
The USCG has published a safety alert informing marine inspectors that ethylene vapors on LNG carriers can activate Carbon Monoxide alarms. Specifically, during an examination of a LNG carrier whose cargo tanks contained ethylene vapors, PSC Officers (PSCOs) received alarms on their portable four gas meters giving a reading of 60 to 100 parts per-million (PPM) Carbon Monoxide (CO).
A certified marine chemist traced the source of the vapors to an eight inch crack on a cargo vapor line. PSCOs initially thought the alarm was related to a combustion event and did not suspect the ethylene vapors were the source, because they did not get a Lower Explosive Limit (LEL) reading on their monitors.
The chemist indicated that the LEL most likely never alarmed because of high winds on deck. He further explained that the molecular weight of Ethylene (28 g/mol) was identical to the molecular weight of CO which accounted for the CO PPM readings. USCG personnel contacted the manufacturer who confirmed that Continue reading “Ethylene vapors activate carbon monoxide alarm says safety alert”