A tritium-powered EXIT sign where illumination is produced by radio luminescence (beta particles from the decay of 12.3 y half-life tritium striking a phosphor). The sign, which measures 21 cm high by 32 cm wide by 4 cm thick, was manufactured by Tri-Vision International, Montreal, and has a stated expiration date of 1995.
The date of manufacture is unknown but the Tri-Vision website states that the company was incorporated in 1986. When constructed, the illuminating unit contained 25 Curies of tritium. It is assumed that the expiration date was dictated by the decrease in illumination as the tritium decays. Information labels state the unit was a Model 2040 with a Serial Number of D40002.
The sign consists of three components – the illumination unit, an open-faced metal container and a removable, bilingual, plastic sheet with the words EXIT and SORTIE.
