Ultra Violet (UV-C) Water Filter UV254-ST45

How UV Works in Sterilising Water

UV-C light (radiation) at a wavelength of 253.7nm destroys the DNA (Deoxyribonucleic acid) vital for the existence of any living organism. 

It was noticed by British scientists in 1877 that sunlight seemed to have a sterilising effect. Close investigation by these scientists revealed that UV light at a wavelength around 254 nm was a very efficient and convenient method of considerably reducing the number of bacteria, cysts, viruses etc in water. 

This method has now been refined using modern technology to irradiate (dose) water with UV light. At a dose of 400J/m2 a reduction of living organisms is dramatic – up to a 4 log kill. Dosage at 300J/m2 is still very effective and is the modern standard for most countries. 

This system is very efficient and does not have the problem of “carry-through” associated with some chemical solutions such as chlorine. UV is also cheap to run and simple to maintain. 

There is one drawback with UV – it is vital the water is sufficiently clear to transmit the UV light efficiently. It is therefore VITALLY IMPORTANT that adequate PRE-FILTRATION is installed before the UV reactor to ensure the UV light transmits through the water to kill the unwanted organisms. Failure to ensure the water is sufficiently clear (usually filtered to at least 5 microns) may result in some organisms not being killed by the UV light. 

It is also vital that the recommended FLOW RATE of the system is not exceeded. The UV light needs sufficient contact time to kill the unwanted organism. It is advisable for the UV system to operate well within the maximum flow rate – please consider this when designing/ specifying a UV system.

Model No: ST45
System Power: 48 Watts
Bulb Power: 40 Watts
Max Flow @ 400mj/s: 34.0 Litres per minute
Max Flow @ 300mj/s: 45.4 Litres per minute
Size (diameter x length): 63.5 x 938 mm
Pack Weigh: 3.98 Kgs
Connections Inlet/Outlet*: ½ BSP-F & ¾ BSP-M
External Relay Model**: ST45V

* Note: Connection ports have both internal and external threads
**Note: Models (suffixed V) incorporate an additional relay to send an external signal in the event of an ALARM - Volt free contact so power input can be AC or DC and any voltage up to 240 volts.

Consideration BEFORE Installation

Pre-Filtration

How dirty is your water – does the dirt increase in periods of heavy rain storms? The measure of clarity of water is TURBIDITY – this is the measure of suspended solids in the water which affect the transmission of UV light through the water. 

IDEALLY the water to be treated by UV should have the following parameters:

• Turbidity: < 1 NTU
• Iron (Fe): < 0.3mg/l (or ppm)
• Manganese: < 0.05mg/l (or ppm)
• Tannins: < 0.1mg/l (or ppm)
• Hardness: < 120mg/l (or ppm)

As well as suspended solids blocking the light, mineral (metal) depositing on the quartz sleeve (the glass tube that keeps the UV bulb dry) can cause “blinding”. The quartz sleeve is heated by the UV bulb and is an ideal place for the above pollutants to precipitate and adhere to. You therefore need to be aware if these deposits occur – you need to have a routine of regular cleaning of the quartz sleeve to maintain efficiency. 

Note: The better your pre-filtration system, the clearer your water will be and the less maintenance on the UV system you will need to do. For more information on PRE-FILTER Systems Contact Us.

Location of Installation 

• Ensure to locate the UV system in a place THAT LEAVES SUFFICIENT ROOM for maintenance. Periodically you will need to withdraw the UV bulb and Quartz Sleeve.
• Protect all systems and pipes from freezing temperatures
• Lag pipes to avoid condensation
• Keep the UV system dry
• You will need sufficient water pressure to push the water through the prefiltration system and yield an acceptable flow rate
• Do not exceed advised pressure limits. If you have high pressure or water hammer – fit a pressure reducer (variable pressure reducers are recommended)
• Do not exceed the FLOW RATE of the system – fit a flow restrictor if necessary

Health and Safety

Warning: UV-C Radiation is harmful to eyes and skin. UV-C is emitted when the lamp is powered up. Persons should never be exposed to UV-C Radiation. Ensure Eye Protection Is Worn. Never expose unprotected skin to UV-C light. 

Warning: Risk of Electric Shock. Dangerous electrical voltage. Only qualified and authorised persons should touch the electrical system. Keep all wiring and components dry. DO NOT attempt repairs yourself (if you are not a qualified technician).

Important: Maximum allowable water pressure for the UV system is 8 bar (125 psi). We strongly recommend you limit input pressure to 6 bar (90 psi) to avoid pressure surges or water shock exceeding the maximum pressure. 
Important: Only use this system for the purpose it was intended. DO NOT USE if any of the system or parts have been damaged.