This Web Exclusive article is provided by Robert E. McLean, CAE, executive director of the Photoluminescent Safety Association (PSA), a trade group based in Arlington, VA. The PSA is dedicated to generating broad-based acceptance of safety-grade photoluminescent products and is an advocate for photoluminescent products before code-setting organizations.
When a crisis occurs in a facility and the occupants are forced to evacuate, the last thing the facility manager (fm) wants to think about is whether the batteries on the exit signs have been changed. With all of the cutbacks as result of today’s economy, can fms be certain their emergency egress systems are ready? Technology improvements to photoluminescent (PL) exit sign options have made this one item on the safety checklist that an fm doesn’t have to worry about in an emergency.
How PL technology works
Photoluminescence uses phosphors derived from non-radioactive natural rare earth mineral crystals. These phosphorous crystals are used in strontium oxide aluminate, which possesses the unique capacity to absorb and store energy from ambient light, like a naturally occurring battery. In darkness, the compounds instantly emit a luminous glow by releasing the stored light energy.
The rapid improvement in PL technology over the past decade has brought to market more effective glow-in-the-dark compounds, providing longer and brighter luminescence capabilities. This improvement has led to PL exit signs and systems receiving UL® listings (UL 924) and acceptance by the International Building Council (IBC), International Fire Council (IFC), and National Fire Protection Association (NFPA).
The UL and NFPA recognize that, as long as nearby lighting is on a few minutes before an emergency occurs, PL exit signs are almost always failsafe. The IBC and IFC regulate safety for new construction and existing construction, respectively, and have mandates for stairwells and passageways to use PL egress markings including handrails and handrail extensions, floor areas, stairs, landings, door areas, and obstacles.
Finding the Way Out
PL Exit Signs
The UL 924 and NFPA 101 Life Safety Codes state that PL exit signs are to be continually illuminated while the building is occupied. During emergencies, these exit signs provide their own illumination, giving off a bright glow. The exit signs are engineered to glow for up to 96 hours in total darkness, providing more than enough time for building occupants to exit a building in low visibility conditions. PL exit signs with readable glow capabilities from 50′, 75′, and even 100′ in the dark are readily available and cost-effective. PL signs contain no consumable parts, and are 100% recyclable.
PL Egress Markings
The IBC and IFC require that buildings occupied above 75′ from the lowest level of fire department vehicle access must equip enclosed stairwells with the following PL markings: steps, landing areas, handrails and handrail extensions, obstacles, door frames, and door hardware.
Inside the stairwell, strips of PL materials are placed: across the leading edge of the top steps and landings; around all landing perimeters within 4″ inches of the floor; around intermediate door frames; on obstacles protruding more than 4″ into the egress path (these are alternating black and PL stripe); along the sides of transfer corridors within 4″ of the floor; and on the final exit door frame.
PL egress markings are positioned low in order to be seen under smoke, allowing occupants to clearly establish their exit path during low visibility.
PL Fire Extinguisher and Fire Hose Signs
Most buildings post signs that identify fire extinguishers and fire hose units. But many of those signs don’t glow or glow very brightly during low visibility, making them practically useless in darkened conditions. PL fire extinguisher and fire hose signs allow building occupants, and firefighters, to locate fire extinguisher and fire hose easily.
PL exit signs are non-electronic and do not have batteries or wiring. Installation is as simple as affixing the sign to the wall or ceiling. An occasional dusting with a damp cloth keeps photoluminescent materials clean.
Acceptance of PL Signage
Back up emergency lighting generators were considered failsafe until the 1993 World Trade Center bombing which destroyed the generator, leaving building occupants to navigate dark stairwells to find their way to safety. After this crisis, PL markings were installed in the towers.
According to the National Institute of Standards and Technology’s final report on the 9/11 disaster, World Trade Center evacuees said that PL markings guided them out of the towers quickly.
New York City has since instituted Local Law 26 that was designed to improve evacuation times during an emergency in all high rise buildings and better protect occupants from the myriad of reasons that electrical back-up systems fail. This led to inclusion of PL markings in the codes to improve occupant safety.
Seconds count…while an emergency requiring evacuation may be rare, having the right safety systems including PL exit signs and egress markings can be the life saving difference and provide occupants and facility managers with peace of mind.