Pulsed UV lamp performance and comparison with UV mercury lamps

Abstract

Pulsed lamps based on electric discharges in xenon are of interest for water treatment because they are free of mercury, have instant-on capability, and may provide enhanced effects due to the high irradiance of pulses or spectral differences. This study provides quantitative comparisons of standard mercury UV lamps with both a commercial flashlamp and a pulsed surface discharge lamp. Unlike mercury lamps, the UV performance of pulsed lamps is a function of operating parameters. In this study the measured UV efficiency of a flashlamp, with a specified practical lifetime, increased as the pulse length decreased, from 4.4% at 796 μs to 9.0% at 71 μs. The surface discharge lamp, which overcomes limitations of flashlamps, had a measured UV efficiency of 17% at 12 μs. In comparison, standard commercial low pressure and medium pressure mercury lamps evaluated in this study had UV efficiencies of 34.6% and 12.2%, respectively. Key words: pulsed UV, water treatment, flashlamp, surface discharge, mercury.