He rushed to the control station, which, according to the second edition of API 553, had been strategically located outside the fire zone for maximum safety. On his screen, the automated valves in Unit 4 were struggling. The standard he studied daily provided the exact criteria for selecting piston and diaphragm-actuated valves to handle exactly this kind of refinery stress.
"Check the fail-safe position," Elias commanded over the radio. He recalled the standard's specific criteria for Safety Instrumented System (SIS) valves api 553 pdf