Method and apparatus for marking a liquid hydrocarbon in a reservoir

A method for homogeneous marking of petroleum hydrocarbon stored within a reservoir on a vehicle, with a marking solution comprising at least one marker, the method comprising:

• inserting a loading arm into the reservoir of the vehicle, said loading arm comprising a marker injection conduit having a free end being operative to dispense a pressurised marker stream, and a gas injection conduit having a free end being operative to dispense a pressurised gas stream;
• positioning within the petroleum hydrocarbon within the reservoir the free end of the marker injection conduit at a marker height from a lowest surface of the reservoir and positioning the free end of the gas injection conduit at a gas height from the lowest surface of the reservoir, wherein the free end of the marker injection conduit is located at the marker height which is larger than the gas height;
• and
• simultaneously dispensing the pressurised marker stream and the pressurised gas stream into the petroleum hydrocarbon.