The degree of congestion in petro-chemical installations has a strong impact on the strength of possible gas explosions. Model predictions and recent full-scale explosion tests showed that there are situations where the consequences of such gas explosions are unacceptably high. These consequences make it necessary to consider several measures including very expensive ones such as control room relocation or strengthening of control rooms. When the costs are too high other mitigation methods may also have to be assessed. One of these methods is mitigation of gas explosions using water spray systems. Such systems are already in use for this purpose offshore, water curtain systems may be applicable onshore.
An overview of recent research into the effects of water spray on the course of gas explosions in congested environments is presented in this paper. How water spray affects the course of gas explosions, under which conditions water spray will be effective as a means for explosion effects reduction is also reported. In addition, the author illustrateg how one can design a water spray system to limit the consequences of possible accidental gas explosions. Finally the potential of increase of ignition probability due to the use of water spray is discussed.