Ultraviolet (UV) radiation is all around us – in the form natural sunlight. In industrial sectors, the non-visible light has numerous applications, from paint curing and non-destructive testing (NDT) to chemical analysis and counterfeit detection. On the light spectrum scale, UV bands can be found between gamma/x-rays and the visible light range.
Specifically, the short-wave UV range falls on the opposite side of infrared and microwaves, which are groups of long-wave bands. Measurements for UV waves range between 100 nm to 400 nm – sometimes reaching 430 nm for specific applications. At the high end of the UV range, the bands overlap with the visible spectrum (400+ nm), resulting in slightly visible ‘violet’ output.
The UV range is classified into three parts: UV-A, UV-B and UV-C. Each group has its own set of unique characteristics and applications. Below takes a closer look at the UV classifications.
UV-A Light (and Black Light)
UV-A measures between 315 nm to 400 nm. It is considered to be the least intense and harmful out of the three UV bands. However, with long-wave characteristics, this type of light can reach deep into the human skin resulting in accelerated aging.
In industrial markets, UV-A lighting systems are mostly found in paint spray booths and manufacturing sites. The luminary is used to speed up the curing process, allowing businesses to boost productivity and production rates. During use, an operator applies a base coating on the surface, consisting of liquid monomers, liquid oligomers and photoinitators. UV-A bands are then administered to activate the molecules. The paint curing process takes roughly 30-125 seconds.
In NDT, UV-A light is heavily utilized. The testing method is effective in uncovering inconsistencies and cracks on surfaces or materials in a non-intrusive manner. Without bending or exerting large amounts of physical pressure on the surface, NDT is capable of keeping the object intact and free from damage during the testing process. In application, an individual applies liquid penetrants or fluorescent dyes on the surface. UV-A light is then applied to highlight inconsistencies on a micro level.
Based on the applications for UV-A light, the lamps must be equipped with robust features to streamline their application. In paint curing, shields are used around the light head to prevent light trespass and improve the intensity of the UV band. While in NDT, a cut-off component ensures stray UV bands exceeding 400 nm are blocked to reduce contamination.
When it comes to mainstream and commercial applications, UV-A fixtures are widely referred to as black lights or Wood’s lamp. Examples of applications include bug zappers and tanning beds.
UV-B bands range between 290 nm to 320 nm and is considered to be more harmful than UV-A light. Prevalent exposure to UV-B rays can result in skin burns or redness, as well as increased risk of skin-related cancer. In medical fields and criminal investigations, UV-B light is leveraged for DNA analysis using a transilluminator. Moreover, UV-B lamps are crucial equipment for phototherapy, which is designed to treat a plethora of medical conditions, such as psoriasis
This type of UV lamp can also be applied in paint, coating, adhesive and ink curing solutions. In animal tanks, UV-A/UV-B light is used to keep reptiles and other pets healthy. The light bands help regulate natural behavior, such as feeding and mating. Some animals rely on UV-B light to absorb calcium and synthesize vitamin D3.
At the lowest end of the UV scale, UV-C ranges between 100 nm and 280 nm. As the shortest UV band, this type of UV light is also the most dangerous to humans. In the air, UV-C bands are stagnated and inefficient due to the presence of oxygen. The most common use for UV-C lamps is non-invasive disinfection in food packaging plants and manufacturing sites. When applied, the light scrambles the DNA of bacteria and other harmful, microscopic creatures. HVAC systems may come equipped with UV lamps for aerial disinfection. This chemical-free application is useful for laboratories, clean rooms and hospitals.
UV-C fixtures also have a place in commercial paint curing. This specific band is used to harden top coatings, making them more resistant and reliable.
Note: To reduce the harmful effects of UV light, it is important to stay protected at all times during application. Best practices include the use of UV-resistant eyewear and ointments or creams for the skin.