Why does high reflectivity matter?
When you see this logo and statement describing your UV disinfection system, it means that the material lining the reaction chamber is Porex Virtek PTFE. With a diffuse reflectivity of up to 97% in the critical UV range, every photon of energy is ensured to be doing its job when this material is used – which means your UV disinfection system is performing at its peak.
So why is this so important? In a semi-closed system such as a UV disinfection chamber, having ultra-high reflectivity is the key to maximizing the internal flux and thus total irradiation and efficacy of the system.
The science behind reflectivity
Using Sumpner’s principle – which estimates mean surface illuminance from direct and indirect components – total average irradiance (E) is the sum of the direct (ED) and indirect (ER) irradiance: Etotal = ED + ER
The direct irradiance (ED) is simply the energy of the UV source measured at the surface, whereas the reflected irradiance ER is a function of the direct irradiance times the surface reflectivity ER = ED x (R/(1-R)) – or the additional irradiance that is amplified by the reflective surfaces.
So what is the difference between a product with a reflectivity of 75% versus 97%? The obvious – but incorrect – answer is 22% (97% – 75% = 22% or about 1/4) but in reality, the total irradiance in closed systems becomes exponential as it approaches 100%. For example, a 75% reflective surface with an initial surface energy from the source of 1 mJ/cm2 would have a total surface irradiance of 4.0 mJ/cm2 (as the system loses 25% of its energy every time it strikes the 75% reflective surface). But for a reflectivity of 97%, the surface irradiance jumps to a whopping 33.3 mJ/cm2 as the system loses just 3% per reflection. The surface irradiance multiplies by eight when moving from a 75% reflective material to a 97% reflective material. This is precisely why we can say that your UV disinfection system is Intensified with Porex Virtek.
Total Irradiance in a Closed System
ETotal = ED + ER