Tritium Exit Sign Technology

The phenomenon that represents the basic principle behind the tritium exit sign is that same one that produces the various colors that come from all sorts of radioactive substances. It is something that concerns the disintegration of a particular element, one with radioactive properties. In this case, that element/isotope of hydrogen is tritium (H-3).

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Unlike the battery operated type of signage, the H-3 sign does not rely on the presence of wires, wires that carry flowing electrons. By the same token, it continues to operate, even in the absence of stored chemical energy, such as that furnished by a battery. The sign’s glow results from the fact that it holds an isotope, one that represents the starting point for cascade.

Origins of the discovery

Rutherford first jotted down his observations regarding such a cascade, while studying heavy radioactive materials, such as radium. He noted that all radiation comes from a disintegrating element or isotope. In the course of that element’s/isotope’s disintegration it becomes transformed into a series of breakdown products. Each breakdown product results from movement of one or more of the electrons that have been spinning around the nucleus of the disintegrating element/isotope.


Whenever such an electron moves to a spin level that is closer to the nucleus, then a quantum of energy is released. That energy represents the power source for the almost magical glow, the glow that comes from a substance that possesses a radiating capacity.

H-3 tritium signs

In the case of an H-3 exit sign, only a tiny quantum of energy has been released, each time an atom in the encased isotope disintegrates. Therefore, the color of the resulting glow remains hidden from the human eye, at least while it competes with the beams from a functioning lighting fixture. However, when those lights go out, then a human eye can detect the glow coming from the disintegrating tritium.

Safely Handling Tritium Exit Signs

Unlike the colorful glows associated with heavier radioactive materials, the one produced by tritium does not pose a great threat to the health of any humans who get hit by the released energy. Still, all tritium-containing exit signs must have a radioactive label. In the U.S. any plant that manufactures such signage must ensure proper placement of that label.

By the same token, that manufacturing facility must provide the buyer of any signage with its license number, a number given to it by the U.S. government. That provision is not an attempt to maintain the color of each sign’s glow. Instead, it demonstrates an effort by the government to keep track of the intact nature of each doorway-topping product. Each of them is supposed to feature dual protection: one high impact tube inside of another one. That dual system holds the radioactive H-3.

Licensed disposal of Tritium signs

Obviously, having mandated utilization of that dual system, the government has a strong interest in keeping track of its integrity. Therefore, each person who buys and uses a tritium exit sign is expected to look for evidence that its tubes are cracked or broken. Upon discovery of any crack or break, he or she is supposed to notify the designated agency, the United States Regulatory Commission. Such notification is meant to guard against continued leakage of a radioactive substance. The value of tritium’s colorful glow diminishes greatly, if that isotope leaks onto material outside of its strong glass tubing.

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