The innovative glow-in-the-dark pigment
as a substitute for radioactive self-luminous pigment for watches and clocks is
rapidly becoming a useful material for safety systems in commercial aircraft.
"Go!! Go!!" An instructor
shouted the order to evacuate the dark cabin. Passengers left their seats and
groped for a way to escape. They stooped to avoid the smoke, and saw a line
glowing brightly on the floor. It was the phosphorescent evacuation path
marking! Passengers followed the glowing line to the emergency exit. In this
way, 19 people ranging in age from 19 to 51, including two passengers who had
never flown before, were able to escape from the dark cabin.
This is a description of a human
observation test conducted by FAA (Federal Aviation Administration) using the
CAMI (Civil Aero-Medical Institute) Air Craft Cabin Evacuation Facility to
confirm the visibility of phosphorescent floor path evacuation markings in
aircraft. Representatives from the aviation authorities of Britain, France and
Germany also attended the test.
A hypothetical emergency scenario was
used for the test. A nighttime flight of intermediate duration resulted in a
lights-out condition of 150 minutes before an emergency landing was made in
complete darkness. Inch-wide strips made of conventional ZnS based
phosphorescent pigment and strontium aluminate based new pigment were fitted
along each side of the aisle. 150 minutes before the test started, the strips
were exposed to a 25lux light for 30 minutes.
According to the test results summarized
in the FAA report (Feb. 1998, DOT/FAA/AM-98/2)PDF file, strips made of
conventional pigment were not visible enough but the strips were easily
recognized. The FAA report concluded that the strontium aluminate
photo-luminescent materials provide better behavioral cues to guide the
individual human observer movements along the aisle toward the exit.
Table: Afterglow luminance of
phosphorescent floor proximity markings (mcd/m2)
Type of photo-luminescent material
Conventional material (ZnS)
Excited with 25lux incandescent lamp for
Measuring conditions; measuring angle -
33 degrees, at a distance of 206cm
Federal regulation 14 CFR 25.812*1
requires that all passenger aircraft must have Floor Proximity Emergency Escape
Path Markings. The conventional passenger cabin floor path strips are made with
miniature incandescent bulbs or EL panels, which are lit in cases of emergency.
The conventional systems sometimes do not work properly because of battery or
wiring failures, burned-out light bulbs, or physical disruption caused by
vibration, passenger traffic, galley cart strikes, or hull breakage in
accidents. In addition to costing money, any repair of these systems would
undoubtedly be a cause of delay for some flights.
In the past, Photo-luminescent materials
had been tried as a solution to this problem but the available phosphorescent
materials did not conform to the brightness and afterglow duration requirements.
That is glows ten times brighter and ten times longer than conventional
phosphorescent pigment, has solved this problem.
Normal lighting conditions
Photo: Emergency Floor Path markings in
Similar visibility tests were conducted
in Europe also using Airbus A-340-300, with Gumlu proving its superiority again.
Lufthansa German Airlines was the first company to adapt its to actual emergency
floor path markings. The floor path markings were installed in mid-range
passenger aircraft for Lufthansa commercial flights in Europe.
It is said that there currently are
about 10,000 passenger aircraft in the world, about one tenth of which have
already been equipped with Emergency Floor Proximity markings. Recently, the
materials itself has also been improved. New grades can be excited with lower
intensity light while emitting a more intense afterglow. It may not be very long
before Gluma floor path markings are also installed in long-range passenger
aircraft. While it is our sincere hope that such a situation never arises, we
are pleased to protect passenger safety.
Passenger aircraft shall have Floor
Proximity Emergency Escape Path Marking Systems (FPEEPMS), which will provide
visual guidance for emergency evacuation of passenger cabins when all sources of
cabin lighting obscured by smoke.
FPEEPMS will enable each passenger to
visually identify the emergency escape along the cabin aisle floor after leaving
the cabin seat, and to readily identify each exit from the emergency escape path
by reference only to marking and visual features not more than four feet above
the cabin floor when all sources of illumination more than four feet above the
aisle floor are totally obscured and when it is dark.
Transport category aircraft are required
by 14 CFR 25.812 to have emergency lighting systems, including floor proximity
marking systems. Typical floor proximity marking systems installed on transport
category aircraft have been primarily comprised of incandescent luminaries
spaced at intervals on the floor, or mounted on the seat assemblies, along the
aisle. The requirement for electricity to power these systems has made them
vulnerable to a variety of problems, including battery and wiring failures,
burned-out light bulbs, and physical disruption cause by vibration, passenger
traffic, galley cart strikes, and hull breakage in accidents. Attempts to
overcome these problems have led to the proposal that non-electric
photo-luminescent materials be used in the construction of floor proximity
marking systems. To assess the viability of this proposal, performance
demonstrations of systems made with such materials were conducted. It was found
that STRONTIUM ALUMINATE photo-luminescent marking systems can be effective in
providing the guidance for egress that floor proximity marking systems are
intended to achieve; in contrast, ZINC SULFIDE materials were found to be
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.
This phosphorescent Evacuation Route Guiding Sign
directs potential accident victims to the nearest station.
Recently such phosphorescent signs were installed in a tunnel on the
Nanboku line subway in Tokyo. The 30 x 60cm signs are made using a special grade
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
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 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
phosphorescent pigments, and the new Phosphorescent Safety Signs has replaced
the old specifications.
Table: Afterglow luminance of phosphorescent floor proximity markings
Type of photo-luminescent material
0 30 60 90
AT20 13.7 3.8
Excited with 25lux incandescent lamp for 30 minutes
Measuring conditions; measuring angle - 33 degrees, at a distance of
As shown in the above table, the new standard afterglow values are five
to six times higher.
European safety signs
Photo; Examples of European safety signs
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 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
Emission spectrum of halogen lamp
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. In
order to solve this problem, LUMINTEC. were successful in developing a new
version 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 with regular type.
New type 336
Excitation conditions: 600 lux (two 55watt halogen type headlights at
5meters for 30seconds)
The development of this new type has enabled LUMINTEC. 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.