Replacement ultraviolet lamp for the Hanovia WS204B disinfection system, part 130065-0040. Medium-pressure UV lamps lose output steadily through life rather than failing outright, so they are replaced on elapsed running hours against the system’s dose record, not when they stop lighting. The WS range covers several chamber sizes and the lamps are not common across them, so order against the specific model — a WS204B lamp is not a WS214, WS216 or WS230 lamp. Reference number 22134-0517.