The ability of sprinklers to supress or control fires depends to a great extent on the rapidity with which they respond. Over the past decade, new sprinklers, such as Early Suppression Fast Response (ESFR) sprinklers for warehouse protection and residential sprinklers for use in residential occupancies, have been developed for which the requirement of fast response plays a key role. Thus, the ability to predict the response time of sprinklers in given fire situations has become increasingly more important. To predict the sprinkler response, knowledge concerning the gas temperature and velocity at the ceiling, is required. Semi-empirical relationships have been developed to predict the gas temperature and velocity at the ceiling for different fire conditions. Parameters such as fire size, fire growth rate and room geometry in two dimensions have been included. Heskestad and Delichatsios 1 published relationships with which the maximum temperature and velocity of fire gases can be predicted as they travel across the ceiling. The relatonships assume at flat ceiling with no obstructions, and the ceiling jet is assumed to be radially axisymmetric. In many buildings these conditions are not fulfilled as obstructions and vents of different types are mounted in the ceiling. Local effects on the temperature and velocity fields caused by beams, smoke curtains, walls, fire vents or water spray from already activated sprinklers, can not be predicted with semi-empirical models. For these cases field model codes are required. Until now, there has been a lack of full-scale fire tests to verify simulations with field models codes. The experiments in (2) * provide the basis for the necessary verifications. With the knowledge of the ceiling jet temperature and velocity at any time and location, the response time of the sprinkler can be calculated. To predict the response time, a mathematical thermal response model for the sprinkler's heatsensitive element is required. The thermal response model includes parameters which describe the heating characteristics of the heat-sensitive element. The thermal response parameters are determined from wind tunnel tests. In (1), an extensive investigation is described of different thermal response models to determined the most appropriate model for incorporation into the field model code JASMINE 2. With an appropirate thermal response model the sprinkler response can be calculated for complicated cases such as and beams are mounted in the ceiling. The interaction of sprinklers and fire vents has been discussed intensively during the last decade without any satisfactory solution. It may be possible to elucidate this question by using a field model code. However, an investigation of the ability of field models to predict local effects around a fire vent opening and the effects of the sprinkler water spray on the ceiling jet flow must first be undertaken. Therefore, as a first step in this direction, extensive experimental data for the verification of a field model code for such complicated results in (2). If it is found that the field model calculations and the test results in (2) correlate well, then the field model codes can be used for more comprehensive studies of the local effects of fire vents, smoke curtains, ceiling slopes or beam constructions on the temperature and velocity field and the turbulence conditions at the ceiling. Ett Brandforskprojekt