What Size Air Compressor Does a Nitrogen Generator Need?

A nitrogen generator needs a steady supply of compressed air, but there is no one compressor size that works for every system. The right air compressor for a nitrogen generator depends on how much nitrogen you need, required purity, and generator’s feed air requirements. Start with those numbers before choosing compressor horsepower.

Start with the Nitrogen You Need

First, determine the highest nitrogen flow your operation will use, not only its average use. Record the purity and pressure needed at the point of use. A system running continuously has different demands than one filling a vessel for a short period.

These requirements determine the generator you need. Its specifications then tell you how much compressed air the generator consumes to produce that nitrogen. The air going in will be greater than the nitrogen coming out because some air is separated and discharged during production.

Higher purity generally takes more feed air for the same nitrogen output. The amount also varies by generator design and operating pressure. This is why a general air-to-nitrogen ratio is a poor substitute for the selected unit’s data sheet.

How to Size an Air Compressor for a Nitrogen Generator

Find the generator’s feed air flow at your required nitrogen output and purity. It may be listed in SCFM or CFM. Check what the unit means and use the same flow basis when comparing it with the compressor’s rated delivery. A compressor’s horsepower alone does not tell you how much air it can supply.

Then check the required feed air pressure at the generator inlet. The compressor must deliver the specified flow at a discharge pressure high enough to account for losses through the air dryer, filters, piping, and valves. Check the compressor’s delivered flow at that pressure, not its flow rating at a different pressure. If the generator data sheet shows several purity settings, use the feed air requirement for the setting you will run.

Check the Rest of the Air System

The compressor is only part of the feed air supply. Nitrogen generators need air that meets their inlet requirements for moisture, oil, particles, and temperature. The required dryer and filters depend on the generator and compressor package. Poor air quality can reduce performance and damage components, so confirm the treatment equipment along with compressor capacity.

Also check these conditions before settling on a size:

• Other air users: If the compressor serves more than the nitrogen generator, include their demand when they run at the same time.
• Peak demand: Size around the production rate the system must meet, including any short periods of high nitrogen use.
• Site conditions: High ambient temperature or elevation can affect compressor output. Use its rated delivered flow under the conditions where it will operate.
• Storage and controls: An air receiver can help manage changes in demand, but it cannot make up for a compressor that is consistently too small.

A feed air compressor and a nitrogen booster also do different jobs. The feed air compressor supplies the generator. If the application needs nitrogen at a pressure above the generator’s output, a separate booster may be needed downstream.

Need a Generator and Compressor for an Upcoming Job?

NiGen supplies nitrogen generators and industrial air compressors for on-site systems, with rental equipment available for temporary projects. If you know the nitrogen flow and purity the job calls for, send us those numbers along with your site conditions. We can help put together an equipment package that meets the generator’s feed air requirements. Request a quote.