ISO 16474-3:2021 Paints and varnishes — Methods of exposure to laboratory light sources —Part 3: Fluorescent UV lamps

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Paints and varnishes — Methods of exposure to laboratory light sources —Part 3: Fluorescent UV lamps是国际标准化组织(International Organization for Standardization，简称ISO)发布的ISO标准，适用于全球。

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Paints and varnishes — Methods of exposure to laboratory light sources —

Part 3: Fluorescent UV lamps

1 Scope

This document specifies methods for exposing coatings to fluorescent UV lamps, heat and water in apparatus designed to reproduce the weathering effects that occur when materials are exposed in actual end-use environments to daylight, or to daylight through window glass.

The coatings are exposed to different types of fluorescent UV lamps under controlled environmental conditions (temperature, humidity and/or water). Different types of fluorescent UV lamp can be used to meet all the requirements for testing different materials.

Specimen preparation and evaluation of the results are covered in other ISO documents for specific materials.

General guidance is given in ISO 16474-1.

NOTE Fluorescent UV lamp exposures for plastics are described in ISO 4892-3.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 1514, Paints and varnishes — Standard panels for testing

ISO 2808, Paints and varnishes — Determination of film thickness

ISO 4618, Paints and varnishes — Terms and definitions

ISO 9370, Plastics — Instrumental determination of radiant exposure in weathering tests — General guidance and basic test method

ISO 16474-1:2013, Paints and varnishes — Methods of exposure to laboratory light sources — Part 1: General guidance

3 Terms a nd definiti ons

For the purposes of this document, the terms and definitions given in ISO 4618 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://w ww .iso. org/ obp

— IEC Electropedia: available at http:// www .electropedia. org/

3.1

radiant exposure

H

amount of radiant energy to which a test panel has been exposed

Note 1 to entry: Radiant exposure is given by the equation:

HE=∫ ⋅dt

where

2

H is the radiant exposure, in joules per square metre (J/m );

2

E is the irradiance, in watts per square metre (W/m );

t is the exposure time, in seconds (s).

Note 2 to entry: If the irradiance E is constant throughout the whole exposure time, the radiant exposure H is given simply by the product of E and t.

4 Principle

4.1 Fluorescent UV lamps, when properly maintained, can be used to simulate the spectral irradiance of daylight in the ultraviolet (UV) region of the spectrum.

4.2 Specimens are exposed to various levels of UV radiation, heat and moisture (see 4.4) under controlled environmental conditions.

4.3 The exposure conditions may be varied by selection of:

a) the type of fluorescent lamp (spectral power distribution);

b) the irradiance level;

c) the temperature during the UV exposure;

d) the relative humidity of the chamber air during the light and dark exposures, when test conditions requiring control of humidity are used;

NOTE Commercial fluorescent UV lamp devices generally do not provide means of relative humidity control.

e) the type of wetting (see 4.4);

f) the wetting temperature and cycle;

g) the timing of the UV/dark cycle.

4.4 Wetting is usually produced by condensation of water vapour onto the exposed specimen surface or by spraying the test specimens with demineralized/deionized water.

4.5 The procedure(s) may include measurement of the irradiance and the radiant exposure in the plane of the specimen.

4.6 It is recommended that a similar material of known performance (a control) be exposed simultaneously with the test specimens to provide a standard for comparative purposes.

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