The Case for High-Visibility Thinking

I audited the control room displays at a Rotterdam chemical plant last November. Every operator station had been configured by a different shift supervisor across twelve years. Different alarm thresholds, different color scales, different refresh logic. On December 14, during a pressure excursion in Reactor 4, three operators saw three different severity readings. The relief valve tripped fourteen seconds late.

One Signal, One Meaning

ANSI Z535 defines exactly four signal words. DANGER for hazards that will kill you, WARNING for hazards that might, CAUTION for minor injuries, NOTICE for property damage. There is no fifth tier labeled "sort of important."