Drastic cut in mercury
Drastic cut in mercury
Osram-Sylvania in the US has managed to reduce the mercury content in its high-pressure sodium (HPS) lamp by 97%. Unlike other attempts at developing a low-mercury HPS lamp, Osram-Sylvania claims to have achieved this decrease without compromising efficacy or the quality of the light emitted from the lamp.
According to Jeremy Pymento at Osram-Sylvania, the new HPS lamp is intended as a retrofit for standard HPS lamps and operates on existing HPS ballasts for corresponding wattages. The lamp's performance characteristics are identical to those of the previous generation of lamps, except for one important feature: When lamps reach the end of their life, their light output decreases, and the light changes to a whitish color, similar to that of mercury-vapor lamps, instead of cycling on and off for a long period. Maintenance crews can thus identify lamps that need replacement. The absence of cycling helps prolong ballast life.
A 100W lamp has a luminous flux of ~9 500 lumens, resulting in a lamp efficacy (excluding ballast) of 95 lumens/W, and for the 400-W lamp, the ratio is 125 lumens/W. The new product line of lamps includes a new 250-W lamp with an efficacy in between that of the two others. These are normal efficacies for HPS lamps.
The great advantage of these lamps is their low content of mercury. Whereas a conventional HPS lamp contains about 30 mg of mercury, the new lamp only has ~1 mg. The lamps also come with a welded, lead-free mogul base instead of the traditionally lead soldered base, thereby further reducing environmental impacts when disposing of used lamps.
Osram Sylvania claims that the new lamps will be about 25% more expensive than their conventional HPS lamps. According to Osram in Europe, the lamp must undergo testing to determine its compliance with current standards before it can be introduced in Europe.
Nils Borg
See also:
Mercury and Lighting: Managing the Problem, IAEEL 3/93)
Mercury: a Broader Perspective (IAEEL 3/93)
More on mercury (IAEEL 1/94)
New HPS lamp not in Europe (IAEEL 1/95)
0% mercury retrofit HPS (IAEEL 1/95)
Note: Osram Sylvania is a North American company. In all other parts of the world, Sylvania and Osram are different companies.