5.1 UV-A and visible light sources are used to provide adequate illumination levels for liquid penetrant and magnetic particle examination. UV-A sources, UV-A radiometers, visible light sources, and illuminance photometers are used to verify specified viewing conditions.

5.2 Fluorescence is typically produced by irradiating the fluorescent dyes/pigments with UV-A radiation. The fluorescent dyes/pigments absorb the UV-A radiation and re-emit light energy in the visible spectrum. This process allows fluorescence to be observed by the human eye.

5.3 UV-A sources may emit visible light above 400 nm (4000 Å), which may reduce the visibility of fluorescent indications. High intensity UV-A sources may cause UV fade, causing fluorescent indications to degrade or disappear.

1.1 This guide addresses the use of UV-A/Visible light sources and meters used for the examination of materials by the liquid penetrant and magnetic particle processes. This guide may be used to establish practices and procedures to measure irradiance and illuminance levels.

1.2 This guide also acts as a reference:

1.2.1 To assist in the selection of irradiance and illumination sources and meters that meet the applicable specifications or standards.

1.2.2 For use in the preparation of internal documentation dealing with liquid penetrant or magnetic particle examination of materials and parts.

1.3 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.

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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.