Germicidal Lamps - 254nm - no filter – Witec AG

Germicidal UV lamps of 254 nm prevent contamination in research laboratories.

• Wavelength = 254nm
• no filter

The UV light emitted by a source is expressed in watts (W) and the irradiation density is expressed in watts per square meter (W/m2).

For germicidal action, the dose is important. The dose is the irradiation density multiplied by time (t) in seconds and expressed in joules per square meter (J/m2). (1 joule corresponds to 1W.second).

Low pressure lamps have their main emission at 254 nm where the action on DNA is 85% of the maximum value. The effective resistance of microorganisms to UV light varies considerably. In addition, the environment of the microorganism in question greatly influences the dose of radiation necessary for its destruction. Water, for example, can absorb some of the effective radiation depending on the concentration of contaminants it contains. Iron salts in solution are well-known inhibitors. Iron ions absorb UV light. The survival of microorganisms when exposed to UV light is given by approximation :

Irradiation time (sec) = Killing dose (mJ/cm²) / Lamp irradiance (mW/cm²)

_*1 Irradiance measured at 2 meters, except * measured at 15cm

It is advisable that the lamps are hung on the ceiling and place in the middle of the room, so that you can have the best UV repartition. The negative parts (i.e. the under-part of a table for example) won’t be sterilized. Indeed, the sterilization is efficient only if the areas to be sterilized are irradiated directly by the lamps. The germicidal lamps can’t work when there are people inside the room. This is why we recommend the door to be fitted with a protection system, so that the lamp switches off when somebody enter into the room. Radiation has to be perpendicular to the area which needs to be sterilized.