UV Disinfection FAQ

UV FAQ – Frequently Answered Questions

Over the years in the UV industry, our team has been asked several UV related questions. Some common questions are below:

If you have any UV related question, or would like any UV related information, please feel free to call our friendly team on (02) 9896 1165 or use the contact us page to get in touch.

  • How to disinfect rainwater?

Rainwater disinfection with UV is a simple and reliable way to use rain water.

You need to use good quality rain water filters to remove any suspended particles. Adequate rainwater filtration is important before the water enters the rainwater UV disinfection unit.

The rainwater UV unit should be sized to deliver minimum UV dose >30mJ/cm2 or 300J/m2 at the end of UV lamp life at the peak flow rate of water. If the rainwater is likely to be used for drinking, we would recommend UV dose>40mJ/cm2 or 400J/m2 t the end of UV lamp life at the peak flow rate of water.

As UVT of the water affects UV dose, please feel free to send us a 100ml sample of the water for a UVT check at no charge. You can find our address here.

Depending on details of the application, you can further specify other UV options like weatherproof UV power supply, UV lamp fail alarm, UV lamp change reminder, UV intensity sensor, UV intensity monitor, etc.

  • How to disinfect tank water?

Water stored in tanks can attract bacteria and other microbes. Stagnant tank water thus can lead to biofilm in tanks. Regular cleaning of the tanks is important.

Please use a good quality tank water filter before the tank water UV disinfection unit. This is important to prevent suspended particles from shielding the bacteria from UV light.

Work out the maximum flow rate from the tank and select a tank water UV unit to deliver min. 30mJ/cm2 at the end of UV lamp life at the maximum flow rate. For drinking water, please size the UV unit for min. 40mJ/cm2 at the end of UV lamp life at the maximum flow rate.

As UVT of the water affects UV dose, please feel free to send us a 100ml sample of the water for a UVT check at no charge. You can find our address here.

  • How to size a UV sterilizer?

Correct UV system selection requires consideration of several factors. Some factors to consider when sizing a UV lamp unit are: Peak flow rate, UVT of water, target microorganism, desired UV dose, source of water, end use of UV treated water, installation details and more.

Feel free to call us on (02) 9896 1165 for a quick chat with our experienced and friendly team about your application, or contact us with any UV sizing questions.

  • What is UV dose?

UV dose probably the most important factor affecting disinfection performance of a UV sterilizer.

In a plug flow UV reactor, UV dose can be expressed as

UV Dose [mJ/cm2] = UV intensity [W/cm2] x Residence Time [s]

Real life UV sterilizers are not plug flow UV reactors. Therefore, we need to consider UVC irradiance and different paths likely to be taken by water particles as they  flow through the UV reactor. We use specialized software to calculate UV dose through our UV reactors. In addition, we apply real world experience gained from a few thousand industrial UV disinfection applications to arrive at UV dose likely to be actually delivered.

  • Is UV light harmful?

If eyes or skins are exposed to UV light, it can damage your eyes or skin. Never look at an operating UV lamp, unless you are using adequately rated, certified UV resistant glasses. Never operate a UV lamp outside of its intended reactor. Never expose your skin to UV radiation.

As long as you follow these simple precautions, UV light is safe to use.

In fact, no bacteria, virus or other micro-organism has been found to be able to resist adequate UV dose.

  • Do you supply UV lamps?

Yes, we supply UV lamps, UV bulbs, UV lamp units, UV ballasts, UV quartz tubes, UV sensors and several miscellaneous UV spare parts.

More importantly, we also offer our experience and expertise to solve UV applications. We can troubleshoot most brands of UV units in the Australian market.

  • What is the cost of UV disinfection?

The cost of UV disinfection in majority of cases works out to a few cents per m3, depending on the type of water, UV dose required, peak flow rate and various other details of the application.

If we consider the total cost of UV disinfection, it generally works out to be surprisingly economical.

We would be happy to provide installation and long term operation costs for your particular application if you contact us with the details.

  • Can UV destroy Ozone?

Yes, adequate UV dose can destroy Ozone.

The high energy UV rays break down molecular bonds of Ozone molecules. UV de-ozonation, or  Ozone destruction UV is essential in industrial applications to prevent residual Ozone from interfering with industrial processes.It is common to measure Ozone concentration before and after the UV Ozone destruction unit to verify the Ozone disassociation.

We have extensive experience with Ozone destruction UV units in pharmaceutical, food & beverage, cosmetics manufacturing and other industrial process applications.

Our experienced team would be happy to discuss your particular application if you contact us with the details.

  • What is UV advanced oxidation?

UV light is often used in combination with Ozone and/or Hydrogen Peroxide to create OH radicals in water. The OH radicals have extremely high oxidation potential.

This type of reactions are used for specialized UV applications like NDMA removal. Such UV advanced oxidation generally requires trials to establish process parameters, before scaling up.

With our own in house product development and manufacturing capability, our experienced team would be happy to help if you contact us with the details of your application.

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