For getting it pumpable, it has to be heated to a temperature of 50 – 60°C. For fuel injection into cylinders of the marine engine a temperature of 130 – 140°C is required. Besides high viscosity high density and high sulphur content are typical characteristics of heavy fuel.
Especially sulphur is on the forefront of public attention, politics, authorities and environmental organizations. In certain areas ship engines are allowed to run only on heavy fuel with a sulphur content of 0,1 percent by weight (m.-%), since January 1st, 2015.*
One more thing being mentioned: The sulphur content of heavy fuel is depending on the sulphur content of crude oil, besides some other factors. Unfortunately low sulphurous crude oils are a rarity today. “Brent Crude”, extracted in the North sea, is one of those rare crude oils.
Nevertheless: It is guaranteed that heavy fuel with a sulphur content of 0,1 m.-% is on stock in German bunker ports.
In shipping heavy fuel is named differently: As bunker oil, bunker B, bunker C, RFO (residual fuel oil), IFO (intermediate fuel oil), MFO (marine fuel oil) or LSFO (low sulphur fuel oil).