Above: Kittiwake Water in Oil electronic cell
Graph shows water distribution for residual fuel.
The Kittiwake Power Plant Laboratory provides a simple water test.
Info Centre >> Fuel and Lube Oil Technical Manual >> 2. Fuel Oil - Characteristics >> 2.8 Water
Usually the level of water in the fuel is very low and 0.1- 0.2% by volume is typical. The introduction of water can come from a number of sources, which include tank condensation, tank leakage or deliberate adulteration. Where steam is used for tank heating purposes, heating coil leakage is another potential source of water. A further potential source is the purifier itself if the gravity disc is incorrect for the density of fuel being treated.
The profit margins on fuel deliveries are often very small and it is tempting to improve this by water addition that is often difficult to detect in a visual examination. Reputable suppliers will deliver fuel with a water content far below ISO 8217 maximum limits.
In practice, the nature of the actual water present may be fresh, brackish or salt depending on the level of sodium as determined by elemental analysis. On a world-wide basis the salt content of sea water varies, but usually in first order terms 100mg/kg of sodium is associated with 1% of sea water. Gross water contamination will be removed in the settling tanks with the final water being removed by the centrifuge. The figure shows the histogram of water content of residual fuels delivered in to the marine market world-wide.