No. 104 - Miljøstyrelsen

20
Figure 2-3. Example of lamp with casing (from the list of A-lamps of the Danish energy
saving trust)
This manufacturer states that this additional casing may be an extra
protection of the consumer since in some cases only the outer glass breaks in
case of accidents. On the other hand this extra casing means that the light
yield (lumen value) is reduced by at least 10 % due to reflection and
absorption in the outer casing. It is possible to change the absorption features
of the outer casing in order to give the lamp more pleasant colour features
(e.g. less bluish and more reddish spectre). According to the manufacturer no
extra mercury is added to compensate for the loss of light yield (lumen).
Furthermore, the same manufacturer has stated that the compact fluorescent
lamp without the extra casing is presently most popular on the market, since it
is normally cheaper. The extra casing increases production costs and thus the
lamp sales price.
2.2 Survey of quantities of mercury
The survey showed that quantities of mercury in fluorescent lamps vary
much. Differences are seen not only from one manufacturer to the other, but
also between types of lamps from the same manufacturer. No pattern has
been found regarding types of lamps whether divided according to lamps with
integral ballast, without integral ballast, straight fluorescent lamps or shape of
lamps.
According to Manufacturer D quantities of mercury depend on the following
factors some of which have an influence on quantities of mercury over time
(also described by Snijkers-Hendrickx et al. (2007)):
� Size of lamp. The larger lamp the larger surface of glass and
phosphor coating to be impacted by the mercury, and thereby
requirement for larger quantity of mercury.
� Lifetime of the lamp. The longer lifetime the more mercury can be
bound to the phosphor coating during the lifetime of the lamp.
� Use pattern. Number of switch on/off cycles. Electrodes ”consume”
mercury during the life of the lamp. Long life fluorescent lamps
thereby require ”surplus” mercury (Sigai & Nesting).
� Dosage technology. If mercury is added in the form of a tablet or as
amalgam, more accurate quantities of mercury can be added
compared with dosage of liquid mercury.
� Material composition. Different materials used for fluorescent lamps
(glass, phosphor coating, etc.) have different capacity to bind
mercury through the lamp life. In addition, impurities in the glass
material may have a decisive role for consumption of mercury in the
lamp life.