Oxygen: Characteristics
Why one litre of liquid becomes 860 of gas
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.What matters commercially is purity, whether the product is gas or liquid, and delivery pressure. Steel and gasification take 95-99.5% oxygen by pipeline; hospitals need pharmacopoeia grade; electronics need ultra-high purity. Liquid oxygen boils at -183 C and expands about 860 times to gas, which sets storage and tanker economics.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Purity | industrial 99.5%; medical at least 99.5% (cryogenic) or 93% (PSA, where pharmacopoeias allow) | sets suitable uses and route | European and Indian Pharmacopoeia (indicative) |
| Boiling point | -183 C | liquid storage needs vacuum-insulated tanks | physical data |
| Expansion ratio | about 860 litres of gas per litre of liquid | liquid is the efficient way to move large volumes | physical data (indicative) |
| Density of gas | 1.429 kg per Nm3 | converts Nm3 prices to tonnes | physical data |
Commercial grades
- Tonnage gaseous oxygen 95-99.5% (steel, gasification)
- Industrial liquid oxygen 99.5%
- Medical oxygen (IP/EP/USP)
- Ultra-high purity 99.999% for semiconductors
- Oxygen 93% from PSA for hospitals