The short answer
Medical oxygen and industrial oxygen are the same chemical substance, often produced by the same process in the same plant. What differs is the regulatory framework: medical oxygen is manufactured, tested, documented and distributed as a pharmaceutical product under Indian Pharmacopoeia (IP), while industrial oxygen is manufactured to IS 309 as an industrial commodity.
They are not interchangeable in either direction, and the reasons are about assurance and traceability rather than about the gas itself.
The differences that matter
| Medical oxygen | Industrial oxygen | |
|---|---|---|
| Standard | Indian Pharmacopoeia (IP) | IS 309 (2005, 4th revision) |
| Regulatory status | A drug — falls under pharmaceutical licensing | An industrial commodity |
| Batch testing | Tested and released against a pharmacopoeial monograph | Tested to industrial specification |
| Traceability | Full batch records, retained samples, release documentation | Purity certificate against the standard |
| Cylinder fleet | Dedicated, controlled medical cylinders | General industrial cylinder pool |
| Cylinder identification | IS 3933 (medical gas identification) | IS 4379 — black body, no band |
| Filling premises | Licensed pharmaceutical-grade operation | Industrial filling station |
| Typical purity | To IP requirement | 99.5% and above |
Why you cannot use industrial oxygen for breathing
The objection is not that industrial oxygen is impure — a good industrial cylinder may well analyse as cleanly as a medical one. The objection is that nobody has verified it to the standard a patient depends on, and the cylinder itself has an unknown history.
An industrial cylinder circulates in a general pool. It may previously have held another gas, been used in a workshop, taken back-contamination from a poorly maintained regulator, or carried residue no one has assayed for. None of that is detected by a check that only measures oxygen percentage. Medical cylinders are kept in a dedicated fleet with controlled cleaning and filling precisely to eliminate that unknown.
There is also a legal dimension: supplying industrial oxygen for human respiration is a regulatory offence, not merely bad practice.
And why you should not use medical oxygen industrially
This direction is safe but wasteful and, in a shortage, harmful. Medical oxygen costs more because of the testing, documentation and controlled cylinder fleet behind it — none of which improves a cutting torch. Diverting medical cylinders into industrial use also removes them from the medical fleet, which is exactly the pressure that caused acute problems during oxygen shortages.
For flame cutting, industrial oxygen in the 99.5% range is what the process requires. Paying pharmaceutical overhead for it buys nothing.
What about oxygen from a PSA plant?
On-site PSA oxygen generation typically produces 93 – 95% purity. That is entirely suitable for flame cutting and most industrial duty, and is often the cheapest oxygen available at high steady consumption.
Medical PSA installations exist, particularly for hospital pipelines, but they are a different equipment specification with their own validation, continuous monitoring and alarm requirements. An industrial PSA plant cannot be repurposed to supply a hospital pipeline without addressing that whole framework.
And if your process specification calls for 99.5% or above, PSA at 93 – 95% will not meet it — a purity question, separate from the medical-industrial one.
How to specify correctly
- ✓For any clinical or human-breathing use, specify medical oxygen to IP — without exception
- ✓For cutting, welding, furnaces and process work, specify industrial oxygen to IS 309
- ✓Never transfer, decant or refill between medical and industrial cylinders
- ✓Keep the two cylinder fleets physically separated and clearly identified
- ✓Check the identification standard: medical follows IS 3933, industrial follows IS 4379
- ✓If a process needs above 99.5%, say so explicitly — that is a purity grade, not a medical grade