2 This practice also describes general performance re-
E 585 Specification for Base-Metal Thermocouple Materi-
quirements for devices used for exposing nonmetallic materials
als
to laboratory light sources. This information is intended
E 644 Test Methods for Testing Industrial Resistance Ther-
primarily for producers of laboratory accelerated exposure
mometers
devices.
E 772 Terminology Relating to Solar Energy Conversion
E 839 Test Methods for Sheathed Thermocouples and
NOTE 2—Certification of conformance to the performance requirements
Sheathed Thermocouple Material
for new exposure devices generally is the responsibility of the manufac-
turer.
G 7 Practice for Atmospheric Environmental Exposure
Testing of Nonmetallic Materials
1.3 This practice provides information on the use and
G 23 Practice for Operating Light Exposure Apparatus
interpretation of data from accelerated exposure tests. Specific
(Carbon-Arc) Type With and Without Water for Exposure
information about methods for determining the property of a
of Nonmetallic Materials
nonmetallic material before and after exposure are found in
G 24 Practice for Conducting Exposures to Daylight Fil-
standards describing the method used to measure each prop-
tered Through Glass
erty. Information regarding the reporting of results from
G 26 Practice for Operating Light-Exposure Apparatus
exposure testing of plastic materials is described in Practice
(Xenon-Arc) Type With and Without Water for Exposure
D 5870.
of Nonmetallic Materials
NOTE 3—The Committee G–3 is developing standard guides for appli-
G 53 Practice for Operating Light- and Water-Exposure
cation of statistics to exposure test results and for addressing variability in
Apparatus (Fluorescent UV Condensation Type) for Expo-
exposure testing of nonmetallic materials.
sure of Nonmetallic Materials
NOTE 4—This standard is technically equivalent to ISO DIS 4892, Part
G 113 Terminology Relating to Natural and Artificial
1.
Weathering Tests for Nonmetallic Materials
1.4 This standard does not purport to address all of the
G 130 Method for Calibration of Narrow- and Broad-Band
safety concerns, if any, associated with its use. It is the
Ultraviolet Radiometers Using a Spectroradiometer
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 06.01.
1 4
This practice is under the jurisdiction of ASTM Committee G-3 on Weathering Annual Book of ASTM Standards, Vol 14.02.
and Durability and is the direct responsibility of Subcommittee G03.03 on Annual Book of ASTM Standards, Vol 15.09.
Simulated and Controlled Exposure Tests. Annual Book of ASTM Standards, Vol 14.03.
Current edition approved July 10, 1997. Published May 1998. Annual Book of ASTM Standards, Vol 12.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
G 151
G 147 Practice for Conditioning and Handling of Nonme- when identical bandpasses are used, do not take into consid-
tallic Materials for Natural and Artificial Weathering Tests eration the effects of temperature, moisture, and differences in
2.2 ISO Standards: spectral power distribution between the laboratory light source
ISO 4892, Part 1 Plastics: Exposure to laboratory Light and daylight.
Sources–General Guidance
NOTE 5—If use of an acceleration factor is desired in spite of the
ISO 9370 Plastics: Instrumental Determination of Radiant
warnings given in this practice, such acceleration factors for a particular
Exposure in Weathering Tests–General Guidance and
material are only valid if they are based on data from a sufficient number
Basic Test Method of separate exterior and laboratory accelerated exposures so that results
used to relate times to failure in each exposure can be analyzed using
2.3 CIE Documents:
statistical methods. An example of a statistical analysis using multiple
CIE Publication Number 85: 1989, Technical Report–Solar
laboratory and exterior exposures to calculate an acceleration factor is
Spectral Irradiance
described by J.A. Simms (1).
3. Terminology
4.1.4 There are a number of factors that may decrease the
3.1 Definitions— The definitions given in Terminologies degree of correlation between accelerated tests using labora-
tory light sources and exterior exposures. More specific infor-
E 41, E 772, and G 113 are applicable to this practice.
mation on how each factor may alter stability ranking of
4. Significance and Use
materials is given in Appendix X1.
4.1 Significance:
4.1.4.1 Differences in the spectral distribution between the
4.1.1 When conducting exposures in devices that use labo-
laboratory light source and sunlight.
ratory light sources, it is important to consider how well the 4.1.4.2 Light intensities higher than those experienced in
accelerated test conditions will reproduce property changes and
actual use conditions.
failure modes associated with end-use environments for the 4.1.4.3 Test conditions where specimens are exposed con-
materials being tested. In addition, it is essential to consider the
tinuously to light when actual use conditions provide alternate
effects of variability in both the accelerated test and outdoor periods of light and dark.
exposures when setting up exposure experiments and when
4.1.4.4 Specimen temperatures higher than those in actual
interpreting the results from accelerated exposure tests. conditions.
4.1.2 No laboratory exposure test can be specified as a total
4.1.4.5 Exposure conditions that produce unrealistic tem-
simulation of actual use conditions in outdoor environments. perature differences between light and dark colored specimens.
Results obtained from these laboratory accelerated exposures
4.1.4.6 Exposure conditions, which produce very frequent
can be considered as representative of actual use exposures
cycling between high and low specimen temperatures, or
only when the degree of rank correlation has been established
which produce unrealistic thermal shock.
for the specific materials being tested and when the type of
4.1.4.7 Unrealistically high or low levels of moisture.
degradation is the same. The relative durability of materials in
4.1.4.8 Absence of biological agents or pollutants.
actual use conditions can be very different in different locations
4.2 Use of accelerated tests with laboratory light sources.
because of differences in UV radiation, time of wetness,
4.2.1 Results from accelerated exposure tests conducted
relative humidity, temperature, pollutants, and other factors.
according to this standard are best used to compare the relative
Therefore, even if results from a specific exposure test con-
performance of materials. A common application is conducting
ducted according to this practice are found to be useful for
a test to establish that the level of quality of different batches
comparing the relative durability of materials exposed in a
does not vary from a control material with known performance.
particular exterior environment, it cannot be assumed that they
Comparisons between materials are made best when the
will be useful for determining relative durability of the same materials are tested at the same time in the same exposure
materials for a different environment.
device. Results can be expressed by comparing the exposure
4.1.3 Even though it is very tempting, calculation of an time or radiant exposure necessary to reduce the level of a
acceleration factor relating x h or megajoules of radiant
characteristic property to some specified level.
exposure in a laboratory accelerated test to y months or years 4.2.1.1 It is strongly recommended that at least one control
of exterior exposure is not recommended. These acceleration
material be exposed with each test for the purpose of compar-
factors are not valid for several reasons. ing the performance of the test materials to that of the control.
4.1.3.1 Acceleration factors are material dependent and can
Ideally, the control material should be of similar composition
be significantly different for each material and for different
and construction and be chosen so that its failure modes are the
formulations of the same material.
same as that of the material being tested. It is preferable to use
4.1.3.2 Variability in the rate of degradation in both actual
two controls, one with relatively good durability and one with
use and laboratory accelerated exposure test can have a
relatively poor durability.
significant effect on the calculated acceleration factor.
4.2.1.2 Sufficient replicates of each control material and
4.1.3.3 Acceleration factors calculated based on the ratio of
each test material being evaluated are necessary in order to
irradiance between a laboratory light source and daylight, even
allow statistical evaluation of results. Unless otherwise speci-
fied, use a minimum of three replicates for all test and control
Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036. The boldface numbers in parentheses refer to the list of references at the end
CIE of this standard.
G 151
materials. When material properties are measured using de- radiant exposure. The repositioning schedule shall be agreed
structive tests, a separate set of specimens is needed for each upon by all interested parties.
exposure period. 5.1.4.2 Place specimens only in the exposure area where
4.2.2 In some applications, reference materials are used to irradiance is at least 90 % of the maximum irradiance.
establish consistency of the operating conditions in an expo- 5.1.4.3 Randomly position replicate specimens within the
sure test. Reference materials, for example, blue wool test exposure area that meets the irradiance uniformity require-
fabric, also may be used for the purpose of timing exposures. ments defined in 5.1.4
4.2.2.1 In some cases, a reference material is exposed at the 5.1.5 Replace lamps and filters according to the schedule
same time as a test material and the exposure is conducted until recommended by the device manufacturer. Follow the appara-
there is a defined change in property of the reference material. tus manufacturer’s instructions for lamp and filter replacement
The test material then is evaluated. In some cases the results for and for pre-aging of lamps or filters, or both.
the test material are compared to those for the reference 5.1.6 CIE Publication No. 85–1989 provides data on solar
material. These are inappropriate uses of reference materials spectral irradiance for typical atmospheric conditions, which
when they are not senSitive to exposure stresses, which can be used as a basis for comparing laboratory light sources
produce failure in the test material, or when the reference with daylight. For example, global solar irradiance in the 300
material is very sensitive to an exposure stress that has very to 2450 nm band is given as 1090 W/m for relative air mass
little effect on the test material. 1, with 1.42 cm precipitable water, and 0.34 cm of ozone
(measured at a pressure of 1 atmosphere and temperature of
NOTE 6—Definitions for control and reference material that are appro-
0°C). Table 1 shows a broad band condensed spectral irradi-
priate to weathering tests are found in Terminology G 113.
ance for global solar radiation at this atmospheric condition in
NOTE 7—Subcommittee G03.01 is developing a standard practice for
selecting and characterizing weathering reference materials used to the UV, visible and infrared portions of the spectrum. This
establish consistency of operating conditions in a laboratory accelerated
represents the maximum global solar irradiance that would be
test.
experienced by materials exposed on a horizontal surface at the
4.3 Results from accelerated exposure tests only should be equator near noon on a clear day at the spring or autumn
used to establish a pass/fail approval of materials after a
equinox.
specific time of exposure to a prescribed set of conditions when 5.1.6.1 Direct radiation from xenon burners, open flame
the variability in the exposure and property measurement
carbon arcs, and some fluorescent lamps contains considerable
procedure has been quantified so that statistically significant amounts of short wavelength ultraviolet radiation not present in
pass/fail judgments can be made.
daylight. With proper selection of filters for these light sources,
much of the short wavelength light can be eliminated. Even
5. Requirements for Laboratory Exposure Devices
when filters are used, however, a small, but significant, amount
5.1 Light Source:
of this short wavelength (less than 300 nm) radiation often is
5.1.1 The exposure device shall provide for placement of
present in the spectral distribution of the filtered light source.
specimens and any designated sensing devices in positions
Fluorescent UV lamps can be selected to have a spectral output
which provide uniform irradiance by the light source.
corresponding to a particular ultravi
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