This European Standard specifies requirements and test methods for nozzles which introduce the extinguishing agent into a CO 2 protected zone. The design of the nozzles will influence discharge rate and thus the pressure drop in the piping network. The extinguishing agent normally arrives at the nozzle in two-phase flow form (liquid-gaseous mixture). It expands into the protected volume to form a gas or a gas-and-dry-ice mixture depending on the nozzle type. This standard should only be used as guidance for testing nozzles which work on different principles.