Patent ID: 8370088

Claim:
A method for determining, in real time, the level of fill of a cryogenic tank intended to contain a diphasic liquid-gas mixture, in which method at least one of: the level, the volume or the mass contained in the tank is calculated at each time step (t, t+Δt . . . ) for the liquid, and possibly also for the gas, the method measuring in each time step the pressure differential (DP=PB−PH) (in Pa) between the upper and lower parts of the tank and at least one of the pressures (PH, PI) of said differential, wherein the method: a) uses a thermal model at each time step (t, t+Δt . . . ) to calculate the mean temperatures of the liquid (Tl) and of the gas (Tg) in the tank from the measured pressure differential (PB−PH) and from at least one of the pressures (PH, PI) of said differential; b) calculates the evolution over time (t, t+Δt . . . ) at least of the density of the liquid (ρl) (in kg/m 3 ) from the mean temperature of the liquid (Tl) and from the pressures (PH) (PB) in the tank; and c) calculates the liquid level (hl) (in m) in the tank by applying to the liquid the general law of hydrostatics of the type: dP=−ρl·g·dhl from the calculated liquid density (ρl) (with dP being the variation in pressure of the liquid, ρl being the density of the liquid, g being the Earth's acceleration due to gravity, and dhl being the variation in height of the liquid).