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MINEARC TECH TOPIC: COMBATING CARBON MONOXIDE


How does Carbon Monoxide enter a sealed refuge chamber and why is it necessary to remove this gas? This MineARC Tech Topic explains how MineARC refuge chambers monitor and remove Carbon Monoxide from within occupied refuge chambers.

MineARC refuge chambers are equipped with three different technologies to monitor Carbon Monoxide levels and remove the harmful gas from within occupied refuge chambers to ensure a safe, breathable atmosphere is maintained.
 

 

CARBON MONOXIDE

Carbon Monoxide (CO) is a colourless, odourless, and tasteless gas that is slightly less dense than air. In the atmosphere, CO is produced from incomplete combustion and is present in exhaust gasses of vehicles and other engines, as well as from the combustion of most fuels. It is also produced in low quantities as part of normal metabolic processes.

If encountered in concentrations above 35ppm it is highly toxic to haemoglobic animals (including humans). The most common symptoms of CO poisoning include headaches, vomiting, dizziness, confusion, disorientation, visual disturbance, fainting, and seizures to name a few. CO poisoning is the most common type of fatal air poisoning. Once CO is inhaled, CO combines with haemoglobin to produce carboxyhaemoglobin, which becomes ineffective at delivering oxygen around the body. Oxygen levels are displaced in the blood causing vital organs to starve and therefore, causing people to suffocate and lose consciousness. CO poisoning is often irreversible as CO molecules will not detach from haemoglobin.

For more information on CO, please view the MineARC Tech Topic: Carbon Monoxide and Carbon Dioxide article.

 

GAS TOXICITY MONITOR

In the event of an emergency like a mine fire, CO can enter a refuge chamber when workers seeking refuge, open the sealed door and the outside atmosphere contains combusted fuels and exhaust gas particles. Or it can be drawn through the compressed (mine) airline if the compressor is near a fire, from the compression of smoke at the compressor. Or from the burning of plastic lines before rupture.

MineARC’s Compressed Air Management System (CAMS) provides clean breathable air to the refuge chamber through a superior four-stage filtration process.


CAMS is also equipped with a gas toxicity monitor which automatically diverts mine air if Oxygen (O2) levels in the airline fall below 19% oxygen in free air, signifying a compromise in the mine air quality and the presence of smoke, CO and Carbon Dioxide (CO2). The gas toxicity monitor activates a solenoid valve at the air intake which automatically shuts off compressed air. Once activated, the CAMS auto shut-off solenoid will remain closed for the remainder of entrapment ensuring no toxins can enter the chamber through the airline.

The gas toxicity monitor detects compressed smoke bursts, where O2 is displaced dramatically, rather than sampling low pressure air for slow release contaminants. Meanwhile, MineARC’s independent gas monitoring within the chamber will determine slow contaminant build up.

 

GAS MONITORING

Independent gas monitoring within the refuge chamber will determine slow Carbon Monoxide contaminant build up. Gas monitoring is an essential aspect of maintaining a life supporting atmosphere within an occupied refuge chamber. Closely monitoring gas levels in the chamber allows occupants to take corrective actions to maintaining a safe and habitable environment.

MineARC’s new Aura-FX Digital Gas Monitoring System is a proprietary fixed gas monitoring unit, designed specifically for use in MineARC Refuge Chambers to provide a more convenient solution to internal refuge gas monitoring. Aura-FX measures O2, CO and CO2 gas concentrations as standard and has the ability to individually monitor up to 11 gases if required. It also measures ambient temperature, internal pressure, and relative humidity. All measurements and trends are displayed on a series of user-friendly, digital screens. Audible voice alarms will prompt occupants to replace scrubbing chemicals or adjust oxygen supply levels in the refuge chamber as required.

The Aura-FX CO Monitor is an electrochemical gas sensor that measures the concentration of CO by oxidising it at an electrode and then measuring the resulting current. To reduce cross-sensitivity to other combustible gases, it has chemical filters for Hydrogen Sulfide (H2S), Nitrogen Dioxide (N02), Nitric Oxide (NO) and Sulfur Dioxide (SO2). The CO has an accuracy level of within just 4ppm within the reading, and a sensor range between 0 and 5,000ppm. MineARC recommends keeping CO levels in the refuge chamber below 30ppm.

When utilised as part of the MineARC System Intelligence network, Aura-FX provides real-time gas monitoring data and analysis of the overall internal environment of the refuge chamber via the GuardIAN dashboard.

 

CO CHEMICAL SCRUBBING

In a sealed and occupied refuge chamber during an emergency and in the event of compressed air failure or contamination, CO is expelled in low quantities as part of the normal metabolic process of humans. This quantity is higher in smokers and is compounded in the enclosed environment of a refuge chamber. It is therefore necessary to chemically scrub the air for CO.

Chemical scrubbing is the process of removing gases, such as CO and CO2, from the air using a catalytic process whereby exothermic chemical reactions change the composition of the gas to water (H2O) and heat as it passes through the system. Scrubbing Systems work in conjunction with active chemicals to ‘scrub’ the build-up of harmful CO and CO2 from the air inside the refuge chamber.


The MineARC ELVP/ELV Scrubbing System uses pre-packaged MARCISORB chemical absorber cartridges. MineARC’s MARCISORB CO2 and MARCISORB CO cartridges provide superior scrubbing capacity, efficiency, are easy to load, safe to handle and dispose of, and can store for long periods. Only one CO cartridge is required per portable refuge chamber.

The MARCISORB CO Cartridge is a highly active transition metal oxide catalyst, formulated for the oxidisation of contaminants such as CO. Air is passed through the MARCISORB CO Cartridge, converting carbon monoxide into CO2 and H2O. The carbon dioxide produced is then removed by MARCISORB CO2. The cartridges are also effective at removing other gases, such as ethylene oxide, hydrogen and ethane.

For more information on Scrubbing Systems, please view the MineARC Tech Topic: Scrubbing Systems article.

For further information regarding Carbon Monoxide, CAMS, Scrubbing Units and chemical cartridges, or Aura-FX, please email info@minearc.com.au to speak to a MineARC representative.