All chemical tankers have at least one installed FWG which should be kept in a clean and efficient working condition and be able to produce fresh water (FW) in quantities close to the rated capacity.
This can only be achieved if all components and associated equipment such as pumps and ejectors are kept in a good working condition.
When there is a possibility of carrying wall wash cargoes the Chief engineer must monitor the chloride levels closely. As far as practicable all steam must be generated from FWG water , so as the quality of steam is good to reduce chlorides in cargo tanks .
During operation of FWG, Evaporator Treatment should be applied to prevent the formation of scale.
The vessel should in all circumstances, be able to produce sufficient FW whilst at sea, for her own consumption. This can be monitored by using a reliable flow meter or consuming from another tank for a day.
Ensure tank washings are not discharged in the same side of FWG intake.
If the sea is having obvious contaminants like Molasses ( as is usual off west coast Nicaragua / Salvador )/ palm oil washings ( usual in North sea ) , plankton etc shut off the FWG.
However, as the temperatures involved in the distillation process may not be high enough to kill all bacteria present in such water, the evaporators must not be used for making drinking or washing water in port, inland waters, estuaries or anywhere there is a risk of generating contaminated water.
The evaporators may be used to produce distilled water for use in the boiler plant, should port/cargo operations deplete the distilled water stocks below a safe operating level.
The Chief Engineer must notify the Master in the event of excessive consumption of boiler or domestic water. Live steaming can consume a lot of water.
Cargo must not be shut out in order to carry an excess quantity of water.
CAPT AJIT VADAKAYIL
30 YEARS IN COMMAND