During the loading of a petroleum tanker, the incoming cargo forces out from the tank its previous atmospheric contents (air-vapor-inert gas).

(a) Explain

(i) The dangers of venting during the loading via open tank hatches. (5)

(ii) Why the pressure/vacuum valves are not used for venting. (5)

(b) Describe with a line diagram showing a typical 'Inert Gas Sysetm' used for inerting the cargo tanks of oil tankers. State what oxygen content you would expect in the flue gases if good combustion is achieved. What are the other constituents of 'Inert Gas'? (10)