Interpretation of Fuel Test Results

The tests performed in the Maritec Fuel Testing Program will give you a better picture of the fuel you have bought and supplied onboard your ship. We explain how:

Density & API Grade

We need to know the density of the fuel for 2 main purposes.

First, we need the Density figure to select the correct size of gravity disc for use in the purifiers and to determine the Net Specific Energy of the fuel.

Second, to know if we have paid for more fuel than we actually received. Fuel is bought and sold by weight (often in Metric Tons) but we measure the quantity received by suppliers in terms of volume.

Example, a bunker surveyor determines the quantity received in a ships tank by the volume of the tank filled with fuel. To obtain the weight of the fuel, we need the density figure. The surveyor would have to multiply the volume by the density to get the weight of the fuel. (in simplistic terms, volume X density=weight). This density figure is usually declared by the supplier.

Now, what if the actual density figure (determined by a lab test) is lower than the declared value by the supplier? Theoretically, the ship would have received less fuel given the volumetric measurements being the same! In such cases, you would have paid for more fuel than was actually delivered and operationally, your ship may not have enough fuel to reach the next port!

Viscosity

We need to know the viscosity of the fuel to verify if we have got the correct grade of fuel onboard the ship. Did we get a grade above ISO specification limits or paid for a lower grade fuel but actually got a higher grade?

We also need to know the viscosity value to determine preheating and injection temperatures for our engine settings. This is because most marine engines require a specific viscosity of the fuel at the injection nozzles for an even spray of fuel into the cylinder chamber for good combustion.