Fire and Gas (F&G) Detection

The primary role of a Fire and Gas detection system is to detect loss of containment of flammable and toxic material and the ignition resulting in fires to provide an early warning to operational and emergency response team personnel so that necessary action can be initiated to control the emergency and avoid escalation.

Considering the flammable and toxic nature of the process streams in this plant, the selection of appropriate type of detectors, their location, voting logic and alarm is important for appropriate and effective design of the system.

The fire & gas detection system shall perform the following three basic functions:

Monitoring: Continuous automatic monitoring of the environment for the presence of flammable and toxic vapour/gases and detection of fire (smoke, heat or flame)

Alarm: Initiate alarm to alert personnel to the presence of flammable and toxic vapour/gases and/or fire.

Protection: Initiates control signals to ESD or Fire Suppression systems or Deluge Systems to control the situation and prevent escalation of the event.

Methodology

• • Definition & identification of fire & gas hazard zones for scope
• • Definition of zone categories & zone grades
• • Identification of the fire & gas hazard scenarios for scope
• • Assigning zone category for each identified fire & gas hazard zone
• • Defining the performance requirements for fire & gas detection
• • Recommendations and findings from fire & gas study
• • Proceed to develop Fire and Gas layout

Fire and Gas Mapping study:

Fire & Gas detector coverage study shall be evaluated to confirm that the required detection criteria to provide the required alarms and control action have been met. The purpose of detector coverage assessment is to confirm that the selected detector layout complies with generally accepted industry performance targets if the system is correctly installed, operated and maintained.

The detector layout shall be analyzed to determine how effective the proposed detector layout detectors with the given voting logic will be in detecting an incipient hazard and initiating a specified safety action. This analysis may reveal the need to improve coverage and / or reduce nuisance trips die to hardware failures.

Applicable codes & Standards:

• • BSI BS EN 54 - Fire Detection and Fire Alarm Systems
• • BS 5839-1 - Fire detection and fire alarm systems for buildings Part 1 - Code of practice for design, installation, commissioning and maintenance of systems in non-domestic premises
• • ISA TR 84.00.07 - Guidance on the Evaluation of Fire, Combustible Gas, and Toxic Gas System Effectiveness