MaintenanceThe main problem with fresh water generators is scale formation on the heating surfaces. Chemical injection systems are fitted to allow anti-scale chemicals into the feed line to help prevent scale formation. This system is quite often neglected, however, it is important to ensure the flowmeter is working correctly and the correct amount of chemical added to the treatment tank. Once scale forms on the heating surfaces the evaporator output will fall off rapidly. The best cleaning method is to circulate descalent chemicals through the heater tube stack. Chemicals should be circulated for a period of time and the chemical manufacturer's instructions should be referred to. The descaling chemical usually has a built in colour indicator to show when it has been exhausted. The tube stack should then be drained and flushed with fresh water. It is impossible to determine the condition of the tubes without removing the lower cover therefore the performance of the unit should be noted after each cleaning session. Occasionally the fresh water generator should be inspected internally. Older models may have a rubberised coating which may start to blister or crack. Any damaged areas should be cut away and the metal underneath thoroughly cleaned of rust and then allowed to dry. Only specially approved coatings should be used for repair and the instructions should be followed carefully as ventilation may also be required. Modern fresh water generators have no coatings and are constructed from corrosion resistant materials. When reassembling after maintenance, ensure all joints and connections are in good condition and have been tightened properly.
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