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
Density & API Grade
We need to know the density of the fuel for 2 main
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
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!
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
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.