Nozzels for water deluge systems are characterized by geometrical factors like spray pattern, spray angle, and by exit velocity, capacity and area coverage. In engineering calculations only the area coverage is needed to fulfil standard requirements, and the other factors are more used as a means to obtain the required application density onto protected surfaces. In assessment of the hazard of gas and liquid fires these characteristics are not sufficient to quantify the effect of water spray on the fire properties.In this report a set of factors and characteristics useful for the calculation of water-fire-interaction is described, together with the possible measurement techniques available to quantify these factors.Based on the present state-of-the-art technology and the best practice at offshore platforms in the North Sea, a set of representative nozzels have been chosen to be used in the MEdium-scalle fire tests of the project "Documentation on active fire fighting systems as a fire safety design parameter".