Nitrogen purity explained: how to select the right purity for each industry
For businesses that utilize nitrogen, understanding the nuances of nitrogen purity is not just a technical detail.
Nitrogen purity is a critical factor that can significantly impact operational efficiency, product quality and insure the safety of the process and its operators. While you may already be familiar with the basics of nitrogen production, choosing the optimal purity level for your specific application is key to unlocking the full benefits of on-site nitrogen generation.
As nitrogen solutions provider, our goal is to ensure you're not paying for purity you don't need or compromising your products with purity that's too low.
As nitrogen solutions provider, our goal is to ensure you're not paying for purity you don't need or compromising your products with purity that's too low.
The importance of purity levels
Nitrogen purity is typically expressed as the percentage of nitrogen in the gas, with the remainder being mostly oxygen and trace amounts of other gases. The required purity level is dictated by the sensitivity of your application to oxygen. For some processes, a small amount of oxygen is acceptable, while for others, even trace amounts can be detrimental.
Here's a breakdown of common nitrogen purity levels and their typical applications:
95% to 98% N2 purity
This purity range is often sufficient for applications where the primary goal is to displace oxygen to prevent oxidation or combustion of the end product.- tire inflation: Using nitrogen of this purity can help maintain tire pressure for longer periods and prevent oxidation of the rubber.
- fire prevention: In environments where there is a risk of fire, such as in coal mines or chemical plants, this purity level can be used to create an inert atmosphere.
99% to 99,99% N2 purity
At this level of nitrogen, the main goals are to extend shelf life of products in the food and beverage industry, where we want to maintain the end product quality: taste, colour, smell. This process can also be called Blanketing. The other application is to inert material in contact with dangerous gases or liquids (Inertization).
- modified atmosphere packaging: by reducing the contact with oxygen hence slowing oxidation and microbial growth, the end product's integrity is preserved (meat, pre-cooked food, cheese/butter or even pharmaceutical products).
- beverage dispensing: In the beverage industry, it is used maintain the flavor profile of beer, wine, milk, soft drinks (juice, mineral water, soda) or oils (olive, soybean, etc).
- controlled atmosphere storage (fruits and vegetables).
- inertization (Oil & Gas plants, natural gas purging, boiler layups, etc).
99.9% to 99.999% N2 purity
Higher purity levels are required for more sensitive applications where even small amounts of oxygen can have a negative impact on the product quality and directly threaten the process safety.
- laser cutting: In laser cutting, high-purity nitrogen is used as an assist gas to prevent oxidation and ensure a clean cut.
- electronics manufacturing: This purity is essential for creating an inert atmosphere during soldering and other manufacturing processes to prevent defects.
- gas-assisted injection molding (gaim): In this industry, nitrogen is used to safely displace raw material, helping to create clear channels and reduce defects.
- protective atmosphere in exlposive area (atex): as an inert gas, nitrogen is used to create a non-flammable atmosphere, especially for maintenance purpose.
99.999% and higher (UHP - Ultra High Purity)
The most demanding applications require ultra-high purity nitrogen to ensure the integrity of the final product.
- chemical industry: UHP nitrogen is used in various chemical processes to prevent unwanted reactions and ensure product purity.
- pharmaceuticals: In the pharmaceutical industry, it is used to create a sterile and inert environment for manufacturing and packaging.
The cost of "too pure"
In many technical and industrial applications, striving for the highest possible purity seems like a safe bet. However, when it comes to on-site nitrogen generation, this mindset can lead to significant and unnecessary expenses. The truth is, the relationship between nitrogen purity and the cost of production is not linear—it's exponential. Understanding this principle is key to optimizing your operational budget without compromising quality.
The primary cost associated with nitrogen generation is the energy required to run the air compressor that feeds the system.
This is because as the oxygen concentration decreases, it becomes harder to isolate and remove the remaining oxygen molecules. The system must work harder, process more air, or run longer cycles to capture those last few parts per million (PPM). This increased workload directly translates to a higher electricity bill.
Example: laser cutting - mild steel components
Application requirement: A metal fabrication shop uses nitrogen as an assist gas for laser cutting 5mm-thick mild steel plates. The nitrogen's role is to prevent oxidation on the cut edge, leaving a clean, paint-ready surface.
Sufficient purity: 99.95% nitrogen is the industry standard for this task. It provides a high-quality, oxide-free cut edge at high speeds.
The "too pure" scenario
The shop invests in a nitrogen generation system rated for 99.999% (often called Ultra High Purity or UHP), typically reserved for cutting exotic materials like titanium or very thick stainless steel.
The financial impact
Capital expense
A UHP nitrogen generator is significantly more complex and therefore more expensive upfront than a standard 99.95% system. The initial investment could be 40-60% higher.
Operational expense
The energy cost to produce 99.999% nitrogen can be over 30% higher than producing 99.95%. For a busy shop, this can mean an extra 2.000-5.000 EUR in annual electricity costs.
The result
The shop has spent more on the initial equipment and continues to pay a premium on its monthly utility bills, all for a cut quality on mild steel that is indistinguishable from one made with the more economical 99.95% purity gas.
How to determine the right purity
To determine the right nitrogen purity for your application, consider the following:
Application requirements
What is the maximum allowable oxygen content for your process?
Industry standards
Are there any industry-specific standards or regulations that dictate the required purity level?
Cost-benefit analysis
What is the trade-off between the cost of higher purity and the potential benefits of improved product quality or process efficiency?
Conclusion
Selecting the right nitrogen purity is a critical decision that can have a significant impact on your business. By carefully evaluating your application's requirements and consulting with experts in the field, you can ensure that you are using the most appropriate and cost-effective nitrogen purity for your needs. This will not only help you to optimize your processes and improve product quality but also to achieve significant savings in the long run.
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OMEGA AIR d.o.o. Ljubljana
Cesta Dolomitskega odreda 10
1000 Ljubljana
Slovenia
Cesta Dolomitskega odreda 10
1000 Ljubljana
Slovenia
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