Closeup image of the red hot electrode or filament in a running 400W medium pressure mercury lamp with the arc stream visible
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Contributor:
Callum Fraser / Alamy Stock PhotoImage ID:
2DA16WBFile size:
17.7 MB (496.7 KB Compressed download)Releases:
Model - no | Property - noDo I need a release?Dimensions:
2489 x 2489 px | 21.1 x 21.1 cm | 8.3 x 8.3 inches | 300dpiDate taken:
4 November 2020More information:
Closeup image of 400W Osram-GEC MA/V medium pressure mercury lamp running at full power. Unlike high pressure lamps which have a much smaller quartz arc tube run at significantly higher pressure, the large aluminosilicate arc tube in the MA lamp runs at a lower pressure and is slightly less efficient, particularly so in the smaller wattages. Due to the inherent weaknesses of the aluminosilicate glass, they can only be run vertically, preferably cap up. If they are run horizontally, the arc can bow upwards which over time can stress and break the glass. These lamps deliver poor colour rendering with a greenish-white cold colour, but were a significant step forward in efficiency from the incandescent lamps they replaced, and saw success in area and street lighting. To be run horizontally they need to be installed in a fixture with a magnetic arc deflector, such as the GEC Dioptron. They were later replaced by high pressure mercury lamps, which employ the same concept of a glass tube filled with argon gas and mercury but offered better efficiency in the lower wattages, significantly improved lifetimes and saw wide use into the beginning of the 21st century particularly in the USA.