Fuel storage tank pressure management system and method employing a carbon canister

A method of managing pressure in a fuel storage tank to prevent fugitive emissions, comprising the steps of:

• when the fuel storage tank is overpressurized:
• receiving a hydrocarbon air mixture from the fuel storage tank into an inlet port of a carbon canister containing hydrocarbon adsorbing activated carbon;
• adsorbing hydrocarbons from the hydrocarbon air mixture onto the carbon inside the carbon canister leaving a substantially cleansed air residual from the hydrocarbon air mixture;
• and
• controlling the venting of the substantially cleansed air through an outlet port of the carbon canister to vent the substantially cleansed air through the outlet port;
• and
• when the fuel storage tank is underpressurized:
• receiving outside air through the outlet port of the carbon canister;
• purging the hydrocarbons contained in the carbon in the carbon canister using the received outside air flowing through the outlet port of the carbon canister;
• and
• returning the purged hydrocarbons to the fuel storage tank.