The Kittiwake Density Meter is included in the Power Plant Laboratory (below) .
Density should be measured in vacuo at a stated temperature.
Power plant laboratory density test reports density in kg/m 3 at 15°C in vacuo.
Info Centre >> Fuel and Lube Oil Technical Manual >> 2. Fuel Oil - Characteristics >> 2.2 Density
Fuel Oil Density
Fuel Oil Density is the absolute relationship between mass and volume at a stated temperature. The SI unit is kg/m 3 at a reference temperature, typically 15°C.
Knowledge of density is required for quantity calculations. The value also needs to be known in order to select the optimum size of gravity disc for the centrifuge. In addition, the density gives an indication of other fuel characteristics, including specific energy and ignition quality (CCAI).
Specific gravity of a substance is the ratio of the mass of a given volume to the mass of an equal volume of water at the same temperature. As it is a ratio there are no units.
Relative density (RD) of a substance is the ratio of the mass of a given volume at a temperature t1 to the mass of a given volume of pure water at temperature t2. Like specific gravity, RD is a ratio and hence no units. For example, RD at 20/4°C. Since 1m 3 of pure water at 4°C has a mass of 1000kg, the density of a substance at t1°C is equivalent to the RD at t1/4°C.
In the United States and some other countries, the density of petroleum products is defined in terms of API gravity. This is an arbitrary scale adopted by the American Petroleum Institute for expressing the relative density of oils.
The terms 'density in vacuo' or 'density in air' are sometimes used on fuel delivery or bunker receipt notes. As density is the absolute relationship between mass and volume and not its weight to volume, by definition density is in vacuo. Although often used, the term 'density in air' is incorrect and should be referred to as a 'weight factor'. This is because a substance weighed in air is supported to a small extent by the buoyancy of air acting on it. Thus the weight of a liquid in air is slightly less than the weight in vacuo. There is no simple relationship between density and 'weight factor' but for bunker fuels the difference approximates to 1.1 kg/m 3 . To convert density at 15°C to the 'weight factor' at 15°C, 1.1 kg/m 3 should be deducted.
Densities are measured over a range of temperatures, usually for convenience, at the temperature at which the fuel is stored. The value is then corrected back in test equipment or by the use of standard tables to the reference