Controlling your nitrogen purity made easy

One of the many advantages of producing your own nitrogen is that you can set the purity level to what your application requires. That is a major difference to purchased nitrogen, which is always of the highest purity – even though most jobs don't need it. So what affects nitrogen purity? And why does it matter?

The second question is easy to answer: High-purity nitrogen costs more because it consumes more energy. Therefore, you want to make sure that you get the purity just right for your application. This is especially true because increasing it beyond what is necessary yields no additional benefits.

In other words, using nitrogen with a purity of 99.99% for a job that calls for a purity of 99.5% wastes energy and money.

To answer the first question, we first have to look at how nitrogen gas is generated. 

Types of nitrogen generators

Two different technologies are used for the on-site production of nitrogen: pressure swing adsorption (PSA) and membrane. The key ingredient in each case is compressed air, which contains 78% nitrogen. In the generator, that nitrogen is separated from the rest of the air.

In a PSA generator, this happens through adsorption. The generator consists of two separate pressure vessels. One of them is used to filter out the nitrogen while the other is regenerating.

As the name indicates, a membrane generator contains a membrane filled with small, hollow polymer fibers. Not all gases, vapors and contaminants can pass through the membrane fiber wall with the same ease. This allows the nitrogen gas to be separated from the compressed air. This is called “permeation.”

A PSA generator allows you to produce a nitrogen with a purity of up to 99.999%. It also requires less compressed air. However, the intake air for the compressor has to be very clean and dry.

The purity a membrane generator can achieve is a bit lower. However, as noted above, most applications do not require the highest purity. One of the benefits of this technology is that the intake air can contain water vapor. 

Factors that impact your nitrogen purity

There are range of factors that could affect purity, some of which depend on the type of generator you use.

The amount of air that flows through the generator is the most important factor. If that intake air volume is too high, it will impact the nitrogen purity because the pressure in the generator rises too fast. That means that the separating technology of the generator can no longer keep up. As a rule of thumb, you want to keep you adsorption pressure between 0.6-0.8 Mpa.

An easy solution is to adjust the amount of air that comes from the compressor.

Another factor could be that the intake air contains too many contaminants. This could clog up the molecular sieve, which would have to be replaced. To prevent this from happening, you can install air treatment equipment such as filters.

However, at some point, the performance of the molecular sieve will diminish, so you should always follow a maintenance schedule.

PSA generators feature a piece of equipment called a solenoid valve. Its failure is most frequently responsible for a decline in nitrogen purity. When you notice that this purity drops, this is one of the first things you should check. 

Where does nitrogen purity matter most?

The purity of your nitrogen is especially important when the nitrogen gas comes into contact with an end product. It matters less if you are using it for fire suppression or inflating tires. On the other hand, the gas has to be very pure in the food industry or the pharmaceutical sector. For these and other industrial applications, you need high purity nitrogen.

Many applications are subject to standards that will define the required purity. For example, there are specific requirements for food grade nitrogen.

Ask the expert

As the expert in air treatment and gas generation, Ash Air knows all about nitrogen purity. If you have any question on how to achieve the right purity, contact us today. Our experts are happy to help.

View 2 Products

Oxygen Generators

Pneumatech gives oxygen to your business. With the PPOG series, Pneumatech offers an attractive replacement for traditional oxygen supply with very interesting returns on investment.

The PPOG1-120 series uses Pressure Swing Adsorption technology to extract oxygen from compressed air, resulting in oxygen purity levels up to 95%.

The PPOG 2-18 HE series is a true game changer in on-site oxygen generation. 30% more efficient than traditional oxygen generators, the PPOG HE gives you the oxygen volume, purity and reliability you need at a massively reduced cost and a smaller environmental footprint.

PSA Oxygen Generators
With the PPOG series, Pneumatech offers an attractive replacement for traditional oxygen supply with very interesting returns on investment.

View 2 Products

Nitrogen Generators

Discover the inner workings, versatile applications, and numerous benefits of an N2 generator. This revolutionary machine effectively separates nitrogen from compressed air, comprised of 78% N2 and 21% O2. A gas generator stands out as the easiest, most flexible, and economically viable method for securing your own nitrogen supply. Elevate your professional approach and embrace the efficiency and sustainability offered by on-site nitrogen generation, exclusively available in New Zealand.

Sub Categories

Membrane Nitrogen Gas Generators PSA Nitrogen Gas Generators High Pressure Nitrogen Skids


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Who we are and how Ash Air can help your business!

Ash Air has been around in New Zealand since 1979, and we’ve grown into a nationwide company with international support and a reputation for quality and reliability.We look after all things compressed air for your business!

  • Rotary Screw and Piston Air Compressors
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Ash Air's range of Chicago Pneumatic, ALUP, Pneumatech, and Atlas Copco products are used extensively around the world in industries ranging from oil and gas to food, automotive and farming, and we bring you these world-class compressors here in the land of the long white cloud.Our technicians are compressed air equipment experts and are dedicated to addressing customer needs. Supported with nationwide coverage, Ash Air offers one of the widest selections of compressed air, vacuum pump, and industrial gas equipment and parts available today in New Zealand.

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