SNC initiative to address oxygen shortage

Diving School under SNC designs Oxygen Recycling System

The Diving School of the Southern Naval Command (SNC) conceptualised and designed an Oxygen Recycling System (ORS) to address the issue of Oxygen (O2) shortage.

The basic concept has been derived from diving sets used by naval divers.

ORS is designed to extend the life of the existing medical O2 cylinders two to four times exploiting the fact that only a small percentage of O2 inhaled by a patient is actually absorbed by the lungs, the rest being exhaled into the atmosphere along with carbon-dioxide (CO2) produced by the body. This exhaled O2 can be re-used, provided the exhaled CO2 is removed. To achieve this, the ORS has a second pipe to the patient’s existing O2 mask, which sucks out the air exhaled by a patient using a low-pressure motor. Both the mask inlet pipe (for O2) and the mask outlet pipe (for exhaled air) are fitted with non-return valves to maintain a positive pressure and unidirectional flow of gases at all times to ensure the patient’s safety against dilution hypoxia, according to a defence press release.

The system was designed by Lieutenant Commander Mayank Sharma of Diving School.

“The exhaled gases, mainly CO2 and O2, are then fed into a Bacterial Viral Filter and Heat and Moisture Exchanger Filter (BVF-HME filter) to absorb any viral contaminants. After viral filtration, the gases pass through a high-grade CO2 scrubber with a High Efficiency Particulate Air (HEPA) filter, which absorbs CO2 and other particulates, allowing enriched O2 to pass through unaffected. The enriched O2 from the scrubber is then pumped back into the inhalation pipe of the patient’s face mask, thereby increasing the flow rate of O2 to the patient, and reducing the use of O2 from the cylinder,” the release said.

The air flow in the ORS is maintained by a medical-grade pump fitted ahead of the CO2 scrubber, which ensures a positive flow, facilitating comfortable breathing by the patient. Digital flow meters monitor the flow rate of O2, and the ORS also incorporates inline O2 and CO2 sensors with automatic cut-offs, which stop the ORS in case O2 levels drop below the normal limits, or the CO2 percentage exceeds normal limits. However, this cut-off does not affect the normal in-flow of O2 from the cylinder, thereby allowing the patient to continue breathing easily, even if the ORS stops due to the cut-offs or for any other reason.

The first fully operational prototype of the ORS was produced on on April 22 and underwent a series of in-house trials and design improvements at the Southern Naval Command, with third-party observers from ISO certified firms. The system also received initial evaluation certificate from the specialsists at Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST) at Thiruvananthapuram. The system will now undergo clinical trials.

The overall cost of the ORS prototype has been capped at ₹10,000 against an envisaged saving of ₹3,000 per day due to the recycling of O2. It can also be used to extend the life of O2 cylinders used by mountaineers/ soldiers at High Altitude, for HADR operations and onboard naval ships and submarines.

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