Can I Have Multiple Purity Levels on a Nitrogen Generator?


The Earth’s atmosphere contains approximately 80 percent nitrogen. Industries ranging from electronics to tire companies use nitrogen on a daily basis; for this reason, many industries create their own nitrogen on site with their own nitrogen generating systems. An on-site nitrogen generator is designed to pull nitrogen out of the atmosphere to provide companies with an unlimited supply of nitrogen so that nitrogen delivery is no longer needed.


Categorizing Nitrogen Grades and Purity Levels

While certain grades of nitrogen are common there is no standardization of nitrogen grades across industries or within a single industry in and of itself, which means the nitrogen manufacturer names the grades and categorizes them accordingly. For this reason, two products with identical purity specifications may be listed under different grade categories, but it is possible for two products with an equivalent grade to have purity specifications that don’t match. Selecting a nitrogen generating system should be based not only on its grade, but also on its purity specifications.

All of On Site Gas’ Nitrogen Generators Have Gas Analyzers

All nitrogen systems available at On Site Gas include gas analyzers: These analyzers ensure precise and current measurement of nitrogen that is being produced. Purity levels are measured in either parts per million (PPM) or percentages. The measurement utilized depends on the setup and requirements of the system being used.

Nitrogen Purity Grades

High-Purity Nitrogen

High-purity nitrogen grades consist of greater than 99.998 percent nitrogen. High purity nitrogen contains less than 20 PPM or less of oxygen and total hydrocarbons. Nitrogen also contains other impurities, including carbon dioxide, water and carbon monoxide. High-purity grades of nitrogen contain no more than, 1.0 PPM of carbon monoxide or 1.0 PMM of carbon dioxide.

Low-Purity Nitrogen

Low-purity nitrogen grades consist of 90 to 99.998 percent nitrogen. Contaminate percentages within these nitrogen grades vary substantially. On Site Gas Systems have lab tested many different purity levels so that we can help determine which purity best suites your particular contaminant requirements.

On Site Gas Offers Multiple Purity Levels on a Single Nitrogen Generator Systemnitrogen

Sometimes, a company needs multiple purity levels. Purchasing or renting a nitrogen generator system for each purity is not only expensive, but inefficient as well. On Site Gas offers nitrogen generator systems that have the ability to provide companies with multiple levels of purity.

Controlling Purities via On Site Gas’ Purity Exchange Valve (PFX)

On Site Gas provides companies the ability to generate three purities with just one system. This is possible via On Site’s purity exchange valve, as switching between purity levels is simple via the nitrogen generator’s touch screen control panel.

Reasons On Site Gas Generation is Superior to Liquid and Cylinder Gas

  • No concerns gas prices will increase
  • No waste, as is common with liquid installations
  • No need to move high pressure cylinders; thus, improving worksite safety
  • Lowest cost per m3
  • No contracts
  • No rental, or delivery fees

At On Site Gas Systems, our technicians have the knowledge, skill and experience to help you choose which system will provide the nitrogen purity levels and grade you need. Whether you need a PSA nitrogen generator or a membrane nitrogen generator with multiple purity levels, or just one purity level, On Site Gas has the innovative, reliable and economical nitrogen generating system to meet your needs. Contact us today to learn more.

PSA Nitrogen Generators vs Membrane Nitrogen Generators: The Differences

Nitrogen generators that are based on membrane and pressure swing adsorption (PSA) technologies are both capable of generating nitrogen gas and use compressed air as a means to feed their systems and produce nitrogen. But when deciding which technology will best serve your business, several issues need to be considered.

Pressure Swing Adsorption Generators

A PSA nitrogen generator uses a Carbon Molecular Sieve (CMS) to adsorb oxygen under high pressure while allowing the nitrogen to pass through for collection in a storage unit.

PSA Nitrogen Generator – The Process

With the majority of pressure swing adsorption nitrogen generators, two vessels are packed with carbon molecular sieves (CMS) to adsorb oxygen as compressed air moves through the vessel. As one vessel is adsorbing the second vessel is depressurized, and a small amount of nitrogen flows downward to release the oxygen collected during the adsorption process. The two vessels alternate between the adsorption and desorption processes. The entire process for a PSA generator takes approximately 60 seconds.

PSA Nitrogen Generator Systems

Purity Levels

PSA nitrogen generators can provide higher gas purities than can be accomplished with a membrane nitrogen generator. PSA generators manufactured by On Site Gas Systems offer the ability to achieve a set purity level between 95% and 99.9995%.


On Site Gas Systems PSA nitrogen generators have only a few moving parts and if properly maintained can last for many years. It is not uncommon for an On Site Gas Systems PSA nitrogen generators to maintain its performance for over twenty years.

Very Little Maintenance

An On Site Gas Systems PSA nitrogen generator requires very little maintenance. With clean, dry feed air most of the annual maintenance is simply changes filter cartages. Pellets that form the hub of the pressure swing adsorption gas filtering process (Zeolite or CMS) have an extensive lifespan and can last for at least for decades.


Pressure swing adsorption generators can provide the same high volume of nitrogen for the life of the generator

Membrane Nitrogen Generators

A membrane nitrogen generator uses a hollow porous fiber to separate the N2 molecules from the others (including O2).

Membrane Nitrogen Generators – The Process

Membrane generators use a porous hollow fibers of various diameters, lengths, efficiencies and materials. Pressure is used to separate the molecules from the stream of compressed air flowing in. This pressure process is referred to as selective permeation.
The fibers are run parallel to one another so as to provide the needed capacity. The semi-permeable fibers allow the faster gases to permeate the walls quickly, releasing back into the atmosphere. For the most part, these faster gases are comprised of carbon dioxide, oxygen, water vapor and hydrogen.

Membrane Nitrogen Generator

Simplistic in Design

With a membrane nitrogen generator, the separation process does not require moving parts. Membranes nitrogen generators offer several custom configurations and system mobility that other technologies do not offer.

Purity Levels

Membrane nitrogen generators manufactured by On Site Gas Systems offer the ability to achieve a set purity level between 95% and 99.9%.


On Site Gas Systems Membrane nitrogen generators have only a few if any moving parts and if properly maintained can last for many years. It is not uncommon for an On Site Gas Systems Membrane nitrogen generators to maintain its performance for many years.

Very Little Maintenance

An On Site Gas Systems Membrane nitrogen generator requires very little maintenance. With clean, dry feed air most of the annual maintenance is simply changing filter cartridges.

Compact and Quiet

These systems run quietly and usually take up a small footprint.
At On Site Gas Systems, our team of technicians has the experience and knowledge to help you choose a cost-effective nitrogen generating system. We offer both PSA and Membrane nitrogen generators so Contact us today to learn more about our innovative nitrogen generating systems.



At On Site Gas, the process of the Pressure Swing Adsorption (PSA) Technology is an extremely clean operation. The only ‘raw material’ is air. On-site generators allow for an uninterrupted supply of gas with a high purity output. This means that you can produce gas where and when you need it, and in the exact quantity and quality you need.Any business that uses more than one cylinder of nitrogen or oxygen a week should consider an on-site nitrogen or oxygen generator. On Site Gas Systems provides generators to businesses all over the world. These systems are not only more convenient than bulk delivery; they can pay for themselves in less than 12 to 15 months.

Custom-Designed, On-Site Oxygen Generators

On Site Gas System’s generators are custom-designed to meet the needs of each client. Generator sizes range from 2 SCFH to 75,000+ SCFH depending on the gas and purity requirement.

A Cost-Effective Solution

This ability to generate nitrogen or oxygen on-site offers businesses considerable savings because it eliminates the need to purchase bulk gas and have it delivered.

Convenience With Pressure Swing Adsorption (PSA) Technology

When one of On Site Gas System’s generators is connected to a business’ air supply (air compressor systems are available), the business has the ability to produce an unlimited supply of nitrogen or oxygen. This is possible through the use of Pressure Swing Adsorption Technology. The use of PSA provides businesses with the convenience of on-demand gas production, thus, essentially eliminating the wait times commonly associated with bulk delivery.

How Pressure Swing Adsorption Works

The air that surrounds us contains roughly 78 percent nitrogen, 21 percent oxygen and 0.9 percent argon (with the remaining balance consisting of other gases): pressure swing adsorption (PSA) technology is designed to separate the nitrogen or oxygen from the rest of the air. This process is possible due to Carbon Molecular Sieve (Nitrogen) or Zeolite (Oxygen). Carbon Molecular Sieve at high pressures, attracts (adsorbs) oxygen, while letting the nitrogen flow to the receiving tank. Zeolite performs the same function with oxygen molecules in our oxygen generators This is the key process behind the best nitrogen and oxygen generators.

The Process of Generation Via PSA

On Site Gas System’s nitrogen and oxygen generator systems consist of two beds: Each bed contains an adsorbing sieve material:

  1. As the high pressure air enters the first tank, it moves through the sieve, and the oxygen or nitrogen is adsorbed depending on the generator type and output gas required.
  2. The process gas is then channeled to a buffer or storage tank.
  3. Directly before the first bed is completely saturated, the feed air is redirected to move through to the second bed, where the same process occurs.
  4. Once that process is complete, the first oxygen or nitrogen generator bed is vented out to the atmosphere, allowing the waste gas to release from the sieve.
  5. Completing regeneration of the first bed requires purging it with a small amount of process gas.
  6. This entire process continues in the oxygen or nitrogen generator until the business’s demand for process gas is met.

The Life of the Carbon Molecular or Zeolite Sieve

Under typical operating conditions (i.e., clean, dry feed air supply), a Carbon Molecular or Zeolite sieve lasts indefinitely.

Productivity of a Pressure Swing Adsorption O2 Generator

The purity of the nitrogen or oxygen gas a business needs affects the productivity of a pressure swing adsorption (PSA). With a fairly small increase in the amount of feed air moving through the sieve, a Pressure Swing Adsorption Generator can produce substantially more process at 95 percent purity than it can at 99.9 percent+.

Reasons Businesses Choose On Site Gas Systems

For nearly 30 years, On Site Gas Systems has been providing businesses all over the world with convenient, cost-effective nitrogen and oxygen generators. ON SITE GAS SYSTEM is FDA, ISO 13485 and ISO 9001 certified, we also comply with ASME, GOST, CRN and PED (among others) to deliver custom-designed oxygen and nitrogen generators to meet even the most demanding engineering specifications.
Because of their durability, our nitrogen and oxygen generators are frequently utilized in the most remote locations and extreme environments. Whether you are in need of portable oxygen generators, a nitrogen filling station or an oxygen generating system, On Site Gas Systems can assist you in creating a gas system that meets your business’s specific needs. Contact us today to learn more.