A Compact Closed-Loop-Regenerative CO2 Removal for Extended SCBA Times

Self-contained breathing apparatus (SCBA) provides clean-breathing gas from a cylinder directly through a respirator allowing a user to remain safe in an atmosphere that is immediately dangerous to life or health (IDLH) due to the exposure of harmful/toxic gases. While SCBAs are extremely useful, the usage time is limited to the amount of compressed breathing air within the cylinder. Closed-Circuit SCBA/Rebreathers recycle the exhaled breath of the user to conserve the breathing gas by adsorbent CO2 using a disposable filter generally made of soda lime (adsorbent). However, this still limits most systems to 4-hours of usage as the filter needs to be replaced. Many human operated tasks require much longer hours within environments with immediately dangerous to life or health conditions. Regenerative adsorbents have been identified for CO2 uptake such as Metal organic frameworks or zeolites, while these sorbents have high uptake capacity, they also require a large amount of energy to remove the CO2 back into the atmosphere. These sorbents also have a highly chemically interaction with water vapor, increasing the overall size of the system beyond portable use. TDA has developed a carbon capture sorbent that consists of a high molecular weight linear polyethyleneimine (LPEI), solely composed of secondary amines. These sorbents have high uptake capacity at lower partial pressures of CO2 making them ideal for low CO2 concentrations similar to a person's exhaled breath. As a result, TDA has developed its next generation closed-loop rebreather for divers which can be used for extending SCBA usage times above sea-level as well. TDA proposes a compact regenerative rebreather to extend SCBA usage times beyond four hours of use while maintaining below 5000 ppm CO2 thresholds using low power for battery operation.