When people hear the word "radioactive," they often think of nuclear explosions or science fiction mutations. But radioactivity—especially in the case of tritium—is much more common and helpful than many realize. In fact, tritium is used safely in medical imaging, scientific research, and one important area you see every day: emergency exit signage.
Next time you’re in a movie theater, retail store, school hallway, or stadium and look up near an exit, take a closer look at the EXIT sign. If the letters glow steadily without flickering or dimming—and there are no wires or batteries—it’s likely a Green Tritium Exit Sign, part of a class of UL-924 Tritium Exit Signs.
What Is a Tritium Exit Sign?
Tritium exit signs, also called non electric tritium exit signs, contain small amounts of tritium gas—an isotope of hydrogen—sealed inside phosphor-coated glass tubes. As the gas decays naturally, it emits low-energy beta radiation, which causes the phosphor to glow. The result: a bright, always-on sign that requires no electricity, batteries, or maintenance.
Because the radiation is so low-energy, these signs are completely safe under normal use as long as the tubes remain intact and sealed. They're approved by the U.S. Nuclear Regulatory Commission (NRC) and have been used safely in thousands of commercial and industrial facilities as nuclear tritium exit signs.
Do Tritium Exit Signs Expire?
Yes. Tritium has a natural half-life of about 12.3 years, meaning the glow will gradually fade over time. Most tritium signs are rated for 10, 15, or 20 years of visibility. After that, the sign will no longer be visible at the required distance and must be replaced.
Why Does Tritium Fade?
As tritium decays, it emits beta particles that excite the phosphor coating in the glass tubes to produce light. Over time, as the tritium gas is consumed, the glow dims. After two decades, only about 25% of the original brightness remains.
Where Are Tritium Signs Used?
Tritium exit signs are ideal in environments where electricity is unavailable or unreliable, such as:
- Underground tunnels and mines
- Elevator shafts and stairwells
- Cold storage facilities
- Outdoor stadiums and arenas
- Oil rigs and marine applications
- Remote outbuildings and unpowered shelters
- No Power Exit Signs applications
Green vs. Red vs. Black Tritium Signs
- Green Tritium Exit Sign: The most common in North America. Highly visible and UL 924 compliant.
- Red Tritium Exit Sign: Required by some local fire codes (e.g., NYC).
Disposing of Expired Tritium Signs
Because tritium is a regulated radioactive material, it must be recycled. The NRC requires proper documentation and handling of expired units to prevent environmental or health risks if broken.
We offer a streamlined Tritium Exit Sign Recycle service for safe and compliant disposal.
Why Tritium Is a Smart Emergency Lighting Option
- Completely self-powered – no wires or batteries
- UL-924 Tritium Exit Sign compliant and always on
- Maintenance-free and sealed
- Ideal for No Power Exit Signs and Glow-In the Dark Exit Signs
- Works in wet, remote, and off-grid locations
Are They UL 924 Listed?
Yes. All of our UL-924 Photoluminescent Exit Signs and tritium models meet UL 924 and state fire codes when installed correctly in accordance with visibility and mounting guidelines.
Final Thoughts
So, is tritium dangerous? Not when used properly. In fact, it’s one of the safest and most reliable forms of emergency egress lighting. With zero maintenance, sleek design, and always-on functionality, tritium exit signs are ideal for modern safety strategies—especially when electric power isn’t guaranteed.
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