A Multi-Level Storage Tank Gauging And Monitoring System Using A Nanosecond Pulse

In this paper, a one-port time-domain/frequencydomain based technique using a short-circuited coaxial geometry inserted vertically in a liquid tank is designed and presented as a multi-level storage tank gauge and monitor. For storage tanks of small physical liquid levels, the attenuation inside the coaxial cable sensor may be neglected and both the physical liquid levels and liquid permittivity can be measured simultaneously, whereas, for large physical liquid levels, as in the crude oil mass storage tanks, the attenuation coefficient of the liquid filled coaxial cable sensor should be considered and predetermined for all level materials in the tanks, and then both liquid levels and permittivity can be measured simultaneously. In this work a multi-level liquid tank contains four different materials; air, combustion engine oil, water, and mud, with physical level thickness of 30cm, 60-cm, 10-cm and 5-cm, respectively, was examined to measure both physical levels, assuming them unknown, and permittivity of each level content. From the measured data, the error of the calculated levels was less than 0.01, which may be improved to be almost neglected by considering the attenuation in the coaxial sensor and using a signal processing unit to display the levels accurately. Keywords— Attenuation, coaxial sensor, crude oil, level gauge system, one-port, permittivity, oil storage tank, time-domain, TDR.