Choosing a UV light source means matching five variables to the process: the photo-initiation or germicidal wavelength, the irradiance at the work surface, the geometry of the lamp, the cooling method, and the expected service life. The right answer is almost never 'the most powerful lamp' - it is the source that delivers the required dose repeatably over the whole production shift.
Match the emission to the absorption of the photo-initiator or to the germicidal action spectrum. UV-LED sources are usually quoted at 365, 385, 395 or 405 nm for curing and 265-280 nm for disinfection, while mercury lamps emit a broad spectrum plus the strong 254 nm line.
Divide the required dose by the residence time to obtain the irradiance the source must deliver at the work surface. Remember that irradiance falls with the square of the distance from a small source and that optics or reflectors change the profile.
LED sources keep their output far longer than mercury lamps but de-rate with junction temperature, so cooling design matters. Compare lamp replacement, electricity and downtime, and plan periodic measurement so that end-of-life is detected rather than assumed.
| Low-pressure mercury | 254 nm line, low power density, long life | Water and air disinfection |
|---|---|---|
| Low-pressure mercury | 254 nm line, low power density, long life | Water and air disinfection |
| Medium-pressure mercury | Broad spectrum, very high power density | Curing, printing, thick films |
| UV-LED | Narrow band, instant on/off, mercury-free | Point curing, small disinfection systems |
The same selection method applies to curing, printing, coating and disinfection projects.
Photo-initiator absorption decides the wavelength
Distance, footprint and line speed
Output de-rates as temperature rises
Plan replacement from measurement
Confirm irradiance on the real production line
Lamp, power, downtime and scrap
Selection cannot be closed on paper: the irradiance the source actually delivers has to be measured on the machine.
| Irradiance (mW/cm2) | The figure quoted in a lamp datasheet must be confirmed in situ | UV-int140 / UV-int150 |
|---|---|---|
| Irradiance (mW/cm2) | The figure quoted in a lamp datasheet must be confirmed in situ | UV-int140 / UV-int150 |
| Dose (mJ/cm2) | Confirms the chosen source and line speed are sufficient | UV-int150 / UV-intS |
| Spectral match | Checks that the emission really matches the absorption peak | UV-int253 for UVC, UV-intM for multi-wavelength |
Only irradiance at the work surface and the chemistry's response to it set the achievable line speed.
Datasheet values are measured under reference conditions; distance, optics, dirt and cooling all reduce the delivered irradiance.
Start from the required dose (mJ/cm2) and the line speed, not from the lamp wattage; the two together set the irradiance you actually need.