Vent system

A vent system comprising:

• a vent stack for venting a tank fluid from a fuel tank that is external to the vent stack, during fueling of the fuel tank, the vent stack comprising:
• a conduit comprising a conduit inlet and a conduit outlet, the conduit outlet opening to atmosphere external to the conduit;
• an opening into the conduit between the conduit inlet and the conduit outlet, the opening fluidically connected, or connectable, to the fuel tank so that the tank fluid from the fuel tank flows through the opening to the conduit outlet, in use;
• and
• a first fluid mover operable to cause a mixer fluid receivable in the conduit inlet to flow through the conduit towards the conduit outlet, thereby to mix the mixer fluid with the tank fluid in the conduit, upstream of the conduit outlet;
• and
• one or more further fluid movers, each of which is operable to cause the mixer fluid receivable in the conduit inlet to flow through the conduit towards the conduit outlet, thereby mixing the mixer fluid with the tank fluid in the conduit, the mixing of the mixer fluid with the tank fluid occurring upstream of the conduit outlet.