"As a precaution the high-pressure ethene polymerization process needs quick release systems to prevent the equipment from damage in case of deflagration events of the reaction mixture. Still several assumptions must be taken to describe this process. It will be presented to what extend the individual processes such as speed of flame front propagation on its own and in interference with venting can be measured as well as the composition of the vented media impacts the rate of decompression. Examples will be shown how monitoring of the medium during venting by video helps to get a more detailed understanding of the overall process. From the measured data trajectories can be computed describing the thermodynamics of the venting. The visualization helps to understand the individual contributions of depressurization, super cooling and welling up. "