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Are you getting the right UV dose?

When specifying a UV disinfection system it is important to take into consideration all variables that will impact an effective UV dose. Two important variables to consider are:

  • UV Transmittance ( % UVT)
  • Peak flow rate


UV Dose = UV Intensity x 100 x Water Contact Time

What is UVT?

UVT is a measure of how much UV light is transmitted through a water source compared to pure water. To give you an idea, the UVT of tap water is usually between 80-85%. The lower the UVT, the lower the UV dose, resulting in insufficiently treated water that may not be safe for consumption or suitable for the given application.

To improve your UVT, pre-treatment is recommended. The pre-treatment must be specified according to the raw water being treated.

Flow rate impact

By increasing the flow rate, the contact time will decrease and so the UV dose will decrease. A low UV dose may not be sufficient to deactivate microorganisms such as E.Coli, Legionella ect, making it a real risk!

UV System Design

A target UV dose must also be established, one that will be sufficient to achieve the required microorganism deactivation or chemical breakdown levels whilst abiding by any regulatory or project requirements.

For example, UV dose recommendations are as follows:

* depending on recirculation rates

The right UV system needs to be matched to each specific application. It is risky to specify UV systems based on generic specification sheets as these often advertise large flow rates which are based on high UVT and low UV doses.

UV-Guard's Expertise

UV-Guard Australia provide technical guidance in the specification of wholistic water treatment systems.

We process engineer designs on a case by case basis by working with our customers closely to understand their needs.

We combine available data such as water quality reports and project information with our engineering judgement to propose pre-treatment options with a UV disinfection system that meets the dose requirements.

We also provide in-house UVT testing of source water to ensure that the systems we propose, meet and exceed the UV dose requirements. Ask the experts!

Industry News

Japanese Scientists win Nobel Prize for blue LED development

Three Japanese scientists have been rewarded for the development of an efficient blue LED.

Red and green LED technology has been around since the 1950's but it is the blue LED that is required to make ultra violet light a possibility.

Their break-through has opened up a number of potential applications including UV disinfection for water purification.

The benefits of LED is that they are more efficient and have a longer life than conventional incandescent light bulbs.

UV-Guard will be keeping an eye on the progress of this technology as it gains momentum in the UV disinfection sector.

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