CO Monitoring with COSAMS
Carbon monoxide can be generated onboard a submarine during both routine and emergency operations, including cooking activities, diesel engine exhaust, chlorate candle use, and onboard fire incidents. In the confined environment of a submarine, accurate and continuous CO monitoring is critical to the safety of all personnel onboard. Without reliable monitoring, the consequences can be fatal.
Carbon Monoxide Sensor Unit
The GFC sensor targets the specific infrared wavelength associated with carbon monoxide. When CO is detected, the sensor triggers an alarm. Because the system is designed to identify a unique wavelength, cross-sensitivity from other gases or water vapor is eliminated.
Monitoring is performed continuously in real time using advanced GFC infrared sensing technology, providing constant protection against CO contamination. The COSAMS system is also designed to prevent false positives and nuisance alarms.
Carbon Monoxide Poisoning
In 2003, a Chinese submarine was discovered drifting in the Bohai Sea. It has been speculated that all 70 crew members died from carbon monoxide poisoning caused by diesel engine exhaust. This incident highlights the critical importance of reliable CO monitoring aboard submarines.
Modern submarine systems are highly advanced, creating an increasing need for accurate and continuous atmospheric monitoring throughout the vessel. Many conventional CO monitoring systems rely on electrochemical sensors. While effective in many applications, electrochemical sensors can be susceptible to cross-sensitivity from gases such as carbon dioxide and hydrogen.
Hydrogen is commonly present onboard submarines due to battery charging systems, creating a significant risk of false CO readings when using standard electrochemical sensors.
To address this challenge, particularly in diesel-powered submarines, the Analox engineering team developed COSAMS: the Carbon Monoxide Submarine Atmosphere Monitoring System. One of the most technically advanced systems offered by Analox, COSAMS is purpose-built to protect submariners through precise and reliable carbon monoxide monitoring.
Real-Time Monitoring
The COSAMS unit provides continuous real-time CO monitoring. Two units are typically installed onboard a submarine: one positioned forward in the accommodation area and another aft in the engine room.
Each COSAMS unit displays local CO concentration on a color LCD screen and transmits a corresponding 4-20 mA signal to the submarine’s Central Air Monitoring System. The user interface also allows sensor calibration and can provide local visual alarms when required.
Infrared Sensing
The submarine environment presents several challenges for conventional off-the-shelf CO sensors. Standard electrochemical cells are highly cross-sensitive to hydrogen, making them unsuitable for submarine applications where hydrogen is continuously produced during battery charging.
Many toxic gas electrochemical sensors are also sensitive to pressure changes. Combined with varying temperature and humidity conditions onboard, these environmental factors require a more advanced sensing solution.
Analox understands the challenges associated with infrared sensing across dynamic pressure ranges and compensates for these effects to ensure accurate performance. COSAMS uses an infrared sensor with gas filter correlation technology to minimize interference from surrounding gases.
Gas Sampling
The COSAMS unit consists of a single enclosure containing all sensors, pneumatic fittings, and display components. The user interface and display are located on the front panel, and the enclosure is designed for wall mounting using shock-proof mounts.
Gas samples are drawn directly from the surrounding submarine atmosphere using an internal sample pump. The sample is analyzed before being safely exhausted back into the environment.
The unit provides:
- Two adjustable audio and visual alarms
- 4–20 mA output
- Up to 90 days of continuous data logging
Maintenance and calibration are designed to be carried out onboard or during dockyard servicing.
