A distributed measurement, control and data management system for loading and unloading hydrocarbon based fluids into rail tank cars comprised of coriolis mass and density meter, microwave based water cut analyzer, flow computer, pressure transmitter, temperature transmitter, resistance temperature detectors (RTD) and thermowell, flow control valve, downloadable computer software interface to Automatic equipment identification (AEI), electronic recognition downloadable software in use with the North American railroad industry to identify individual rail tank cars, downloadable computer software for placing a web service call through a computer network to provide rail logistics service to obtain individual rail tank car physical characteristics and capacities, downloadable computer software with calculation routines to determine gross and net volumes of oil and produced water and compensates these volumes for temperature and pressure and network printer, namely, computer hardware for providing an audit trail through a chronological record log for all data transfer transaction measurements for retrieval by the customer's networked production accounting; process control and primary measurement equipment for loading and unloading hydrocarbon based fluids for rail tank cars; coriolis mass and density meter, microwave based water cut analyzer, flow computer, pressure transmitter, temperature transmitter complete with resistance temperature detectors (RTD) and thermowell, and flow control valve for a rail tank car loading and unloading system for the transfer of hydrocarbon based fluids and produced water; interface system hardware for a rail tank car loading and unloading system for the transfer of hydrocarbon based fluids and produced water; computer software with calculation routines for measuring and controlling a rail tank car loading and unloading system for the transfer of hydrocarbon based fluids and produced water