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MB/V High Pressure Mercury Discharge |
Although the company made its own arc tubes and in fact the whole lamp for the hard glass MA products, it did not engage in the production of quartz arc tubes for the later MB style. It is believed that the arc tube in this lamp was sourced from Mazda, and sealed into the outer envelope at Crompton's works. Crompton was a very successful player in the production of MA lamps owing to its uniquely simple design which did not require the outer bulb to be sealed and gas-filled. As a small manufacturer this cost saving allowed it to compete well against the major lighting firms.
However this same design could not be applied to MB lamps for several reasons. Most significantly, the molybdenum foil seals in the quartz MB style arc tube are quite sensitive to oxidation, and the arctube therefore has to be run inside an inert atmosphere - carbon dioxide in these early lamps, and later nitrogen. Owing to the expense of having to buy in the new quartz arc tubes from a competitor, Crompton lost its stronghold of the mercury lamp market as the MB series gradually took over, and once the MA lamp had been rendered obsolete the company exited the discharge lamp production business. Alternatively it sourced in finished lamps in under its own name, as it continues to do so today.
Precise dating of this lamp is difficult owing to the 2-year date code cycle employed on Crompton lamps. The pinched arc tube seals date it as post 1950 though.
| Manufacturer: | Crompton Parkinson Ltd. | |
| Lamp Power: | 80 Watts | |
| Lamp Current: | 0.8 Amps | |
| Lamp Voltage: | 115 Volts | For 200-250V Mains |
| Cap Type: | B22d-3/38x30 | Brass + vitrite |
| Bulb Finish: | Pearl | Soda-lime soft glass |
| Bulb Type: | PS-80 | PS-25 in eighths/inch |
| Overall Length: | 160 mm | 6¼ inches |
| Light Centre Length: | 120 mm | 4¾ inches |
| Arc Length: | 20mm | ¾ inch |
| Electrodes: | Backwound tungsten | Double carbonate emitter |
| Atmosphere: | Inner: Hg | Ar (8 atm) | Outer: Nitrogen |
| Luminous Flux: | 3,000 lumens | @ 100 hrs |
| Luminous Efficacy: | 37.5 lm/W | @ 100 hrs |
| Colour Temperature & CRI: | CCT: 6000K | CRI: Ra 16 |
| Chromaticity Co-ordinates: | CCx: 0.315 | CCy: 0.380 |
| Burning Position: | Universal | Horiz. lumens 10% less |
| Rated Lifetime: | Not published | |
| Warm-up & Re-strike Time: | 4 minutes | 5 minutes |
| Factory: | Guiseley | England |
| Date of Manufacture: | November 1954 | Date Code: 59 |
| Original & Present Value: | Unknown | |
