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Column No.6 Safety and Nemoto - (4) "Phosphorescent Evacuation Signage" (May. 31, 2000)On March 8, 2000, a subway accident took place in Tokyo. Trains derailed, six people were killed and sixty injured. If this accident had taken place in a tunnel instead of an open area, these numbers would certainly have been much higher. It is easy to imagine the panic caused if the accident victims were unable to determine the correct direction to evacuate the scene. In such situations, it would be very helpful if Glow-in-the-dark signs were installed in tunnels to show passengers the direction and distance to the nearest station.  Recently such phosphorescent signs (see photo) were installed in a tunnel on the Nanboku line subway in Tokyo. The 30 x 60cm signs are made using a special grade of LumiNova® phosphorescent pigment, which does not need any exclusive lighting apparatus for excitation. The light leaking from the windows of the passing trains is enough to activate these signs. After the successful field test on this subway line, it is expected that these signs will also be installed in other lines currently under construction. Glow-in-the-dark signs are helpful not only for subways but also for other underground areas such as shopping malls, underground passages, and basements in the event of a blackout. Therefore the installation of Glow-in-the-dark signs is regulated by Japanese fire safety law. The Fire Fighting Agency's 1988 guidelines regarding "Exit signs and Evacuation route guiding signs" specified that the: "Installation of emergency signs made of phosphorescent materials is recommended since they emit light even in the dark. Such signs should conform to JIS Z 9100 (Phosphorescent signs) and JIS Z 9115 (Self-luminous signs)" This JIS standard for phosphorescent signs was recently revised because of the drastic increase in the afterglow intensities obtainable when using LumiNova® phosphorescent pigments, and the new JIS Z 9107 (Phosphorescent Safety Signs) has replaced the old specifications. JIS Z 9107 - 1998 Design examples of phosphorescent signs (A selection)
Table: Afterglow luminance of phosphorescent floor proximity markings (mcd/m2) - by FAA report
As shown in the above table, the new standard afterglow values are five to six times higher. Currently, only LumiNova® can meet or exceed this new standard.
As far as international standards are concerned, ISO/FDIS 15370 *1(Evacuation route guiding signs on passenger ships) regulates that the width of the evacuation pass markings can be reduced down to 25mm (when using LumiNova®) from the conventional 75mm (using ZnS based pigment). ISO/CD 17398 *2(Safety signs) is currently under discussion for a revision taking this new JIS as a reference. Phosphorescent material usage in European countries for fire safety signage has the highest utilization in the world. Approximately 100 metric tons per year of Phosphorescent pigment for sheet products is used. Many European sheet manufacturers have already begun to shift their production to high performance LumiNova®. We are extremely pleased to know that our LumiNova® makes such a contribution to the safety sign industries.
Do highway tunnels not require phosphorescent signs? Under normal conditions, light is not of concern because of tunnel electrical lighting and headlights of the vehicles using it. However, should an accident or an electrical malfunction occur, tunnel lighting could become a problem. Phosphorescent materials that are effectively excited by headlights would be very helpful for use in highway tunnels. Unfortunately, modern headlights are equipped with halogen lamps. As shown in the above figure, their emission spectrum is not rich in the UV that is the most effective for the excitation of LumiNova®. In order to solve this problem, Nemoto researchers were successful in developing a new version of LumiNova® which can be excited by halogen lamps. The phosphorescent features of this new grade are shown in the table below. Table; Comparison of new type of LumiNova® with regular LumiNova®
The development of this new type of LumiNova®.has enabled Nemoto to produce phosphorescent signs not only for highway tunnels but also for roads where ambient lighting is not present. This new version will be useful for accident prevention on rural roads or similar places where only headlights are available for excitation of the safety signage. Remarks: |
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