Secondary Filters & Membrane Air Dryers
Secondary filters are used for a variety of applications and can remove particles as small as 50 nanometres in size. These secondary filters can remove fumes, odors, vapor, mist, moisture, oil, and tiny particles from the air stream.
In addition, special "point-of-use" air drying devices (called membrane air dryers) may be used to depress the pressure dewpoint by selectively passing water vapor out of the compressed air stream as it passes through the inside hollows of a bundle of narrow, thinly-coated, membrane fibers. A small amount of "sweep air" must then be purged around the outside of the bundle of hollow fibers carrying the compressed air. Purge or "sweep" air is thus expanded (to atmospheric pressure) and subsequently vented to the atmosphere. The "dryer" purge air which is carried or swept along the outside of the hollow bundle of fibers creates a vapor pressure gradient between the "wet" compressed air on the inside the fibers and the "dryer" sweep air on the outside the bundle. This results in delivery of cleaner, dryer air before the compressed air is sent into any "moisture-sensitive" equipment(s).
Membrane air dryers, however, may be easily damaged through any contact with liquid droplets (water or oil) so they should be protected with a high-efficiency coalescing (nano) air filter, positioned either immediately upstream (or integrated within) the membrane air dryer housing. Membrane dryers are primarily used with equipments that are especially sensitive to water vapor such as paint booths, two-part mixing equipment (polyurethane sealants), polyurea dispensers, PUR-applicators (edge-banding equipment), laser-cutting machinery, CMM's, industrial ink-jet printers, or even for laboratory use.
Read more about this topic: Pneumatic Filter
Famous quotes containing the words secondary, filters and/or air:
“Scientific reason, with its strict conscience, its lack of prejudice, and its determination to question every result again the moment it might lead to the least intellectual advantage, does in an area of secondary interest what we ought to be doing with the basic questions of life.”
—Robert Musil (1880–1942)
“Raise a million filters and the rain will not be clean, until the longing for it be refined in deep confession. And still we hear, If only this nation had a soul, or, Let us change the way we trade, or, Let us be proud of our region.”
—Leonard Cohen (b. 1934)
“Soun is noght but air ybroken,
And every speche that is spoken,
Loud or privee, foul or fair,
In his substaunce is but air;
For as flaumbe is but lighted smoke,
Right so soun is air ybroke.”
—Geoffrey Chaucer (1340–1400)