Fuels Technical Information

Water is the most common fuel contaminant and the level of water present is very low. Typically this is 0.1-0.2% V/V and as can be seen from the cumulative distribution some $$% of samples contain less than 0.3% water.

The ingress of water can come from a number of sources, which include tank condensation and tank leakage, and can generally be avoided by good management. Where steam is used for tank heating purposes the pressure in the coils is usually greater than the head pressure in the tank, hence any leakage will result in an increased water content in the fuel.

A further potential source is the purifier if an incorrect gravity disc is used for the fuel being treated, or if the water control soleniod vales are leaking on the centrifuge.

The leakage of water into fuel tanks either from adjacent water ballast tanks or from the sea itself through bulkheads, is of course a matter of routine hull maintenance, however the various tank fittings and penetrations necessary can form sources of potential leakage.

Sounding pipes should be securely capped at all times when not in use. Air pipes must remain open and consequently be arranged to terminate as high as possible, or be fitted with approved self closing devices to avoid breaking water. They should be in protected locations, safe from mechanical damage during cargo handling or from flooding when washing down decks.

The nature of the water present in the fuel may be fresh, brackish or salt depending on the level of sodium present as determined by elemental analysis On a world wide basis the salt content of sea water varies, however, usually in first order terms 100mg/kg of sodium is associated with 1% of water.