Methane being extremely flammable, the fire and gas detection (FGD) system in LNG facilities should be capable of early detection of flammable gas leading to shutdown/isolation and depressurization.
Usually catalytic combustion type gas sensors are used for detecting LNG vapors; however, for these combustion gas sensors to work the vapors within flammable range have to reach the gas sensor and by then the release may have already spread within the facility. Therefore, LNG facilities should consider Ultrasonic gas detectors – these detect hydrocarbon gas leaks by sensing the distinct high frequency acoustic ultrasound emitted by all high-pressure gas leaks.
While ultrasonic sensors provide early detection of leaks, they are unable to distinguish the ultrasonic activity generated from other spurious noise that is generated by mechanical equipment in close proximity.
To systematically devise a fire and gas detection system for a LNG facility, we recommend considering the following performance characteristics for the detection system:
- Area Covered
- Response time