A safety instrumented function (SIF) in a safety instrumented system (SIS) contains a sensor, logic solver and final element. All must function properly in the event of a safety demand to take the process into a safe state in coordination with other SIFs. The final element consists of several parts including the isolation valve, actuator, […]
Bulk liquid storage tanks often contain fluids that are hazardous, flammable and/or explosive. These tanks require not only a control system to control levels but and overfill prevention system (OPS) as layer of protection beyond the control system. This basic process control system (BPCS) is commonly referred to as an automatic tank gauging (ATG) system […]
The world of functional safety has its own tribal language and acronyms, e.g. safety instrumented systems (SISs), safety instrumented functions (SIFs), logic solvers, final elements (FEs), safety integrity level (SIL), probability of failure on demand (PFD), etc. In a Hydrocarbon Engineering article, Keep in the Safety Loop, Emerson’s Riyaz Ali does an excellent job of […]
The safety valve within a safety instrumented function (SIF) must be tested regularly to help assure proper operation in the event of a safety demand. Operators usually perform an offline full stroke test during a scheduled shutdown because of the impact of this test on the process. But when a SIF (a.k.a. safety loop) requires […]
Emerson’s Sergio Diaz and Alexandre Peixoto presented Best Practices for a Cybersecure SIS at the 2019 Emerson Exchange conference. Sergio opened that the goal of this presentation is to provide practical information to maintain a more defendable security posture for safety instrumented systems (SISs). Like control systems, defense in depth is an important concept for […]
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