This publication describes the basic principles to calculate appropriate safety and separation distances for the industrial gases industry. It is intended that EIGA members use this publication as an aid to writing or revising any publications that involve specifying safety and separation distances for safe equipment layout. Historically, the term safety distance has been used for an effect-based distance. This is consequence based and gives conservative safety distances. Because of increasing density of industrial installations, there is a need for more realistic safety distances. This has led to risk-based safety distances. Determination of safety and separation distances is a subject that requires detailed knowledge of risk and consequence modelling and as such this publication should only be used by specialists with this knowledge.