Abstract: A liquid handling system for filling tanks, such as tank trucks, particularly suitable for handling volatile fluids, employing a fill conduit and an emergency shutoff valve located at the upper end of the fill conduit. The emergency valve employs an annular, normally open, valve element axially displaceable to a shutoff position upon the liquid level within the tank reaching a predetermined maximum depth. Valve element operation is regulated by a control piston subjected to subatmospheric pressures produced by liquid flow through the valve and upon the liquid level reaching a predetermined depth the control piston is actuated to cause the valve element to terminate fluid flow. The emergency shutoff valve may be employed in conjunction with a variable rate flow valve connected in series therewith to produce a versatile tank filling system.