UV Sterilizer is widely used on board ship as an disinfectant to treat drinking water. On board ship Fresh water is used for the most part by huge boilers, running machinery and crew every day. On an average the crew consumes about 69 litres/day/person and in case of passenger ships, 222 liter/day/person. Ship takes only a minimum quantity of fresh water from the port for domestic services (since it is not allowed to use the freshwater generator in port).
The water so produced by fresh water generator or stored in double bottom tanks are sterilized to avoid any unknown transfer/spread of micro-organism. As jacket water used in fresh water generator are only 70-75 degree hot which is insufficient to kill all the germs and bacteria in the fresh water. So it is mandatory to sterilize fresh water on board for human consumption.
UV Sterilization of potable water is safe and reliable method of disinfecting it, this method cause photo-chemical reactions in the cells of micro-organisms, thus killing up to almost 100% of the bacteria and viruses. The UV rays has short wavelength; it kill or inactivate microorganism by destroying nucleic acid and disrupting their DNA. Thus making them impaired to perform important functions, like reproduction and damage to human being. Wavelength of 260 nm–270 nm is termed as “Germicidal UV”.
U.V sterilizer fitted on board ship have following constructional properties:
- Ultra-Violet Sterilizer consist of a casing which has mirror finished inside of it.
- Consist of two cleaning plug
- Return Block made up of Cast Iron.
- four Clamping Nut
- Two Quartozoid Glass tube
- Three UV lamps or Germicidal lamps.
- Drain plug at the bottom.
- Four Rubber gasket or O-Ring.
- Three Observation Window.
Why U.V sterilizer are preferred over other popular disinfectant?
U.V is preferred on board ship above other disinfectant because of its supreme tendency to kill all kinds of germs. Under controlled and tidy condition (regular maintenance) it give its best results at an economical rate. But it requires clean water, free of small particles and minerals; To penetrate and disinfect radially which is always present on ship.
Other factors responsible of using U.V over others are:
- It is a powerful disinfectant that kill different variety of germs including bacteria, viruses and parasites.
- It provide high quality disinfection.
- There is no such problem like reaction to pipes or corrosion.
- Have no effect on taste and odour of water.
- They do not require any chemicals.
- Requires very little energy, as much as it is require to light 60watt bulb
- Low Maintenance, just change the UV lamps bi-annually.
Precaution to take
- Never to look at the UV lamp with naked eyes.
- Always close power supply when opening the cabinet.
- Don’t pressure too much when assembling the gland fittings.
- Take care while cleaning Quartozoidal glass, as they are very thin.
Maintenance of UV Sterilizer
Before carrying out maintenance, ensure that inlet valve and outlet valve to and from UV Sterilizer respectively is shut and by-pass valve is open, so as not to interrupt the water supply
- Mirror finish inside of the casing should be cleaned to enable UV rays to reflect effectively.
- The UV lamp has effective germ killing life of 6 months, a book is maintained to monitor the replacing time.
- Use wetted cloth to clean quartozoidal glass tube.
- Do not disturb the glass tube unless required.
Quartozoidal glass tube has O-ring around it and clamping nut is use to screw the tube.