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Medium Pressure Mercury Vapour
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Updated
16-XII-2022 |
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Medium pressure mercury lamps are classified as the MA type. They operate at a vapour pressure of about one atmosphere, the discharge dissipates between 10 and 100 watts per centimetre of arc length, and their arc tubes are made of a special thermally-resistant aluminosilicate hard glass.
This was the first successful mercury lamp for general lighting applications. The technology was developed in 1931 by Osram-GEC of England, by combining its expertise in glassmaking with a fundamental new electrode design conceived by Osram in Germany. The concept was introduced in 1932 and proved tremendously successful. By 1933 the lamp technology had been licensed to the European manufacturers, in 1934 to the Americans, and was soon adopted worldwide.
The first lamp was a 400W rating limited to vertical use. Later achievements permitted horizontal and then universal operation, and other power ratings were developed. However, the lower power lamps of 150W and 90W were not commercially viable, due to a rapid decrease in efficacy as lamp power is reduced. This problem was not solved until the developmennt of the MB High Pressure lamps. Improved variants of the MA lamps were made with a fluorescent bulb and in a self-ballasted design. Detailed information on the development and fundamentals of medium pressure mercury lamps can be found at the MA Technical Section. |
| | British Lamps |
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Osira |
150W |
| Osira MA/V low wattage lamp |
| 1936-37 |
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Mazda |
400W |
| Mercra MA/V early British design |
| 1944 |
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Philips |
250W |
| Philora MA/V early British design |
| 1945 |
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Mazda |
250W |
| MA/U improved universal burning design |
| 1955 |
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Crompton |
250W |
| MA/V with air-filled outer bulb |
| 1959 |
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Osram |
400W |
| MA/V of late design for vertical use |
| 1963 |
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Mazda |
1000W |
| MA/H horizontal floodlighting |
| 1952 |
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| | European Lamps |
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Osram |
265W |
| HgH 1000 of early German construction |
| 1957 |
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Osram |
450W |
| HgH 2000 of later German construction |
| 1945 |
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Philips |
450W |
| HO 450 of later Dutch construction |
| 1956 |
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| | American Lamps |
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Westinghouse |
400W |
| A-H1 of early American design |
| 1942 |
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GE |
400W |
| A-H1 of early American design |
| 1947 |
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GE |
250W |
| H-2 with unusual bare arc tube design |
| 1944 |
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GE |
400W |
| H25-DE of late American design |
| 1959 |
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| | Soviet Lamps |
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MELZ |
500W |
| IGAR-2 of high power Russian design |
| 1957 |
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| | Coloured Lamps |
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Siemens |
400W |
| Sieray MA/H coloured lamp for floodlighting |
| ~1940 |
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Siemens |
400W |
| Sieray MA/H coloured lamp for floodlighting |
| ~1940 |
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