Posted by Ingo on June 29, 2000 at 01:23:16:
In Reply to: Ingo What does HQI and HQL stand for? (more) posted by John Styner on June 28, 2000 at 10:04:10:
I donīt know exactly what the letters stand for---maybe they are not used in the US and you call them just metal halides??????..I donīt know. Anyhow, both are mercury vapor bulbs. Visible light of a more or less continuous spectrum (in contrast to the distinct bands in the HG spectrum) is created in HQL Bulbs only at the coating of the bulb. Although HG spectrum contains UVA,Band C bands, only light with wavelengths >400nm is emitted from the coating. In HQI bulbs, the gas in the bulb is enriched with dysprosioum and sodium jodide which serve as fluorophores and hence a coating of the bulb is not necessary. If the quartz glass of a HQI bulb is not modified, a lot of uva, b and c is emitted. If a protective glass is in front of the burner, all UVB and C is filtered out. In contrast, uvb and c can pass quartz glass without significant absorbance.
Hope that helps
Ci@o
Ingo