Membrane drying uses the process of selective penetration of the gas components into the air.
The membrane dryer is a cylinder that houses thousands of small hollow polymer fibers with an inner coating. These fibers have selective permutation to remove water vapor.
When filtered, wet compressed air enters the cylinder, the membrane coating allows water vapor to penetrate the membrane wall and collect between the fibers. While the dry air continues through the fibers of the cylinder at almost the same pressure as the incoming wet air.
The permeated water is discharged into the atmosphere outside the cylinder. The penetration or separation is caused by the difference in the pressure between the inside and outside of the hollow fiber.