Explosions and fires are responsible for millions of dollars of losses in the chemical and/or oil & gas industries each year. Because such a great potential for loss exists, it's common for these industries to employ safety instrumented systems (SIS) to provide safe isolation of flammable or potentially toxic material in the event of a fire or accidental release of fluids. Typically, safety instrumented systems consist of three elements: 1. Field sensors used to collect information needed to determine if an emergency situation exists. These are dedicated to SIS service and have process taps that are separate and distinct from the normal process information. 2. A logic system that determines what action is to be taken based on the information gathered. Highly-reliable logic solvers are used that provide both fail-safe and fault-tolerant operation. 3. A final control element that implements the action determined by the logic system. This final control element is typically a pneumatically-actuated valve.
展开▼
