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UV Education

UV Made Easy

1. UV Basics:



UV is a chemical-free method of disinfecting process water and sugar syrup with varying levels of bio-security. Hanovia’s UV disinfection systems use powerful lamps that emit UV radiation which efficiently and effectively eliminate bacteria, viruses, spores and moulds. There is no need for chemical handling, dosing equipment or waste management.

The following steps take you through the UV disinfection process:

1) Process water travelling into the chamber is exposed to UV light from the lamp(s).

2) The UV lamp delivers a defined amount of power that produces UV at the effective dose for the target microorganisms. Every microbe has a different sensitivity level to UV light, some needing more exposure than others. This is very much like human skin, as it takes different exposure times from the sun for different individuals to become burnt.

3) The UV light penetrates the DNA of the microbes, destroying the bond between adenine and thymine bonds and preventing reproduction and DNA repair. This takes seconds and is very effective, but the length of the chamber and power of the lamps are important design factors for achieving the required results.

The germicidal wavelength range with the maximum effectiveness against microbes is 250-280 nm, with the relative peak DNA absorption of UV at 264 nm. Depending on the application and required power usage, Hanovia supplies systems with low pressure or medium pressure lamps. The table below shows the advantages of each type of lamp technology.



2. Lamp Type:

Low pressure lamps use less power and emit a monochromatic wavelength of 254 nm, which is effective against microbe’s sensitive to this wavelength of light. Medium pressure lamps emit roughly 10 times more energy, with a polychromatic wavelength output of between 200 and 400 nm. Although medium pressure UV consumes more power, it is more effective against stubborn microbes travelling at high flow rates. A single medium pressure UV lamp system has the same effectiveness as a multi-lamp or multi-system low pressure system.

Benefits of using LP or MP lamps:



Low Pressure Medium Pressure Supporting Comments
Low power use   Low pressure lamps are more efficient, but are lower powered
Efficient at higher flow rates   Medium pressure lamps run at a much higher power density to low pressure lamps so one medium pressure lamp can treat a much higher flow (3 to 4 times) than a single low pressure lamp.
Space restrictions   Medium pressure lamps for the same UV output are around a third of the length of a low pressure lamp and so systems are much smaller
Lamp life   Low pressure lamps typically last 9000 to 15000 hours while the latest generation medium pressure lamps last about 9000 hours
Save on maintenance & spares   For the same conditions medium pressure UV systems generally have a smaller footprint and use fewer lamps than Low pressure system
Disinfection efficiency   Medium pressure has a higher UV light energy output and not only breaks a microbe’s DNA bond but also ruptures the cell wall. Some microorganisms are much more sensitive to these multiple wavelengths produced by medium pressure lamps.
Low running temprature   Low pressure lamps run at about 120°C, whereas medium pressure runs at 600°C to 800°C
High water temperature   Medium pressure UV systems are hardly affected by the water temperature, whereas low pressure can only operate between 5-40°C
Status ‘ON’ after no water flow   In many cases LP systems can operate for longer without any water flow than MP systems.

3. Key Features of a UV System:

UV Intensity sensor:
This instrument measures the intensity (W/cm2) of UV light passing through the water. This intensity is used to calculate how much dose (mJ/cm2) is being delivered.

Temperature sensor:
A hardwired trip switches the system off at high temperatures

Auto-wiper:
Like a wiper on a car cleans your windscreen so you get better visibility, the auto-wiper cleans the quartz so UV light is not being blocked. This can be done without having to interrupt the treatment process.

UV lamp inside quartz sleeve: The UV lamp is protected by the quartz sleeve from any solids in the process water.

Cabinet & Control:
Provides the user with information on the performance of the UV system and controls power to the system.

4. How do you validate a UV system using a 3rd party?

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