Fire and Gas Detection and Mitigation Systems

• Lawrence Beckman

Keywords: Fire and gas, NFPA 72, IEC 61511, risk reduction, LOPA

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Abstract:

Fire and Gas Detection systems are key components in the overall safety and operation of any production facility and its on-site personnel. These facilities have had serious safety problems over the years. Some recent statistics provided by the NFPA (National Fire Protection Association) reveals that between 1985 and 2004, there were 10 U.S. petroleum refinery fires with three or more deaths. In March of 2005, the BP Texas City Refinery explosion and fire killed 15 people and injured 200 others.

The Fire and Gas Detection system continuously monitors heat, smoke, temperature, and toxic or combustible gas levels with the use of dedicated field devices. If any combination of them (within a zone) exceeds a pre-determined level, the system will raise the alarm and take automatic action to close operating valves and damper doors, release extinguishants, cut off electrical power and vent dangerous gases.

Fire and Gas Detection Systems are included under the provisions of the OSHA 1910.119 (PSM) Regulation, Subpart L (Fire Protection) as they are intended to prevent or minimize the consequences of catastrophic releases of toxic, reactive, flammable or explosive chemicals. The NFPA 72 National Fire Alarm Code addresses the application, installation, location, performance and maintenance of fire alarm systems and their components. However, Gas Detection Systems are not included, in spite of the fact that detection of a release is the cornerstone upon which subsequent fire-fighting action depends.

Work is in progress by the ISA S84 WG 6 Committee to treat Fire & Gas Detection and Mitigation Systems as Safety Instrumented Systems in the process sector, and require that an appropriate SIL (Safety Integrity Level) rating or RRF (Risk Reduction Factor),per IEC 61511 performance criteria, be achieved. Considering the importance of these systems to maintaining the operational integrity of the overall facility, this work is absolutely essential.

This paper discusses the application of Fire and Gas Detection and Mitigation Systems in process facilities, and the capabilities of these systems to meet the requirements of both NFPA 72, and a Safety Integrity Level of SIL 1 or 2, in compliance with IEC 61511. © 2010 Inside Publishing. All Rights Reserved.

Volume: 2010   Issue: 1

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