4.1 UV-A lamps are used in fluorescent penetrant and magnetic particle examination processes to excite fluorophores (dyes or pigments) to maximize the contrast and detection of discontinuities. The fluorescent dyes/pigments absorb energy from the UV-A radiation and re-emit visible light when reverting to its ground state. This excitation energy conversion allows fluorescence to be observed by the human eye.

4.2 The emitted spectra of UV-A lamps can greatly affect the efficiency of dye/pigment fluorescent excitation.

4.3 Some high-intensity UV-A lamps can produce irradiance greater than 10 000 μW/cm² at 15 in. (381 mm). All high-intensity UV-A light sources can cause fluorescent dye fade and increase exposure of the inspector’s unprotected eyes and skin to high levels of damaging radiation.

4.4 UV-A lamps can emit unwanted visible light and harmful UV radiation if not properly filtered. Visible light contamination above 400 nm can interfere with the inspection process and must be controlled to minimize reflected glare and maximize the contrast of the indication. UV-B and UV-C contamination must also be eliminated to prevent exposure to harmful radiation.

4.5 Pulse Width Modulation (PWM) and Pulse Firing (PF) of UV-A LED circuits are not permitted.

Note 1: The ability of existing UV-A radiometers and spectroradiometers to accurately measure the irradiance of pulse width modulated or pulsed fired LEDs and the effect of pulsed firing on indication detectability is not well understood.

1.1 This practice covers the procedures for testing the performance of ultraviolet A (UV-A), light emitting diode (LED) lamps used in fluorescent penetrant and fluorescent magnetic particle testing (see Guides E709 and E2297, and Practices E165/E165M, E1208, E1209, E1210, E1219, E1417/E1417M and E1444).2 This specification also includes reporting and performance requirements for UV-A LED lamps.

1.2 These tests are intended to be performed only by the manufacturer to certify performance of specific lamp models (housing, filter, diodes, electronic circuit design, optical elements, cooling system, and power supply combination) and also includes limited acceptance tests for individual lamps delivered to the user. This test procedure is not intended to be utilized by the end user.

1.3 This practice is only applicable for UV-A LED lamps used in the examination process. This practice is not applicable to mercury vapor, gas-discharge, arc or luminescent (fluorescent) lamps or light guides (for example, borescope light sources).

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

1.5 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.