Oxygen recycling system designed by Indian Navy offers hope in the current oxygen crisis

Workers load oxygen cylinders in a vehicle at the Deen Dayal Upadhyay (RIPON) Hospital in Shimla on May 20.

India’s endeavour to provide adequate supplies of oxygen to its hundreds of thousands of COVID-19 patients has been given a much-needed boost. Lieutenant Commander Mayank Sharma, a naval officer at Indian Naval Ship (INS) Venduruthy who is presently posted at the Southern Naval Command’s famed Diving School, has conceptualised and designed an oxygen recycling system (ORS) that extends fourfold the life of medical oxygen cylinders.

The ORS is expected to substantially enhance the existing oxygen capacity in the country and alleviate the existing oxygen shortages. The Diving School itself has expertise in oxygen recycling since the same basic concept is used in some of the diving sets used by the school’s divers.

The first fully operational prototype of the ORS was produced on April 22. It underwent further in-house trials and design improvements, including at the hands of third-party ISO-certified firms. Thereafter, on the directives of the NITI Aayog, the system underwent detailed analysis and assessment by a team of specialists at Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Thiruvananthapuram. A few additional modifications were suggested by the team of specialists at SCTIMST, who found the concept and design of the ORS feasible. All components used in the ORS are indigenous and freely available in the country. On May 13, the Indian Navy filed an application to have the system patented.

The overall cost of the ORS prototype has been estimated at Rs.10,000, which should be viewed against the envisaged saving of Rs.3,000 a day because of the recycling of oxygen.

The ORS utilises the simple fact that only a small percentage of the oxygen that is inhaled by a patient is, in effect, absorbed by his or her lungs. The rest of the oxygen is exhaled into the atmosphere along with the carbon dioxide that the body produces. This exhaled oxygen can be reused, provided the exhaled carbon dioxide is removed.

To achieve this, the ORS adds a second pipe to the patient’s existing oxygen mask. This pipe sucks out the air exhaled by a patient using a low-pressure motor. Both the mask’s inlet pipe which supplies oxygen and the outlet pipe (for exhaled air) are fitted with non-return valves to always maintain a positive pressure and the unidirectional flow of gases to ensure the patient’s safety against dilution hypoxia.

The exhaled gases, mainly carbon dioxide and oxygen, are then fed into a bacterial viral filter and heat and moisture exchange filter (BVF-HME filter) to absorb any viral contaminants. After viral filtration, the gases pass through a high-grade carbon dioxide scrubber with a high efficiency particulate air (HEPA) filter, which absorbs carbon dioxide and other particulates, allowing enriched oxygen to pass through unaffected. The enriched oxygen from the scrubber is then pumped back into the inhalation pipe of the patient’s face mask, thereby increasing the flow rate of oxygen to the patient and reducing the use of oxygen from the cylinder.

The Diving School had in March demonstrated a miniaturised lab model of the ORS to Prime Minister Narendra Modi during the Combined Commanders Conference at Kevadia, Gujarat.