Download Ultraviolet Disinfection Systems

Ultraviolet Disinfection Systems
Ultra Violet (UV) light is the portion of the sun’s light, which causes skin to burn. It is also
a powerful disinfectant capable of deactivating bacteria and viruses. UV leaves no
residue in the water so the taste of the water will not be affected.
An ultra violet unit consists of a powerful lamp protected by a quartz sleeve, within a steel
cell, through which the water passes. Some older models, which use a plastic cell,
should be avoided as the UV light may degrade the plastic.
When choosing an ultra violet unit you should make yourself familiar with the
maintenance procedures, and the lifetime of the UV lamps. Check that the dose is
sufficient for your needs - the dose will be reduced towards the end of the lifetime of the
lamp. Finally, ensure that a warning device is fitted, in case the unit fails.
Effects of Water Quality
If your water contains suspended solids, you will need to install a pre-filter. Solid
particles act as a shield, protecting bacteria and viruses from the UV light. A 50-micron
filter is normally recommended to remove the suspended solid matter.
If the water has a noticeable yellow colour it probably contains organic matter derived
from peaty soils. The organic chemicals are able to absorb UV light making disinfection
less effective. Sometimes increasing the ultra violet light dose may solve the problem.
Organic matter can normally be removed using a graphite pre filter cartridge. If metals
are present a more sophisticated system will be required.
Some chemicals, e.g. the chemicals that cause temporary hardness (magnesium and
calcium carbonate) may deposit on the quartz sleeve. If this occurs it will be necessary
to clean the unit in compliance with the manufacturers directions and it may be necessary
to pre-treat the water.
Installation of the Unit
The unit needs to be installed inside a building, as it is prone to frost damage. The unit
should be installed before any taps, which might be used for drinking water. It is
preferable to install the unit tap-side of any storage tank to reduce the risk of back
contamination.
Following the installation of the UV unit, your plumber should use a chlorine solution to
flush existing contamination from the pipes.
Lamps and filters should always be replaced at times recommended by the
manufacturer. When the lamp is changed, or if sediment has passed through the unit,
the quartz sleeve should be cleaned. Citric acid may be necessary for this purpose.
Page 1 of 1