FRESH WATER SYSTEM BACTERIAL GROWTH PREVENTION
Regardless how sterile the fresh water is when it comes from a fresh water maker or when it is taken in port, there will always be small deposits of bacteria somewhere in the system regardless of how well it has been cleaned. And bacterial growth will occur, especially is the temperature is favourable for it. One common way to inhibit bacterial growth is by adding chlorine to the water.
However, in addition to the difficulty of dosing the chlorine correctly and safely, chlorination causes corrosion in the piping, the water will taste and smell of chlorine, and the effect is not very long lasting since the chlorine tends to evaporate from the water. A good alternative is to add silver ions to the water.
A correct and accurate dosing is easy to arrange with a silver electrode in the water since the amount of silver added to the water corresponds directly to the electrical current lead to the electrode. Silver ions do not cause any corrosion or any smell or taste to the water, and their inhibiting effect is much longer lasting than with chlorination. The UK Maritime and Coastguard Agency recommends in its Merchant Shipping Notice MSN1845(M) that a minimum of 0,1ppm of silver ions is added to the water in the FW holding tank to ensure that the silver ion concentration stays at 0,08ppm in the whole FW system.
STERILIZING BASED ON SILVER ION INJECTION
In order to dose a correct amount of silver ions into the holding tank, a small water flow through a chamber with a silver electrode is lead to the FW holding tank. The current through the silver electrode, and thereby the dose of silver ions is adjusted automatically with a signal from a flow meter measuring the amount of new water flowing into the FW holding tank. This dosing equipment is called SILSTER 168.
SILSTER 168 Fresh Water System Sterilizing with Silver Ions
The Fresh Water Silver Ion Sterilizer type SILSTER 168 is based on a well proven method used for ages. Using silver ions for disinfection is completely harmless to humans, meeting the requirements of European Community directive 80/778/EEC. As an added benefit you avoid the piping corrosion normally caused by chlorination.
The SILSTER 168 automatically sterilizes the water of the fresh water holding tank with no need for crew interaction and practically no maintenance need. Also bunkered water can be sterilized without manual setting of current and time. The long lasting sterilizing effect of the silver ions combined with the fact that it doesn’t change the taste, smell or colour of the water makes it ideal for a number of applications.
TECHNICAL AND INSTALLATION FEATURES
– Capacity up to 240 m3/day with 0.1 ppm silver ion concentration
– Silver ion concentration within requirements of EC directive 80/778/EEC
– Dual smart inputs for water maker status or flow meters
– Automatic disinfection of bunkered water, no time & current setting needed
– User interface with LCD display and keypad
– Relay outputs for function alarm and valve control
– Power supply 85VAC … 285VAC
– Electrode life time 2500 m3 (with 0.1 ppm silver ion concentration)
– Detachable instrument panel for flexible installation.
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