Nitrogen Generator using Pressure Swing Adsorption
Pressure swing adsorption (PSA) is a technology used to separate a gas from a mixture of gases. Different gases have varying affinities for adsorbent materials called molecular seives, or zeolites. When one gas is attracted to the surface of such a material, the exiting gas is enriched with the remaining gas.
For example, if one passes air through a bed of zeolite under pressure, the oxygen is attracted more strongly to the material. Nitrogen, which has a lower affinity for the porous surface of the zeolite, passes through the bed. Two beds are required. When the first bed has adsorbed as much gas as possible, a solenoid switches to another bed of material. The previous bed vents the enriched oxygen mixture back into the air, regenerating the system, and allowing continuous production of nitrogen.
This brief tutorial will show you how to build your own. It will first go over the theory and then the construction. Each webpage goes over a different aspect of the device. This is an industry-grade device that you can build in your own garage and is a serious project. Having a PSA device enables you to have an endless supply of pure N2. You can use it to fill your tires, power tools, or even cool it to make liquid nitrogen. All of the supplies are easy to obtain.
Below is a picture of my PSA on a movable plateform. Shown are two tower beds connected with 316 1/4" stainless pipe. The input goes through two filters. Two valves control flow into and out of each tower bed. A controller,shown in the center, directs the valves. At the bottom, one can see the high pressure tubing joining to the rotometer.