Industrial Grade Nitrogen Purity Levels for Different Industry Uses

Due to its inert nature, gaseous nitrogen can be used in various purging, blanketing, and flushing operations. Depending on the process involved, different grades of nitrogen purity are needed to fulfill unique manufacturing needs.

This article discusses the categories of nitrogen gas for industrial use and their appropriateness for different manufacturing processes.

What Is Nitrogen Purity?

Nitrogen purity refers to the proportion of nitrogen gas present in a sample taken from its stream compared to impurities present. Nitrogen gas can be categorized as high purity or low purity depending on the ratio of pure gas to contaminants like oxygen, water vapor, carbon monoxide, and carbon dioxide.

This categorization based on nitrogen concentration plays a key role in determining the suitability of nitrogen for any industrial process.

High-Purity vs. Low-Purity Nitrogen

The purity of a sample of nitrogen gas is determined by the percentage/concentration of pure nitrogen in it. For gas to be classified as high purity, it must possess at least 99.998 percent nitrogen while lower purity nitrogen gas usually contains a higher proportion of impurities.

High-Purity Nitrogen Gas

Gaseous nitrogen with concentrations above 99.998% is considered a high-purity fraction. High nitrogen purity can be graded in different ways by different manufacturers; however, it is mostly considered to be a “zero-grade” fraction. Zero-grade nitrogen purity is categorized as such because it contains less than 0.5 parts per million of hydrocarbon impurities.

Other key characteristics of high-purity nitrogen gas are:

Oxygen concentration ≤ 0.5 parts per million
Carbon monoxide/carbon dioxide no more than 1.0 parts per million
Water not greater than 3 parts per million

Low-Purity Nitrogen Gas

Nitrogen gas ranging between 90 to just under 99.9% is considered to be low-purity. Common low-purity nitrogen gas brands include:

Zero
Pre-purified
Oxygen-free
Extra dry
Industrial

How to Check the Purity of Nitrogen Gas

Nitrogen gas manufacturers name their products differently; there are no standardized naming conventions. As a result, a low-purity gas from one producer might be mistaken for a high-purity gas by another based on its name alone. The only definitive way to determine a gas rating is to check the manufacturer’s guide on their unique gas concentrations.

Nitrogen Gas Purity Classification

Classifying pure nitrogen gas is done with the grading system using digits within each minimum purity rating. The first digit of each grade refers to the number of “nines” present in it while the second digit represents the number following the last nine. For example, grade N3.0 is equal to 99.9% nitrogen purity and is a pure grade gas purity classification (no second digit attachment).

Pure grade nitrogen classifications include N2.0, N3.0, N4.0, N5.0, N6.0, and N7.0.

What Is Ultra High Purity (UHP) Nitrogen Gas?

Ultra-high nitrogen purity levels refer to a nitrogen gas concentration of 99.999% with negligible impurities. UHP nitrogen specifications are strict with variations rendering the classification invalid.

The oxygen content of UHP gas can be no greater than 2 parts per million by volume (ppmv), total hydrocarbons cannot exceed 0.5 parts per million by volume, and moisture no greater than 1 part per million by volume). UHP nitrogen gas is typically used in scientific applications.

What Is Oxygen-Free Nitrogen (OFN)?

Oxygen-free nitrogen is defined as gaseous nitrogen containing no more than 0.5 parts per million of oxygen. OFN gas is typically maintained at 99.998% nitrogen purity. This grade of nitrogen gas is useful in scientific research and calibration processes where oxygen impurities might alter outcomes or cause incorrect results.

Nitrogen Purity Grades by Industry

As mentioned above, the concentration of nitrogen required in different industrial processes varies greatly. The key consideration in choosing a grade of nitrogen is the effect of impurities on the selected application. Sensitivity to moisture, oxygen, and other contaminants are critical factors to consider

Pharmaceutical-Grade Nitrogen

Pharmaceutical manufacturing processes require high nitrogen purity levels to prevent contamination and alteration of their final products. Many drugs require high-grade nitrogen with a purity between 97-99.99%. This high to ultra-high purity nitrogen is used for nitrogen blanketing storage tanks, receptacles, and other equipment used in drug manufacturing.

High-purity nitrogen is also used in drug packaging to help retain freshness and keep active ingredients from deteriorating.

O&G-Grade Nitrogen

Gaseous nitrogen with purity levels ranging from 95-99% is useful in the oil and gas industry to reduce the risk of fires and explosions in associated processes. Chemical storage tank inerting and pipeline purging with gaseous nitrogen help minimize the risk of sudden combustion of their contents.

Pipeline maintenance services frequently use pressurized nitrogen for pipeline cleaning and pipeline decommissioning processes.

Food-Grade Nitrogen/Beverage Grade Nitrogen

Nitrogen is commonly used in different steps of food/beverage production, packaging, and storage. Nitrogen in food packaging and processing is used to preserve the shelf life of processed food/drinks by eliminating food oxidants, preserving flavor, and preventing rancidity. Food-grade nitrogen gas requirements typically fall between 98-99.5% purity.

Industrial Nitrogen Grade Purity

Understanding the nitrogen grade requirements for each application is essential for selecting the appropriate nitrogen supply source and ensuring optimal performance and reliability. Some industrial applications and their nitrogen-grade requirements are outlined below.

Electronic & Semiconductor Manufacturing Grade Nitrogen – The typical nitrogen grade requirements in electronics and semiconductor production are usually at least 99.99-99.999%. Some processes, like parts cleaning and adhesive blanketing, utilize lower concentrations of nitrogen (95-99.5%).
Plastics Manufacturing Grade Nitrogen – Nitrogen grade requirements for plastics synthesis is 95-98% for injection molding processes, 99.5% for gas-assist injection molding, and 98-99.5% for blown film extrusion.
Metalworking Grade Nitrogen – Metalworking grade nitrogen varies widely from 95-99% for heat treatment to 99-99.999% for laser cutting processes.
Power Generation Grade Nitrogen – Power generation processes like gas seal purging, boiler layup, natural gas line purging, and demineralized water blanketing require nitrogen gas with purities between 95-99.6%.

NiGen’s Onsite Nitrogen Generators Cover Most Applications

At NiGen, we specialize in supplying and maintaining efficient onsite nitrogen generators tailored to meet the diverse needs of various industrial manufacturing processes. With our extensive range of products and services, we ensure that all nitrogen requirements are fulfilled at every stage of your production cycle.

9 May 2024