OSRAM DULUX F - Manual (Page 23)

Economical long-life light sources with plug-in bases
Compact Fluorescent Lamps OSRAM DULUX ®
Technical Guide
21
Relation between cold spot temperature in a fluorescent lamp and the mercury vapour pressure in the dis-
charge.
OSRAM DULUX® CONSTANT (amalgam lamps)
In contrast to standard cold spot lamps, OSRAM DULUX ® CONSTANT (amalgam lamps) were spe-
cially designed to achieve the optimum light output over a wide ambient temperature range.
CONSTANT technology enables the use of fluorescent lamps in applications where very high or on
the other hand very low lamp-ambient temperatures prevail. Circumstances, where the cold spot
fluorescent lamp technology already suffers on a significant light flux depression.
CONSTANT lamps use amalgam and its special physical properties to control the vapour pressure
in the lamp. Amalgam is an alloy consisting of mercury and different metals such as Bi, In, Ag. The
Hg-vapour pressure (and consequently the luminous flux) is then controlled by the composition and
the temperature of the amalgam. A CONSTANT lamp does not have a cold spot like a conventional
lamp. The amalgam is located either in a tube-end tip inside of the socket, or on the framework,
mounted on one of the electrodes.
Amalgam generally needs a higher operation temperature itself, compared to the liquid Hg in a cold
spot controlled lamp. This causes a certain delay (time shift) on the run-up behaviour. In order to
shorten the run-up time of the CONSTANT lamp, a second, so called run-up amalgam flag is in-
stalled in the close vicinity of the emitter coil. The run-up amalgam is heated very quickly by the coil
and releases a certain amount of mercury to the discharge, which speeds up the run-up of the lamp
luminous flux.
The use of amalgam enables a significantly expanded temperature range with optimal Hg vapour
pressure and consequently, a lamp light output above 90% of the nominal. (See chart below).
0,1
0,01
0,001