Luminance is the angular, rectangular, and surface density of luminous flux falling on, passing through, or emerging from a surface in a given direction. It is also defined as the surface density of luminous intensity in a given direction. On its own, the decay time is the time elapsed from the end of the stimulus until the brightness decreases to 0.3 mcd/m2.
In the field of safety, the Fire Protection Installation Regulations (RIPCI) stipulates that photoluminescent signs need to meet the requirements of the UNE 23035 standard.
This standard (UNE 23035-4 in particular) establishes the minimum values of luminance and decay time that photoluminescent signs need to meet in order to be classified as Type A or Type B. The standard also specifies the test procedures to be followed for measuring luminance and calculating fade times.
On the other hand, it is necessary to carry out an accelerated aging test on photoluminescent signs by means of salt spray according to the UNE 23035-4 standard. In these tests, fade time and brightness need to be determined. For this evaluation, the signal will be evaluated before and after the artificial atmosphere corrosion test. As for the salt spray test, it needs to be carried out in accordance with the guidelines of ISO 9227:2017. It should be noted that the luminance and decay time values obtained after the aging test cannot be reduced by more than 5% relative to the values obtained before said test.
The testing of photoluminescent products is based on the measurement of said products after excitation with a specific illumination for a certain time. After the stimulus ceases, the brightness emitted by the product needs to be measured for a given period of time. From these measurements, decay times can be calculated by extrapolation.
Different standards for conditioning the photoluminescent signal determine the excitation or stimulation conditions, as well as the measurement conditions and the calculation of the decay time.
The following tests are required:
According to the UNE 23035-1:2003 standard, it is used to determine the decay time and brightness in photoluminescent products and signs. Fire Safety. Photoluminescent signage. Part 1: Measurement and identification.
UNE 23035-1. Luminance and decay time are measured in accordance with UNE EN 23035:2003. Fire Safety. Photoluminescent signage. Part 2: Measure the product at the point of use.
ISO16069:2004. Graphical symbols - Safety signs - Safe way guidance system (SWGS).
Measures luminance, the light response under low stimulus conditions.
DIN 67510-1:2009. Phosphorescent pigments and products - Part 1: Measurements and marking by the manufacturer.
ASTM E2073-10 Standard Test Method for Photopic Brightness of Photoluminescent (Phosphorescent) Labels.
Ships and marine technology - Low position lighting on passenger ships - Arrangement ISO 15370.
Determination of brightness and decay time before and after corrosion in a salt spray atmosphere according to UNE EN ISO 9227:2012
Determination of specular gloss at 20º, 60º and 85º UNE EN ISO 2813:2015
Artificial aging due to exposure to artificial radiation UNE EN ISO 16474:2014/UNE EN ISO (Xenon arc lamps) 11341:2005.
