An Oxygen Refilling Unit using Liquid Oxygen is a medium scale enterprise that refills oxygen cylinders by converting liquid oxygen into gaseous form under controlled pressure. The process involves procurement and storage of liquid oxygen in cryogenic tanks, controlled vaporization, filling cylinders with precise measurements, pressure testing, quality checks, and delivery. Oxygen cylinders are essential for medical use in hospitals, clinics, and ambulances, as well as industrial applications such as welding, metal cutting, and chemical processes. The unit requires moderate to significant investment in equipment such as cryogenic storage tanks, vaporizer units, filling stations, pressure regulators, and safety monitoring systems, along with skilled and trained operators. With the increasing demand for medical oxygen due to healthcare needs and industrial oxygen for manufacturing processes, the market potential is substantial. By producing high quality, safe, and ISO certified oxygen cylinders, the unit can achieve consistent demand, repeat orders, and profitable operations, while also exploring opportunities in bulk supply to hospitals, clinics, and industries.