206889 ⎘
Discharge tubes and lamps; Disassembly or repair of discharge tubes; Discharge tubes with liquid poolcathodes; constructional details; Cathodic cups; Screens; Reflectors; Filters; Windows; Protection against mercury deposition; Returning condensed electrode material to the cathodic cup; Liquid electrode level control Gas fill; Maintaining or maintaining desired pressure; Producing, introducing or replenishing gas or vapour during operation of the tube; Getters; Gas cleaning; Electrode cleaning