The Norwegian petroleum industry has developed a standard for the technical safety of offshore installations (NORSOK S-001). When dimensioning accidental load with this standard, the deluge or fire water spray is considered for equipment and pipes, but not for the structural elements or fire partition. The flow properties of the flow from fire water nozzles, like droplet size and velocity distribution within the spray, are known to influence the fire suppression efficiency of the water nozzle. This work presents preliminary results from an image-based method for characterizing the flow properties of the spray from a medium velocity nozzle. The data will be used as input to Computational Fluid Dynamic (CFD) fire codes. The experimental rig consists of a high-speed camera, a copper vapor laser, and a fire water nozzle and water supply system. The high-speed camera captures images of the droplets in the spray, and an image processing code measures the spray properties. Some preliminary results are presented which show the importance of the largest droplets in the spray.