A safety instrumented function (SIF) within a safety instrumented system (SIS) consists of a sensor, logic solver, and final element. As part of the IEC 61511 global safety standard, these elements within the SIF must be tested during the operational phase of the safety lifecycle. Of the 3 elements, the final control element, typically a […]
Author: Riyaz Ali Partial stroke test is one of the viable means to check mechanical integrity of Final Element of Safety Instrumented Function (SIF) loop. Generally, end users struggle on question of credit of PST for improvement in SIL (Safety Integrity Level). IEC 61508 and IEC 61511 define diagnostic coverage factors (DCF), but do not […]
For manufacturing processes with hazardous substances that are combustible or can cause harm to people and property, flame and gas detection systems are often used as part of the risk mitigation strategy. This 11-minute video, Rosemount Flame and Gas Layers of Protection describes how these sensors are used in layers of protection for the process […]
A safety instrumented function (SIF)’s purpose is to reduce the risk of a specific hazard. For example, an upset condition in an oil and gas production separator may cause a series of SIFs within a safety instrumented system (SIS) to shut in the wells feeding the separator. A SIF contains a sensor, logic solver and […]
Safety instrumented systems provide a layer of protection beyond the control system to safely shutdown the process during abnormal situations. A safety instrumented function (SIF) or “safety loop” includes the sensing device, logic solver and final control element to perform safety function upon demand. Flow measurement devices are often the sensing devices in these SIFs. […]
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