Liquid nitrogen generators help filter the air in the atmosphere — roughly 21% oxygen and 78% nitrogen — using either Membrane or Pressure Swing Adsorption technologies.
Then it transforms the gas into liquid by compressing and cooling nitrogen gas below its evaporation point of about − 196 °C [− 320 °F].
In this article, we explain why, at Rutherford & Titan, we only carry liquid nitrogen generators with Pressure Swing Adsorption (PSA).
Understanding Pressure Swing Adsorption (PSA) Generators
Pressure Swing Adsorption (PSA) Generators use compressed air to create a continuous nitrogen stream.
These generators have two towers filled with Carbon Molecular Sieves (CMS) that are moved by compressed air pumped into the bottom of the active tower.
Then the air passes through the CMS, which adsorbs trace gases, like oxygen, so that the nitrogen can continue moving through the tower. The active tower then vents all accumulated trace gases.
PSA Nitrogen Generators are more effective and are preferred for use when there is a purity requirement of at least 99.5%, resulting in an O2 of 0.5% or less.
Understanding Membrane Nitrogen Generators
Membrane nitrogen generators move compressed dry air through hollow membrane fibers to separate the nitrogen from the other gases.
Oxygen and water vapor are released into the atmosphere, while the nitrogen is redirected to a distribution system for application or storage.
Different membranes can help generate a varying range of nitrogen purity, from less than 90% to 99.9%.
While it is possible to have a high degree of nitrogen purity with these generators, it is typically used when the purity requirement is less than 99.5% with an oxygen level of 0.5% or greater.
Why We Favor PSA Generators
At Rutherford & Titan, we favor PSA generators because they guarantee smoother operations and better purity than their counterpart.
The production of liquid nitrogen using a membrane generator can easily be affected by several variables, including flow rate, membrane quantity, membrane size, and pressure.
In other terms, membranes are tubes that can be obstructed by particles and require extremely clean and dry air supply when compared to CBS.
Last, Carbon Molecular Sieves —used in PSA generator — is more effective at removing trace gases because it has narrower pores than the membranes.