An inert gas fire-extinguishing system which reduces a risk of and extinguishes fires in a protected room, the inert gas fire-extinguishing system comprising:
- at least one high-pressure gas tank in which an oxygen-displacing gas is stored under high pressure, wherein the high-pressure gas tank is connected to a collecting line via a quick-release valve, and
- an extinguishing line connected on one side to the collecting line via a pressure-reducing device and on the other side to extinguishing nozzles,
- wherein the pressure-reducing device includes at least two parallel branches, each having a pressure regulator, wherein each parallel branch is connected to the collecting line and the extinguishing line via a controllable valve,
- wherein each pressure regulator is configured to reduce a high input pressure to a low output pressure according to a known pressure-reducing characteristic curve,
- the inert gas fire-extinguishing system further comprising:
- a control device to automatically effect, based on measurement by a sensor of at least one fire characteristic in the protect room, a multi-stage inerting process in which the oxygen content in the protected room is first reduced to a first lowered level and then further reduced to another preset lowered level or successively to multiple preset lowered levels,
- wherein the control device is configured to control the valves of the pressure-reducing device to set the lowered level such that the oxygen content in the protected room reduces in accordance with a preset inerting curve,
- wherein the control device is configured to control the valves of the pressure-reducing device to reduce the oxygen content to the first lowered level such that only one first parallel branch of the at least two parallel branches is connected to the collecting line and the extinguishing line, and
- wherein the control device is further configured to control the valves of the pressure-reducing device to further reduce the oxygen content to a second lowered level such that only one second parallel branch of the at least two parallel branches is connected to the collecting line and the extinguishing line, and
- wherein the pressure-reducing characteristic curve of the pressure regulator arranged in the first parallel branch differs from the pressure-reducing characteristic curve of the pressure regulator arranged in the second parallel branch,
- such that the reduction of the oxygen content in the protected room from the first lowered level to the other preset lowered level is performed as needed according to a desired inerting curve, which is a function of temporal changing of the oxygen content such that the sequence of events may be varied according to need by controlling the valves, of the pressure-reducing device, respectively disposed in each of the parallel branches.