Density is an essential parameter to measure because fuel is delivered by volume but price and energy is measured by mass.
Below: The Kittiwake Density Meter for easy measurement of fuel density.
Info Centre >> Fuel and Lube Oil Technical Manual >> 4. Fuel Oil - Test Results >> 4.5 Test Parameters - Density
Measuring Fuel Oil Density
From the commercial point of view, density is an essential parameter to measure because residual fuel is ordered by weight but supplied by volume. If the actual value is less than that stated, there will be a proportional shortfall in the quantity of product supplied.
From the technical aspect, the incorrect gravity disc may be selected for setting the traditional purifier.
Some 40% of fuel deliveries have a density in the range 985-991 kg/m3 at 15°C and only some 2% are a density overshoot of 991 kg/m3. Consider first the significant proportion close to the density limit. This emphasises the importance of operating two traditional centrifuges in series: a further requirement is to ensure that they are operated under a steady state condition so as to maintain the interface in the correct position in the disc stack. In the event of the fuel being marginally over the 991 kg/m3 limit, it is possible to operate both centrifuges as clarifiers as long as the water level in the fuel is low. If the purifier is fitted with a gravity disc for a greater fuel density than the actual value, the effectiveness of the purifier is reduced because the interface moves towards the centre.
High density fuels (<0.966) can often be handled in a standard centrifuge when operated as a clarifier with frequent blowdown. This assumes a low water content in the fuel as bunkered (<0.5%), so that the centrifuge bowl does not fill up with water between blowdown cycles.
Mass = Power.
Fuel Density is important. For example: