Abstract: A tank trailer mounted metering system is disclosed. The system includes a fluid conduit extending between an inlet and an outlet. The inlet is configured for connecting to a fluid supply, and the outlet is connected to a tank of a tank trailer. The system also includes a pump positioned along the fluid conduit between the inlet and the outlet. The pump is configured to move a fluid through the fluid conduit. The system includes an air eliminator box positioned along the fluid conduit between the pump and the outlet. The air eliminator box is configured to remove air from the fluid. The system also includes a mass flow meter positioned along the fluid conduit between the air eliminator box and the outlet, and an orifice plate positioned at an outlet of the mass flow meter.