Replacement Cartridge Set for BEKO QWIK-PURE25Oil/Water Separator. Pre-filter(gal) Cartridge Capacity(gal) Weight(lbs) CARTRIDGE SET for QWIK-PURE25 - 1 x 1.2 1.8 Compressed air holds a lot of water vapor, and once that vaporbecomes cooled into a liquid (condensate) what's created is adirty, oily watery mixture that can't simply be sent down thedrain. Since the condensate is approximately 95% water and 5% oil,condensate management systems (oil/water separators) have beendeveloped to reduce or eliminate the amount of oil in thecondensate.