Nitrogen, making up over 75% of the earth’s atmosphere, is our most common pure element. It can also be found in soil, bacteria and fossil fuels. Both plants and animals rely on nitrogen consumption (or its constituents) to maintain life; either in pure form, or when combined with other elements. Over the years, clever scientists and industrialists have found many practical uses for this colorless and odorless gas. Its inert nature makes it valuable for a wide range of applications, as well as safe to manage. The air around us is the most abundant source of nitrogen, and as necessity is the mother of invention, some of those same clever scientists developed ways to isolate and store it.


Membrane Isolation


Terra Universal’s Nitrogen Generators give users complete control of nitrogen production

One popular technique of separating nitrogen from oxygen, argon, carbon dioxide, neon, helium, krypton, hydrogen and xenon (in order of percent volume), and adulterants such as oil and particles, is by use of a membrane. This physical separation method relies on molecule size and membrane permeability. Add to that some variable pressure, and we get a predictable and reliable process for generation of 99.5%-pure nitrogen.

Terra Universal membrane generators produce nitrogen gas on an as-needed basis for a variety of applications. While membrane separation does not result in the ultra-high purity (99.99% and above) nitrogen required for some applications, its convenience and speed makes it the obvious choice for the majority of users. Having an on-site gas supply eliminates reliance on nitrogen storage tanks, which require regular refilling and, when they run low, can disrupt critical applications.

Terra offers three sizes/capacities of Nitrogen Generators. The flow-rate ranges represent different purity levels; the higher the purity, the lower the flow rate:

  • Part # 2700-12B: 20″W x 12″D x 35.5″H; flow range of 7.5 – 12.5 SCFH
  • Part # 2700-11B: 24″W x 12″D x 49.25″H; flow range of 49 – 75 SCFH
  • Part # 2700-09B: 18″W x 18″D x 81.25″H; flow range of 126 – 223 SCFH

Based on what your lab needs, select the appropriate size. How do you know what is required? Use these sample applications to help:

Terra's Nitrogen Generator flow-rates and associated purity levels

Terra’s Nitrogen Generator flow-rates and associated purity levels

Each is a standalone cabinet design that requires only a source of compressed air in order to provide a steady stream of purified nitrogen. One of the biggest benefits of membrane separation is the cost of operation, which is that of running the air compressor to feed the generator; the supply of air is never-ending and free! Membrane modules have no moving parts, making them long lasting and maintenance free. Because they rely on kinetics (force from the compressed air), there is no electrical power source for which to pay and maintain. Once the initial capital equipment is obtained, operating costs are minimal.

Hollow Fibers

Membrane module showing hollow fibers and compressed air flow

Membrane module showing hollow fibers and compressed air flow

Each separator module consists of a bundle of hollow membrane fibers. The porous membrane allows faster-flowing, smaller-molecule oxygen (and other gases) and moisture to permeate out, while “trapping” the slower, larger nitrogen so that it travels through the fiber, and into the storage tank. An outer case keeps the oxygen and moisture away from the hollow bore so that they can be drawn off. All the operator has to do is turn on the air compressor, and within a matter of a few minutes, the system will reach the necessary purity level. Once the level is achieved, the operator can simply open the feed valve to start streaming nitrogen into the process line.

Filters do need to be replaced on occasion, but the generators come with “coalescing” filters that trap and remove particulates, oils and organic contaminants from the feed air. They extend the life and efficiency of the main membrane. Terra nitrogen generators are also equipped with lighted low-pressure alarms that indicate a drop in inlet pressure; check for gas-line kinks or compressor malfunctions.

Terra Universal Nitrogen Generators offer whatever flow level is necessary for applications such as storage within desiccators, processes inside gloveboxes, backfill of vacuum chambers, and supply for ionizers or analytical equipment. Because the efficiency of the membrane is dependent upon pressure differentials, higher pressures enable greater levels of purification, albeit at a lower flow rate. Other variables such as humidity and temperature also affect purity and flow rate. Read more details here.

Terra's High-Capacity Nitrogen Generator

Terra’s High-Capacity Nitrogen Generator

High-Capacity Generator

Customers requiring a higher volume of nitrogen or a complete turnkey solution should consider Terra’s High Capacity Nitrogen Generator. With a 200-gallon compressed-air storage tank and a 60-gallon nitrogen holding tank, this generator can provide nitrogen as needed without the requirement for continuous operation. When continuous operation is required, the 50 HP rotary screw compressor provides up to 157 ACFM to the generator.

This model is designed for those installations that either lack a sufficient supply of compressed air on-site, or where using the built-in compressor would be more efficient than running high-pressure lines to the system.

Final Thoughts

Nitrogen’s use in labs, cleanrooms, packaging lines, manufacturing facilities, food processing plants and other locations prevent the majority of chemical and biological reactions. Food prepared in a nitrogen-rich atmosphere is less likely to spoil due to the lack of oxygen, for instance. Nitrogen is also used for fire safety as it prevents combustion, making it possible to work safely with flammable materials. Another example? Nitrogen is fed into pipelines to safely drive liquids through the passageways without causing chemical reactions. Generating nitrogen on-site is a convenient and budget-friendly way to meet the needs of almost any organization.

Read Terra’s Whitepaper for more insight into on-site nitrogen generation. Click to see more information about the products.

Reposted November 30, 2016