This part of EN 15004 contains specific requirements for gaseous fire-extinguishing systems, with respect to the IG-55 extinguishant. It includes details of physical properties, specification, usage and safety aspects. This part of EN 15004 covers systems operating at nominal pressures of 150 bar at 15 °C, 200 bar at 15 °C and 300 bar at 15 °C. This does not preclude the use of other systems, although design data for other pressures are not available at this time.