4″ Internal Valve is designed to normal and emergency shutoff functions and tank liquid level control with low surge, low pressure drop, and high reliability. When used with the F613 jet level sensor or F619B float operated pilot valve, fuel pressure provides the actuation force for opening and closing the valve during tank filling. The basic valve can be used for off-loading. Single or dual stage tank filling control is available by adding one or two pilot valves. A lug is provided for attachment of a lanyard to manually open the valve for emergency off-loading.