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Self Luminous Tritium Exit Sign Facts

A Guide to Tritium Exit Signs

Unlike standard exit signs that require electrical hookup to charge and backup batteries during power outages, self luminous tritium exit signs use a completely self-sustaining light source. Self luminous signs are illuminated via radioluminescence, when the phosphor coating inside glass tubes interact with electrons emitted by suspended tritium gas. The radioactive electrons excite electrons in the phosphor substance, creating visible light. The emitted light from a radioluminescent exit sign is not perceptible during the day, but at night (or when general lighting is interrupted) the 'EXIT' legend stands out in complete darkness.

Are nuclear exit signs dangerous?

The radioactive tritium gas is suspended in airtight glass tubes, making them completely harmless when intact. If one of the glass envelopes break, leaking tritium gas into the atmosphere, there is still no real hazard to humans. Since tritium is a hydrogen isotope in a gasous form, it quickly dissipates into the air. Even if all the tubes break, the amount of tritium exposure is less than half the dosage an average human absorbs from natural radioactive sources, like sunlight.

How long do they last?

Tritium exit signs come in two lifespan options: 10 and 20 years. A sticker on the sign shows the expiration date. It is advisable to order a replacement sign 4-6 months before this expiration date, as the lead time for these signs is significantly longer than standard electronic signs.

Are tritium signs legal?

Self luminous exit signs meet all the requirements of the NFPA 101: Life Safety Code, OSHA, Underwriters Laboratories (UL) and the FAA (non-electrical signs are standard aboard commercial airliners).

How do I know if the sign is working?

You do not have to press a button or do anything to activate SL signs. The sign is already "on". But during the day, or when general lighting is on, the sign will look like its off. This is because there is a very small amount tritium contained in the sign. This light, however, is on all the time can be clearly seen the second lights are turned off.

Why do you need so much personal information just to buy an exit sign?

By law, self luminous exit signs must be registered with the U.S. Nuclear Regulatory Commission (USNRC). Before we can ship out a sign, we must provide the following end-user information to the USNRC to authorize:

Company Name - who and where the signs will be installed. 

Address of Installation - street, state, zip code.

Contact Name, Title, Email Fax and Phone Number - for the person ultimately responsible for the signs.

Can I throw tritium exit signs in the trash?

The answer is a resounding "no". While harmless, these signs are monitored by the USNRC and require strict documentation and processing for the disposal process. Luckily you can Contact Us to take care of all your disposal needs!