| 摘要 |
In a level measuring device for containers filled with fluid, preferably tanks in tank installations, the fill level height h is determined from the transit time of ultrasound pulses which are emitted by first sound pulse transmitters along a main measuring path extending from the bottom region of the tank to the fluid surface and are reflected from the fluid surface to first sound pulse receivers. Temperature sensors are provided for finding the temperature distribution throughout the fill level height h. Processing the measurements provides a mean temperature TM in the fluid volume. In addition to the main measuring path there is a reference path in the fluid volume, with second sound pulse transmitters and receivers and a reference temperature sensor for measuring a reference temperature TRef. The reference path makes it possible to find the sound velocity v*(TRef) in the fluid volume at the reference temperature TRef from the measured difference in transit time, so that a temperature-corrected sound velocity v(T) in the fluid volume: v(T)=v*(TRef)[1+Kkx DELTA T], and thus a temperature-corrected fill level height h(T)=v(T)xtH, are found, in which DELTA T=TM-TRef, and Kk is a medium-dependent correction factor. The measuring device and a process for determining the fill level use a measuring tube with first and second sound waveguides.
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