1.1 This part of EN 15004 contains specific requirements for gaseous fire-extinguishing systems, with respect to the IG-541 extinguishant. It includes details of physical properties, specification, usage and safety aspects. 1.2 This part of EN 15004 covers systems operating at nominal pressures of 150 bar, 200 bar 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.