Coalescing filters consolidate water vapor present in compressed air by forcing the air stream through a microscopically porous medium. The pores of the medium are large enough for air to flow through but not water, therefore separating the two to a degree. However, coalescing filters are often highly fragile making the internal microscopic lattice of the device sensitive to contaminants. Due to this, coalescing filters are recommended for use in second-stage air filtration or in pairs for first-stage air filtration.
