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Philips MHN-T 70W Open Fixture Metal Halide |
The aggressiveness of thulium iodide towards the quartz arc tube was tamed by using it in conjunction with dysprosium and holmium iodides. These also assisted in correcting the slightly greenish-yellow coloured light of the thulium lamp.
Still the problem of arc tube explosions would sometimes occur, and to enable the development of a new series of compact open-fronted luminaires to accompany this new lamp, it was necessary to make it in a shatterproof format. Two heavy-walled quartz shrouds surround the arc tube, the ends of the shrouds being capped with metal plates.
A slim clear tubular outer jacket is employed, to capitalise on the very short arc gap, and allow excellent optical control when positioned at the focal point of a reflector. With standard E27s screw bases the arc tube position is not well controlled with respect to the lampholder. Consequently the base of this lamp was re-designed as a push-fit pre-focussed design. The base was originally manufactured in white polycarbonate, but owing to the slight discolouration that is sometimes noticed at end of life, it was changed to a nickel plated brass metal shell after a few years. The mechanical arrangement and dimensions of this lamp are the same as for Philips SDW-T White SON, and the two types could therefore be built into the same luminaire to provide a choice of colour.
| Manufacturer: | Philips Lighting | |
| Lamp Power: | 75 Watts | |
| Lamp Current: | 1.0 Amps | |
| Lamp Voltage: | 90 Volts | |
| Cap: | PG12-2 | |
| Bulb Finish: | Clear hard glass | |
| Bulb Type: | T-32 | |
| Overall Length: | 91 mm | |
| Light Centre Length: | 149 mm | |
| Electrodes: | Backwound tungsten | 7mm arc gap |
| Atmosphere: | Ar | Hg (Dy,Ho,Tm) Ix | |
| Luminous Flux: | 5500 lumens | |
| Luminous Efficacy: | 73 lm/W | |
| Colour Temperature & CRI: | CCT : 4200K | CRI : Ra 85 |
| Chromaticity Co-ordinates: | CCx : ~ 0.36 | CCy : ~ 0.36 |
| Burning Position: | Universal | |
| Rated Life: | 6000 hours | |
| Warm Up / Re-strike Time: | 2 minutes | 5 minutes |
| Factory: | Turnhout | Belgium |
| Date of Manufacture: | October 1996 | |
| Original / Present Value: | N/A | |
