The safety of an industrial site depends in particular on the characteristics of the safety devices employed and the equipment installed. In France, the safety evaluation of an installation is carried out, in particular, through hazard analysis. However, the absence of objective criteria for safety device evaluation makes the task difficult. Different pieces of equipment that assure the same function don't necessarily have the same safety level. Consequently, INERIS undertook a study including: an outline of the various practices based on an inventory of French regulation and a comparison with regulations applied in other European countries; an accidentology allowing one to focus on some important safety devices; a description of the various devices that can be encountered on a L.P.G site, accompanied by a collection of descriptive boards of safety devices used with L.P.G.; a presentation of the concept of devices that are " Important For Safety ", with definitions of commonly-used terms; and a presentation of some approaches for taking into account safety devices in the evaluation of the risks or specific methods used for the evaluation of a L.P.G. site.