A nitrogen generator works by separating nitrogen molecules from the oxygen molecules in compressed air. Atmospheric air is compressed by an air compressor and passed through a hollow fibre membrane, filtering out parts of air, mostly oxygen and collecting extremely pure nitrogen gas. 

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Holtec Gas Systems use two different types of Nitrogen Generation: Pressure Swing Absorption(PSA) as well as Membrane Application. 

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        In a Pressure Swing Absorption nitrogen generator, compressed air is drawn from the atmosphere and directed into one absorbing mechanism. Under pressure, oxygen in the compressed air gets "stuck" in the pores of the carbon-molecular sieve (CMS), allowing the remaining constituents (mostly nitrogen) to pass through the system unhindered.