[en] A system for measuring the liquid volume in input and plutonium product accountability vessels, based upon a desktop-computer-controlled electromanometer, was installed at the Tokai-Mura reprocessing plant. In-tank temperatures, pressure measurements relating to volume and density, and load-cell weights are measured cyclically and recorded. The system feasibility was demonstrated through a series of tests including vessel calibration and the effects of thermal expansion, and through use during thirteen months of on-line plant operation. The value to the operator of the recording, display, replay, data handling, and report generation features of the system was demonstrated as was the enhanced precision of the electromanometer as compared to the conventional water-filled manometer system. The automated electromanometer system consists of a pneumatic scanner, a precision electromanometer, electronic scanner, a digital voltmeter, and a desktop computer with disc and tape mass storage, cathode-ray tube (CRT) graphics display, and printer output. The desktop computer is used to control the pneumatic and electronic scanners and the digital voltmeter and to log in the measurement data