eveson-17 A Possible Solution Enforce discipline and control complexity Limits have changed from structural integrity and physical constraints of materials to intellectual limits Improve communication among engineers Build safety in by enforcing constraints on behavior Example(batch reactor) System safety constraint: Water must be flowing into reflux condenser whenever catalyst is added to reactor Software safety constraint Software must always open water valve before catalyst valve Computers and Risk Stages in Process Control System Evolution 1.Mechanical systems Direct sensory perception of process Displays are directly connected to process and thus are physical extensions of it Design decisions highly constrained by Available space Physics of underlying process Limited possibility of action at a distancec ￾✂✁✂✄☎✁✂✆☎✝✂✞✠✟✌☞✱✮ ✙✝✂✖✠✚✂✛✂✜✁✂✒✆✣✢✂✞✂✤✠✥✧✦✆☎★ A Possible Solution Enforce discipline and control complexity Limits have changed from structural integrity and physical constraints of materials to intellectual limits Improve communication among engineers Build safety in by enforcing constraints on behavior Example (batch reactor) System safety constraint: Water must be flowing into reflux condenser whenever catalyst is added to reactor. Software safety constraint: Software must always open water valve before catalyst valve ￾✂✁✂✄☎✁✂✆☎✝✂✞✠✟✌☞✱✬ ✙✝✂✖✠✚✂✛✂✜✁✂✒✆✣✢✂✞✂✤✠✥✧✦✆☎★ Stages in Process Control System Evolution 1. Mechanical systems Direct sensory perception of process Displays are directly connected to process and thus are physical extensions of it. Design decisions highly constrained by: Available space c Physics of underlying process Limited possibility of action at a distance