How Liquid Nitrogen Is Made

Liquid nitrogen looks magical, but its production is a precise industrial process based on physics. Since 78% of the atmosphere is nitrogen, manufacturers simply start by taking in regular air.

Step 1: Cleaning the Air

The air is filtered to remove dust, moisture, and CO₂. Otherwise these components would freeze and clog the system.

Step 2: Compressing and Cooling

The clean air is compressed to high pressure, then cooled down. Compression heats the air, so heat exchangers bring it back to a low temperature.

Step 3: Deep Cooling — Joule–Thomson Effect

The compressed air is forced through a small valve. As it expands, it rapidly cools — this is the Joule–Thomson effect. Repeating this cycle brings the air to extremely low temperatures.

Step 4: Separating Nitrogen

At different boiling points:

• Nitrogen: –196°C (–321°F)

• Oxygen: –183°C (–297°F)

the gases separate inside tall cryogenic distillation columns, allowing manufacturers to isolate nearly pure nitrogen.

Step 5: Liquefaction

The nitrogen is cooled below –196°C until it becomes a liquid. It’s then stored in insulated Dewar tanks and delivered for scientific, industrial, medical, and educational use.