Electrolysis tanks take a supply of water from a single source, very often an existing sea waterline within the vessel that has spare capacity. The water passes through the electrolysis tank where a high dosage of copper and (iron or aluminium) is added from the Cathelco anodes.
The treated water then passes to a manifold where it is distributed to the required sea water intake at the necessary volume. Calculations ensure that when the sea water is introduced back into the main flow of water the dosage rate (copper/iron/aluminium) is diluted to give the required normal dosage for the total seawater flow in order to control bio-fouling.
On board vessels
Electrolysis tanks are generally used to replace existing chemical or chlorination systems, where it is not possible to place the anodes directly into the sea chests or strainers.
The advantage of using an electrolysis tank is that anodes can be replaced on a regular basis, often 6 months to 1 year, ensuring they are completely consumed with very little wasted material. Using pipes to deliver the high dosage of copper ions to the sea water intakes means there are no submerged parts that need to be considered for replacement, also the system is easier to inspect and maintain.
Sea water lift pumps
Sea water lift pumps on offshore platforms use the electrolysis tank to deliver treated water to the bottom of each pump. This is because the available area to fit anti-fouling units is very limited and long maintenance periods are often stipulated which would necessitate the use of large units. By using an electrolysis tank the anodes can be replaced more frequently at regular intervals. This allows the maintenance period of the pumps to be increased due to the increased fouling/corrosion suppression protection they receive from the Cathelco tank system.