Germicidal Ultra Violet(UV)This technology is often confused with Vacuum Ultra Violet Ozone Generator systems. They are in fact two very different technologies. Both technologies use lamps that operate in the UV light spectrum. Germicidal lamps produce output near the upper end of the UV-C spectrum at 253.7 nanometers. Ozone generating lamps operate just below the UV-C spectrum at the 185 nanometer range.
Germicidal UV lamps are used in water treatment and in air treatment such as HVAC air intake ducts.
For purposes of this discussion, we will discuss water applications only.
Germicidal UV is used in many water purification systems such as ponds, swimming pools, water treatment plants and home drinking water systems.
The application consists of placing a Germicidal UV lamp in a clear housing. This housing is then directly installed into the plumbing. Water and many contaminants contained in the water are exposed to the glow from the lamp. Many manufacturers of this technology state a microorganism kill rate of 91% with some as high as 99% of the organisms actually exposed to the glow.
There are several issues with this technology. One is initial cost, another is ongoing maintenance and lamp replacement costs, and another is clarity of the water being purified. Initial product cost and installation cost is greater than other technologies.
Lamp replacement is another issue. Manufacturers state the lamp life requires the lamps to be replaced as often as every six months. Some allow ten to eleven months. While the lamp cost is one concern, the actual process of replacement cost is another as it is invasive to the plumbing.
Depending upon water clarity, not all contaminants will be exposed to the actual glow. This is due to light blockage from other contaminants, so kill rates will be lower. Remember, only contaminants visible to the lamp glow are affected.
One issue that exists is the accumulation of debris or chemicals on the surface of the lamp cartridge hindering exposure to the glow. This requires a periodic cleaning to obtain the full benefit of the system. Some manufacturers have addressed this by installing an actual wiper that transverses the light column automatically, which is additional initial and ongoing cost, and may not totally correct this issue.