Method and device for determining the filling mass of a cryogenically stored gas in a container

A method for determining a filling mass in a thermally insulated container for a cryogenically stored gas, comprising the acts of:

• determining the filling mass using a known container volume and a calculated density of the cryogenically stored gas in the container, wherein the calculated density is calculated from a container pressure measurement and a temperature measurement;
• and
• measuring, by a temperature sensor, a mixing temperature of a liquid phase and a gaseous phase of the cryogenically stored gas, wherein the liquid phase is extracted by way of a first extraction supply line at a geodetically lowest point and the gaseous phase is extracted by way of a second extraction supply line at a geodetically highest point of a cavity of the container,
• wherein the temperature sensor is placed downstream of the geodetically lowest and highest points, after a convergence of the first and second extraction supply lines to a single extraction line leading out of the container, on an inside or outside of said single extraction line, at a location where complete and thorough mixing of the liquid phase and the gaseous phase of the cryogenically stored gas from the first and second extraction supply lines has already taken place.