Canned Obsolescence: Why Nitrogen Generators Belong in Your Lab

Forget about renting nitrogen tanks — laboratory applications aren’t on the same level as buying helium for a kid’s birthday balloons. As far as the old-fashioned nitrogen delivery via tank and truck, why wait to have crucial laboratory supplies left on the cleanroom stoop like old milk bottles? Critical operations can’t wait for traffic. What happens when production stops because the gas supply has depleted, or when valuable experiments or products are ruined because of moisture exposure? How much time should personnel have to spend refilling each tank? And where in the space-starved facility should the bulky supplies wait for use? Terra’s Nitrogen Generator creates its own clean nitrogen for desiccators, glove boxes and vacuum chambers in-house, so control of the quantity and purity rests with the lab!

Nitrogen Generation 411

<span style="font-family:'docs-Calibri'">Nitrogen membrane requires no power or moving parts; a compressed air feed produces 99% pure nitrogen to eliminate reliance of canisters.</span>

Here’s how it works:

Ambient air consists of approximately 78% nitrogen and 21% oxygen, along with a spattering of other elements. The process of creating purified nitrogen starts with an air compressor, which sends pressurized, ambient air through the nitrogen generator’s set of coalescing pre-filters to remove particulates, oil and moisture. The pre-filters extend the life of the main filter: the nitrogen membrane module.

Nitrogen Membrane Module

The specialized module forces the air through semi-permeable membrane fibers, which separates the gases and compounds. Because nitrogen is a “slower” gas than oxygen (and carbon dioxide and water), it will not diffuse through the membrane in the time of exposure; oxygen’s greater solubility makes it more likely to permeate the membrane. The other air leaves the filter, and the nitrogen continues to a separate container. No chemicals, no hassle — just an occasional filter change and a simple system that functions based on the physical properties of ambient air, which creates up to 99.9% pure nitrogen — perfect for the majority of laboratory uses.

For even purer nitrogen, leave the pressure as-is, but slow the process down to allow time for more unwanted gases to pass through the filter. That way, even with the nitrogen membrane the nitrogen purity can reach 99.99%.

Pressure Swing Adsorption

Diagram explaining Pressure Swing Adsorption

Another type of nitrogen filtration, typically used in ultra-pure nitrogen applications, is pressure swing adsorption (PSA). The PSA system uses multiple cylinders that take turns bearing the pressure — the compressed air blows into one side, into a filter called a Carbon Molecular Sieve (CMS) that adsorbs almost all elements except N2, then switches to use the other side while the first one is blown clean with pure nitrogen to ready it for use to isolate more nitrogen. It seems like a far more convoluted method than the membrane — and it absolutely is — but if the task requires 99.999% pure nitrogen, that’s the way to go. The space required for PSA takes more than the nitrogen membrane module, so smaller cleanrooms and laboratories might favor the more economical method.

Cost Savings for On-Site Nitrogen Generation

The greatest cost of nitrogen generation after the up-front purchase of the generator itself is the continual energy of running the air compressor — though some facilities already run compressed air to operate other machinery. But even if they don’t, and purchasing a compressor seems daunting, rest assured that producing in-house nitrogen still has the best financial benefit. Over time the cost of the equipment becomes negligible compared to the never-ending cycle of tank deliveries, and if the lure of on-site nitrogen generation isn’t enough already, contact our representatives—they can help calculate the long-term cost to prove the juice is worth the squeeze.

Airflow Rates vs. Purity: The Tricky Part Made Simple

Learning how to control the generator system could give a potential buyer pause — nitrogen canisters have direct purity and easily adjusted airflow, which might seem convenient in the face of daunting calculations for generating pressure, airflow and purity. But the system requires the simple turn of a knob to operate, and the examples below clarify it.

Terra offers three sizes/capacities of Nitrogen Generator. The charts and diagram below show the operation of Terra’s Nitrogen Generators given 200 PSI and 113°F. The flow-rate ranges represent different purity levels; the higher the purity, the lower the flow rate.

If you want a certain purity of nitrogen, you have to adjust the rate of air flowing out of the nitrogen membrane module. The lower the outflow rate, the more time the module has to comb through the air and separate nitrogen from the other gases.

Inlet Air Feed vs Expected Nitrogen Output
Inlet / Outlet in SCFH flow for specified purity at 200PSI and 113°F
Product Purity95% Purity96% Purity97% Purity98% Purity99% Purity99.5% Purity99.9% Purity
Part # 2700-094655
Part # 2700-111274
Part # 2700-12110

The purer the nitrogen, the lower the outlet flow. If your application requires stronger outlet flow but the same purity, the inlet flow and pressure must also increase.

Here are the volumes (SCFH) for each model at a similar temperature and at different pressures:

Flow vs. Purity @ 50°C (122°F)
(Based on 77° ambient)
 Part # 2700-09
Flow in SCFH
Part #. 2700-11
Product Purity
Part # 2700-12
Product Purity
Product Purity99%98%97%95%99%98%97%95%99%98%97%95%
@ 150 psi6629311188171418125432546916222841
@ 135 psi5788151042150515822328541214192536
@ 125 psi522737943136514320225837412182232
@ 110 psi437620795115312017021831610151927
@ 100 psi38154269610121041481912779131724
@ 90 psi326465598871891271642388111421
High Capacity Nitrogen Generator

For a higher volume of nitrogen or a complete turnkey solution, choose 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 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.

The solution to clunky tanks, wasted time and late deliveries lies in the air around you. Forego the stress of an antiquated system, and tap into the biggest supply of nitrogen available with Terra’s Nitrogen Generator.