© Handermann 2013 FunctionalSafety.net There are 4 safety system states (internal failures) -UP or OK state: no failure and the process is available; -SAFE state: the safety system fails in a way that the safety function (SF) is carried out without a demand and the process tripped; -DANGEROUS state: the safety system fails in a way that the SF cannot carried out in case of a demand. The process is available but not protected; -INTERMEDIATE state: the safety system can still be carried out despite of one ore more internal failures. The process ist available but it is about time to repair the safety system; There are 3 safety system failures -Random failures -Common cause failures -Systematic failures A safety system is functionally safe if random, common cause and systematic failures do not lead to malfunctioning of the safety system and do not result in injury or death of humans or spills to the environment or loss of equipment or production.