Patent ID: 6931925

Claim:
A method for determining the current filling level of a liquid in a container having an immersion pipe dipped into the liquid in the container, and a tubing system connecting the immersion pipe to a pumping device; the method comprising: (a) measuring the ambient gas pressure p 0 in the tubing system at a time t 0 ; (b) using the pumping device to increase the gas pressure in the tubing system; (c) measuring the gas pressure p 1 at a time t 1 when a first discontinuous pressure change occurs due to a liquid column being forced out of an exit end of the immersion pipe; (d) calculating at least one of the difference in pressure between p 0 and p 1 and the difference in time between t 0 and t 1 ; and (e) determining the current filling level of the liquid in the container by the difference in at least one of pressure and time, wherein the current filling level is related to the difference in pressure or time.