The ABCs Of UV Light

March 17, 2005
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For many contractors and service techs, ultraviolet (UV) lights have become a much more common system accessory. They have certainly piqued the interest of residential and commercial consumers.

Most of these people do some preliminary searching online when they are looking into indoor air quality (IAQ) solutions. When they find information on UV lights, they will come across what may be unfamiliar scientific terminology - nanometers, UVV, UVC, and the light spectrum. They may find some basic information on UVC, but there isn't much out there about UVV, and UVV is one of the best weapons in the arsenal against poor IAQ.

So, before the customer's nerdy kid shows up both his own parents and you, here are the basics of UV light - the science, the technology, UVV, and some facts from the National Aeronautics and Space Administration (NASA).

Figure 1. Visible (white) light is made up of colors that range from violet, to blue, to green, to yellow, to orange, to red. Red light has the least energy of these light bands; blue is the most energetic.

The Light Spectrum

UV is part of the light spectrum. According to NASA, the full spectrum includes radio waves, infrared, visible light, UV, X-rays, gamma rays, and cosmic rays.

Let's take a trip down memory lane. Remember the light prism on the cover of Pink Floyd's "Dark Side of the Moon" album? When white light goes through a prism, it is broken down into its component colors. (See Figure 1.)

Visible (white) light is made up of colors that range from violet, to blue, to green, to yellow, to orange, to red. Red light has the least energy of these light bands; blue is the most energetic.

Beyond the red end of the spectrum are the infrared (literally "beneath red") lightwaves and radio waves. We know that infrared light can be used as a form of heat. Radio waves are harnessed to carry TV and radio transmissions.

Ultraviolet (literally "beyond violet") light, X-rays, and gamma-rays are beyond the blue/violet end of the visible spectrum.

UV light (as well as X-rays and gamma rays) is a form of radiation that is invisible to the human eye. Radiated energy is given off by many objects, such as light bulbs, fire, and stars. X-rays, gamma-rays, and UV light emitted by stars are absorbed by the Earth's atmosphere.

UV rays are made artificially in UV lights, like this Sanuvox Quattro UV light, by passing an electric current through a gas or vapor.

The UV Spectrum

UV light has shorter wavelengths than visible light. It has four natural types of energy bands of its own, though not all penetrate the upper atmosphere.

UVC is shortwave UV; it includes germicidal UV. Like all lightwaves, it is measured in nanometers (nm). UVC's 220- to 290-nm wavelength can be used for air, surface, and water disinfection. Overexposure to UVC causes skin redness and eye irritation, but does not cause skin cancer or cataracts.

UVB (290 to 315 nm) is the part of sunlight that leads to sunburn and skin cancer. Most of the solar UVB is absorbed by the stratospheric ozone layer; however, exposure can be dangerous.

UVA (315 to 400 nm) is longwave UV, also known as blacklight. (For those of us who had blacklight posters, or whose brothers had blacklight posters, it's another trip down memory lane.) UVA is responsible for safe skin tanning and is used to treat certain skin disorders.

UVV is also called vacuum UV; its wavelength is 187 nm. According to Sanuvox Technologies, Montreal, 187 nm is a naturally occurring wavelength but it doesn't usually penetrate the upper atmosphere.

UVC and UVV

UVC destroys the DNA of microbial contaminants, rendering them sterile. If microbes are irradiated with a large enough dose of UVC, they can no longer reproduce and over time disappear from the indoor environment.

UV rays are made artificially in UV lights by basically passing an electric current through a gas or vapor. These lamps resemble ordinary fluorescent tubes. Sometimes these lamps use a reflector for the UV rays; other models provide direct air and surface sterilization by irradiating the air and surfaces in direct view of the lamp.

Some models provide indirect air irradiation by enclosed UV lamps; these irradiate air as it passes through the UV unit. These units are not used for surface irradiation. HVAC airstream irradiation uses powerful, high-output UV lamps designed specifically for the cold, moving air in ductwork. In-room, stationary UV may be used for surface and indirect air irradiation in hospital operating rooms and laboratories. Extreme care must be used in placing these so as not to shine them directly at occupants.

"UVC's primary uses are for the destruction of bacteria and other microorganisms that pass through the [Sanuvox] aluminum chamber," stated manufacturer Sanuvox Technologies. "The Centers for Disease Control recommends this method for destroying viruses such as tuberculosis.

"UVV is primarily used for oxidization; this is the portion of the lamp which will neutralize odors in the air. Both UV wavelengths work together to destroy the contaminant," the company said. "UVC penetrates the cell's membrane, destroying the cell's DNA. UVV destroys the chemicals of the dead cell."

Sanuvox's "J" lamp produces both UVC and UVV light. "Both UV wavelengths attack microorganism, chemicals, and odors on a molecular level," said company president Normand Brais, Ph.D., "actually changing the DNA of the cell. These changes result in incorrect codes being transmitted from the modified DNA, which leads to the destruction of the microorganism."

More Cool Stuff

When properly designed and applied, HVAC coil irradiation units are said to produce a 99-percent kill rate (according to a McGill University study using Sanuvox UV object cleaners). The most effective practice is to combine coil irradiation with airstream irradiation. However, is this necessary for all cases?

As you might expect, the efficiency of UV Germicidal Irradiation (UVGI) decreases farther away from the UV lamp, explained Brais. "A common misconception is that a UV lamp installed in a duct will treat all the air passing by it. In fact, at just 2 inches from the surface of the glass of the lamp, the UV efficiency drops more than 80 percent, and the decline is exponential.

"This is true for all types of glass and lamps; this is a fundamental principle of UVC light."

According to the company, in a typical application the Sanuvox purifier will have treated an average of more than 80 percent of the contaminants in the air in two hours. "The purifiers will destroy the contaminants quicker than they will be introduced into the environment."

The company credits its aluminum reflector tube for this efficiency. "If the reflector tube was not present on the Sanuvox, then the entire duct would be lit up, but much less germicidal action would be taking place," Brais said. "The aluminum reflector tube is needed to intensify the UVC energy."

A little extra information can make the difference between a poorly informed consumer sitting on the fence of purchase indecision, and one who makes that decision with confidence in the product and in the contractor. It's like flipping on a light switch.

Sidebar: UV Program For Contractors

MONTREAL - Do your customers suffer from allergies or asthma? Do they have pets? Is there a smoker in the home? Is mold a problem? Can you explain how your company's products and services can help customers solve their problems?

Sanuvox Technologies says it would like to make sure you have the tools you need to help educate customers.

The manufacturer's Factory Authorized Dealer Program is designed to not only help dealers increase their sales potential, but also demonstrate their leadership in the IAQ market.

According to the manufacturer, "A contractor will sell an occasional unit. However, a Sanuvox Factory Authorized Dealer will be dedicated to promoting Sanuvox as the leading air purification company and develop a real business. And, of course, the real benefit will be comprehensive factory support."

Each Factory Authorized Dealer receives:

  • A dealer starter pack.

  • Factory authorized sign-up promotion.

  • Participation in a co-op advertising program.

  • Customer referrals.

  • Participation in the VIP and demos program.

  • Home show specials.

  • Dealer recognition.

  • Factory support.

    For more information, contact the company at 888-726-8869; info@sanuvox.com; or sign up through a local Sanuvox wholesaler.

    Publication date: 03/21/2005

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