introduction
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ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

Voluntary, related standards and conformity assessment related ISO specific and express the meaning of terminology as well as in relevant ISO technical barriers to trade (TBT) adhere to the principle of the world trade organization (WTO) information, please refer to the following URL:iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 6, Ageing, Chemical and Environmental Tolerance.

The third edition cancels and replaces the technically revised second edition (ISO 9370:2009).

The main changes from the previous edition are as follows:

– A more precise description of the calibration procedure for selective (UV) radiometers;

– Annex B was introduced to better explain possible spectral mismatches (systematic errors) in selective filtered radiometers.

introduce
The period of natural weathering, accelerated natural weathering, artificially accelerated weathering, or artificially accelerated radiation exposure is defined only in terms of time, ignoring the influence of changes in spectral irradiance of the source and the moisture and/or temperature difference between different exposure tests. Defining the period of natural weathering exposure in terms of total exposure to solar radiation has been shown to be helpful in comparing the outcomes of these exposures at different times in the same location. However, it is also important to monitor solar UV radiation exposure from natural weathering exposure and UV radiation exposure from artificially accelerated weathering or artificially accelerated irradiation exposure.

Two methods of measuring UV radiation are commonly used. The first is the use of physical criteria, i.e. exposure to a reference material that shows a property change proportional to the dose of incident ultraviolet radiation. The preferred option is to use a radiometer that responds to ultraviolet light. This document describes this method. It recommends the important characteristics of the instruments used and provides guidance for the selection and use of these radiometers.

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

1 Range
This document specifies an instrumental method for measuring irradiance on a flat surface. This includes not only natural solar radiation, but also enhanced natural solar radiation and radiation produced by laboratory light sources.

To measure natural weathering and solar radiation that accelerates natural weathering, instrumental techniques include continuous measurements of the sun, solar ultraviolet and spectral solar (ultraviolet) irradiance, as well as the accumulation or integration of instantaneous data to provide radiation exposure.

To measure radiation in artificially accelerated weathering or artificially accelerated irradiation, instrumental techniques include the continuous measurement of total or defined bands of ultraviolet radiation, visible spectral irradiance and/or ultraviolet spectral irradiance, and the accumulation or integration of instantaneous data to provide radiation exposure.

This document does not specify procedures for the use of blue wool standards, chemical dosing or polymer or other thin film dosing.

2 Normative references
The following files are referenced in text in a manner that constitutes part or all of the requirements of this document. For dated references, only the cited version applies. For undated references, a new version of the reference (including any revisions) applies.

ISO 9059, Solar energy – Comparative calibration of a field pyrometer with a reference sunshine meter

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

ISO 9060, Solar Energy – Specification and classification of instruments for measuring hemispherical sun and direct solar radiation

ISO 9846, Solar energy – Calibration of pyrheliometer using a sunshine meter

ISO 9847, Solar energy – Calibration of on-site pyrheliometers compared to reference pyrheliometers

ASTM E816, Standard test method for calibrated pyrometers compared to reference pyrometers

ASTM E824, standard test method that moves calibration from reference to field radiometer

ASTM G90, Standard practice for accelerated outdoor weathering of non-metallic materials using concentrated natural sunlight

ASTM G130, Standard test method for calibration of narrow band and wide band ultraviolet radiometers using spectroradiometers

ASTM G138, Standard test method for Calibration of spectroradiometers using standard irradiance sources

ASTM G183, Standard Practice for Field Use of pyrheliometers, sunshine meters, and ultraviolet radiometers

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

3.1 Artificial accelerated weathering

When exposing materials in a laboratory aging device, these conditions may be more periodic and intense than those encountered outdoors or in service

Note 1: This involves laboratory radiation sources, heat, and moisture (in the form of relative humidity and/or water spraying, condensation, or soaking) to try to produce the same changes more quickly as long-term outdoor exposure.

Note 2: The device may include devices for controlling and/or monitoring light sources and other weathering variables. It may also include exposure to special conditions, such as acid fog to simulate the effects of industrial gases.

3.2 Artificial accelerated irradiation

Exposing the material to a laboratory radiation source is designed to mimic solar radiation filtered by window glass or radiation from an indoor lighting source, and the sample can withstand relatively small changes in temperature and relative humidity to try to produce the same changes more quickly as when the material is used in an indoor environment

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

3.3 Blocking

The ability of a filter to suppress or not transmit radiation outside the intended passband, usually expressed as a fraction or percentage of incident radiation

3.4 Broadband

Characteristics of filters and radiometers with a half-maximum (3.15) full width between 20 nm and 70 nm

Note 1: It usually describes filter radiometers that measure in the range of 300 nm to 400 nm.

3.5 Center Wavelength

continuous

The wavelength is located at the midpoint of the full width and is separated by a half maximum (3.15)

Note 1: See Figure 1.

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

3.6 cosine receptors

A radiative transfer device that samples the radiative flux according to the cosine of the incidence Angle and collects all the incident radiation in the 2π sphericity (i.e., in the hemisphere) using, for example, an integrating sphere or a planar diffuser

3.7 Cut-off Wavelength

When moving from the peak transmittance to the long wavelength blocking region, the transmittance decreases to a wavelength of 5% of the peak transmittance

Note 1: See point 4 in Figure 1.

λ wavelength (nanometer)
Sλ normalized spectral response
1 Central wavelength (continuous wave)
2 1/2 height Full Width (FWHM)
3 Cut-off wavelength
4 Cut-off wavelength

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

3.8 Cut-off Wavelength

The transmittance increases to 5% of the peak transmittance when moving from the short wavelength barrier to the emission region

Note 1: See point 3 in Figure 1.

3.9 Detector

A photoreceptor, which forms part of a radiometer, converts incident radiation into an electrical signal to determine the irradiance of a surface

3.10 Diffuse solar radiation

The sum of the radiation reflected from the sky and (if in the field of view) from the ground in the 2π spheroidal field of view on a plane surface, excluding radiation in the solid Angle of 5° to 6° centered on the solar disk

Note 1: See 3.11.

3.11 Direct radiation

Direct solar radiation

Direct beam radiation

Solar irradiance is contained within a restricted solid Angle (usually 5° to 6°) centered on the solar disk

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

Note 1: If direct normal solar radiation is known, the direct radiation on the inclined plane can be calculated by multiplying the direct normal solar radiation by the cosine of the Angle defined by the plane normal and the line from the foot of the normal to the center of the solar disk.

3.12 Direct normal solar radiation

Direct solar radiation is incident on a plane perpendicular to the solar beam

Note 1: Direct normal solar radiation is measured with a pyrometer.

3.13 Drift

Measures the rate of change of the responsiveness of the instrument over time, indicating the stability of the instrument based on time

3.14 Visual Field

The full Angle of the cone is defined by the center of the receiver surface and the boundary limiting the aperture

3.15 Full-width half-width FWHM

< In passband Transmittance is the interval between wavelengths of 50% of the peak transmittance, often referred to as the “bandwidth”.

3.16 Hemispherical solar radiation

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

< On a inclined plane. The sum of the direct solar radiation incident on a flat surface plus all the sky and ground reflected radiation in the surface 2π spherical field of view

Note 1: If the slope of the plane is zero degrees (i.e. horizontal), hemispherical solar radiation is often called global solar radiation or global horizontal radiation.

3.17 Interference filter

A filter that defines the spectral composition of transmitted radiation by interference effects

Note 1: Most interference filters consist of thin layers of metal and dielectric and therefore have high transmittance over selected spectral bands.

3.18 Radiation E

The radiant flux per unit area, measured in watts per square meter (W⋅m−2), is incident on a surface

3.19 Global solar irradiance

The solar radiation flux, both direct and diffuse, is received by the horizontal plane per unit area from a solid Angle of 2π sphericity

Note 1: It is expressed in watts per square meter (W⋅m−2).

3.20 Spectral irradiance Eλ

Irradiance at each wavelength interval

Note 1: It is usually expressed in watts per square meter per nanometer (W⋅m−2⋅nm−1).

3.21 Long-pass filter

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

The transmission wavelength is longer than the cutoff wavelength while suppressing the shorter wavelength filter, which is characterized by a sharp transition from minimum transmittance to maximum transmittance

3.22 Narrow band

Characteristics of interference filters with a half-peak full width (3.15) not exceeding 20nm

Note 1: In the same type of narrowband filter, the reproducibility of the center wavelength and FWHM is usually within ±2nm.

3.23 Passband

< In band pass filters > The wavelength interval between cutoff and cutoff

Note 1: See Figure 1.

3.24 Peak wavelength

Wavelength at maximum transmittance

Note 1: The peak wavelength is not necessarily the same as the central wavelength (see Figure 1).

3.25 Diurnal intensity meter

A radiometer for measuring global (or, if tilted, hemispherical) solar irradiance

3.26 Daily thermometer

A radiometer used to measure direct normal solar radiation

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

3.27 Radiation exposure H

Time integral of irradiance

Note 1: It is measured in joules per square meter (J⋅m−2).

3.28 Radiometer

An instrument for measuring electromagnetic radiation, consisting of a detector, any necessary filters and diffusers, and a signal processing device

3.29 Reference radiometer

An instrument used to achieve a standard measurement value relative to an accepted radiation scale, such as the World Radiation Reference Spectral irradiance scale, with a specified traceability path and a specified measurement uncertainty

Note 1: Reference radiometers are used only to calibrate other radiometers by comparison, replacement, or other direct relationship.

3.30 Field radiometer

Instruments deployed in the field or in the laboratory accelerated weathering devices for routine radiation measurements, calibrated to a recognized standard scale by comparison, replacement, or other direct relationship to the reference radiometer transfer scales

3.31 Short-pass filter

The transmission wavelength is shorter than the cutoff wavelength while suppressing longer wavelength filters, which are characterized by a sharp transition from maximum transmittance to minimum transmittance

3.32 Spectroradiometer

An instrument used to measure the variation of spectral irradiance with wavelength in a narrow wavelength interval within a given spectral region

ISO 9370-2017 General Guidelines and basic test methods for instrumental determination of radiation exposure during Weathering testing of Plastics

3.33 Source tracing

The ability to link measurements of a standard attribute to a claimed reference (usually a country or document) through an uninterrupted chain of comparisons, all of which have claimed uncertainty

3.34 Broadband

Characteristics of filters with a half-peak full width (3.15) of at least 70nm

Note 1: It usually describes a filter radiometer with, for example, a wide passband of 300nm to 800nm.

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