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Matching the UV Lamp to the Objective
Effective Disinfection & Chloramines Removal
There are two types of UV lamps; Monochromatic (Low-Pressure) and Polychromatic (Medium-Pressure). The distinct difference between these two lamp types
is their "UV Spectral Output". The term "UV Spectral Output" describes a specific spectral group of UV light (wavelengths). The "Light Spectrum" graph
identifies the four UV spectral areas: Vacuum-UV, UV-C, UV-B and UV-A.
The term "UV Absorbance Spectra" describes specific UV light spectral areas
(wavelengths) that are absorbed by specific elements that include: DNA (living microorganisms), chloramines (monochloramines) and free-chlorine.
When applying UV treatment to a swim or fountain application we have a three-part objective. First, we apply the UV system to the pool filter loop to
provide instant germicidal protection against harmful waterborne pathogens that include cryptosporidium. Second, we specifically target monochloramine for
chloramines removal. Third, we are specifically not targeting free-chlorine in the pool water.
Recent research from Duke University and the
University of North Carolina, Chapel Hill reveals that Polychromatic (Medium-Pressure) UV lamps and their broad UV spectral output decays free-chlorine.
Beware: Medium-Pressure UV system manufacturers mistakenly boast that the broad UV spectral output of these lamps is more effective. In reality, their
broad spectral output makes it more difficult to pinpoint the correct UV dose for your specific objective.
The research reveals that the narrow
"UV Spectral Output" (peak @ 254 nm) of Monochromatic (Low-Pressure) UV lamps coincides with both, the maximum UV absorption spectra of monochloramine
(246 nm) and
DNA (264 nm).
SafeGUARD CLP Series UV Sterilizers
SafeGUARD CLS Series UV Sterilizers
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"Impact of Chlorine and Monochloramine on Ultraviolet Light Disinfection"
"The absorption maximum of free-chlorine is somewhere around 290 nm which falls in the range of polychromatic UV light from medium-pressure UV lamp
output. The absorption maximum of monochloramine is approximately 246 nm, close to the low-pressure UV lamp output at 254 nm. Therefore, when decay
rates are based on delivered UV energy, monochromatic UV (254 nm irradiation) proves more effective than polychromatic UV light in the photochemical
degradation of monochloramine."
"Monochromatic UV light is more effective in degrading monochloramine, and polychromatic UV light is more
effective in degrading Free-Chlorine".
-Duke University/University of North Carolina
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Click Here to view the complete Duke University/University of North Carolina study.
Monochromatic (Low-Pressure) UV Lamps
Proven the Most Effective Lamp Type for Germicidal Disinfection! |
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Chart A
Chart A reveals the "Bulk UV Spectral Output" of Monochromatic (Low-Pressure) UV Lamps and that it lies will within the
"Germicidal Action Curve" establishing them as the preferred lamp type for germicidal disinfection. Click chart to enlarge.
View the Duke/UNC Study. |
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Chart B
Chart B reveals that the "Bulk UV Spectral Output" of Polychromatic (Medium-Pressure) UV Lamps lies well outside the
"Germicidal Action Spectrum" establishing them as a poor choice for germicidal disinfection. Click chart to enlarge.
View the Duke/UNC Study. |
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Chart C
Chart C reveals the "Maximum UV Absorbance Spectra" of Chloramines, specifically Monochloramine (246 nm) and its close
spectral relationship to the "Bulk UV Spectral Output" of Monochromatic (Low-Pressure) UV lamps. Notice that Low-Pressure UV lamps and their
"Bulk UV Spectral Output" is far below the UV absorbance spectra of free-chlorine (290 nm).
Click chart to enlarge.
View the Duke/UNC Study. |
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Chart D
Chart D once again reveals the "Maximum UV Absorbance Spectra" of Chloramines, specifically 1. Monochloramine (246 nm),
2. Di-Chloramine (297 nm) and 3. Tri-Chloramine (340 nm), but reveals the broad UV spectral output of Polychromatic (Medium-Pressure) lamps and
their close proximity to the UV absorbance spectra of free-chlorine (290 nm). This proves that Polychromatic (Medium-Pressure) UV lamps decay
free-chlorine in pools, causing an increase in Chlorine consumption adding to the operational cost of the system. Click chart to enlarge.
View the Duke/UNC Study. |
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Additional advantages that Monochromatic (Low-Pressure) UV lamps deliver above-and-beyond Polychromatic (Medium-Pressure) UV lamps:
- Low-Pressure UV lamps provide 9,000 hours of useful life until reaching 80% efficiency, as compared to Medium-Pressure's best, 4,000 hours.
- SafeGUARD UV Systems are proven to lower Free-Chlorine usage. View Testimonials.
- Low-Pressure UV lamps operate at 107° F - 108° F in contrast to Medium-Pressure lamps, which
operate at 1,600° F.
- SafeGUARD UV lamps' annual replacement cost is dramatically lower as compared to that of
Medium-Pressure UV lamps.
- Low-Pressure lamps use simple, long-lasting transformers versus Medium-Pressure's complex,
highly sensitive ballasts.
SafeGUARD CLP Series UV Sterilizers
SafeGUARD CLS Series UV Sterilizers
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