Fixed Gas Detection System CGS 50/500 and CGD 50/500

Common issues

• False alarms or slow drift caused by calibration/span gas exhaustion or IR cell contamination
• Condensation or salt deposits blocking sample line filters on sample-draw versions
• Loss of communication between detector head and central control/display unit
• IR source degradation over time reducing sensitivity near end of service life
• Sensor response drift outside class tolerance requiring more frequent recalibration than the nominal manufacturer's interval
• Cable gland or junction box corrosion in the cargo deck environment causing intermittent faults
• Water ingress into detector housings at exposed deck locations
• Wrong gas range/type setting after a software update, giving incorrect %LEL or vol% readings

Inspection checklist

• Verify calibration certificate is current and within the manufacturer's interval
• Function-test each detector head with span/test gas and confirm response time
• Check detector housings, cable glands and junction boxes for corrosion or water ingress
• Confirm alarm relay outputs and common alarm register correctly at bridge and cargo control room panels
• Inspect sample line filters and tubing on sample-draw versions for blockage or condensation
• Verify redundant power supply and battery backup on the central unit
• Check hazardous-area (Ex) certification plates and markings are intact and legible
• Cross-check detector zone allocation against the cargo tank and void space arrangement drawing
• Review the fault/event log for repeated self-diagnostic faults

Service intervals

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• IR detector head / sensor cartridge (order via Consilium with the system serial number - do not substitute a generic sensor)
• Sample line filters and tubing (sample-draw versions)
• Cable glands and junction box seals rated for the hazardous zone
• Calibration/span gas bottles for the target gas
• Central unit power supply or battery pack
• Detector housing gaskets and O-rings

Safety

• This detector is part of the primary gas hazard warning system for LNG/LPG cargo areas - never disable it without a documented, time-limited permit to work
• Working on live detector loops in a classified hazardous area requires hot-work / Ex-rated equipment procedures
• An undetected drifted or failed sensor gives false confidence and can mask a real gas release
• Calibration gas cylinders are pressurised - secure and vent per the SDS when testing

Class survey

Fixed gas detection for LNG/LPG cargo systems normally falls under Continuous Survey Machinery together with cargo containment survey requirements. Class checks calibration records, functional test results, and alarm setpoints against the approved detector arrangement plan. Missing or overdue calibration certificates are a common survey finding.