Nitrogen generators are used to create anoxic conditions in sealed enclosures and envelopes. Common uses are for anoxic treatment of insect infestations, anoxic and hypoxic storage, and anoxic showcases.
All nitrogen generators use electrically powered compressors to force the air through a filtering system that removes oxygen and water, leaving almost pure nitrogen. Regardless of the filtering mechanism (see below), higher purity involves higher pressures and reduced flows. All compressors produce some heat and noise; most require regular maintenance. For larger installations, or installations where a great deal of nitrogen is used, they are well worth the expense.
Filtering the flow of compressed air may be accomplished by using a reverse osmosis filter. In this type of mechanism, the feed air is continuously passed through extremely fine capilliary tubing in a pressure resistant outer casing. Oxygen and moisture escape through the walls of the capilliaries into the outer casing, and are then exhausted to the atomsphere. The air remaining in the capilliaries contains little more than nitrogen, which is usually directed to a small storage tank before use.
The Pressure Swing Absorbtion method uses a pressure vessel filled with activated carbon. Pressurized air is introduced in the pressure vessel. Under pressure, the activated carbon holds oxygen and moisture within its pores, leaving only nitrogen gas free. Once an appropriate pressure has been reached in the pressure vessel, the pressure in the container is slowly reduced and the nitrogen is removed until pressures approach normal. Upon return to normal pressure, the activated carbon releases the oxygen and water, which is drained, and the cycle is repeated. This system is known by the acronym PSA. A system known as VPSA uses a vacuum to increase the filtering efficiency of the activated carbon.
Keepsafe Microclimate Systems works directly with manufacturers of nitrogen generators and can assist you in choosing, integrating, commissioning, and utilizing nitrogen generators. Please enquire.