Method for the operation of a tank unit for storing a gaseous fuel and tank unit for storing a gaseous fuel

A method for the operation of a tank unit (1) for storing a gaseous fuel for a vehicle, wherein the tank unit (1) comprises:

• at least one tank vessel (TB1, TB2, ..., TBn) having at least one valve mechanism;
• a gas conduit system (GL) to which the at least one tank vessel (TB1, TB2, ..., TBn) is connected via the valve mechanism;
• a first pressure sensor in a high-pressure region and a second pressure sensor in a mid-pressure region of the gas conduit system (GL), wherein the respective tank vessel (TB1, TB2, ..., TBn) is connected to the high-pressure region of the gas conduit system (GL) and the high-pressure region is connected to the mid-pressure region by a control valve;
• and
• a control unit connected to the pressure sensors and the at least one valve mechanism;
• the method comprising the steps of:
• shutting down a gas output from the mid-pressure region (MD) of the gas conduit system (GL);
• detecting a first pressure in the high-pressure region by means of the first pressure sensor and first temperatures in the high-pressure region and a second pressure in the mid-pressure region by means of the second pressure sensor and second temperatures in the mid-pressure region;
• determining an average temperature in the mid-pressure region and an average temperature in the high-pressure region based on the determined first and second temperatures;
• determining a first comparative density in the high-pressure region based on the first pressure and the average temperature in the high-pressure region and a second comparative density in the mid-pressure region based on the second pressure and the average temperature in the mid-pressure region;
• re-detecting the first pressure, the first temperatures, the second pressure, and the second temperatures in the high-pressure region and the mid-pressure region prior to re-drawing gas from the mid-pressure region of the gas conduit;
• determining current averages of temperatures in the mid-pressure region and the high-pressure region from the re-detected first and second temperatures;
• determining a current density in the high-pressure region and the mid-pressure region from the current averages of temperatures and first and second pressures;
• and
• comparing the current density in the high-pressure region and the mid-pressure region to the respective comparative density and verifying a deviation between the respective current density and the comparative density in terms of a leak at the high-pressure region and/or the mid-pressure region according to a predetermined verification protocol.