Batch metering refers to the measurement and control of a predetermined quantity of oil dispensed, transferred, or processed in a single operation. Unlike continuous flow metering, where the objective is to measure an ongoing flow rate, batch metering focuses on accurately totaling the volume or mass of oil delivered during a discrete transaction. Batch metering is used in applications such as tank truck loading, ship bunkering, drum filling, additive injection, and batch blending. The accuracy of batch metering directly affects the commercial fairness of oil transactions and the quality of blended products.
A typical batch metering system consists of a flowmeter, a flow computer or batch controller, and one or more control valves. The operator enters the target batch quantity into the controller, which opens the control valve and monitors the flowmeter totalizer. As the accumulated total approaches the setpoint, the controller initiates a valve pre-close to slow the flow rate before the final shutoff, minimizing the overshoot caused by valve closing inertia and the inertia of the flowing fluid. This "pre-act" function is essential for achieving high batch accuracy—typically better than 0.1% of the setpoint quantity—in high-speed loading operations.
Modern batch controllers offer additional features such as multiple product metering (switching between different oil products), automatic calibration correction using stored K-factors, thermal volume correction, density compensation, and data logging of completed batch transactions. In truck loading and ship bunkering applications, batch metering systems are connected to higher-level terminal management systems that control access, assign batch transactions to specific vehicles or vessels, and generate delivery tickets. These tickets serve as the legal record of the oil quantity transferred and must reflect the meter reading accurately. Ensuring that batch controllers are correctly programmed, regularly calibrated, and maintained in good working order is essential for fair and efficient oil transfer operations.