Degremont Technologies - a subsidiary of Suez Environnement

Spectral distribution of uv light during aging of medium pressure UV lamps

As part of a project to validate a UV reactor for disinfection of drinking water, the germicidal output of four medium pressure lamps housed in a continuously operating reactor was followed as a function of time. Spectra were measured monthly and were used in conjunction with radiometer readings to calculate germicidal fluence rates (using DNA absorbance weighting) at the radiometer sensor position with the lamps operating at full power (4 kW) during each measurement. Based on the measured fluence rates, the power was adjusted so that the UV lamps operated continuously to deliver a germicidal output of approximately 70% of that obtained at full power at the end of an initial 100 h “burn-in” period when the lamps were new.

The experimental protocol was designed to ensure reproducibility of spectrometer and radiometer positioning and response.

Under the conditions of this test, lamp aging has been relatively slight. The average depreciation in germicidal fluence rates for all four lamps was 17% after 3980 h of operation. Slightly more depreciation was observed in the UVC than in the UVB region (18% versus 15% for the average of all lamps). Consistent with this, the germicidal fluence rate depreciated slightly more rapidly than the total (200 to 350 nm) fluence rate. These changes indicate a more rapid depreciation of the shorter wavelengths, but the extent to which this is due to inherent changes in the lamp spectra compared to solarization of the quartz sleeves cannot be determined from the present data. Efforts will be made to separate these two effects by examining the quartz sleeves at the end of the tests.

Customer comments

No comments were found for Spectral distribution of uv light during aging of medium pressure UV lamps. Be the first to comment!