Mercury vapour lighting is a type of High Intensity Discharge (HID) lighting. Other types of HID include high pressure sodium, and low pressure sodium. All HID lamps work on the same principle: an electrical arc across a gas or vapour using the gas or vapour as a conductor, the same way incandescent lamps use a tungsten filament as its conductor. The discharge tends to favour the blue end of the spectrum, so 'colour corrected' versions use a coating to add more of the red end of the spectrum. These bulbs have a slow warm-up time, emiting only a faint glow for the first couple of minutes, but taking about ten minutes to come to full. If you quickly turn them off and back on, it takes several minutes again to regain full brightness. Like other HID bulbs, UV can be a safety concern (in fact, mercury vapour bulbs are an industrial source of UV).
Currently, mercury vapor is being forcibly phased out of use in the US due to the high quantity of mercury used and their relative inefficiency compared to other forms of HID lighting. Currently only the lamps can be replaced, ballasts are no longer being sold. This phase-out does not include specialty lamps such as UV sources.
Currently, mercury vapor is being forcibly phased out of use in the US due to the high quantity of mercury used and their relative inefficiency compared to other forms of HID lighting. Currently only the lamps can be replaced, ballasts are no longer being sold. This phase-out does not include specialty lamps such as UV sources.
