F&G Detector Layout & Coverage – Comprehensive I&C Engineering Checklists for EPC Projects

F&G Detector Layout & Coverage — Final Self-Verification Checklist

Use this before the first formal review (internal/external). Align with Fire & Gas Philosophy, C&E Matrix, Alarm/Trip Schedule, Risk Assessments (HAZID/HAZOP/LOPA), Area Classification, and client standards.

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Header & Document Control

Document number/title per project standard; “F&G Detector Layout & Coverage” states unit/area/building and sheet numbers.
Revision purpose (IFR/IFA/IFC/IFD) correct; prepared/checked/approved names and dates completed; change log maintained.
References listed with numbers & revs (F&G Philosophy, C&E Matrix, Alarm/Trip Schedule, P&IDs, Plot Plans/GA, Ventilation/HVAC, Area Classification, Electrical/SLD, Equipment Layouts, Client Specs).

Scope & Basis of Design

Scope covers point gas, open-path gas (OPGD), flame (UV/IR/UVIR/Multi-IR), smoke/heat, beam/aspirating where applicable; portable docking/external systems excluded or clearly noted.
Design basis stated (client philosophy + applicable standards e.g., NFPA 72 / EN54 / IEC 60079 / IEC 61511 guidance); authority requirements captured.
Risk inputs identified: HAZID/HAZOP nodes, leak sources, dispersion/CFD results (if any), ventilation patterns, occupancy and evacuation strategy.

Hazardous Areas & Environment

Area classification zones/groups/temperature class shown; Ex protection type per device (Ex d/e/i/n, EPL) suitable; ingress protection and ambient rating fit location.
Environmental factors considered: wind/ventilation, gas buoyancy (light/heavy), heat sources, rain/sun/salt spray, vibration; sun/rain shields or housings specified where needed.

Detector Placement Rules

Point gas: heights align to target gas density and ventilation; proximity to leak sources respected; avoid dead air/obstructions; access for bump testing provided.
Open-path gas: transmitter/receiver line-of-sight clear; beam heights and lengths within vendor limits; multiple beams arranged to cover corridors/air intakes; misalignment tolerance considered.
Flame: fields of view (cones) modeled; no blind spots; background IR/UV sources assessed; distance to target hazards within vendor response range; tilt/aim documented.
Smoke/heat/beam: ceiling heights/stratification addressed; spacing per code; return air paths considered; beam reflectors accessible and aligned.

Coverage Analysis & Verification

Quantitative/graphical coverage performed (heat maps/LOS plots) for gas and flame; acceptance criteria per philosophy met; worst-case scenarios evaluated (wind, ventilation states, doors open/closed).
Obstruction analysis complete (equipment/steel/ducts); persistent blind spots identified and justified or mitigated (additional detectors/relocation).
Ventilation/building pressurization modes considered (normal/emergency/purge); air intakes/occupied rooms protected with appropriate detector types and setpoints.

Zoning, Voting & Cause/Effect

Zones defined and labeled consistently with C&E Matrix; detectors assigned to correct zones/areas; boundaries match layouts and logic drawings.
Voting logic documented (1ooN/2ooN, cross-zone, confirmatory technologies); degradation rules on fault (bypass/fail) noted per philosophy/SRS.
Outputs/initiators referenced (ESD/PSD, HVAC trips, deluge/pre-action, dampers/doors, sounders/beacons, cause/alarm priorities) with cross-refs to C&E clauses.

Setpoints, Priorities & Timing

Alarm and trip setpoints per philosophy and vendor guidance (LEL/ppm/O₂, flame thresholds, smoke/heat criteria); units consistent across drawings and schedules.
Delays, latching/reset policy, and mode-based suppression (maintenance/start-up) defined; auto re-enable rules captured; SOE/first-out requirements noted.

Mounting, Access & Mechanical

Mounting heights, brackets, posts, and vibration isolation detailed; maintenance reach and safe access provided (platforms/ladders), no conflicts with doors/egress or crane swings.
Weather protection (hoods, shades, heaters) specified where needed; beam/OPGD housings aligned and protected from vehicle impacts; reflective hazards addressed.

Cabling, Supervision & Interfaces

Wiring philosophy shown (supervised loops/EOL, addressable vs conventional, 4–20 mA/HART/relay); shield/armour bonding per standard; red/fire-rated cables where required.
Segregation/separation from power/VFD trays respected; penetrations via MCT with firestopping; JB/panel IDs and terminal numbers referenced to Termination Diagrams.
Hardwired outputs and system links identified (FGS ↔ ESD/DCS/HVAC/Deluge); loss-of-comms behavior defined; network nodes (if applicable) located with diversity paths.

Power, UPS & Fail-Safe

FGS PSU/UPS sizing includes detector loads, sounders/beacons, solenoids/relays; autonomy per philosophy/authority requirements; A/B supply paths defined.
Fail-safe arrangements (de-energize to trip where required) and relay monitoring shown; power distribution, fuses/CBs, and EPO/EMO interfaces indicated.

HMI, Annunciation & Evacuation

Graphics and alarm texts consistent with philosophy; zone/first-out indications visible in CCR and local panels; SOE timestamp source/resolution stated.
Sounder/beacon layout covers occupied areas; dB(A) at operator ear level and candela criteria achievable; evacuation routes and muster points considered.

Constructability & Coordination

3D model clash check complete (piping/steel/HVAC/electrical); detector FOV/LOS models align with as-modeled obstructions; vendor models used where available.
Construction access and testing methods defined (test gas ports, flame test clearances, beam alignment tools); temporary works/permits identified.

Testing, Commissioning & Lifecycle

Pre-commissioning/FAT/SAT plans reference each detector/zone; bump tests, calibration, flame tests, beam alignment checks, and SOE/first-out verification defined with acceptance criteria.
Maintenance strategy captured (calibration intervals, proof test coverage for SIF-related functions, spare detectors/heads, access equipment); bypass/inhibit rules with re-enable plan documented.

Data Integrity & Final Polish

Detector IDs, zone IDs, and coordinates consistent across layouts, C&E, Alarm/Trip Schedule, Instrument Index, and Termination Diagrams; no duplicates or orphans.
Legends, symbols, notes, and scales consistent; PDFs export with selectable text; print areas/page breaks set; hidden CAD filters cleared.
Revision history and transmittal list updated; confidentiality/footer correct; open items and assumptions listed with owners and due dates.

Quick Sign-Off

Preparer

Checker

Date

Use this checklist before issuing the F&G Detector Layout & Coverage drawings for first formal review.

Tagged Engineering Deliverable Check List

F&G Detector Layout & Coverage – Comprehensive I&C Engineering Checklists for EPC Projects

F&G Detector Layout & Coverage — Final Self-Verification Checklist

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