How a nitrogen generator works

Nitrogen generator function: the primary function of a nitrogen generator is to provide a continuous, reliable, and on-demand source of nitrogen tailored to the required purity level. This makes it essential for industries where oxidation must be controlled or prevented, such as:

• Electronics manufacturing: preventing corrosion of circuit boards.
• Food and beverage industry: extending shelf life by reducing oxygen exposure.
• Automotive and tyre inflation: improving stability and safety.
• Chemical processing: providing an inert atmosphere to prevent unwanted reactions.

By generating nitrogen in-house, businesses gain more independence and flexibility, while avoiding regular deliveries and handling of high-pressure gas cylinders.

A nitrogen generator works by separating nitrogen molecules from oxygen and other gases in compressed air, producing a controlled stream of nitrogen gas. This process is known as nitrogen gas production and can be achieved through different nitrogen production methods.

To generate nitrogen from air, the generator first receives a flow of clean, dry compressed air. Inside the unit, a separation technology isolates nitrogen molecules, while oxygen, carbon dioxide, and water vapour are removed. The result is a purified nitrogen output that can be used immediately or stored for later use.

Two main technologies are used in modern nitrogen generation systems:

1. Membrane nitrogen generators – compact units that separate gases using semipermeable fibres.

2. Pressure Swing Adsorption (PSA) nitrogen generators – systems that use carbon molecular sieves to achieve very high nitrogen purity.

The choice between these depends on the required nitrogen quality and application. For example, inflating tyres or fire suppression may only require 90–99% purity, where a membrane unit is sufficient. In contrast, industries such as food packaging or plastics often need purities up to 99.999%, which can only be achieved with PSA technology.

A nitrogen generation system is the complete installation required to produce, store, and distribute nitrogen on-site. While the generator is the central component, several other elements work together to ensure stable operation and gas quality.

A standard nitrogen production plant consists of:

1. Air compressor: supplies the compressed air.
2. Dryer: removes moisture from the air.
3. Filters: capture oil vapour and solid particles.
4. Air receiver: stabilises pressure and flow.
5. Nitrogen generator: separates nitrogen from oxygen and trace gases.
6. Nitrogen receiver: stores produced nitrogen for peak demand.

Nitrogen can either be consumed directly from the generator outlet or buffered in a storage tank for continuous supply.

Adsorption is the process in which atoms, ions or molecules from a substance (compressed air in this case) adhere to a surface of an adsorbent.

A PSA generator isolates nitrogen, and the other gases in the compressed air stream (oxygen, CO₂ and water vapour) are adsorbed, leaving behind essentially pure nitrogen.

PSA traps oxygen from the compressed air stream when molecules bind themselves to a carbon molecular sieve. This happens in two separate pressure vessels (tower A and tower B), each filled with a carbon molecular sieve, that switch between a separation process and a regeneration process.

Clean and dry compressed air enters tower A. Since oxygen molecules are smaller than nitrogen molecules, they pass through the pores of the sieve. Nitrogen molecules cannot fit through the pores, so they bypass the sieve resulting in nitrogen of desired purity. This phase is called the adsorption or separation phase. Most of the nitrogen produced in tower A exits the system, ready for direct use or storage.

Next, a small portion of the generated nitrogen is flowed into tower B in the opposite direction. This flow pushes out the oxygen that was captured in the previous adsorption phase of tower B. By releasing the pressure in tower B, the carbon molecular sieves lose their ability to hold the oxygen molecules, which detach from the sieves and get carried away by the small nitrogen flow coming from tower A. This ‘cleaning’ process makes room for new oxygen molecules to attach to the sieves in a next adsorption phase.

PSA technology enables continuous, high-capacity nitrogen flow in demanding applications at purity levels up to 99.999%. PSA generators have a higher initial investment cost than membrane generators, but they offer the advantages of higher flow and higher purity levels that some industries and applications demand.

PSA units deliver ultra-high purity but are more complex, while membrane systems are simpler and more robust. In both cases, nitrogen generator maintenance is essential for consistent performance.

Membrane systems typically require less service, as they have no moving parts and fewer sensitive components - this makes them well-suited for environments where downtime must be avoided.

PSA systems require more attention to intake air quality, filters, and adsorption media, but when paired with a structured nitrogen generator maintenance schedule, they deliver the highest levels of purity and performance for demanding applications.

Nitrogen is widely applied in industry because it is inert, odourless, and prevents oxidation. An on-site generator supplies nitrogen at the right purity and flow, reducing reliance on bottled deliveries while ensuring a stable gas supply.

Key applications include:

• Chemical processing: nitrogen is used to create inert conditions that prevent explosions or unwanted reactions. A nitrogen generator in the chemical industry allows operators to maintain safety while reducing gas procurement costs.
• Food and beverage production: controlled atmospheres help extend shelf life and preserve flavour. In packaging lines, a nitrogen generator for the food industry flushes oxygen from packets, while in a beverage factory, nitrogen protects liquids during bottling and storage.
• Automotive sector: nitrogen-filled tyres maintain pressure for longer and reduce oxidation of the rubber. Using a nitrogen generator for tires ensures a reliable supply for service centres and fleet operators.

In short, when asking "What is a nitrogen generator used for?", the answer covers a wide spectrum, from laboratories and plastics to aquaculture and pharmaceuticals, anywhere an oxygen-free or low-oxygen environment is required.

Producing nitrogen in-house gives companies direct control over output, purity, and pressure. Beyond flexibility, there are significant operational and financial advantages compared to relying on external suppliers.

Key benefits include:

• Cost stability: independence from market price fluctuations for bottled or bulk nitrogen.
• Lower logistics costs: no transport fees, delivery scheduling, or return handling of cylinders.
• Safety improvements: eliminates the risks of storing and handling high-pressure bottles.
• No waste: avoids boil-off losses from liquid tanks and unused residual gas in cylinders.
• Reliability: continuous supply available around the clock, reducing risk of production downtime.
• Long-term savings: while the equipment requires upfront investment, operating costs are significantly lower over time.

These factors make on-site nitrogen generation not only a technical solution but also a way to improve safety, efficiency, and cost management in daily operations. Read more about the benefits of onsite nitrogen generation.

Every application has different needs when it comes to nitrogen flow, purity, and operating conditions. The right system ensures efficiency, safety, and long-term cost savings. For some industries, a compact membrane generator may be sufficient, while others require the ultra-high purity delivered by PSA technology.

Because the choice depends on both technical and economic factors, it is often best to review requirements with a specialist who can match the system to the process.

Ask an air system professional about the best solution for generating nitrogen in-house.