Abstract: The depressurization system comprises a main valve (8) provided with a pneumatic actuator with an opening spring (10) which can be connected at one side to a pressurized container (1) housing a gas inside it and at the other side to the atmosphere, defining this opening spring (10) a predetermined mechanical pressure, so when the pressure inside the pressurized container (1) is bigger than the predetermined mechanical pressure, the main valve (8) remains closed, and when the pressure inside the pressurized container (1) is lower than the predetermined mechanical pressure, the main valve (8) opens, allowing the pressurized gas from container (1) be discharged into the atmosphere. It does not require any external power supply for their main operation, allowing to fulfill appropriately their role in accident scenarios, even with total loss of electric power.