Tank system and method for monitoring a tightness of a tank system

A tank system (100) for supplying a fluid to a consumer (115), wherein the tank system (100) comprises:

• at least one tank (101),
• a mechanically controlled pressure regulator (111),
• a system separation valve (107),
• wherein the system separation valve (107) is connected to the pressure regulator (111) via an intermediate line (121) in a fluid-conducting manner,
• wherein the at least one tank (101) comprises a tank valve (103),
• wherein the tank valve (103) is connected to the system separation valve (107) via a tank line (105) in a fluid-conducting manner,
• a computing unit (119),
• wherein the computing unit (119) is electrically connected to the tank valve (103) and the system separation valve (107),
• wherein the computing unit (119) is configured
• in a first step, while fluid flows from the tank system (100) to the consumer (115), to first close the tank valve (103) of the at least one tank (101), and
• in a second step, to close the system separation valve (107) so that a tank pressure in the at least one tank (101) is greater than a tank line pressure in the tank line (105) and the tank line pressure is greater than a system line pressure in the system line (113), and the pressure regulator (111) opens to connect the intermediate line (121) in an intermediate region between the system separation valve (107) and the pressure regulator (111) to a supply line (123) between the pressure regulator (111) and the consumer (115) in a fluid-conducting manner, and
• wherein the computing unit (119) is further configured
• to infer a first fluid mass in a region upstream of the system separation valve (107) at a first instant based on a first tank line temperature determined at the first instant and a pressure in the tank line (105) and to infer a first fluid mass in a region downstream of the system separation valve (107) at the first instant based on a first system line temperature determined at the first instant and a pressure in the system line (113),
• wherein the computing unit (119) is further configured
• to infer a second fluid mass in the region upstream of the system separation valve (107) at the second instant based on a second tank line temperature determined at a second instant and a pressure in the tank line, and to infer a second fluid mass in the region downstream of the system separation valve (107) at the second instant based on a second system line temperature determined at the second instant and a pressure in the system line (113),
• to monitor a tightness of the tank system (100) based on a change in the first fluid mass in an area upstream of the system separation valve (107) compared to the second fluid mass in the area upstream of the system separation valve (107) and/or a change in the first fluid mass in the area downstream of the system separation valve (107) compared to the second fluid mass in the area downstream of the system separation valve (107).