What is Ultraviolet?

An important thing to know is that ultraviolet (UV) is not a single entity, but a wide band of
wavelengths. The chief natural source of UV is the sun, most of which is in the region between 300nm - 400nm. Artificial sources of UV include incandescent, gas discharge, low pressure mercury, medium pressure mercury metal halide, electrodeless and xenon lamps.

UV radiation is electromagnetic radiation in the part of the spectrum between x-rays and
visible light. It differs from visible light only in that the UV wavelengths are too short to be seen by the human eye. The boundary between visible light and UV is a wavelength of 400nm (4000 Angstroms).

Medical literature divides UV into three ranges: UVA (315 - 400nm) where the filtered (BLB) is used for fluorescence blacklight effects while unfiltered UVA is used in UV curing and photochemical reactions. UVB (280 - 315nm) is used in scientific applications such as genetic visualization. UVC (200 - 280nm) unfiltered UV is used in germicidal crosslinking applications and when properly filtered, for mineral fluorescence. This is a small sampling of applications.

An interesting characteristic of UV radiation occurs when it falls upon certain substances
known as phosphors, where it causes the phosphors to emit specific radiation. This phenomenon is known as fluorescence. Everyday fluorescent lighting is basically a UV lamp constructed of a type of glass bulb that blocks UV rays. The inside of the bulb is coated with a thin layer of fluorescent material that receives UV generated by the lamp and in return emits a visible light.

One effect of ultraviolet energy upon certain substances is a phenomenon that takes place at the atomic level. High frequency UV photons collide with atoms and part of the photon energy is transferred to the atoms by boosting electrons to the high energy states. Upon de-excitation, as electrons fall back to lower energy states, energy is released as photons of light. Since only a portion of the incoming photon energy was transferred to an electron, these emitted photons have less energy than the incoming UV photons so their wavelengths are longer than the excitation photons. This process is called fluorescence.

In some materials, the fluorescence lingers and disappears slowing after the UV source is removed. Here, the electron returns slowly to its original state, and this delayed fluorescence is call phosphorescence.

Ultraviolet Dosage Required For Destruction Of Organisms (uW-s/cm2)

Ultraviolet energy levels at 254 nanometer units wavelength Required for 99.9% destruction of various microorganisms UV energy in microwatt-seconds per square centimeter

Germicidal Actions / UV Actions

Ultraviolet radiation in the 200-300 nanometer (nm) range is extremely effective in killing microorganisms such as airborne and surface bacteria, viruses, yeasts and molds. Low-pressure, mercury-arc germicidal lamps are specially designed to produce the highest amounts of UV radiation - typically about 90% of the total rated energy is at 253.7nm. This radiation is very close to the peak of the Germicidal Effectiveness Curve of 265nm, the most lethal wavelength to microorganisms (see graph at below). Germicidal lamps are used extensively in air and water purification applications such as are found in the food and beverage industry, medical, and sterilization applications. In addition, they are used in drinking water and ultrapure water purification as well as sewage treatmnt.

Ozone Action

"VH" germicidal lamps generate energy at 185nm in addition to the 253.7nm line. This UV emission produces abundant amounts of ozone in air. Ozone is an extremely active oxidizer, and destroys microorganisms on contact. Ozone also acts as a deodorizer. One of ozone's advantages is that it can be carried by air into places that the UV radiation cannot reach directly. To meet your specific need, Our offers germicidal lamps with different degrees of ozone production. "VH" lamps are typically used in the treatment of air, pool and spa water, and T.O.C. reduction.

High Output Lamps

High Output (HO) germicidal lamps yield 1/3 to 2/3 more UV output than standard lamps of
the same length. Ballasting is available in 120v and 220v. These HO lamps are designed to operate with standard preheat ballasts, which are significantly lower in cost and size than traditional Slimline (Instant Start) ballasts. Custom designed lengths can also be supplied.

The unique single-ended design, originated by Light Sources, is particularly suited for test
tube-shaped quartz sleeve applications. The end of the lamp with the pins is positioned at the open end of the sleeve at the top. This reduces electrical problems associated with condensation at the bottom of vertical units. Electrical continuity is accomplished through the use of two external Teflon coated wires. Longer lengths employ spacing rings. The 4-pin single ended design permits the use of standard Circline sockets. The lamps are supplied with ceramic bases, which are resistant to UV and ozone. They will not burn or deteriorate, and they eliminate quartz sleeve fogging.