GE Lamps - Manual (Page 96)

GE LIGHTING - ENTERTAINMENT LIGHTING CATALOGUE 94
Hard glass Halogen compared with Quartz Halogen
The tungsten halogen principle is now so well known and documented elsewhere that it is considered
unnecessary to describe it here. However should you require details of this principle then please
contact GE Lighting Ltd or your nearest Subsidiary Company. It is important to distinguish between hard
glass lamps that merely have a halogen compound added to the filling gas and lamps such as those
enumerated, which are of quartz construction. The former are from the point of view of life and
performance identical to conventional glass lamps of the same rating, the halogen only serving to
prolong the usefulness of the lamp by preventing internal blackening due to evaporated tungsten.
However, once a lamp is constructed from quartz with its higher melting point, instead of glass, the
designer can make use of the much greater strength of the small envelope. It is then possible to
increase the filling pressure which by reducing tungsten evaporation from the filament prolongs the
life of the lamp to at least twice that of a glass lamp of equivalent efficacy.
GE S&S 2000 9/03/00 9/3/00 1:32 pm Page 96