Nitrogen: What is it and where is it used?
21 April, 2022
Nitrogen is all around us. It is the biggest component of the air we breathe, but we don't use it. In this article we take a look at some of the many things it can be used for.
PSA nitrogen generator: how pressure swing adsorption works
A PSA nitrogen generator produces high-purity nitrogen on-site, while eliminating cylinder deliveries, reducing costs, and putting you in greater control of your supply. This guide walks you through how pressure swing adsorption works, how PSA compares to membrane technology, which industries rely on it, and what installation and operating costs to expect.
How PSA nitrogen generators work: the pressure swing adsorption process
Understanding the PSA nitrogen generator working principle starts with purity. Different applications require different nitrogen purity levels. Tire inflation and fire prevention typically need 90–99%, while food and beverage or plastic molding demand 97–99.999%. PSA technology reliably delivers across this full range.
The pressure swing adsorption working principle is based on one key property: oxygen molecules (3.46 Å) are slightly smaller than nitrogen molecules (3.64 Å). When compressed air passes through a carbon molecular sieve (CMS), oxygen enters the sieve's pores and is trapped, while nitrogen bypasses them and exits as the product gas.
The 4-phase PSA cycle
The process runs continuously across two CMS-filled pressure vessels (tower A and tower B) cycling through four phases:
- Adsorption: Clean, dry compressed air enters tower A. Oxygen is trapped in the CMS pores and nitrogen exits for use or storage. A small portion of that nitrogen flows into tower B.
- Pressure equalization: Pressure between the two towers equalizes, preparing for the phase switch and recovering energy.
- Regeneration: Tower B depressurizes, releasing trapped oxygen through the exhaust, carried out by the nitrogen flow from tower A. The CMS is restored for the next adsorption cycle.
- Switching: The towers swap roles. Tower B begins adsorption, while tower A regenerates.
This continuous cycle operates within technical parameters of 4–13 bar inlet pressure and 10–25°C, with the inlet air required to be clean and dry. Hence, a dryer between compressor and generator is essential.
Purity is controlled by adjusting the cycle timing. Longer adsorption phases yield higher flow but lower purity. On the other hand, shorter cycles prioritize purity over volume. The air factor (the ratio of compressed air consumed to nitrogen produced) is a key efficiency metric. A lower air factor means lower energy consumption and running costs.
How does PSA work?
See how a PSA nitrogen generator produces high-purity nitrogen on-site. Cutting delivery costs and giving you greater control of your N2 supply.
How carbon molecular sieves separate nitrogen from air
The carbon molecular sieve (CMS) is the core PSA adsorbent material that makes nitrogen separation possible. Its precisely engineered pores exploit a small but critical size difference: oxygen molecules measure 3.46 Å in diameter, slightly smaller than nitrogen molecules at 3.64 Å. This allows oxygen to enter and be trapped within the sieve's pores, while nitrogen passes through as the product gas.
Adsorption happens rapidly (oxygen fills the CMS pores within seconds) making fast cycle times and continuous nitrogen production achievable. A well-maintained CMS typically lasts 10 or more years, though performance depends on inlet air quality, operating pressure, and temperature consistency.
The CMS is particularly sensitive to moisture and oil contamination. Wet or dirty inlet air degrades adsorption capacity and shortens sieve lifespan significantly. Keeping inlet conditions within the specified range of 4–13 bar and 10–25°C, with properly filtered and dried compressed air, is essential to maintaining both purity output and long-term CMS performance.
First, tank A is in the adsorption phase while tank B regenerates. In the second stage both vessels equalize pressure to prepare for the switch. After the switch, tank A starts regenerating while tank B generates nitrogen.
PSA vs membrane nitrogen generators: which is right for you?
Choosing between a PSA and membrane nitrogen generator depends on your purity requirements, operating conditions, and total cost of ownership. The comparison below covers the key technical, economic, and operational factors to help you identify the right technology for your application.
| PSA | Membrane | |
| Purity | 95 to 99.999% (efficiently up to 99.999%) | 95 to 99.5% (efficiently up to 99.5%) |
| Efficiency | Higher | High |
| Performance vs. temp. | Lower at high temp. | Higher at high temp. |
| Setup complexity | Medium: requires dryer, filters, air receiver, nitrogen buffer | Low: compact, fewer components |
| Noise level | Medium | Very low |
| Water (vapour) sensitivity | ISO 8573-1 Class 4 | ISO 8573-1 Class 4 |
| Oil sensitivity | ISO 8573-1 Class 1 | ISO 8573-1 Class 1 |
| Typical ROI vs. cylinders or liquid | 6 months to 2 years | 6 months to 3 years |
PSA nitrogen generator applications and industrial uses
PSA nitrogen plants serve a wide range of industries where a reliable, high-purity nitrogen supply is critical to product quality, safety, or process integrity. Covering purities from 95% up to 99.999%, an industrial nitrogen generator eliminates dependence on delivered gas, giving facilities direct control over purity, flow, and cost.
Key applications include:
- Food and beverage: modified atmosphere packaging, beer brewing, and wine bottling to prevent oxidation and extend shelf life
- Electronics manufacturing: wave soldering, reflow ovens, and component storage to prevent oxidation during sensitive processes
- Pharmaceutical: API protection, tablet coating, and sterile environments to meet strict regulatory standards
- Metal processing: heat treatment, laser cutting, and welding depending on the application and material
- Chemical industry: blanketing, purging, and reaction environment control
- Oil and gas: pipeline maintenance, tank blanketing, and drilling operations
- Glass manufacturing and automotive: inert atmosphere applications
The versatility of PSA technology across variable flow rates and purity levels makes it the preferred nitrogen generator for demanding industrial environments.
Installation, maintenance and operating costs
PSA nitrogen generator installation requires a stable compressed air supply, electrical connection, adequate ventilation for blow-off exhaust, and sufficient floor space for the generator and associated components (compressor, dryer, filters, and air receiver). System sizing depends on your required nitrogen flow rate and target purity level. Higher purity demands more compressed air input and a larger system footprint.
Maintenance requirements are low compared to many industrial systems:
- Inlet filters: periodic replacement as part of routine servicing
- System checks: regular monitoring of pressure, temperature, and dew point sensors
- Oil filtration: coalescing and carbon filters require servicing when an oil lubricated compressor is used
A typical installation: Air compressor, dryer, filters, air receiver, nitrogen generator, nitrogen receiver. The nitrogen can be consumed directly from the generator or through an additional buffer tank (not shown).
From a PSA nitrogen generator cost perspective, the primary operating expense is electricity consumed by the air compressor. Compared to cylinder or liquid nitrogen delivery, on-site generation can in many cases achieve payback within approximately one to three years depending on consumption volume and local energy costs, after which nitrogen costs will be substantially lower. Total cost of ownership over a 10-year period is often lower than supply contracts for many medium-to-high consumption applications, assuming comparable operating conditions and pricing.
Get expert advice on PSA nitrogen generators
Our nitrogen specialists can help you determine the right PSA system capacity, purity levels, and configuration for your specific industrial application.
What purity levels can PSA nitrogen generators achieve?
PSA nitrogen generators achieve purities from 95% up to 99.999%, making them suitable for a wide range of applications. From general industrial use at lower purity levels through to pharmaceutical, electronics, and food and beverage processes that require the highest purity grades.
How much does a PSA nitrogen generator cost to operate?
The primary operating cost is electricity consumed by the air compressor. Compared to cylinder or liquid nitrogen delivery, on-site PSA generation typically achieves payback within 6 months to 3 years, after which running costs are significantly lower. Total cost of ownership over 10 years is consistently lower than third-party supply contracts for medium-to-high consumption applications, as well as small ones.
What maintenance is required for PSA nitrogen generators?
PSA nitrogen generator maintenance is straightforward: routine inlet filter replacements, regular monitoring of pressure, temperature, and dew point sensors.
How do you size a PSA nitrogen generation system for your application?
Sizing depends on two key parameters: your required nitrogen flow rate and your target purity level. Higher purity demands more compressed air input and a larger system footprint. Our nitrogen specialists can help assess your consumption requirements and recommend the right system capacity and configuration for your application.
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