What Is UV Light?

Tech Talk 1.

UV treatment of water is becoming increasing popular for a variety of reasons. In order that a UV treatment system be correctly selected, sized and implemented for a given application, a clear understanding of how UV systems perform their function is required. It is also very important that the necessary process information is gathered and communicated to the UV system supplier in order that a suitable UV system is delivered. Finally, it is important to understand the process by which UV systems (intended for water and waste water applications) are validated. This is important as it is crucial in ensuring the UV system is suitable to perform the intended duty. In this, the first of our Tech Talk series, we will look at what UV light actually is.
 

What is UV light anyway?

Ultraviolet (UV) light is a naturally occurring component of sunlight. It falls in the region between visible light and X-Rays in the electromagnetic spectrum (Figure 1). Generally, UV light is considered as falling between 100nm & 400nm in wavelength; however UV light in itself can be categorized even further into separate regions. Although scientists hold varying opinions as to the exact boundaries of these regions, it is generally considered to be approximately as follows: Far UV (or “vacuum”) 100nm – 200nm, UVC 200nm – 280nm, UVB 280nm – 315nm and UVA 315nm – 400nm. Of these UV regions, UVB and UVC are recognized as having the most significant germicidal and photolytic properties. These regions are however, significantly filtered out by the Earth’s atmosphere. As such, if we are to fully utilise the germicidal and photolytic properties of UVB and UVC light, we have to generate them here on Earth using commercially produced UV lamps. Keep an eye out for our next Tech Talk article which will investigate how a UV lamp really works.