Philips SL*18 Demonstration Lamp

This is a special demonstration lamp created to show the technologies behind the Philips SL compact fluorescent lamp, which was launched to the market just a few months later in its final format of the SL*18.

The design was still refined a little following the creation of this sample. Most notably the light diffusing coating of the outer bulb still takes the form of a fine coating of silica powder, as used on its predecessor, the SL1000. Here the coating has been left partially clear to show the internal construction, and also the ends of the discharge tube are uncoated to reveal the internal electrode assembly. In the final production version, a prismatic moulded glass bulb was used instead, which led to a small increase in luminous flux and avoided the coating process. The length of the production lamp was also increased slightly, and the size of its ballast was enlarged - presumably to avoid difficulties with overheating and to extend lamp life.

The resulting SL*18 production lamp was the first one-piece self ballasted compact fluorescent lamp which had the potential to supersede incandescent lamps in many applications, offering energy savings of 75% and a five-fold longer lifetime.

A crucial development that made this lamp feasible was the invention by Louis Vrenken of the rare earth phosphors with an aluminate host lattice, in place of the usual silicates or tungstates. These new materials slowed the rate of lumen depreciation, a degradation process that had been too fast to achieve a useful lifetime in tubes of such narrow diameter when using traditional phosphors.
Manufacturer: NV Philips Gloeilampenfabrieken
Lamp Power: 18 Watts
Lamp Current: 0.196 Amps
Lamp Voltage: 220 Volts
Cap Type: E27s/27 Ni plated brass + vitrite
Bulb Type: T-72
Bulb Finish: SiO2 Coated Soda-lime glass
Electrodes: Triple coiled tungsten Triple carbonate emitter
Atmosphere: Inner: Ar|Hg Amalgam Outer: Air
Luminous Flux: 900 lumens @ 100h hours
Luminous Efficacy: 50.0 lm/W @ 100h hours
Colour Temperature & CRI: CCT: 2700K CRI: Ra=80
Chromaticity Co-ordinates: CCx: 0.462 CCy: 0.412
Rated Lifetime: 5,000 hours to 70% survival
Warm-up & Re-strike time: 3 minutes Instant re-strike
Burning Position: Universal
Overall Length: 160 mm 63/8 inches
Light Centre Length:
Mass: 520 grams
Factory: Terneuzen The Netherlands
Date of Manufacture: October 1980 Date Code 0K
Original Value: No commercial value